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rspa_1906_0036

0950-1207

On methods whereby the radiation of electric waves may be mainly confined to certain directions, and whereby the receptivity of a receiver may be restricted to electric waves emanating from certain directions.

413

421

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

G. Marconi, LL. D., D. Sc.|Dr. J. A. Fleming, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0036

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0036

10.1098/rspa.1906.0036

Electricity

Meteorology

Electricity

On Directed Emission and Reception of Electric Waves . 413 The composition of the " heavy hydrocarbons " is somewhat uncertain . One hundred volumes of gas require 576 volumes of air for complete combustion . One hundred volumes of gas burnt in 900 of air give about 133 volumes of steam , 57 of C02 ) and 780 of inert gases ; assuming that there is no dissociation . On Methods whereby the Radiation of Electric Waves may be mainly confined to Certain Directions , and whereby the Receptivity of a Receiver may be Restricted to Electric Waves Emanating from Certain Directions . By G. Marconi , LL. D. , D.Sc . ( Communicated by Dr. J. A. Fleming , F.R.S. Received March 15 , \#151 ; Read March 22 , 1906 . ) This Note relates to results observed when for the usual vertical antenna employed as radiator or absorber in wireless telegraph stations there is substituted a straight horizontal conductor placed at a comparatively small distance above the surface of the ground or water . When an insulated horizontal wire , AB , such as is shown in sketch 1 , is connected at one end to a sphere of a spark gap , the other sphere of which EARTH FIG. ! is earthed , and sparks are caused to pass between the spheres , it will be noticed on investigating the space around such an oscillator that the radiations emitted reach a maximum in the vertical plane of the horizontal wrire , AB , and proceed principally from the end , A , which is connected to the spark gap , wThilst the radiation is nil , or reaches a minimum , in directions which are approximately 100 ' from the direction in which the maximum effect occurs . I have also noticed that any horizontal conductor ot sufficient length 414 Dr. G. Marconi . On Directed Emission [ Mar. 15 , placed upon or at a short distance above the surface of the ground , and connected at one end through a suitable detector to earth , will receive with maximum efficiency only when the transmitter is situated in the vertical plane of the said horizontal receiving conductor , and in such a direction that the end connected to the detector and to the ground is pointing towards the transmitting station . If , therefore , such a horizontal conductor be swivelled about its earthed end in a horizontal plane , the bearing or direction of any transmitting station within range of the receiver can be ascertained . I have carried out a number of tests with transmitters and receivers having radiating or receiving antennae or conductors arranged as follows:\#151 ; ( 1 ) Transmitting conductors consisting of horizontal wires , the radiations being received at a distance by means of the usual vertical wires suitably attuned . ( 2 ) Both transmitting and receiving conductors consisting of horizontal wires . ( 3 ) Transmitting conductors consisting of one or more vertical wires with or without capacity areas at top , such as have been generally employed in wireless telegraphy , the radiations being received by means of horizontal conductors . At long distances I almost invariably used as a detector my magnetic receiver.* At shorter distances I utilised a Duddell thermogalvanometer , f by means of which it was possible to measure the root-mean-square values of the currents induced by the oscillations in receiving wires disposed in various positions relative to the transmitting conductors . With arrangements such as are referred to in ( 1 ) , the following tests have been carried out:\#151 ; 1 . Transmitter.\#151 ; Horizontal wire 100 metres in length , direct excitation , spark length 2 cm . , wave-length approximately 500 metres . Receiver.\#151 ; A vertical wire 8 metres in length , tuned to the period of the transmitter by means of a syntonising coil , and connected to a magnetic detector and to earth in the usual manner . Results.\#151 ; Signals quite distinct at 16 kiloms . in the vertical plane of the horizontal transmitting wire and in the direction of its earthed end ; weak at 10 kiloms . in the same vertical plane , but in the reverse direction ; inaudible at 6 kiloms . at right angles to the directions above mentioned . 2 . Transmitter.\#151 ; ( At Mullion , Cornwall ) ; consisting of horizontal conductor 150 metres in length , composed of four parallel wires about 3 mm. in * See ' Roy . Soc. Proc. , ' London , 1902 , vol. TO , p. 341 . t ' Phil. Mag. , ' 1904 , vol. 8 , p. 91 . 1906 . ] and Reception of E diameter , placed 1'50 metres apart , supported at a height of 20 metres , and all connected to earth through the spark gap of an induction coil placed in a building on the ground ; spark length about 2 cm . Receiver.\#151 ; At the Haven , Poole ( distance , 240 kiloms . ) ; consisting of vertical wire 50 metres long , connected through a syntonising coil to a magnetic detector and to earth . Results.\#151 ; A movement of 15 ' of the plane of the transmitting conductor out of the right direction was sufficient to cause signals to become indefectible at Poole . Polar diagram 1 ) ( fig. 2 ) gives the values of the received current in microamperes , with conditions as marked under the diagram . The values of current in micro-amperes shown in each diagram are the mean of a considerable number of readings , the transmitted energy being kept as nearly as possible constant by means of a suitable interrupter applied to the sending induction coil . _ .250 iransmi+tind \#151 ; * 190* ISO Curve showing observed Cument in micro _ ^ a+ear+ head end of Receiving Conductor under Receiving -Hie conditions oi Direction shown below Iransrni-f-hng ConductorHonjontel.ro'tettng from 0*fo 3\lt ; oO* I 5 metres above ground Receiving Conductor:-Vertical , -fixed height ' 18 metres I A-iW -r/ Tansm i tfing Conductor - 6o melre 5 C\#187 ; ^(.Receiving Conducrtor \#166 ; 18 metres Distance of Transmission - 26 o metres Fig. 2 . With the arrangement mentioned at ( 2 ) i.e. , both transmitting and receiving conductors horizontal , the following results , among others , were obtained :\#151 ; 1 . Transmitter.\#151 ; Conductor 200 metres in length , supported at a height of 15 metres above ground ; spark length about 2 cm . Receiver.\#151 ; Similar conductor supported 1 metre above ground , connected at one end to a detector and to earth as usual . 416 Dr. G. Marconi . On Directed Emission [ Mar. 15 , Results.\#151 ; In the direction for maximum effect ( as already explained ) readable signals at 25 kiloms . At about 90 ' from said direction at 12 kiloms . , nothing ; in the same direction at 5 kiloms . , weak signals . 2 . Transmitter.\#151 ; Consisting of four wires each 330 metres in length , separated from one another by a distance of 1*4 metres , supported at a height of 20 metres above ground and connected by means of a nearly vertical conductor to a spark producer ; spark length , 3 cm . Receiver.\#151 ; Consisting of one wire 220 metres in length , covered with insulating material , placed on the ground and connected to the end nearest the sending station through a syntonising coil to a magnetic receiver and to earth . Results.\#151 ; When in the vertical plane of the transmitting antennae , and in the best direction , weak but distinct signals were received at a distance of 160 kiloms . ; at 45 ' from said direction and at 150 kiloms . distance nothing was received ; at 25 ' from the best direction , and at 160 kiloms . distance , very weak signals were received . The results over shorter distances are given by the readings obtained on the thermogalvanometer , and are shown in the polar diagrams E and B. Transmitting T Curve showing observed Currentm micro-amberes j at earthed end of Receiving Conductor under Receiving conditions of Direction shown below.*2 1 ? an\#187 ; mitfin\#163 ; Conductor Horizontal , revolving -from 0#to36O* I SO metres above ground Receiving Conductor : Horizontal fixed 1 50 metres above ground . . f transmitting Conductor . 60 metres en$ '7 ^Receiving Conductor *\#166 ; Go metres Distance of Transmission-26o metres Fig. 3 . With arrangements such as are mentioned at ( 3 ) , \i.e . , the transmitting conductor consisting of the usual vertical type and the receiving conductor horizontal , the following results among others merit attention :\#151 ; . 1906 . ] and Reception of Electric Waves . deceiving Transmitting ConductorHorizontal fixed I 50 metres -from ground . Receiving ConductorHorizontal rotating Worn 0Qto S6o\#174 ; I 50 me+res from the ground Lcn th of f'fran9rT1 , ttino Conductor . So metres * ' \Receivmg Conductor 30 metres Distance of Transmission *EZS metres Fig. 4 . At Clifden , Connemara , Ireland , by means of a horizontal conductor 230 metres in length , laid on the ground and connected at one end to a magnetic receiver and to earth , it is possible to receive with clearness and distinctness all the signals transmitted from the Poldhu station ( situated 500 kiloms . distant ) provided that the free end of the said conductor points directly away from the direction of Poldhu . No signals can be received if the horizontal wire at Clifden makes an angle of more than 35 ' with the line of direction of Poldhu . The signals from the Admiralty station at Seilly can be received at Mullion , Cornwall ( distance about 85 kiloms . ) by means of a horizontal wire 50 metres in length , 2 metres above ground , provided said wire is placed in a radial position with respect to the sending station and with its free end pointing away from it . But it is unreceptive if placed so as to make an angle of more than 20 ' with the line of direction of the station at Scilly . Some tests have also been carried out for the Admiralty in the vicinity of Poldhu in conjunction with H.M.S. " Furious/ ' For this purpose eight horizontal wires 60 metres in length , supported at a height of about 2 metres , were arranged radially and made to converge in a small building situated in a field near Poldhu . These radial wires were so arranged as to divide the circle into eight equal sectors . By means of a suitable switch any one of the ends of these wires at the position where they converged together could be connected to earth through a magnetic receiver . Dr. G. Marconi . On Directed Emission [ Mar. 15 , The wireless telegraph station on H.M.S. " Furious " consisted of an ordinary vertical wire aerial about 50 metres in length , connected to a suitable spark gap . The station on the ship transmitted at intervals , and the ship followed a course describing an arc of about 180 ' round Poldhu , keeping at distances varying up to 16 miles . By means of the horizontal wire arrangement , the bearing of the ship from Poldhu could be determined at any time by noting on which particular wire or wires the reception of signals was strongest , and also by observing which wires were non-receptive . It was also found possible to receive simultaneously and without mutual interference different signals sent by means of oscillations of the same wave-length , coming from the ship and from the Lizard wireless station ( 10 kiloms . away ) whenever the ship was in such a position that its bearing from Poldhu made an angle of at least 50 ' with the bearing of the Lizard For further values and curves of received current in receivers , I refer to station . Diagrams A , A ' , C , C ' . A Wf , U0'L \#163 ; 70* Irvarumiftin^ 2S\lt ; * r Receiving okear-Haed end of Receiving Conduc-far under -Hie . condi-kion* of Direc-toon shown below Transmitting Conductt\gt ; r-Vettt\amp ; al , -fiAed hei^M " 44 metres Receiving Gonduc't'br - Horizontal , rofahng from Fig. 5 . 1906 . ] and Reception of E Waves . Transmifhng Receiving Curve showing observed Current in micro **mjoeres al-ear-Wied end of Receiving Conductor , under the conditions of Oirection shown below Transrnit'fing Conductor \#166 ; \#166 ; -Vertical , -fixed . hetghf ' AA metres Receiving Conductor:- Honjonfal.rerfahn^ -from o* to 3"\gt ; o* on ground . , , , . / 'fransmiH'ing Conductor *45mehes 't v. Receiving Conductor - SOmetres Dis+ance of Transmission - 680 metres Fig. 6 . Transmilling Receiving Curve showing Current in micro amperes at esrthed end of Receiving Conductor under the ? conditions of Direction shown below -Iran snuffing ConductorFtoldhu Stefron Aerial consisting of multiple vertical conductors with large capacity atfhe tbp Receiving Conductor:- Horizontal rotating from 0*fo 3eo* 150 metres above ground I Art* j ^ansn'1'^ , n\#163 ; Conductor Of y Receiving Conductor So metres Distance of Transmission 650 metres Fig. 7 VOL. LXXVII.\#151 ; A. Dr. G. Marconi . On Directed Emission [ Mar. 15 , Tran6millto\amp ; ' Receiving \lt ; *\gt ; * i8\lt ; f '7\#171 ; * Curve showing observed Curnenhn micro-ano*\gt ; tf res at earthed end ot Receiving Conductor under the conditions of Direction shewn below Transmitting Conductor-.-Potdhu Station Aerial consisting of multiple vertical conductors with large capacity at the top Receiving Conductor --Horizontal .rotating from 0 ' to 360 " on ground , Lenoth of I *^ranarn , MnS Conductor \ ' \ Receiving Conductor - So metres Distance of Tran3mission 650 metres Fig. 8 . Referring generally to the results mentioned in this Note , I have observed that , in order that the effects should be well marked , it is necessary that the length of the horizontal conductors should be great in proportion to their height above the ground , and that the wave-lengths employed should be considerable\#151 ; a condition which renders it difficult to carry out such experiments within the walls of a laboratory . I have found the results to be well marked for wave-lengths of 150 metres and over , but have not been able to obtain as well-defined results when employing much shorter waves\#151 ; the effects following some law which I have not yet had time to investigate . There also appears to be a decided advantage in so far as effects at long distances are concerned in utilising a directly excited radiating conductor\#151 ; that is , an insulated conductor in which the high frequency oscillations are started by means of a suitable spark discharging it to earth or to another body , as was usual in my early forms of Hertzian-wave wireless telegraph transmitters . If inductive excitation is employed , that is , if the oscillations are induced in the radiating conductor from another oscillating circuit , the comparative results in various directions appear to be in the same proportions as those noticed when using the method of simple excitation , but the distances over which the effects can be detected are much smaller at parity of the power employed at the transmitter . 1906 . ] and Reception of Electric Waves . 1 have noticed that the most advantageous length of the receiving horizontal wires , in order to obtain results at maximum distances , is about one-fifth of the length of the transmitted wave , if said wires are placed at a distance above the ground ; but the receiving wires should be shorter if placed on the ground . It would be instructive to investigate more thoroughly the difference of the results and curves obtained by means of horizontal wires placed at different heights above ground , and also the effect of varying the length of said wires . When using horizontal receiving wires arranged as described in this Note , I have often noticed that the natural electrical perturbations of the atmosphere or stray electric waves , which are generally prevalent during the summer , appear to proceed from certain definite directions which vary from time to time . Thus , on certain days , the receiving instruments when connected to wires which are oriented in such a way as to possess a maximum receptivity for electric waves coming from the south , will give strong indications of the presence of these natural electric waves , whilst on differently oriented wires the effects are at the same time weaker or imperceptible . On other days these natural electric waves may apparently come from other directions . It would be exceedingly interesting to investigate whether there exists any relation between the direction of origin of these waves and the known bearing or direction of distant terrestrial or celestial storms from whence these stray electric waves most probably originate . A considerable number of observations would be necessary to determine whether there exists any relation between the bearing of storm centres and the direction of origin of these natural electric waves . I propose to carry out some further investigations on the subject . I ought to explain that the experiments described in this Note were carried out during a period of many months , and that as other results achieved over greater distances coincide generally with those here described , I have not thought it necessary to make special reference to them . I should also mention that the tests over short distances were carried out over practically flat country , whilst those over considerable distances took place over hilly country , such as the West of England , and in some cases partly across sea and partly across land . VOL. lxxvii.\#151 ; A.

rspa_1906_0037

0950-1207

On the figure and stability of a liquid satellite.

422

425

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir George Howard Darwin, K. C. B., F. R. S.

abstract

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0037

en

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0037

10.1098/rspa.1906.0037

Fluid Dynamics

Astronomy

Fluid Dynamics

422 On the Figure and Stability of a Liquid Satellite . By Sir George Howard Darwin , K.C.B. , F.R.S. ( Beceived January 17 , \#151 ; Read February 8 , 1906 . ) ( Abstract . ) More than half a century ago Edouard Roche wrote his celebrated paper on the form which a liquid satellite will assume when revolving , without relative motion , about a solid planet.* As far as I know , his laborious computations have never been repeated , and their verification and extension form a portion of the work contained in the present paper . Two problems involving almost identical analysis , but very distinct principles , are here treated simultaneously . If we imagine two detached masses of liquid to revolve about one another in a circular orbit without relative motion , the determination of the shapes of each of them is common to both the problems ; it is in the conditions of their secular stability , according to the suppositions made , that the division occurs . The friction of the tides raised in each mass by the attraction of the other is one cause of instability . If now the larger of the two masses were rigid , whilst still possessing the same shape as though liquid , the only tides subject to friction would be those in the smaller body . It amounts to exactly the same whether we consider the larger mass to be rigid or whether we consider it to be liquid , and agree to disregard the instability which might arise from the tidal friction of the tides generated in it by the smaller body . Accordingly I describe secular stability in the case just considered as " partial/ ' whilst complete secular stability will involve the tidal friction in each mass . The determination of the figure and partial stability of a liquid satellite is the problem of Roche . It is true that he virtually considered the larger body or planet to be a rigid sphere , but in this abstract the distinction introduced by the fact that I treat the planet as ellipsoidal may be passed over . It appears that , as we cause the two masses to approach one another , the partial stability of Roche 's satellite first ceases to exist through the deformation of its shape , and certain considerations are adduced which show that the most interesting field of research is comprised in the cases where the satellite ranges from infinite smallness relatively to the planet to equality thereto . The limiting partial stability of a liquid satellite is determined by considering the angular momentum of the system , exclusive of the rotational momentum of the planet . This corresponds to the exclusion of the tidal * 4 Mem. Acad. Sci. de Montpellier/ vol. 1 , 1847\#151 ; 50 , p. 243 . On the Figure and Stability of a Liquid Satellite . 423 friction of the tides raised in the planet . For any such given angular momentum there are two solutions , if there is any . When these two solutions coalesce for minimum angular momentum , we have found a figure of bifurcation ; for any other larger angular momentum one of the solutions belongs to an unstable series and the other to a stable series of figures . Thus , by determining the figure of minimum partial angular momentum , we find the figure of limiting partial stability . The only solution for which Roche gave a numerical result was that in which the satellite is infinitesimal relatively to the planet . He found that the nearest possible infinitesimal satellite ( which is also in this case the 'satellite of limiting partial stability ) has a radius vector equal to 2*44 radii of its spherical planet . He showed the satellite to have an ellipsoidal figure , and stated that its axes were proportional to the numbers 1000 , 496 , 469 . In the paper the problem is solved by more accurate methods than those used by Roche , and it is proved that the radius vector is 2*4553 , and that the axes of the ellipsoid are proportional to 10,000 , 5114 , 4827 . The closeness with which his numbers agree with these shows that he must have used his graphical constructions with great care . For satellites of finite mass the satellite is no longer ellipsoidal , and it becomes necessary to consider the deformation by various inequalities , which may be expressed by means of ellipsoidal harmonic functions The general effect for Roche 's satellites of finite mass in limiting partial stability is that the ellipsoidal form is very nearly correct over most of the periphery of the satellite , but at the extremity facing the planet there is a tendency to push forth a protrusion towards the planet . In the stable series of figures up to limiting stability this protrusion is of no great magnitude , but in the unstable series it would become strongly marked . When the unstable figure becomes much elongated , we find that it finally overlaps the planet , but before this takes place the approximation has become very imperfect . Turning now to the case of complete secular stability , where the tidal friction in each mass is taken into account , we find that for an infinitely small satellite limiting stability occurs when the two masses are infinitely far apart . It is clear that this must be the case , because a rotating liquid planet will continue to repel its satellite so long as it has any rotational momentum to transfer to orbital momentum through the intervention of tidal friction . Thus an infinitesimal satellite will be repelled to infinity before it reaches the configuration of secular stability . As the mass of the satellite increases , the radius vector of limiting stability decreases with great rapidity , and for two equal masses , each constrainedly spherical , the configuration is reached when the radius vector is 2*19 times the radius of either body . Sir G. H. Darwin . On the [ Jan. 17 , When we pass to the case where each liquid mass is a figure of equilibrium , the radius vector for limiting stability is still infinite for the infinitely small satellite , and diminishes rapidly for increasing mass of the satellite . When the two masses are equal the radius vector of limiting stability is 2*638 times the radius of a sphere whose mass is equal to the sum of the masses of the two bodies . This radius vector is considerably greater than that found in the case of tire two spheres , for the 2*19 radii of either sphere , when expressed in the same unit , is only 1*74 . Thus the deformations of the two masses forbid them to approach with stability so near as when they were constrainedly spherical . In all these cases of true secular stability , instability supervenes through tidal friction , and not , as in the case of Roche 's problem , through the deformation of figure . When Poincare announced that there was a figure of equilibrium of a single mass of liquid shaped something like a pear , he also conjectured that the constriction between the stalk and the middle of the pear would become developed until it was a thin neck ; and yet further that the neck might break and the two masses become detached . The present revision of Roche 's work was undertaken in the hope that it would throw some light on the pear-shaped figure in the advanced stage of development . As a preliminary to greater exactness , the equilibrium is investigated of two masses of liquid each constrainedly spherical , joined by a weightless pipe . Through such a pipe liquid can pass from one mass to the other , and it will continue to do so until , for given radius vector , the masses of the two spheres bear some definite ratio to one another . In other words , two spherical masses of given ratio can be started to revolve about one another in a circular orbit , without relative motion , at such a distance that liquid will not pass through a pipe from one to the other . The condition for equilibrium is found to be expressible in the form of a cubic equation in the radius vector , with coefficients which are functions of the ratio of the masses . Only one of the three roots of the cubic has a physical meaning , and in all cases the two masses are found to be very close together ; but the system can never possess secular stability . When the masses are no longer constrainedly spherical the equation of condition for equilibrium , when junction is effected by a weightless pipe , becomes very complicated and can only be expressed approximately . It appears that in all cases , even of Roche 's ellipsoids in limiting stability , the masses are much too far apart to admit of junction by a pipe ; but when we consider the unstable series of much elongated ellipsoids , it seems that such junction is possible , although the approximation is too imperfect 1906 . ] Figure and Stability of a Liquid Satellite . 425 to enable us to draw the figure with any approach to accuracy . If two ellipsoids are unstable when moving detached from one another , junction by a pipe cannot possibly make them stable . This then points to the conclusion that the pear-shaped figure is unstable when so far developed as to be better described as two bulbs joined by a thin neck . Mr. Jeans has considered the equilibrium and stability of infinite rotating cylinders of liquid.* This is the two-dimensional analogue of the three-dimensional problem . He found solutions perfectly analogous to Maclaurin 's and Jacobi 's ellipsoids and to the pear-shaped figure , and he was able to follow the development of the cylinder of pear-shaped section * until the neck joining the two parts had become quite thin . The analysis , besides , points to the rupture of the neck , although the method fails to afford the actual shapes and dimensions in this last stage of development . He is able to prove conclusively that the cylinder of pear-shaped section is stable , and it is important to note that he finds no evidence of any break in the stability up to the division of the cylinder into two parts . The stability of Maclaurin 's and of the shorter Jacobian ellipsoids is well established , and I imagined that I had proved that the pear-shaped figure with incipient furrowing was also stable . But M. Liapounofff now states that he is able to prove the pear-shaped figure to be unstable from the beginning . For the present at least I still think it is stable , and this belief receives powerful support from Mr. Jeans ' researches . But there is another difficulty raised by the present paper . I had fully expected to obtain an approximation to a stable figure consisting of two bulbs joined by a thin neck , but although the present work indicates the existence of such a figure , it seems conclusive against its stability . If then Mr. Jeans is right in believing in the stable transition from the cylinder of pear-shaped section to two detached cylinders , and if I am now correct , the two problems must part company at some undetermined stage . M. Liapounoff will no doubt contend that it is at the beginning of the pearshaped series of figures , but for the present I should dissent from that view . One question remains : If the present conclusions are right , do they entirely destroy the applicability of this group of ideas to the explanation of the birth of satellites or of double stars ? I think not , for we see how a tendency to fission arises , and it is not impossible that a period of turbulence may naturally supervene in the process of separation . Finally , as Mr. Jeans points out , heterogeneity introduces new and important differences in the conditions . * 4 Phil. Trans. , ' A , vol. 200 , pp. 67\#151 ; 104 . t 4 Acad. Imp . des Sci. de St. P6tersbourg , ' vol. 17 , No. 3 , 1905 .

rspa_1906_0038

0950-1207

On the coefficient of viscous traction and its relation to that of viscosity.

426

440

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Fred. T. Trouton, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0038

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0038

10.1098/rspa.1906.0038

Measurement

Tables

Measurement

]\gt ; th of Viscous Traction its Relation to Viscosity . By . T. Received Read February experiments are macle on he viscous flow of pitch and other nces of similar character , in form of rods or cylinders , by the torsional method , is that the rate of turning lmder torsion of these rods is not strictly proportional to couple . Thus the rate of flow of the material under stress cannot be in simple proportion to stress . If it is wished to exact the rate of flow with shearing forces , by means of the torsional lncthod , a complication is at once nlct with , alisin/ from5 the fact that the of flow in a rod is not of the same value evcryw]lere , but necessarily varies from nothing at the centre to a maximum at the surface of the rod . lVith the view of , a nlorsuitftble way of the phenoJnenon , trials were made with different of observing the flow of bodies , un . conditions in which the said ection does not apply . The results obtained in these ways exbibit the same departures from linearity as was ested by the results obtained by the method of torsion . types of flow examined were : ( 1 ) the flow produced in a rod or cylinder of material when under traction ; ( 2 ) when under axial con the flow of a freely descending strean of the material ; ( 4 ) the rate of bending of rod beam of material under its own weight when supported only at the ends . The latter method , however , from the defect as the torsional method , namely , from an value a range from zero ) to a certain or bars of the material under tion were suspended from one end , while to other vcights were attached . The rod was thus subjected to a force which continuously drew it out . The rate of elongation per netre length of rod could then be determined . The rods { 0 these ) by the method described in the already referled to . For the purpose of the actional forces the rod was thickened { each end worked into all cubicaJ , as shown in , so as to fit a metallic ) or receptacle open to one vol. On th Coefficient of Viscous , etc. side , Oy )hich the rod could be from a support at the top and a attached at the lower end . The ) in the box for the rod was slotted out to one side so as to admit the rod being slid into its place . ting the stress in the rod we must add to the weight attached to the hook the weight of the box and of the pitch below the point of obsel.vation on the rod . The weight of rod nnder observation produces an increase in the stress from the lower end upwards , its amount half } is obviously half that of the rod between the lower and upper mark . For points above and elow t middle the stless is in defcct of the mean value by equal amounts , so that , linearity for the flow , the correction will l half the weight of the poltion of the rod in the observation . The rate of elongation of the rod was observed by nteans of a cathetometer . In observations with certain materials such as shoemaker 's wax the plan was adopted of under a liquid of the density as the material itself for the purpose of eliminating the stress due to its own weight , which much too great to adm-it of accurate otherwise made on the rate of flow . lower end of the rod , in such cases , was made fast while the tractive applied at the top means of a cord and pulley . The rods were thus drawn upwards . This was done in order to be able the more easily to surround the rod with a liquid , having the same density as its material , and thus to eliminate the action of the rod 's own wei . For the a widc vertical tube was fitted to the apparatus and surrounded the rod under examination . Solutions of salt in water were used for the liquids . of riments . results obtained with pitch other stances showed the time rate of elongation per centimetre of a rod under tension is approximately proportional to the force of traction per square nctre cross section or , where is the force applied , the area of the cross section , the velocity at any point on the rod , and . F. T. Trouton . fictent of Viscous [ Feb. 12 , a constant for any iven material . This we term the coefficient of vis( lction of the tcrial . values found for for a few of the substances experimented with are iven to show the order of tho coefficient . For an inar variety of pitch at C. ) For the same with a admixture of tar For shoemaker 's wax at C. . . of \mdash ; The observations made on the rate of flow of rods of these substances show that it is faster immediately after the application of the force than afterwards . As an example , the following table is given , in which the elongation is in arbitrary units and the in minutes and seconds to the nearest five seconds . These observations are plotted in fig. 2 . FIG. 2 . . 1906 . ] Traction and its to that of Viscosity . It will be seen th the initial rate of flow is faster than the final rate . This is similar to what was observed in the case of the viscous flow of rods under torsion . * It was also noticed that there was a slow partial movement towards recovery on removal of the force of traction , which gradually fell to zero with time , just as had been previously observed in the case of torsional forces . with Variation of Trnctive Force.\mdash ; Experiments made with erent values of the tractive force show that the rate of flow is not strictly proportional to the force . The results of determinations made with a variety of pitch given in Table II an shown in fig. 3 are ypical . Table II . 1oo 200 300 The ordinates represent rate of elongation , while the abscissae represent the force pplied to the in grammes . It will be seen from the that except the origin the law is linear . For forces above a certain value the rate of flow may be Jressed as . The rate of elongation 'Phil . Mag vol. 19 , p. 347 , 1904 . Prof. . T. Trouton . Coefficient of [ Feb. 12 taken for the curve was in every case that after the initial had been passed . Th of Flow of rtictcs i'-out \mdash ; The mode of flow the particles of a rod while being drawn out is of interest . Vith the view experimentally ascertaining if the particles lying in a cross section moved bymmetrically on taking place , that is to say , if half of the particles ttered uniformly out a cross section , are lefb ively behind , were of having approximately the same coefficient of viscou , traction , but of different colours . Two different coloured rods were unite end to end and then drawn out , the surface of demarcation being atched . of diffel'Gllt colouled( were tried for this purpose and , provide they ( approxitnately of the same fusibility , answered well . thus mnde vere warnled and drawn out and the face where theJ joined observed . This ined a plane ; sometimes did not remain a cross section . tendency was noticed for the centra . portion to a different rate to the peripheral parts . The flow show . itself to be cluite synlltetricnl the , as one wouId naturally expect Similar results were obtained with shoemakel.'S wax . In this case tion of one end cted by the addition of a small quantity ol vermilion . On -out , the line of demarcation be seen . ' of periments on the rate of a-vial contraction of cylinders under xial compression those obtained for the fraction of rods , as detailed above . That is to say:\mdash ; ( l ) The rabe of contraction on first application if the stress is a little faster that finally reached ( see ; ( 2 ) there is a slow movement towards recovery on removal of the stress ; and ( 3 ) the final rate of flow increases at a rate with the increase in the applied stress when the 1 tter is above a certain value . In the case of traction , the of the rod or cylinder be compared with its diameter , in most cases it between and 30 the but for compression on account of , it is well the to be not more than about three times the dianleter of the cylinder . The plied by on a plate which j covered the top of the cylinder , which stood rate of depression of the cylinder observed by of a neter . The coefficients obtained from on compression made in this were found to bout the halne in nitude as those obtained from traction . For instance , with 1906 . ] its to of Viscosity . a certain pecilnen of a rather soft pitch , the compressional coefficient was found to be , while the coefficient for traction of the same material to be FIG. 4 . Time minubes . of a Stream its own The stream of the material under examination was obtained by it to flow through a circular hole in the bottom of a wide tin vessel . After a steady state is reached , the outline of the stream is of the character shown in fig. . The stream gradually tapers down to a very fine thread , which breaks off intermittently from its lower end . At any point distant from the top let be downward velocity of the material , then the time-rate of ation per centimetre of the material at this point is . The tractive force is to the mass of the column below this point . Let the cross section be , we have then , proyided the velocity is small , My . Thus we may write , where is the volume of material supplied per second , and d the slope of the tangent to the surface at the point of the column where is the diameter . Jfcthod of Dctcrmi'ning \mdash ; An optical method can bc adopted for determining the slope of the surface of the column at a definite point . A beam of light a horizontal slit and lens is allowed to fall on the Prof F. T. Trouton . Coefficient of Viscous [ Feb. 12 , column and is reflected into a telescope which is pointed upwards to receive it . The of half the between the incident and reflected beams is evidently the slopc of the surface curvature . FIG. 6 . The value of can be got by off the column at the point in question , and wei(e . The value varies , it is true , according as the column breaks off at its lower end or otherwise , but only to a ible extent . The vaJue found for the coefficient of viscous traction by this method for a mixture of pitch and tar in the ratio of 7 to 1 was ; and for a mixture of the same materials in the ratio of 3 to 1 about . These about the same values as obtained by the other methods . of of a Strc its \mdash ; To determine the shape of the column we have the following considerations . At any point we have seen that the force of traction is , ( 1 ) where A is the area of the cross section , so that const . Also , ( 2 ) when is the density of the material . 1906 . ] Traction its Relation to of Viscosity . If the rate of fall is small , the acceleration term may be ected , and we Substitute for from the relation , where is the mass of material falling per second ; and substitute for A. Then , after differentiating and , we have , where . The solution of this equation is When is very small it represents a filament , such as in the present case . The limiting solution when is . This last expression was found , as described below , to fit experimental data with sufficient accuracy . In order to experimentally examine the question , mixtures of pitch and tar were made sufficiently thick or glutinous for the flow to be slow enough to enable the acceleration term to be neglected . The culvature assumed by the column was experimentally determined by observing the diameter of the column at various heights . This was done in some cases by means of a cathetometer , in others by casting the shadow of the column from a distant source of light on a long vertical sheet of paper placed close to the column , and then tracing out the shadow with pencil . The cathetometer telescope had a scale in the eye-piece , with which the horizontal breadth of the column at the different heights was observed according as the telescope was raised to various positions along the column . From these readings , in conjunction with the height readings , the curve made by the pitch in falling could be plotted . It was then possible to fit an equilateral hyperbola to it . The following table ( p. 434 ) gives the results obtained with rather a thick mixture . The first column gives the height in centimetres ; the second one half the observed diameter ; the third column gives the calculated value of the radius derived from the formula The values of the constants used were and . This last is the height above the bottom of the vessel at which ) horizontal asymptote is situated . The divisions of the scale of the eye-piece corresponded to cm . This was subdivided by eye , so that the crreement is quite within the limits to be expected . There was some difficulty at times in ding the diameter , especially towards the lower end , as the column would sometimes sway slightly about , even it was placed inside a case with of the end breaking off . to shelter ieasure tffecGP fCoefficient oiscous [ Table by Tcthod.\mdash ; From the value of the constant in the coefiicicnt of viscons traction may be calculated . Thus as found above , we was at a nJean temperature of C. A rod from the same mixture of tar and } ) for by the traction method the value at C. Another rod from the same mixture boave at C. reement will be considered sufficiently to confirm the theory when the chal.acter of the material is Unfortunately , though very materials of any desired viscosity , these mixtures suffer from the that when they heated for the manufactule of the test rods they lose some of their more volatile constituents , becoming more viscous in consequence . bjj nlodification from the perbolic form , which the of material undergoes when it is not so viscous to render the inertia term ible , may ) appreciated by noting when } } ) is hyperbolic tho acceleration third of the fallen , so that at fJrst t ) incltia tetll 1nay bc quite itlnay at lower points become and sensibly reduce the tction effect . In this the contour at oints assumes of the hypelbolic and approximates the c3 In limit viscosity is ) ) ] tcly ided the ) 1906 . ] Traction and its Relatio to that ofViscosity . drops due to surface tension . Comp ring the two cases , for points and , where , we have for the non-inertia case ) , for the non-viscous case ) . Where both causes act , some intermediate shape will be by the materisl . Descending columms of viscous liquids , such as the familiar one of honey falling from a spoon , fornl instances of this . of a If a rod of pitch is laid across between two horizontal supports it will be funnd to continuously downwards . rate at which this occurs the consistency of the material . To find how the rate of depends on the coefficienlt of viscous traction , can resolve the stresses in t'ne material at any cross after the manner usual in the cases of stressed bealns . This ives compressional forces above and tractive below a tain point in any cross section . Taking this as being at the central ontal line of the cross section , we have for the moment of the force about this line where , is the rate per unit of elongation , or the contraction as the case may be , at any point situated at distances from the central line , and where is the breadth there . This value for may be approxinlately expressed in terms of the rate at which a plane in the material at the point rotates at the moment when it is at right to the axis ; thus , }here is this rate of rotation at any cross section , so Now , the rate of sagging at the celltre , is given ; and , recollecting that \mdash ; , where ? ? is the mass of the rod between the supports and its length , we get , after arranging and intewhere I is the moment of inertia of the cross section of the rod . One of the methods employed to test this formula was to coulpare the rate of tging rods different quantities involved ) unaltered . A rod of pitch of circular ) section ) laid between } supports which could be placed at various distances } ) , and the tinltl of the same distance in each obserYcd . itll cases the F. T. Trouton . of Viscous [ Feb. 12 , initial rate of not included in the measurements . To allow this to done the rod was made with a camber and the observations only just beforc position . It will be seen on comparing rods of erent 1 , if represents the time , at any iven span , to the standard distance , that COllst . The following table gives in the first column the temperature the time of the experiment , in the second column the span , in the third the time taken to fall through a standard distance , and in the fourth the value found for this constant in each case . Table The last two experiments were made on a different day from the others , and were made at a slightly temperature . This may in for the smaller value found the constant . The curve obtained by against is shown in fig. 6 . 1906 . ] fraction and its to that of Viscosity . Initial Rate of \mdash ; As other cases previously dealt with , so in the case of beams , the initial rate of flow is greater than subsequently . The table , obtained from experiments with a certain variety of pitch , illustrates this . In the first column are given the distances fallen from zero by the central point of a rod or beam of pitch . In the second column the time taken to each point . The curve obtained by plotting these is shown in fig. 7 . FIG. 7 . Time in secs . Table dimensions of this rod , which was circular , were follows : between supports , mean radius , mass between supports , final rate of . This , using above formula , . The same rod by the traction method A number of other lnixtures of pitch and tar of proportions were experimented with . These gave approximately the same value for coefficient of viscous traction as that found by either column method or by the direct traction method . Some of the mixtures of pitch and tar were too soft to deal with as a beam in air , so they were experimented with under water or brine . In this way the downward 1noment could bc very reatly reduced , or , if desired , could be even changed in , when , of course , the V0L . LXXVII. . 21 Prof F. T. Trouton . Coefficient of Viscous [ Feb. 12 , was gave the value when operated under water . ends of the beam hadtobehelddownyfno . rticular mixture density : The value previously found for it the column method was . The velocity in this case was perhaps too great to negect the inertia in the column method , and account for the highervaluee of thecoefficientn obtained ) it . , an accoun or betwccn of Viscons of Viscosity . It is obvious that there must be an intimate relation between the coefficient of viscous traction and the coefficient of viscosity as ordinarily defined . The tractional force applied to a rod may be resolved , is usual in questions of elasticity , into two equal shears , which are situated at angles to each other and at to the direction of traction , with a uniform force of dilatation . The value of either shearing stress , and also of the dilatation stress , is in each case one-third of of the tractive stress . In the first instance on the application of the tractive force , the resolved effects produced corresponding to these resolved stresses will consist of a dilatation and of shearing strain . It car only be to the flow resulting from the latter that the elongation of is due . similar can take place in the of the stress of dilatation , which only can have an initial effect . The continued application of each shear will produce a flow , criven in each case by , where is the stress , the coefficient of viscosity , and ) the rate of of direction of any line in the matelial in the plane of the shear as it passes through the direction normal to the shearing stress . The resulting flow in the di1ection of the axis is obtained by adding the resolved components of the two flows in that direction ; so that the two effects , adding the components , and the axial ation to that per umit length , we find that Sin ce , and , where is the tractive force netre , we get , so that the coefficient of viscosity is to onethird of the coefficient of viscous traction . * terms of the mole usual of cous f constant stress-modulus , the ument would take the following form : onsider i viscous cylinder tion at rate ; if is but slightly coulpressible , it mtlbt at the contraction at rate all ausverse directionb . If the osity the of tension of intensity there is tension of intensity 1906 . ] and its to that of Viscosity . In order to compare the coefficient of viscous traction with that of viscosity for the same material , two distinct plans were adopted . One was to select a material sufficiently viscous to allow the coefficient of viscosity to be determined by means of the torsion of a rod made of it , also which allowed the coefficient of viscous traction to be found by directly drawing out the rod , or by the method of the horizontal beam . The second plan was to select a lnaterial sufficiently fluid to admit of the coefficient of viscosity being determined by the rate of flow a tube under a pressure head , while at the same time not so fluid but that the coefficient of viscous traction could be observed by the method of the beam or by the method of the column descending under its own weight . The following are the results obtained for the value of and in the case of several materials of wide in the value of the constants . It will be seen that the value of is , generally speaking , in fair reement 1-ith three times the value of , the viscosity . A variety of pitch which gave by the traction method was found by the torsion method to have a viscosity . Another variety of pitch gave by the traction method and by the beam method , while the viscosity was found to be by the torsion A material made by adding a little tar to pitch by the traction method and by the torsion method . A similar material containing a little more by the bion method by the torsion method . A specimen of shoemaker 's wax by the tlaction method and ' by the torsion method . For making a comparison by the tube method a ) of pitch and tar of about three to one was used . This passed sufficiently freely through a tube to enable the coefficient of viscosity to be determined . This was found to be , while the coefficient of viscous traction was found ) the beam 1nethod to be . Another mixture of somewhat similar proportions , but better filtered , gave by the tube method and by the descending column method . acting on the surfaces of the cylinder amount in all to a uniform hydrostatic pressure ether with a of intensity . Of these the pressure is entirely neutralised by the reaction arising from the slight compression of the materials which it produces ; while the . tension , having au intensity-coefficient , alone remains to operate in other ways , as in the text . 'Phil . , p. 34 1904 . . W. H. Dines . Temperature [ Nov. 10 , These results collected in Tablo , where it will be seen that the coefficient iscuus traction is times that of viscosity . Table The Gradients on the Coast of Scotland at Oxshott , Surrey . By W. H. , F.R.S. ( Received November December 7 , In a paper by Dr. Shaw and the author read before the Royal Socievy on an accoullt of an investigation into the conditions of the upper air over the sea in the ohbourhood of inau , on the West Coast of Scotland , was viven . Since that time two fresh series of observations in the same locality have been obtained , the lesults of which are submitted . In each case bservations of temperature and were made by -recording ments sent up by of one or more kites , which wele flown from the deck of a steam vessel . The pense has been met by a grant of X200 made by the Government Grant Committee , a grant of by the British Association at the port ] of f40 at the ; and also by ill atloltynlous contribution of by ellow of the Soci hese gtants ) not becll used entireIy for the vatious , but havG q neans of on meant 1 al , too , paratus for a ation crried out by . SiInpson on ) Sca has ovided . For vatious inan in a tug was hired , Lords Commissioners of ' ' , vol. 202 , ) . Quart . , No. 13

rspa_1906_0039

0950-1207

The vertical temperature gradients on the West Coast of Scotland and at Oxshott, Surrey.

440

458

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

W. H. Dines, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0039

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0039

10.1098/rspa.1906.0039

Meteorology

Thermodynamics

Meteorology

440 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , These results are collected in Table YI , where it will be seen that the coefficient of viscous traction X is roughly three times that of viscosity . Table VI . A. fl. A. A/ a* . 4 -3*x 1010 1'4 x 1010 3-07 6 -7 x 109 2 -2 x 109 3*04 3 -6 x 1010 1 1 -0 x 1010 | 3-60 5 -9 x 106 2 -0 x 106 2*95 3 -3 x 101(1 J 3-30 9 -3 x 105 2 -8 x 106 3*25 12 -9 x 109 4 -2 x 10s 3-07 7 '6 x 105 2 -6 x 105 2-91 The Vertical Temperature Gradients on the West Coast of Scotland and at Oxshott , Surrey . By W. H. Dines , F.R.S. ( Received November 10 , \#151 ; Read December 7 , 1905 . ) In a paper by Dr. Shaw and the author read before the Royal Society on May 14 , 1903 , * an account of an investigation into the conditions of the upper air over the sea in the neighbourhood of Crinan , on the West Coast of Scotland , was given . Since that time two fresh series of observations in the same locality have been obtained , the results of which are now submitted . In each case observations of temperature and humidity were made by self-recording instruments sent up by means of one or more kites , which were flown from the deck of a steam vessel . Expenses . The expense has been met by a grant of \#163 ; 200 made by the Government Grant Committee , a grant of \#163 ; 50 made by the British Association at the Southport Meeting , and of \#163 ; 40 at the Cambridge Meeting ; and also by an anonymous contribution of \#163 ; 25 by a Fellow of the Royal Meteorological Society . These grants have not been used entirely for the observations at Crinan , but have afforded the means of carrying on experimental work at Oxshott ; by them , too , apparatus for a separate investigation carried out by Mr. G. Simpson on the North Sea has been provided . ! For the observations at Crinan in 1903 a tug was hired , and the Lords Commissioners ol the * ' Phil. Trans. , ' A , vol. 202 , pp. 123\#151 ; 141 . t 'Met . Soc. Quart . Journ. , ' vol. 32 , No. 137 , pp. 15\#151 ; 25 . 1905 . ] Gradients in the West of Scotland and Surrey . 441 Admiralty , at the request of the Royal Society , kindly provided a very convenient vessel , H.M.S. " Seahorse , " for six weeks , commencing on June 19 , 1904 . The Meteorological Council lent the necessary instruments , and bore the expense of maintaining a base station during both summers . They also greatly assisted the work by sending a daily telegram with a forecast of the weather , and a statement of the magnitude of the barometric gradient . Material Collected . The results obtained consist of 16 fairly satisfactory traces at Crinan in August , 1903 , of 29 traces at Crinan in June and July , 1904 , and of 75 traces at Oxshott . The average height for the first set ( Crinan , 1903 ) is 4500 feet , the second set ( Crinan , 1904 ) give 5340 feet . The averages for Oxshott are 3300 feet for 1904 and 5200 feet for 1905 . A meteorograph kindly supplied me by M. Teisserenc de Bort was used in 1903 ; since the beginning of 1904 a new form of meteorograph , which is described in the Quarterly Journal of the Royal Meteorological Society , * has been used . With the exception of the months of July , August , and September , 1904 , when there has been sufficient wind ascents have been made at Oxshott on the days appointed by the International Aeronautical Commission , these days being , as a rule , the first Thursday in each month . The other ascents at Oxshott have been made rather with a view of testing and , where possible , improving the apparatus than of obtaining definite information . Owing to the inconvenient situation of the place , which is close to many thickly -populated suburbs , the rule was made of never using more than one kite . This rule was rigidly adhered to until the commencement of the present year , but since it was found that increased experience and an improvement of the apparatus had led to a great diminution in the number of mishaps , the rule was broken through , and the number of kites extended to two . It is still not considered desirable to use more than two , or to let out more than from 10,000 to 12,000 feet of wire . It may be of interest to others engaged in similar work if I state that out of the 75 ascents at Oxshott , on five occasions the kite and meteorograph have broken away or fallen to the ground ; on one occasion this was due to the breaking of the wire near the kite under a pull of 200 lbs. ; on another occasion to the breaking of the front stick of a kite under a pull of 230 lbs. ; once to a careless fastening at the end of the wire , and twice to some unknown cause . The loss of material has been one kite broken beyond repair , and about 2000 feet of wire . The meteorograph has never been lost or damaged , since being secured in the middle of the kite it is well protected . * Vol. 26 , No. 135 , pp. 217\#151 ; 227 . 442 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , On the three occasions when the kite has been detached from the wire it has fallen at a horizontal distance of about six times its vertical height , and the wire has been wound in undamaged almost to the end . The average ratio of the vertical height to the length of wire employed has been a little over 6/ 10 . Observations at Crinan in 1903 . The results obtained in the summer of 1903 have been published in the Journal of the Royal Meteorological Society.* This set of observations were not so numerous or so consecutive as might be wished . The steam tug employed was in many ways unsuitable , and the weather rendered kite flying difficult as well as unpleasant . The observer at Malin Head , the reporting station nearest to Crinan , reported a gale to the Meteorological Office on 20 occasions during August , 1903 , and the captain of the tug often feared to take out his vessel , which was old , on account of the weather . The following is a brief summary of the results:\#151 ; The average decrease of temperature for the first 500 metres was 20,2 C. , for the second 500 metres 3'*4 , and for the third 3'*6 , the total decrease for 1500 metres being 9'*2 , or at the rate of 0'*6 C. per 100 metres . The winds were nearly all between south-west and north-west . The temperature observed at the kite when at the level of Ben Nevis was always above the temperature of the summit at the same time , the differences ranging between 1'*6 C. and 6'*1 C. , and the average excess was 3'*3 C. One trace of especial interest was obtained : a thunderstorm broke out without previous warning while a kite was flying at a height of 4400 feet ( 1300 m. ) , and a meteorograph was drawn in through the actual region of the electrical disturbance , but the trace showTed no peculiarity of any kind . For convenience of reference Table A , which appeared in part in the previous paper and , excepting the values for Oxshott , has been published in the Journal of the Royal Meteorological Society , is here reproduced . Observations at Crinan in 1904 . The results obtained from H.M.S. " Seahorse " are exhibited graphically in fig. 1 . The diagram ( fig. 1 ) has been drawn on the same plan as before . The isothermal lines for each degree Centigrade are put in as fully as the observations will permit , and where these have failed the isotherms are connected by dotted lines as a guide to the eye . The letters S , M , D , and YD refer to the humidity , S denoting a value between 100 and 95 per cent. , M between 95 and 80 , D between 80 and 60 , and YD below 60 per cent. No great degree of accuracy is claimed for these values . * Quart . Journ. , ' vol. 25 , No. 130 , p. 155 . 1905 . ] Gradients in the West of Scotland and Surrey . Table A.\#151 ; Table of Average Temperature Gradients in Degrees Centigrade for 100 Metres for Vertical Columns of different Heights . Height of column . 500 1000 1500 2000 2500 500 to to to to to 1000 . 1500 . 2000 . 2500 . 3000 . 0-50 0-50 0*51 1 *10 0*80 0-71 0*68 0 *56 C. per 100 metres approximately 1 ' F. per 300 feet . V 140 met res , 0 *7 0 . 0*52 0*54 0*53 0-62 0*56 0*56 0*52 0*50 0*48 0*46 0*44 0*68 0*73 0*77 0*53 0*34 0*49 0*51 0*77 0*57 0*37 0*30 Berlin balloon ascents ... ... ... ... ... ... ... ... . . Kite ascents , U.S ... ... ... ... ... ... ... ... ... ... . Average gradient for mountains ... ... ... ... ... ... . Average gradient for Ben Nevis , July and August Adiabatic gradient for saturated air , initial temperature 12 ' C ... ... ... ... ... ... ... ... ... ... ... . . Average summer gradient over sea , west J ^9 ? ' ' coast of Scotland ... ... ... ... ... ... ... . . j Average gradient near London ( Oxshott ) , 1904 and 1905 ... ... ... ... ... ... ... ... ... ... ... ... ... ... Fig. 2 is taken from the official publications of the Meteorological Office , and shows the movement of the depressions for June and July , 1904 . The heights at which clouds appeared are somewhat uncertain . In determining cloud heights by an ascent of a kite there are three possible contingencies ; the kite may become indistinct but not entirely vanish during the passage of an opaque cloud , and in this case the height of the kite certainly agrees with that of the lower surface of the cloud . This case is unusual . In the second case the kite disappears into or emerges from a thick cloud sheet ; here again the height of the lower surface is perfectly determinate , but it seldom happens that the disappearance and the emergence , perhaps an hour later , occur at anything like the same height . The third case is the most usual , when the kite disappears in or behind an opaque cloud , or becomes indistinct owing to a semitransparent cloud . All that can be said here is that the cloud level is below the height of the kite , and an inspection of the humidity trace often shows that the kite at the time was in very dry air , and therefore not in the cloud at all . If it is a large thick cloud that is in question , the kite need not have been above its upper level , but merely , from the observer 's point of view , behind some part of it . The wind direction , wind force on the Beaufort scale , and weather each day are shown below in the diagram ( fig. 1 ) . Where the wind direction at the level of the kite differed much from the surface direction , it has been put in at the corresponding height , and the absence of any letters on the diagram indicates that the surface and upper wind were substantially the same . The 444 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , barometer curve shown at the top is copied from a Negretti and Zambra 's barograph that was kept at Crinan . The period under review , June 20 to July 28 , 1904 , had weather of a somewhat exceptional character for the locality . The prevalent summer wind is certainly west , i.e. , between south-west and north-west , but while Fig. 1 . June 30*50 in , 20 , 21 25 24 25 26 27 ' 28 29 30 29*50 . . W SSW SW SSW W W W SE NW sw THE fflTTE red r c b cr r rain . t thunder . b blue sky . c detached clouds . o overcast . the " Seahorse " was at Crinan the wind with few exceptions came from between east and south-west . There were strong winds from some southerly point on several occasions until July 15 , but after that date very light winds from the east and south-east were the rule . On three days no ascent could be obtained , and it may be remarked that never before when employing a vessel did we fail to get some sort of daily ascent . 1905 . ] Gradients in the West of Scotland and Surrey . After July 19 the barometer trace becomes almost a straight line , and it was found that the winds failed entirely at the height of a few thousand feet . This was most noticeable on July 20 , the only day after the 15th on which there was a good breeze . Although at the surface the force was 6 on the Beaxtfort scale , a " strong breeze " and three kites were tried , not one Fig. 1\#151 ; continued . July u u t ; / y 1/ c t/ w c *A closed curve thus Q denotes a temperature inversion . 30*50 in . 50*00 . . \#163 ; \lt ; D \#163 ; 9*50 - o \#163 ; 9'00 2,000 m. 1,000 m. could be got to rise above 2000 feet ( 670 metres ) . Fig. 2 shows how few depressions passed near Crinan during the six weeks of observation , and the absence of west and north-west winds to some extent defeated the object of the investigation , namely , a determination of the oceanic temperature gradient , but on the other hand the unusual prevalence of land winds have afforded the means of comparison with the preceding years when different conditions prevailed . 446 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , The table of gradients and the diagram indicate a departure from the preceding results in the steeper gradient for the first 500 metres , and in the comparatively numerous temperature inversions between 1000 and 2000 metres . A steep gradient in the daytime in summer is a characteristic of continental observations , * and it is not surprising that the prevalence Fig. 2 . , 2 . MOVEMENTS OF DEPRESSIONS . / . 3rd to 11th , irregular t about Spain , arh Jbai to our southern , distru jVo tracks ca\gt ; v 2\gt ; e s7u June , 1904 . of land winds should produce a steeper gradient . Such marked inversions of temperature have not been observed at Crinan in the preceding years of observation , and the inference certainly is that temperature inversions between 500 and 2500 metres are unusual off the Scotch coast with westerly * The gradient 1T0 for the first 500 metres of the United States Weather Bureau ascents ( see table ) is beyond the adiabatic rate for dry air . These were chiefly , if not entirely , day-time ascents in the summer . 1905 . ] Gradients in the West of Scotland and Surrey . 44 winds . It is noteworthy that if we take the average gradient up to 1500 metres ( 5000 feet ) it has been practically the same in each of the three summers ; although the observations at Crinan , or rather over the sea in the neighbourhood of Crinan , in 1902 and 1903 were , on account of the prevalence of westerly winds , equivalent to observations over the North Atlantic . Fig. 2\#151 ; continued . Z. MOVEMENTS OF . DEPRESSIONS . July , 1904 . Comparison with Ben Nevis . Table B shows the relation between the temperature on the summit of Ben Nevis and the temperature of the free air about 60 miles to the southwest at the same time . The temperature given by the kite is the mean of those obtained on the ascent and descent , and the Ben Nevis temperature 448 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , is that of the exact hour that stands nearest to the middle of the kite ascent . The figures are in striking contrast with those relating to the two preceding years . For the first time the temperature at the kite was occasionally found to be below that on the summit of the mountain . Owing to the use of larger kites and a lighter meteorograph , it was possible to get observations on days on which in the summer of 1902 it would have been impossible , on account of the lightness of the wind , to reach the level of Ben Nevis , but it is obvious that this is not a sufficient explanation , since the days on which Ben Nevis was the warmer were not days of exceptional calmness . Table B.\#151 ; Difference of Temperature between Ben Nevis and a Kite at the same level about 60 miles to the south-west . Date . Kite . Ben Nevis . * Difference , B.N. \#151 ; kite . W eather under kite . Dry . Wet . June 21 , 12 * 2*4C . 1 *2 1 *2 -1 *2 W. , 4 yb 22 , 12 3*3 2*5 2*5 -0*8 W. , 4 , c 24 , 12 5*5 3*2 3*2 -2*3 S.E. , 2 , c 28 , 12 6*0 8*2 5*8 2*2 E.S.E. , 1 , c 29 , 12 7*5 10 *5 7*6 3*0 S.E. , 3 , b 30 , 2 p.m 8*0 11*1 6*6 3*1 S.E. , 4 , c July 1 , 3 " 3-6 2*8 2 *8 -0*8 S. , 6 , r 2 , 12 *1 . 2 *4 2*4 2*4 0*0 S.W. , 3 , r 4 , 11 A.M 2 *4 1*7 1*7 -0*7 S.S.W. , 3 , r 5 , 12 I. 5 *0 2 *3 2*3 -2*7 W. , \gt ; 2 , c 6 , 11 A.M 8*8 7 *8 7*8 -1 *0 S.S.W. , 7 , r 7 , 12 1 *4 0*6 0*6 -0*8 S.W. , 6 , c 8 , 11 A.M 4-3 3*9 3 *9 -0*4 S.S.W. , 7 , r 13 , 2 p.m 4*9 7*1 7*1 2*2 S.S.W. , 4 , b 15 , 11 A.M 6*7 6*6 6*6 -0*1 S.S.W. , 5 , c 16 , 3 p.m 1.5*0 3*2 3 *2 -1 *8 W.S.W. , 3 , b 19 , 12 8*8 12 *3 8*7 3*5 S.S.E. , 2 , b 21 , 12 7*5 7*5 7*5 0*0 S.8.E . , 2 , b 22 , 11 A.M 9*0 7*5 7*5 -1 *5 S.K. , 1 , c 25 , 12 10*1 8*5 7*5 -1 *6 E. , 1 , b 26 , 12 1.5*0 7*4 6*7 2*4 E. by S. , 3 , c 28 , 12 1.11 *5 11 *4 8*6 -0*1 E. , 1 , c * Denotes a temperature inversion at about the height of Ben Nevis . Explanation of letters :\#151 ; b. Blue sky . c. Detached clouds , o. Overcast , r. Bain . With the exception of July 13 , on each day on which the mountain was the warmer the air on its summit was dry , and mostly very dry ; with the same exception also the winds were south-east . It is noticeable too that the differences were small on the five rainy days given in the table . In the preceding paper it was suggested that the lower temperature of the mountain was due to the adiabatic cooling of the air as it was forced up the mountain slope by the prevailing westerly winds , the temperature gradient so produced being greater than the ordinary gradient in the 1905 . ] Gradients in the West of Scotland and Surrey . 449 free air ; and the results obtained in 1904 seem to me to support this conclusion . Oil rainy days the gradient in the free air , at least throughout the vertical region in which rain is forming , must be the adiabatic one , for the dynamic cooling of an ascending current is the only admissible cause of any but the lightest rain , and on such days the adiabatic cooling should produce much the same temperature on the mountain and in the free air . With a fairly clear sky and a south-east wind the air would be warmed , by contact with , the ground before reaching Ben Nevis , and it is probable that any excess of moisture it may have had originally would be deposited on the slopes of .the mountains lying to the east and south . A westerly wind , on the other hand , could not be dry , coming from the sea , and , as is usually the caser would produce clouds and a saturated condition on Ben Nevis . Different instruments were used in each year and the question arisen whether these differences are due to instrumental errors . An error may arise from an incorrect base line or from an incorrect scale . The former error is excluded by the fact that in each year the instruments were compared almost daily with verified thermometers , and an error exceeding half a degree must have been detected . Some error from the second cause is certainly possible , but it could not have been large . The usual range of temperature at Crinan during the summer is small , the temperature during the daytime seldom exceeding 20 ' C. or falling below 12 ' C. , so that an error in the scale amounting to 1 in 16 may , perhaps , have escaped detection . No means existed of obtaining low temperatures artificially , and the meteorograph used in 1902 was never compared with a thermometer at temperatures outside the ordinary range of the district . That used in 1903 was obtained from M. Teisserenc de Bort , he sent me particulars as to the scales , and I do not doubt that they were correct . I tested the meteorograph used in 1904 over the whole range of likely temperatures before going to Crinan , and although the zero of these instruments is liable to alteration , the scale is not . Hence , on the whole , , I consider that while an instrumental error of something under lu C. is possible , it is hardly likely that the differences are due to this cause . The fact that temperature inversions were far more prevalent in 1904 than in the previous years shows that the average weather conditions were different . Temperature Gradients and Weather Classification . The temperature gradients over the sea on the west coast of Scotland have now been ascertained on 68 days , and it seems desirable to separate and arrange them according to the weather in which they were observed . 450 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , The classification of weather is that suggested by Dr. Shaw in a paper read before the Scottish Meteorological Society in December , 1904.* South-easterly Type . A pressure distribution favourable for winds between east and south for the 24 hours to which the observations refer . South-westerly Type . Favourable for winds between south and west . North-westerly Type . * Favourable for winds between north and west . North-easterly Type . Favourable for winds between north and east . Variable Anticyclonic . Variable winds during the prevalence of an anticyclone . Variable Cyclonic . With sequence of winds incidental to the passage of a cyclone . A cyclonic region is taken as one in which the isobars are concave to the low-pressure region and probably form closed curves round the low-pressure centre . An anticyclone is one in which they are concave to the high-pressure region . In cases where the isobars are approximately straight the region is classed as intermediate , and it has been necessary to add the term " transitional " for cases where for the interval in question the type is changing . The results are shown in Table C , next page . It must be borne in mind that these gradients refer to the daytime and to the summer . Inasmuch as the daily temperature variation on the sea is very trifling , or perhaps even non-existent away from the ship which carries the thermometers , we may take the conditions as being those prevailing , without reference to the hour , during the summer months . There is no reason to suppose they would be different in the winter , but in the absence of direct information no definite assertion can be made . The observations from strata over 2000 metres have been omitted , as they are not sufficiently numerous to lead to any conclusion , and , indeed , the figures given in the table are such , that when considered in connection * 'Journal of the Scottish Meteorological Society/ Third Series , Nos. 20 and 21 . 1905 . ] Gradients in the West of Scotland and Surrey . 451 with the number of observations , it would not be unreasonable to say that the differences are of such an order that they may be purely chance ones . Table C.\#151 ; Gradients , in metres , at Crinan for various Types of Weather . No. of observation . 0 to 500 . 500 to 1000 . 1000 to 1500 . 1500 to 2000 . Mean . Cyclonic . 28 0 *48 0 *60 0-46 0 -54 0 *52 Intermediate . 31 0 *76 0-54 0*42 0 *52 0 *56 Anticyclonic . 4 ... ... 0 *66 Observations wanting . Transition . 5 0 *54 0-56 0*50 0 -40 0 *50 North-westerly type . 24 ... ... . 0*66 0*62 0*44 0*32 0*51 South-westerly . 21* ... ... . 0-72 0-60 0-40 0 '58 0 '58 South-easterly . 11 ... ... . 0 *58 0 *48 0 *26 0 '58* 0 *44 North-easterly . Not sufficient observations . Variable . 7 ... ... . 0 *46 0 *60 Observations wanting . 0 *53 # Only two observations and therefore not included in the mean . The noticeable points are the small gradient from 0 to 500 metres in cyclonic weather compared with the high value for the same strata for the intermediate type , and the low value from 1000 to 1500 for the southeasterly type . This latter result is due to the temperature inversions occurring in 1904 , but it is not possible to say definitely whether a small gradient is the usual accompaniment of the south-easterly type . It will be necessary to obtain more observational information before forming a definite opinion on the whole question . The absence of observations for the higher strata with the anticyclonic and variable types shows plainly that these types are accompanied by very light winds at a small height , since the want of observations can only be due to the want of sufficient air motion to raise the kites . The one safe conclusion to be drawn seems to be that the different types of weather are not characterised by any peculiarity of gradient , neither is there any reason Mr. W. H. Dines . Vertical Temperature [ Nov. 10 for expecting that they should be , except in special cases . Anticyclonic conditions , it is well known , produce during a winters night on land a sharp inversion in the lower strata , and the same conditions during a summers day produce the steepest gradient that the conditions of equilibrium will admit of , but the two results tend to cancel each other and give on the whole an average gradient . It is almost certain , too , that neither result occurs over the open sea . The gradient in the precise region in which rain is forming , or , more strictly , in which vapour is being condensed , must in general be the adiabatic gradient for saturated air , but , compared with the volume of the whole mass of the atmosphere , such regions are very small indeed . Let us call such a region of ascending air A. Whether this region be the rainfall area of a large cyclonic disturbance , or merely that of a small local shower from an isolated cloud , there must be associated with it a compensating region , B , in which the air is descending . Ferrel has pointed out that owing to the latent heat of condensation the air in and over the region A must be relatively warm , and that this warmth will suffice to produce the circulation . % But there is a point which may be easily overlooked . The adiabatic rate for dry air , such as will be found in B , is far greater than for the saturated air which is found in A , and if the passage from A to B be a purely adiabatic one , the temperature in B will be far higher than in A , a condition which would immediately reverse the direction of the circulation . Hence the circulation cannot occur , unless it be a forced one , and not a convectional effect . Where A is a mountain slope up which a wind is blowing , we have a forced circulation , with a foehn wind in the region B , but in the free atmosphere it is very difficult to see what source of power there can be to produce a forced circulation . It seems more likely that the change from A to B is not adiabatic , and that the region B is very extensive when compared with A and perhaps some considerable distance from it , also that the air which is descending in B , to replace in the lower strata that which is rising in A , is air that ascended some time since and has had time to become cool by admixture with other air and perhaps also to some extent by radiation . If this is the case there will be no special gradient produced by the condensation of vapour anywhere but in the small and limited regions where the condensation is occuring . In support of the above suggestions I may quote the results* obtained by unmanned balloons , which show that over cyclonic regions at * " Uberdie Temperaturabnahme mit der Hohe bis zu 10 km . , nach den Ergebnissen der internationalen Ballonaufsteige ; " ' Sitzungsberichte der Kaiserl . Akademie der Wissenschaften in Wien , Mathem.-naturw . Klasse,5 vol. 113 , Abt . IIa , May , 1904 . 1905 . ] Gradients in the West of Scotland and Surrey . 453 great heights the air is relatively warm , and over anticyclonic regions relatively cold . The temperature inversions are easily explained on the same hypothesis . The almost invariable accompaniment of an inversion of temperature has been , both at Crinan and Oxshott , a large decrease in the relative humidity , and this leads to the conclusion that the warmth is due to the compression of descending air rather than to the presence of a horizontal current of air from a warmer quarter . Inasmuch as descending air is warmed 1 ' C. for every 100 metres of its descent , it must soon become specifically lighter than the air around it and will tend to spread out as a sheet of warm air ; just as wine .or spirits may be made by careful pouring to form a separate layer on the surface of water . Hence each ascending current that is accompanied by much condensation of vapour should tend to form an inversion elsewhere . No doubt temperature inversions may be formed by a warm current of air coming from a warm quarter and overlying a cold stratum , but from my own experience I do not think this method to be of frequent occurrence in England . It is probably a mistake to suppose that our present instruments and methods can detect changes of temperature which may well suffice to set in motion large masses of the atmosphere . The vertical component of the velocity in the ordinary cyclone is extremely small\#151 ; a few hundred feet per hour perhaps . This may be inferred from the rate of rainfall , and also from the velocity and incurvature of the winds . Now on a non-rotating earth such an updraft would certainly require only a very small excess of temperature to produce it . In actual practice the temperature depends chiefly upon the direction of the wind , the northerly winds of the cyclone being cold and the southerly warm , and the changes so produced may well mask all other effects . Gradients at Oxshott . The temperature gradients at Oxshott are given in Table D. It has been previously stated that the majority of these ascents were not made with the definite idea of obtaining information , but rather with that of testing the apparatus . In consequence the kites have generally been allowed to rise as fast as they would , and have also been drawn in rapidly . Under these circumstances while the average gradient is perfectly clear , the gradient for short steps is not so easy to determine . For this reason it is given in the table in steps of 1000 instead of in steps of 500 metres . But while this applies to the individual ascents , it is not likely that there is much error in the average for each step of 500 metres , and these values have therefore been inserted in Table A for the sake of comparison . VOL. LXXVII.\#151 ; A. 2 K Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , Table D. Date . O\#151 ; IOOO . Wind . Below . Direction . Force . Above . Direction . Type of weather . 1904 . Feb. 19 ... 0*40 22 ... 0*90 Mar. 10 ... 0*60 18 ... 0*68 22 ... 1 *04 23 ... 0*95 30 ... 1 *08 Apr. 4 ... 1 -10 6 ... 0*85 7 ... 0-75 8 ... 1*10 13 ... 0*43 28 ... 0*84 29 ... 0*33 May 13 ... 1*03 Sept. 30 ... 0*64 Oct. 3 ... 0*73 5 ... 0 '32 6 ... 0*73 7 ... 0*60 8 ... 0*70 Nov. 3 ... 0*28 8 ... 0*74 30 ... 0*48 Dec. 1 ... 0*40 5 ... 0*84 13 ... 0*53 16 ... 0*58 17 ... 0*72 29 ... 0*42 1905 . Jan. 4 ... 0*63 5 ... 0*66 28 ... 0-44 30 ... 0*29 Feb. 3 ... 0 61 4 ... 0*56 10 ... 0*62 17 ... 0*70 Gradient . 1000\#151 ; 2000 . 0*00 0*48 0*46 0-46 0*22 S.W. 6 N.N.W. 3 N. by E. 5 S.W. 3 s.w. 4 N. by E. 6 S.W. 3 w.s.w. 7 w.s.w. 3 W.N.W. 6 W.S.W. 6 s. 7 w.s.w. 3 s.s.w. 4 w.s.w. 6 s.s.w. 4 N.E. 3 W.S.W. 4 w.s.w. 6 N.W. 5 N.W. 6 W. 3 w.s.w. 7 w.s.w. 4 w.s.w. 3 s.w. 6 N.W. 5 s.w. 6 s.w. 7 w. 5 w.s.w. 6 w. 5 w. 2 w.s.w. 4 w.s.w. 7 S.W. by W. 5 W.S.W. 3 t w. 5 W. W. W. by S. __# N.N.W. 8 . by W. w.s.w. s.w. S.W. by W.t W. by N. at 700J W. by N. N.W. W. N.W. N.W.S N. by W. W.S.W. w.s.w. W.N.W. N.W. || N.W. by W.T N.W. W.N.W. ff W.N.W.JJ W.N.W. * * * S ** T. N.W. , I N.E , A S.W. , A N.W. , I N.W. to N.E. , I N.W. , I N.W , I N.W , I N.W , I N.W , I S.W , I S.W , A S.W , I S.W , I S.W , I N.E , A S.W , C N.W , I N.W , I N.W , T. I N.W , I N.W , I S.W , I S.W , I N.W , C S.W , I s.w. I N.W , A N.W , I N.W , C **N.W , A N.W , I N.W , I N.W , I N.W , I N.W , I * Slight inversion at 900 m. f Very dry at 1500 m , 30 per cent. J W.S.W. at 1000 . Inversion 4 ' C. at 1200 m. , 20 per cent , humidity . S Inversion 2 ' C. at 900 m. || Wind very strong at 800 m. , light at 1700 m. T Inversion 7 ' C. at 900 m. ; very dry . ** Unusually high barometer , 30'90 and over , ft Wind very strong at 600 m. JJ Inversion at 1800 m. , 40 per cent , humidity . 1905 . ] Gradients in the West of Scotland and Surrey . Table D\#151 ; continued . Wind . Date . Below . Above . Type of weather . 0\#151 ; 1000 . 1000\#151 ; 2000 . Direction . Force . Direction . 1905 . Feb. 18 ... 0*46 -0*08 S.W. 6 W.N.W.* S.W. , c Mar. 2 ... 0-72 0*00 N.N.E. 6 N.E. N.E. , I 3 ... 0*90 \#151 ; N. 3 N. by E. N.E. , A 6 ... 0*69 0*00 W.S.W. 3 N.W. N.E. , C 8 ... 0*58 \#151 ; s.s.w. 5 S.W. S.W. , C 17 ... 0-67 \#151 ; s.s.w. 6 S.W. by W. S.W. , I 25 ... 0*64 \#151 ; s.w. 3 W.S.W. S.W. , c 28 ... 0*63 \#151 ; s.w. 5 W.S.W. S.W. , I 29 ... 0-73 0*32 s.w. 5 W.S.W. S.W. , c 31 ... 0 *67 0*67 W. by S. 5 W.N.W. N.W. , A Apr. 1 ... 0-90 0*23 S.S.W. 3 W.S.W. T. A. to C. S.W. 4 ... 0*74 0*47 w. 4 N.W. S.W. , C 7 ... 1 *06 0*65 N.W. 4 N.W. by W. y. C 13 ... 0*77 0*72 S.S.E. 5 \#151 ; S.E. , C 17 ... 0*28 \#151 ; N.E. 7 E.N.E. N.E. , C 20 ... 0*64 \#151 ; N.N.E. 5 \#151 ; N.E. , I 24 ... 0*48 \#151 ; W.N.W. 3 \#151 ; N.E. , c 25 ... 0*80 0*30 S.W. 4 W. by S. S.W. , 1 27 ... 0*73 0*00 S.W. 5 W.f S.W. , I 28 ... 0*63 \#151 ; S.S.W. 7 \#151 ; S.W. , c May 5 ... 0*58 0*32 N.N.E. 4 E.N.E. N.E. , I 8 ... 1 *00 \#151 ; N.N.W. 3 \#151 ; N.W. , I June 1 ... 0*85 0*70 S.W. by W. 5 W. by N. S.W. , A 14 ... 0*69 \#151 ; N.E. 4 \#151 ; S.E , I 19 ... 0*79 0*62 S.W. 3 W.S.W. S.W. , I Aug. 10 ... 0*93 \#151 ; S.W. 4 \#151 ; S.W. , c 11 ... 0*78 \#151 ; w. 3 \#151 ; N.W. , 0 16 ... 0*70 \#151 ; E.N.E. 5 \#151 ; N.E. , I 18 ... 1-00 \#151 ; S. 6 \#151 ; S W. , c 21 ... 1 *05 \#151 ; S.S.W. 3 S.W.t S.W. , I 26 ... 1 *10 0*07 s.s.w. 3 s.s.w.S S.W. , c 30 ... 0*53 0*50 N.W. 3 N.N.W. N.W. , c Sept. 2 ... 0-65 \#151 ; w. 4 \#151 ; N.W. , I 18 ... 1*00 0*00 E.N.E. 6 E. by N. || N.E. , c 23 ... 0*62 0*73 E.N.E. 4 \#151 ; N.E. , c 28 ... 0*95 0*54 E.N.E. 5 \#151 ; N.E. , c 30 ... 0*90 0*08 N. 4 N. by W.T N.W. , I The wind force is estimated from the pull and behaviour of the kites , and from the daily weather chart . The anemometer is too sheltered to be reliable . # Upper wind weak , t Inversion at 1100 m. X Gradient 10*5 m. to 900 m. , then inversion 4'*5 C. Humidity 40 per cent , at 1200 m. S Inversion with dryness 40 per cent , at 1800 m. || Inversion at 1100 m. Humidity 30 per cent. T Inversion 4'*5 C. at 1700 m. , No ascent of a less height than 666 metres is included in Table D. Where one gradient only is tabulated this is the average from the surface to the 456 Mr. W. H. Dines . Vertical Temperature [ Nov. 10 , highest point reached , which may have been anywhere between 666 and 1500 metres . It will be noticed that nearly all the ascents have been made with winds from some westerly point ; this is because it is difficult to start a kite with an east wind owing to a belt of trees and houses which lie to the west . But few ascents are tabulated for the summer months , owing partly to my absence in 1904 , and partly to want of sufficient wind in 1905 . In general there is not sufficient wind for kite flying in the south-east of England during the summer . There are in the table a few cases in which the adiabatic rate for dry air has been exceeded . This appears to me to be an impossibility , but it is unnecessary to discuss the question , since it has been fully gone into by Mr. H. H. Clayton , * who gives what seems to be a satisfactory explanation . The gradients at Oxshott are steeper than those at Crinan for the first thousand metres , but less steep for the second thousand . The first fact is easily explained , for the daily range of temperature is confined to the lower layers of air , it is larger inland and the Oxshott ascents have all been made in the daytime , when the surface temperature is near its maximum value . It is somewhat remarkable that the average gradient taken up to 2000 metres is almost identical in each case , although the values for the separate steps differ considerably . Can it be that there is some form of compensation , so that if in one step of 500 metres the gradient is increased , the same cause or set of causes tend to lower it in another step ? We have the following figures :\#151 ; Average to 2000 metres at Crinan in 1902 )\gt ; 0*54 0*53 " " Oxshott , 1904 and 1905 ... 0*50 The last step is missing for Crinan on August , 1903 , but up to 1500 m. it was 0*61 . Perhaps this increased value is associated with the bad weather of that time . Convection Currents . It very soon becomes obvious to anyone engaged in flying kites that there are great irregularities in the direction of motion of the air , both vertically and horizontally . The horizontal variation is shown beyond dispute by the changing azimuth of the kite , and the vertical variation may be inferred but cannot be predicated with absolute certainty by the changing altitude . Thus , if a kite is flying with 5000 feet of line the altitude may vary from 20 ' to * 'Annals of the Astronomical Observatory of Harvard College/ vol. 58 , part 1 , pp. 14 , 15 . 1905 . ] Gradients in the West of Scotland and Surrey . 457 50 ' or even 60 ' , but these angles , at least up to 55 ' , may be dependent on the velocity only and not on any vertical component . It has happened more than once that the angle of a kite with 3000 feet of wire has exceeded 70 ' , and these instances , which were all associated with the presence of a large massive cumulus cloud , show undoubtedly the existence of a strong vertical component . It is seldom , however , that the angle exceeds one which might be produced naturally by a strong horizontal current at the level of the kite . Hence on a day when the altitude is constantly changing through a large angle , although one feels certain that convection currents produce a large part of the change , it is not possible to say how large a part . These currents are . most likely produced by changes of temperature , and it is of interest to ascertain the precise difference of temperature between the falling and rising currents . With this object in view I have been carefully over the records obtained on such days , but with one exception have failed to find any important difference in the temperature at a definite level when the kite was rising , and when it was falling . This exception occurred on June 19 , 1905 , at 4.20 p.m. A kite was flying at the end of 8000 feet of wire , at a height of about 4500 feet , hidden behind a large cumulus cloud , the strain upon the wire being steadily maintained at 40 to 50 lbs. The tension in the wire rose rapidly but without jerks to 200 lbs. , and remained at this value for about 2\ minutes ; it fell back again in the same manner to 50 lbs. , at which value it remained steady . On winding in the kite the temperature trace was found to be somewhat blotted at the critical point , as , unfortunately , too much ink had been put on the pen , but it was sufficiently distinct to give the following data . In the course of a few minutes the kite had risen and fallen again through a vertical height of 1300 feet . This change of height was associated with a rise of tempera- , ture of 4 ' C. , but the temperature was not symmetrical with regard to the height . About three minutes before the updraft occurred the temperature was 5 ' C. at a height of 4500 feet , it then rose steadily to 9 ' C. at 5800 feet , the highest point reached , and declined to 7 ' C. as the kite fell back to its original level . During the same period the relative humidity rose from 90 to 100 per cent. , and fell back to 95 per cent. In this particular instance there is little doubt that the kite was caught in a powerful ascending current . The rise of temperature with elevation could hardly be due to the ordinary inversion , because it was associated with an increase of the humidity , whereas a temperature inversion is generally accompanied by great dryness . It is probable that these currents are sometimes responsible for the breaking away of a kite , for this is not by any means the first time a similar phenomenon has been noted , but it is the Sir W. D. Niven . [ Mar. 22 , first time that the kite has escaped undamaged and the trace been decipherable . In general a steady and uniform wind is associated with steady temperature conditions , but when the temperature at a given height is subject to much fluctuation , so that the meteorograph registers different temperatures each time it passes through that height , the wind also is usually variable in direction and velocity , but these latter conditions are not necessarily accompanied by a steep temperature gradient . The Calculation of Ellipsoidal Harmonics . By Sir W. D. Niven , K.C.B. , V.-P.R.S . ( Received March 22 , \#151 ; Read March 29 , 1906 . ) 1 . The object of this note is to show how ellipsoidal harmonics of the fourth , fifth , sixth , and seventh degrees may be calculated . Some of the fourth and fifth degrees are easily found , depending as they do upon the solution of a quadratic equation . When , however , the type of the harmonic of the fourth degree is \#169 ; i \#169 ; 2 where , if we employ G-reek letters for current co-ordinates , \#169 ; 1 = _P_ + _2 ? 1_+_\#163 ; __1 1 a2+01b2+0xc2 + t2 " 2 y2 @2 = - ? ---b H---5---1 , 2 a2+02 b2+02 e2+ and , in order that \#169 ; 1 @2 may satisfy Laplace 's equation , the quantities 0U 02 are to be found from a2+01 + b2+01 + c2+0 ! +0i-02 a ? +02 b2+02 02\#151 ; 01 0 , 0 , ( 1 ) ( 2 ) the elimination of 92 leads to a sextic equation in 9\ . Since , however , the roots occur in pairs as in ( 1 ) and ( 2 ) , if we put 0l + 02 = 2u , 0i \#151 ; 02 = 2v , ( 3 ) the equations for u and v derived from ( 1 ) and ( 2 ) will be of lower degrees than the sixth . When the substitutions ( 3 ) are made in ( 1 ) the latter becomes ---- -----1----1------1----------f-- = 0 , ( 4 ) a2-\-u + v b2 + u + v c2-\-u + v v and equation ( 2 ) will be the same with the sign of v changed .

rspa_1906_0040

0950-1207

The calculation of ellipsoidal harmonics.

458

464

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir W. D. Niven, K. C. B., V.-P. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0040

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0040

10.1098/rspa.1906.0040

Formulae

Tables

Mathematics

]\gt ; Sir W. D. Niven . [ Mar. 22 , first time that the kite has escaped and the trace been decipherable . In general a steady and uniform wind is associated with steady temperature conditions , but when the temperature at a given height is subject to much fluctuation , so that the meteorograph registers different temperatures each time it passes that height , the wind also is usually variable in direction and velocity , but these latter conditions are not necessarily accompanied by a steep temperature gradient . The Calculation of rmonics . By Sir W. D. NIVEN , K.C.B. , V.-P.R.S . ( Received Iarch 22 , \mdash ; Read March 29 , 1906 . 1 . object of this note is to show how ellipsoidal harmonics of the fourth , fifth , sixth , and seventh rees may be calculated . Some of the fourth and fifth rees are easily found , depending as they do upon the solution of a quadratic equation . When , however , the type of the harmonic of the fourth degree is where , if we employ Greek letters for current co-ordinates , and , in order that ? satisfy Laplace 's equation , the quantities are to be found from , ( 1 ) , ( 2 ) the elimination of leads to a sextic equation in . Since , however , the roots occur in pairs as in ( l ) and ( 2 ) , if we put , ( 3 ) the equations for and derived from ( 1 ) and ( 2 ) will be of lower rees than the When the substitutions ( 3 ) are made in ( 1 ) the latter becomes , ( 4 ) and equation ( 2 ) will be the same with the sign of 1906 . ] The Calculation of Etlipsoidal rmonics . Multiplying up in ( 4 ) , arranging in powers of and putting for the sum of the quantities , P2 for their sum taken two and two and for their product , we find . ( 5 ) As this equation is true when is entered for , it follows that . ( 6 ) Hence . ( 7 ) This is a cubic in which when solved leads to the values of corresponding to those of 2 . To express the cubic in a convenient form let be in ascending order of magnitude and write . ( 8 ) Then will , ( 9 ) and , ( 10 ) Entering these values in ( 7 ) , we obtain . ( 11 ) As the roots of this equation are all real the equation may be solved by Avhe method given in treatises on trigonometry . By putting , ( 12 ) we obtain , ( 13 ) where , The solution is then where The corresponding expression for the difference of the roots is given by . ( 14 ) The equations ( 12 ) , ( 13 ) , completely determine the values of and they show that there are three harmonics of the type considered . 3 . Harmonics of the types may be calculated Sir W. D. Niven . [ Mar. 22 , in similar fashion , but the working being in all respects like that in SS1 , 2 need not be repeated . Equations ( 1 ) and ( 2 ) will , of course , be different . For instance , if we are considering the first term in equations ( 1 ) and ( 2 ) must be multiplied by 3 , and if we are considering the second and third terms must be multiplied by 3 . The results for the seven harmonics described above will now be stated in the final forms suitable to the solution of S2 , i.e. , in the forms similar to those expressed by the three ations ( , ( 13 ) , ( 14 ) . ; ; ; ( 27X ) ; ( 27X ) ; ; ( 33X ) ; ; ( 33X ) ; ; ( 33X ) ; ; ( 39X ) ; . 1906 . ] The Calculation of soidal 4 . The results given in the preceding section exhaust all the cases in which the harmonic has two factors . We pass on to the harmonic of ixth d with three such factors We have to solve the following set of equations:\mdash ; . ( 15 ) . ( 16 ) . ( 17 ) Following the method of S1 , we now put ( 18 ) Lnd , with these substitutions , equation ( 15 ) becomes . ( 19 ) Or , on multiplying up , . ( 20 ) Similarly , . ( 21 ) The third equation need not be written . In these equations have the same meanings as in S 1 , except that is now the mean of three 's instead of two . As the determination of . , from the equations appears not to be practicable , will be ound in terms of First eliminate from ( 20 ) and ( 21 ) that O. There esults . ( 22 ) will be noticed that is a symmetrical function of , for it is . This quantity , as it appears frequently in the Nork , will be denoted by Sir W. D. Niven . hIar . Combining ( 22 ) with another equation of the same form , with the letters interchanged , we find , ( 23 ) To obtain subtract ( 21 ) from ( 20 ) , ] use of . There results ) Writing two other similar equations and adding the three we find , 01 removing the factor 3 , . ( 26 The elimination from , ( 24 ) , ( 26 ) of and the product of the difference of may now be made and we obtain . ( 27 This is a biquadratic in , showing that there are four harmonics of the under discussion . The equation giving must now be found . It must clearly be'of th , ( 28 where and is to be determined from the condition Now the square of the product on the left is , by a known theorem , equal where are the roots of or , we obtain The of llay be taken , for the roots all lie between and ) , and if they are in ascending order of numerical fnitude , and will be positive and ative . 1906 . ] The of Ellipsoidal Harmonics . 5 . The harmonics of seventh degree can be determined in a similar manner . As , however , the expressions are somewhat longer to write , it will sufficient to state the leading subsidiary results for one type in such a that similar relations can be easily found for the other two by interange of letters . The type chosen is ( A ) 5 ( B ) 5 ( c ) 4 . From these three results the equation for the sum of the roots and , with he aid of , the equation for the difference of the roots can be eadily formed , as in S4 . 6 . To verify results proceed as follows : , which is quivalent to equation ( 1 ) or ( 2 ) , for instance , one value of being thus , will give a second between and , say ought then to satisfy equation ( 13 ) with zero . In like manner : we put or will be one root and the other will lie etween and , say , and ought then to atisfy ( 13 ) with unity . By this means the of the results given 1 S 3 has been tested both when and Further it appears that of the three members of any type of harmonic rith two factors one member has both roots between and nother has both between and , and the third has one root in one ompartment and the other in the other . Again , with harmonics with three factors one has all three values of between and , a second all etween and and the other two have respectively one in one partment and two in the other . [ Added March 29 . Approximations.\mdash ; The solutions boiven above pplicable whether the ellipsoids are prolate or oblate , but in some of the hysical problems in which the harmonics under consideration might be equired , either is nearly equal to or to , and in those cases the exact xpressions would be efully replaced by series in powers of or , being applicable to a prolate and to an oblate ellipsoid . for instance , the harmonic , we have already found the equation 11 ) , which is suitable to the prolate form . The corresponding equation for he oblate is most readily obtained by writing The Calculation of Ellvpsoidal rmonics . in the relation ( 7 ) . We then obtain To solve this last in series , in powers of , observe that the part of the equation not involving may be written and proceed by successive approximations . The roots will then be found to be and the corresponding values of , for the differences , ( 30 ) If we compare the equation in with that in , it is clear that if we write instead of and change the signs of the series for , we shall get the values of and the corresponding differences . This method applies to harmonics of the fifth degree , except that in the cases and , we shall not hnve the same simple relations between the equations in and When we reach the partition line between prolate and oblate ellipsoids , and at this particular point the expressions for the roots are simpler . ]

rspa_1906_0041

0950-1207

On the observations of stars made in some British stone circles. \#x2014;Second note.

465

472

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir Norman Lockyer, K. C. B., F. R. S., LL. D., Sc. D.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0041

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0041

10.1098/rspa.1906.0041

Astronomy

Biography

Astronomy

465 On the Observations of Stars made in some British Stone Circles.\#151 ; Second Note . By Sir Norman Lockyer , K.C.B. , F.R.S. , LL. D. , Sc. D. , Director Solar Physics Observatory . ( Received March 19 , \#151 ; Read March 29 , 1906 . ) In a preliminary note communicated to the Royal Society on March 15,1905 , I stated that I was attempting to continue here the researches in temple orientation carried on by myself in Egypt in 1891 , by Mr. Penrose in Greece .in 1892 , and by both of us at Stonehenge in 1901 . I pointed out that from the observations I had made at the Hurlers and Stanton Drew , of which I gave an account , it seemed probable that the outstanding stones of our ancient monuments had been erected to assist astronomical observations . Since the date of the preliminary note I have , in intervals of leisure , visited many of the British monuments , and friends have been good enough to make observations at others . I propose in the present note to state as briefly as possible the chief results I have obtained in cases where the enquiry has been complete enough to warrant definite conclusions being drawn . I have not in all cases been able to make a complete survey of the azimuths and the height of the sky-line of the existing monuments , and everywhere the destruction has been so serious that a complete story in any locality is out of the question . Clock-Stars . The practice so long employed in Egypt of determining time at night by the revolution of a star round the pole was followed in the British Circles . This practice was to watch a first magnitude star , which I named a " clock-star , " * of such a declination that it just dipped below the northern horizon so as to be visible for almost the whole of its path . One of the earliest temples in Egypt concerning which we have historical references to check the orientation results , was built to carry on these night observations at Denderah , lat. N. 26 ' 10 ' . The star observed was a Ursae Majoris , decl . N. 58 ' 52 ' , passing 5 ' below the northern horizon ; date ( for horizon 1 ' high ) about 4950 B.c. , i.e.y in the times of the Shemsu Heru , before Mena , as is distinctly stated in the inscriptions . After a Ursse Majoris had become circumpolar in the latitude of Denderah , 7 Draconis , which had ceased to be circumpolar , and so fulfilled the conditions to which I have referred , replaced it . Its declination was 58 ' 52 ' N. about * ' Dawn of Astronomy , ' 1894 , p. 343 . Sir N. Lockyer . On the Observations of [ Mar. 19 , 3100 B.C. , and it therefore could have been watched rising in the axis prolonged of the old temple in the time of Pepi , who restored it then , and is stated to have deposited a copy of the old plan in a cavity in the new walls . So far as the enquiry has gone , these clock-star observations were introduced into Britain about 2300 B.c. In my statement concerning them I will deal with the astronomical conditions for lat. 50 ' N. , as it is in Cornwall that the evidence is most plentiful and conclusive . In that latitude and at that time Arcturus , decl . N. 42 ' , was just circumpolar and therefore , with a sea horizon , neither rose nor set . Capella , decl . N. 31 ' , when northing , was 9 ' below the horizon , so that it rose and set in azimuths N. 37 ' E. and N. 37 ' W. respectively ; it was therefore invisible for a long time and was an awkward clock-star in consequence . Fig. 1 represents diagrammatically the conditions named , the circumpolar paths of Arcturus and Capella being shown by the smaller and the larger circle respectively . AB represents the actual sea horizon and A'B ' a locally raised horizon , whilst the dotted portion of the larger circle represents the non-visible part of Capella 's apparent path . Pig . 1 . What the British astronomer-priests did therefore in the majority of cases was to set up their temples in a locality where the N.E. horizon was high , so that Arcturus rose over it and was invisible for only a short time , as shown in the diagram by the raised horizon A'B ' . The two following lists contain the names and positions of monuments where Arcturus was used as a clock-star . In the first , the elevation of the 1906 . ] Stars made in some British Stone Circles . sky-line in each case has been actually measured , and the meaning and date of the alignment are therefore fairly trustworthy ; but in the second list the elevations have been estimated from the differences of contour shown on the 1-inch Ordnance map , and the dates must be accepted as open to future revision . Arcturus as a Clock-Star . i. Monument . Position . Alignment . Az . Hills . Decl. N. Date B.C. Lat. N. Long. W. o / / / o / / / o / o / o / Tregeseal 50 7 50 5 39 20 Circ . to Carn Kenid- N. 12 8 E. 4 0 42 33 2330 ]ack Circ . to barrow 800 ' N. 20 8E . 3 50 40 29 1970 dist. The Hurlers* ... 50 31 0 4 27 20 S. circ . over cent , circle N.11 15E . 3 24 41 38 2170 Cent. circ . over N. N. 14 18 E. 3 24 41 9 2090 circle N. circ . over N.E. N.18 44E . 3 24 40 6 1900 barrow Merrivale 50 33 15 4 2 30 Direction of smaller N.24 25 E. 5 0 39 55 1860 avenue Fernworthy ... 50 38 30 3 54 10 Direction of avenue N. 13 O . 1 15 39 7 1720 Second direction of N.14 20 E. 1 15 38 51 1670 avenue Stanton Drew ... 51 22 0 2 34 30 Cent , of Grt . Circle N.17 59 E. 2 33 38 38 1620 to Quoit F ern worthy ... 50 38 30 3 54 10 Direction of avenue N. 15 45E . 1 15 38 34 1610 Merry Maidens 50 3 40 5 35 25 Circ . to stone in the road N. 11 45 E. 0 12 38 27 1590 Stanton Drew ... 51 22 0 2 34 30 S.W. circ . to cent. N. 19 51E . 1 44 37 30 1420 of Gt . Circ . 1 * The dates here given for the Hurlers are earlier than those stated in the preliminary paper with an assumed sky-line . The actual elevation of the horizon has , in the meantime , been supplied by Captain Henderson . The alteration of the Stanton Drew date is not so great because the hills are lower . ii . Position . Decl. Date Monument . Alignment . Az . Hills . Lat. N. Long. W. N. B.C. Trowlesworthy ... O / / / 50 27 30 o / / / 4 0 20 Direction of prim- ' / N. 7 O . 2 52 o / 41 24 2130 ary avenue Direction of final N. 12 O . 2 52 41 6 2080 avenue 40 39 2000 Longstone ( Tregeseal ) Tee Moor 50 8 10 5 38 10 Longstone to Chun Cromlech N. 9 O . 1 43 50 26 30 | 3 59 40 Direction of avenue N. 22 O . 2 28 38 17 1560 1 Sir N. Lockyer . On the Observations oj [ Mar. 19 In some cases , for one reason or another , this arrangement was not carried out , and Capella , in spite of the objection I have stated , was used in the following circles :\#151 ; Capella as a Clock-Star . Monument . Position . Alignment . Az . Hills . Decl. N. Date B.C. Lat. N. Long. W. i. Boscawen-Un ... Merry Maidens ... ii . The Nine Maidens Stripple Stones ... o / / / 50 5 20 50 3 40 50 28 20 50 32 51 O / It 5 37 0 5 35 25 4 54 30 4 37 5 Circ . to Stone Cross Circ . over " The Pipers " Direction of Nine Maidens row Centre to N.E. bastion N. 43 15 E. N. 38 26 E. N. 28 0 E. N. 26 OE . o / 2 7 0 20 0 0 0 22 29 26 29 58 33 47 34 38 2250 2160 1480 1320 At the Merry Maidens , however , with nearly a sea-horizon , when Arcturus ceased to be circumpolar , and rose and set in azimuth jST . 11 ' 45 ' E. , it replaced Capella and was used as a clock-star after 1600 b.c. The May- Year . The first astronomical immigrants into Britain brought the May-year with them . This year is quartered by the suiTs passage four times through 16 ' 20 ' decl . N. and S. , the Gregorian dates being May 6 , August 8 , November 8 , and February 4 . There is evidence that this year was used in Babylon , Egypt , and afterwards in Greece . In the two former countries May was the harvest month , and thus became the chief month in the year . The dates were apt to vary slightly with the local harvest time . The earliest temple aligned to the sun at this festival seems to have been that of Ptah at Memphis , 5200 b.c. This date of the building of the temple is obtained by the evidence that the god Ptah represented the star Capella , as there is a Ptah temple at Thebes aligned on Capella and outside the solar limit . There was also , in all probability , a similar temple at Annu ( Heliopolis , lat. N. 30 ' 10 ' ) , but it has disappeared . The light of the sun fell along the axis when the sun had the decl . N. 11 ' , the Gregorian dates being April 18 and August 24 . Another May temple is that of Menu at Thebes ( lat. N. 25 ' ) , date 3200 b.c. , sun 's decl . N. 15 ' , Gregorian date , May 1 . The researches of Mr. Penrose in Greece have provided us with temples 1906 . ] Stars made in some British Stone Circles . oriented to the May-year sun at Athens ( including the Hecatompedon and older Erechtheum ) , Corinth , and iEgina . The explorations of Sir H. Layard at Nineveh have shown that the temple in Sennacherib 's palace was also oriented to the May sun . Alignments in British monuments designed to mark the place of the sun 's rising or setting on the quarter-days of the May-year have been found as follows:\#151 ; Monument . Position . May and August . February and November . Lat. N. Long. W. Eising . Setting . Eising . Setting . o in o / / / Merry Maidens 50 3 40 5 35 25 X X X Boscawen-Un 50 5 20 5 37 0 X X ? Tregeseal 50 7 50 5 39 20 X ? Longstone ( Tregeseal ) 50 8 10 5 38 10 X ? Down Tor 50 30 10 3 59 30 X Merrivale 50 33 15 4 2 30 X The Hurlers 50 31 0 4 27 20 X ? Stonehenge 51 10 40 1 49 30 X X Stanton Drew 51 22 0 2 34 30 X Stenness 59 0 10 3 13 40 X X X * It was the practice in ancient times for the astronomer-priests not only to watch the clock-stars during the night , but also other stars which rose or set about an hour before the sun so as to give warning of its approach on the days of the principal festivals . Each clock-star , if it rose and set very near the north point , might be depended upon to herald the sunrise on one of the critical days of the year , but for the others other stars would require to be observed . That this practice was fully employed in Britain is shown below:\#151 ; May Warnings . Monument . Star . Date , or dates , b.c. Stonehenge Pleiades ( E ) 1950 Merry Maidens Pleiades ( E ) 1930 Antares ( S ) 1310 The Hurlers Antares ( S ) 1720 Pleiades ( E ) 1610 Merrivale Pleiades ( E ) 1610 1420 Boscawen-Un Pleiades ( E ) 1480 Tregeseal Pleiades ( E ) 1270 Stenness Pleiades ( E ) 1230 Longstone ( Tregeseal ) ... Pleiades ( E ) 1030 ( E ) = rising . ( S ) = setting . VOL. LXXVII.\#151 ; A. 470 Sir N. Lockyer . On the Observations of [ Mar. 19 , August Warnings.\#151 ; Sunrise at the August festival was heralded by the rising of Arcturus which , as we have seen , was also used as a clock-star . The alignments and dates given in the Arcturus table therefrom hold good for August . At the Hurlers , where the hill over which Arcturus was observed fell away abruptly , we find Sirius supplanting Arcturus as the warning star for August in 1690 B.c. November Warnings.\#151 ; So far I have discovered no evidence that any star was employed to herald the November sun . There are two obvious reasons for this :\#151 ; In the first place , at the November festival the celebration took place at suns^ , and the sun itself could be watched . Secondly , the prevalent atmospheric conditions which obtain in Britain during November would not be conducive to the making of stellar observations at the horizon ; and the people who built these temples only observed risings or settings . February Warnings.\#151 ; In just the same way that Arcturus served the double purpose of clock-star and herald for the August sun , so did Capella serve to warn the February sun in addition to its use as a clock-star . The alignments and dates given in the Capella table , will , therefore , hold good for its employment at the February quarter-day . The Solstitial Year . I have evidence that the observation and worship of the solstitial sun , such as was carried on in Egypt , at Karnak and possibly places of still greater antiquity , * was continued in other stone temples in Britain besides Stonehenge . Although some of the alignments already found are in all probability solstitial , the variation of the sun 's solstitial declination is so small that the most careful determination of their azimuths and angular elevations of the horizons must be made before the declinations and consequent dates can be arrived at . Such a determination was made by Mr. Penrose and myself at Stonehenge in 1901 and reference to our paperf on the subject will show that , even after taking the greatest precautions , we were unable to fix the date of the monument with a smaller limit of error than 200 years . Those monuments at which possible solstitial alignments have so far been found are given in the following table :\#151 ; * ( Dawn of Astronomy/ p. 78 , London , 1894 . t ' Roy . Soc. Proc./ vol. 69 , pp. 137\#151 ; 147 . 1906.1 Stars made in some British Stone Circles . Monument . Summer solstice . Winter solstice . Rising . Setting . Rising . Setting . Stonehenge . ^ X Stanton Drew X Stenness X X X Boscawen-Un X Tregeseal X Longstone ( Tregeseal ) ... X In several instances , as for example at the Boscawen-Un circle , there are two stones near to the solstitial sight-line , one of which can never have been used to indicate the solstitial line . Nearly the same thing occurs at Stonehenge where the isolated monolith , the Friar 's Heel , is near , but to the east of the solstitial sight-line ( i.e.9 the avenue ) . It seems probable that the solstice festival being of fundamental importance with the temple builders , they needed some days of warning instead of the hour or so provided by an heliacal rising or setting of a star . For this reason the stone was erected so that sunrise would take place in its direction some days before the solstice . In all the cases yet noted this stone is on the equator side , i.e.y to the E. of the true solstitial line and so would act as a warner . The Equinoctial Year . Only in one or two of the temples yet investigated has any evidence of an equinoctial worship been discovered . Even in these cases it is not conclusive , so for the present I leave this part of the question open . My best thanks for assistance in the present enquiry are due to the following:\#151 ; To Colonel Duncan A. Johnston , RE . , C.B. , late Director-General of the Ordnance Survey , and to Colonel B. C. Hellard , B.E. , the present Director-General , I am indebted for the azimuths of the side-lines on various 25-inch maps and of several important sight-lines . Mr. W. E. Bolston , F.RA . S. , one of the computers in this observatory , has calculated the declinations of the sun and stars corresponding to the azimuths determined , the consequent dates being taken from the tables prepared by Mr. J. N. Stockwell , Dr. W. J. S. Lockyer and Dr. O. Danckwortt . In obtaining local particulars and measurements I have received invaluable assistance from Captain J. S. Henderson and Mr. Horton Bolitho 2 l 2 472 Hon. R. J. Strutt . On Radium in the Earth 's [ Mar. 30 , at the Hurlers , Professors Lloyd Moi^an and Morrow and Mr. Dymond at Stanton Drew , and Messrs. H. Bolitho , H. Thomas and Captain Henderson in south-west Cornwall . To Lord Falmouth and Mr. Wallis I am also under obligations , as they were good enough to assist my inquiries by allowing an opening to be made in a stone wall at the Merry Maidens to view the alignment to the Pipers . On the Distribution of Radium in the Earth 's Crust , and on the Earth 's Internal Heat . By the Hon. R. J. Strutt , F.R.S. , Fellow of Trinity College , Cambridge . ( Received March 30 , \#151 ; Read April 5 , 1906 . ) CONTENTS . PAGE S 1.\#151 ; Introduction ... ... ... ... ... ... ... ... ... ... ... . 472 S 2.\#151 ; Choice of Material ... ... ... ... ... ... ... ... ... 473 S 3.\#151 ; Method of determining Radium Content ... ... ... 473 S 4.\#151 ; Results for Igneous Rocks ... ... ... ... ... ... ... 478 S 5.\#151 ; Meteorites ... ... ... ... ... ... ... ... ... ... ... ... 479 S 6.\#151 ; The Earth 's Internal Heat ... ... ... ... ... ... ... 480 S 7.\#151 ; Internal Heat of the Moon ... ... ... ... ... ... . . 484 S 8.\#151 ; Summary of Conclusions ... ... ... ... ... ... ... . . 485 S 1.\#151 ; Introduction . Professor Rutherford* has given a calculation which suggests that there may be enough radium in the earth to account for the temperature gradient observed near the surface . The question is of great interest from a cosmical point of view . For if we find that the earth 's internal heat is due to radio-activity , and if we assume , as has been usual , that this heat is due to some vestiges of the cause operative in the sun and stars , it would follow that these latter are heated by radio-active changes also . Professor Rutherford 's calculation was based on some data given by Elster and Geitel on the amount of radium emanation which diffused out from a sample of clay . These data were obtained at a time when the quantitative determination of minute amounts of radium was not well understood , and are moreover inadequate to give any general idea of the average amount * ' Radio-activity , ' p. 494 , 2nd Edition .

rspa_1906_0042

0950-1207

On the distribution of radium in the Earth's crust and on the Earth\#x2019;s internal heat.

472

485

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Hon. R. J. Strutt, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0042

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10.1098/rspa.1906.0042

Tables

Thermodynamics

Tables

]\gt ; Hon. . J. Strutt . On in the Earth 's [ Mar. 30 , at the Hurlers , Professors Lloyd and Morrow and Mr. Dymond at nton Drew , and Messrs. H. Bolitho , H. Thomas and Captain Henderson in south-west Cornwall . To Lord . Wallis I also under ations , as they were ( ( enough to assist my iii1 allowi e to be made in stone the JMerry lIaidcns to view the ment to the the Distribution of in the Earth 's Crnst , on the Earth 's Heat . By the Hon. R. J. , Fellow of Trinity ) ( Received Inrch30 , \mdash ; Read Apri15 , 1906 . ) Heat of the Moon .\mdash ; Summary of Conclusions 485 S Professor Rutherford* has given a calculation which sug.ests that there may enough lium in the earth to account for the uemperature radient observed near the surface . rfhe question is of great interest from a cosmical point of view . For if we find that the carth 's internal heat is due to radio-activity , and if we assume , as ) usual , this heat is due to some of the cause operative in the sun and stars , would follow that these latter are heated radio-active changes also . Professor 's calculation was based on some data iven by Elster and Geitel on the amount of dium enation which diffused out from a samI ) of clay . These data wer obtained at a time when the determination of minute amounts of radium was not well understood , are moreover to rive any general idea of the average amount -activity , ' p. 494 , Edition . 1906 . ] Crust , and the Earth 's Lternal Heaf . of in the earth 's crust . I have , therefore , made an exten sive ation of the amount of radium in various representative rocks . This forms the subject of the present paper . The results are very surprising . Considerable detail will therefore be iven , in order to enable readers to judge whether there is any probability of these results substantially incorrect . S of The earth 's crust , which is alone accessible to us , consists of neous rocks , and of sedimentary material which results from the action of geological chahges upon these rocks . No doubt the radium content of the original igneous rocks might be inferred fairly well from the examination of a large number of sedimentary ones . It is , , much more satisfactory to examine the igneous materials directly , for then they can be classed themselves as to their radium content . I have examined a few sedimentary rocks , but do not attach much importance to them , and rely chiefly on ults obtained with original neous llaterial for the average radium content of the earth 's . The results with regard to sedimentary rocks will be iven in a future paper . I hope also to determine which of the numerous minerals contained in igneous rocks carry the.radium , a subject not in the present communication . Meteorites have a special interest of their own . A few determinntions have been made on them , and are incidentally included in this ) S3.\mdash ; Metlod of Radium in the rocks was atiyely determined by means of its emanation . A solution of the rock was stored till the tion h mulated . This latter was then extracted by , and introduced into an electroscope . The increased rate of leak produced was a measure of the alnount of radium present . This measul.e was made bsolute by through the same process with a uranium of known radium content . In order to make certain of exbracting the emanation , it is essential to decompose the rock completely by chemical ency . In the case of and metallic meteorites , this can be efected by SiJlution in hydrochloric acid , but in the case of siliceous materials , fusion with alkaline carbonate is necessary . The standard procedure was as follows :ramlnes of the rock was bloken up in an iron lnortar , and then finely . ground in an one , until Hon. R. J. Strutt . On in the Earth 's [ Mar. 30 , it would pass through a sieve of 90 threads to the inch . This process could be carried out by an unskilled assistant in less than an hour , and ensured easy decomposition of rock . Two hundred and fifty grammes of a mixture of anhydrous scdium and potassium carbonates was melted in platinum basin . For this purpose the basin was surrounded with an extemporised furnace casing of asbestos millboard , and heated from below by means of a oas blowpipe . The blowpipe was supplied with air from an automatic blowing apparatus worked by water pressure . As soon as the carbonate was melted , the rock powcier was thown on to its surface in snlall portions at a time until it had all ) added . The fusion usually continued for about an hour after all effervescence was over . The residue was then ested with hot water to dissolve out the alkaline silicates and carbonates . The portion insoluble in water was dissolved in hydrochloric acid . Some silica always separated from the acid solution , and was allowed to remain floating in it . The two solutions , aqueous and acid , were set aside in separate flasks closed with indiarubber stoppers . Mixing them was ayoided , because of the bulky and unmanageable precipitate of silica which would have been down . with hydrofluoric acid has some advant over the use of sodium carbonate . It requires , however , more minute pulveris tion of the material , and is more costly in practice to difficulties of and . After one or two trials its use was abandoned . The two flasks , the respective solutions were ] lowed to stand for deterlninate number of days . the minimum . More colnmonly a fortnight or weeks was allowed . During this time , any radium contained in the rock was generating emanation . After three weeks the quantity has practicallyleached a maximum . The fraction this maximum generated in any lesser period could be calculated from the equation for the rise of activity , inally given Rutherford and Soddy . I described a method for quantitatively . the emanation in ' . Soc. Proc , vol. 76 , 1905 , p. 89 . An improved modification of that nlcthod h been employed in the investigation . The flask ( see figure ) CJntains the solution . The accumulated emanation is at first partly dissolved , partly contained in the air which occupies the upper part of the flask . flask is uncorked and attached to the lower end of the condenser as rapidly as possible , so as to avoid loss of emanation . A is then boiled to expel radium emanation . The steam which issues is ndensed in and drops back . The air with emanation passes out 06 . ] Crust , and the FIG. 1 . into the gasholder , displacing the water which previously filled it . This boiling is continued for one hour . At the end of that , the cooling water is run off from the jacket of B. Steam is allow ed to pass so as to wash out all air and emanation from A and from the connecting tubes into C. The indiarubber connection at is then nipped , the burner under the flask immediately withdrawn . In this way the emanation is collected in the gasholder . It merely remains to transfer it to the electroscope when cold . The latter is exhausted , and the emanation allowed to pass into it through the stop-cock and a drying tube . Air is then admitted to the electroscope up to atmospheric pressure . After an interval of three hours , to allow the active deposit to form , the rate of leak is read . The normal leak of the electroscope was repeatedly determined in the course of the investigation . * To do this conveniently , it is very desirable to have the pinchcock attached to a firm support , so that it can be screwed up with one Hon. R. J. Strutt . On Radium in the 's [ Mar. 30 , The are ) values scale-divisions per hour , 24 , , 241 , 24 , 23 , . Mean , 23 nearly . These values were taken soon after exhaustion of the electroscope and admi isio of If the left closed , the leak was found to have risen apprecial ) , after ) lapse of a dny . A similar effect been noticed at the Cavendish , and is , 1 believe , under investigation there . It does not come into question here , since time neyer allowed for it to enter . In work of this kind , the effecb to be looked for is small , it is most necessary to make certain that the emanation really comes from material under investigation , and not from an . extraneous source . I was deceived in this way in that mercury off an emanation . In the present case , every precaution was taken . The laboratory hsd never had radio-active materials introduced into it . Solutions of the employed were separately tested for emanation , after they had stood closed for a fortnigbt , with the following results:\mdash ; Rate of leak . Sodium carbonate , 250 ramlnes Potassium carbonate , Hydrochloric acid , 500 . Water 2000 ( -.c . In none of these cases does the leak measurably exceed that normal to the electroscope . It 1nay , , bc concluded that tlJe r used to decompose the rocks responsible for the emanation obtained . Cambridge tap water was used to ulake the solutions and to fill the gasholder ) . water inally contains dissolved emanation , as Professor J. J. Thonnson has shown . It was therefore carefully boiled to expel this before use . The test iven above was made on water which already been boiled setting it aside , shows that no measurable quantity of enlanation is generated by dissolved matel.ial when the supply has been expelled . The ( boiled ) water in the asholder was after each expel.iment . uthcrford and have ined the radium content of lerals in absolute measure . They find that the radium associated with 1 gramtle of uraninm is ranlme . I use this value rather than own they tested the production of their standard , while I had no test puriCy of mine . ' Amer . . Sci. , 1905 , p. . Proc , p. 88 . 1906 . ] Crust , and The uranium minerals used for standardisation were Torbernite ( copper uranium phosphate ) containing 60 per cent. ( per cent. uranium ) and pitchblende , . cent. ( per cent. uranium ) . The rate of leak due to the emanation produced by a few milligrammes of each of these in } was determined . From this the quantity of radium was deduced , which would in an produce emanation to give a leak of one division per hour . This is the constant given in the last column of the following table . Standardisation Experiments . Rate of leak* Mineral . inema ttConstant Percentage of due to uranium ( metal ) . one dny . same sample Torbernite . . . . . Torbernite same sample Pitchblende same sample 624 *Corrected for normal leak of the electroscol ) The mean value for the constant is , or in other words a leak equal to one scale-division per hour represents gramme of radium in the sample examined , if the latter has had time to produce its maximum amount of emanation . Two specinlen determinations will now be given in detail , the first of granite from the Cape of Good Hope , the second of oliyine rock from the Isle of Rum . These are respectively representative of high and low radium content . Granite , 50 grammes.\mdash ; Solutions stood from March 21 to March 26 , per cent. of the maximum amount of emanation . Scale-div . per . Corrected . Emanation from acid solution 103 Emanation from alkaline solution 31 Total scale-div . per hour . Thus the equilibrium amount of emanation would ooive scale-divisions per hour , or per gramme of rock scnle-divisio1ls per hour . Th gramme of rock contains gramme or gramme radium . Hon. R. J. Strutt . On Radium in the Earth 's [ Mar. 30 , Olivine of rammes.\mdash ; Solutions stood from January 31 to February 19 , giving practically the equilibrium amount of emanation . Scale-div . per hour . Corrected . Emanation from acid solution Emanation from alkaline solution Total . scale-div . per hour . One gramme of rock would scale-division per hour , and contains gramme radium . This last exalnple represents , as mentioned above , nearly the lowest radium content encountered neous locks . It will be noticed that the leak produced by the emanation is , even in this unfavourable case , about half that normal to the electroscope , and is , therefore , quite well marked . It will be noticed also that the alkaline solution contains only a small proportion of the total radium present in the original rock . sults for Rocks . The results for neous rocks now be iven in tabular form and in order of content ( see next ) . It will be observed that , in general , rocks like , with a high of silica , are richer in lium than basic rocks . The rule , however , is by no means Uranium ores occur several of the rocks examined ; thus the granites . Nos. 2 and 6 occur near the pitchblende bearing yeins were worked at Wheal Trenwith , St. Ives . The syellite rocks , Nos. 3 , 8 , and 11 also contain local deposits of uranium minerals . These various rocks are fairly rich in radium , but do not stand in a class themselves . Tfius the concentration of lium in such deposits is extremely local , and cannot disturb any general conclusions as to the total amount of radium in the earth 's crust . Confirlnatory of this conclusion is the fact that the temperature gradient at Wheal Trenwitl ] , St. Ives , is quite Considerable quantities of occur in mine , but are evidently insufficient to cause isturl)ance i the distribution of temperature . * See Prestwich , ' Controverted Questions in Geology , p. 216 . Crust , the feteorites . Determinations have been made on one stony meteorite , on three samples meteoric iron , and on a sample of native iron from Ovifak , Disco Island , Greenland . The quantities available have been ions , and are entered on the list of results . Where the radium is entered as , it is to be underBtood that no leak was obtained which could clearly be distinguished from that normal to the electroscope . It will be observed that the stony meteorite contains about as much radium as those basic terrestrial rocks , which it resembles in eneral composition . No evidence was obtained of the presence of radium in iron meteorites . The Greenland iron contains a little radium . This was probably present in the siliceous material contained in this iron , which had been filtered off , decomposed by fusion and added to the main solution . Hon. R. J. Strutt . On in the Earth 's [ Mar. 30 , Quantity taken . Radium per grn Stony lleteoric iroll . gusta hnta C iron S jat . If be the mean mass of radium per cubic centimetre in the earth , the heat production of radium per gramme per second , then the total heat production must be , per second , If be the thermal conductivity of the surface rocks , then the total outflow of heat per second will be where ( is the temperature radient near the surface , as observed experimentally . If the ealth is in a thermally steady state , then these expressions will be equal , i. e. , or For I take the value For the temperature adient 1 F. in feet , or , in C.G.S. system , One gramme of radium calories per hour . This g)ives for the value , the 's radius , Thus If , therefore , we assume the earth to be in therlual equiliblium , then , even if the whole of the internal hcat is due to dium , the mean quantity per cubic cannot much exceed boramme per cubic See Prestwich , . cit. . cit. 1906 . ] , and the Heat . ceutimetre , aJways that the heat production of radium is not materially diminished under the conditions prevailing inside the earth . Rutherford , *taking somewhat different values for the constants involved , ve the value , equivalent to gramme per cubic centimetre . It will be observed that all the neous rocks examined , without exception , contain far more radium per cubic centimetre than this . The poorest of all , Greenland basalt , contains more than 10 times as mueh ; au average lock something like 50 or 60 times . The question must be faced : Why has not the earth a tenlperature gradient far larger than that observed ? The calculation given aboye assumes , \mdash ; ( 1 ) That the earth is in thermal equilibrium , i.e. , that the amount of heat which escapes per second is equal to the produced in time . ( 2 ) That no other source of internal heat than radium exists . ( 3 ) That gramnle of radium produces as much heat inside the earth as at the surface . As to the first sumption , to suppose that the earth is cooling only ravates the di.fficulty . To assume that it is getting hotter is an explanation not likely to be regarded with favour . I have not yet considered it quantitatively . As to the second sumption , there can be little doubt that a quantity of uranium proportional to the amount of radium exists in the rocks . Moreover , a trace of thorium is not improbably present . These sources of heat are not likely to be important , as compared with radium . There is , too , the possibility of the radio-activity of ordinary materials . If , however , heating effect from them is assumed , of the order of magnitude to be expected from the ionisation they boive , a temperature ooradient would result like 1000 times larger than that observed . I think this is conclusive against the theory that they have a genuine radioactivity of this order of magnitude . There remains the third assumption , stated above . This cannot be passed over so htly as the others , but will be more conveniently discussed later . I shall suppose for the moment thst it is justified , and the earth cannot contain more on the than gramme of radium per cubic centimetre . For surface rocks the experiments show that per cubic *Loc . cit. Too little to be detected in the ordinary course of analysis . See ' Nature , ' December 21 , 1905 . Hon. R. J. Strutt . On in tloe Earth 's [ Mar. 30 , cen timetre is a representative value . is , if anything , an understatement . Thus more than about 1/ 30 of the earth 's volume can consist of material similar to that encountered on the surface . This gives a depth of about 45 iles for the rocky crust , the total absence of radio-active material within . I shall next consider the distribution of temperature in a crust of this thickness . The curvature of so thin a crust is relatively small , and may , without appreciable sacrifice of accuracy , be arded . Let be the depth at any point , measured from the outer surface , the quantity of radium per cubic centinJetre , the heat developed in one second by 1 gramme of radium , the temperature at the depth , and the thermal conductivity . Then the equation of conduction is which gives by integration ' where and are constan ts . If the surface of the earth be assumed to be at C. , then when If be the thickness of the crust , , when . This is clear , since the temperature must be a maxirnum at the inner boundary of the crust . The terior core , free from radium , must be at a uniform temperature throughout . these values we get and Hence the numerical values adopted in this paper , . The curve appended shows this distribution of temperature graphically . The maximum temperature at the bottom of the crust will be here . This gives tenlperature considerably below the melting point of No doubt the assumption of constant conductivity at all temperatures is unsatisfactory feature this calculation . It is difficult to know what other assumption to make , bowever . Some experiments of Lord Kelvin and Mr. Erskine Murray ( ' . Soc , vol. ) seem to indicate a diminution of conductivity with 1906 . ] Crust , and the 's lnternal Heat . Depbh les . FIG. 2.\mdash ; Calculated distribution of in earth 's interior . This result has been obtained on the proyisional unptio that the heat production of radium is the same throughout the earth 's crust as mder surface conditions . In justification of this , a paper by Mr. W. may be referred to . The activity of radium emanation and its products are shown to be substantially the same at temperatures of as at he ordinary temperature , though evidence was obtained of a slight change of activity in one of the products . Thus there is no reason at present to think that notable change of activity sets in before is reached . I wish to express myself with some reserve on this subject . Further experiments might conceivably show a rapid loss of activity as this temperature was approached . In that case the conclusions here drawn as to the earth 's internal condition would require modification . I was inclined at first to think it incredible that the earth 's crust could have so small a thickness as 45 miles , and was therefore much interested to hear that Professor Milne had come to a substantially identical conclusion , from a study of the velocity of ation of earthquakes through the earth 's interior . He gives miles as the thickness . This is quite On the other hand , Mr. C. H. Lees found the thermal conductivity of window glass to increase with temperature ; and at high temperatures rock magmas must approach the quality of glass ; indeed , they sometimes even retain that quality on cooling ( obsidian and pitchstone ) . The mean thermal conductivity of rock cannot be much more than that assumed , for otherwise the internal temperature would not be high enough to produce phenomena . 'Roy . Soc. Proc , vol. 77 , p. 241 . Bakerian Lecture , 1906 . . R. J. Strutt . Radium in the Earth 's [ Mar. 30 , consistent with my data , if ocks like boranite , rich in radium , are assumed to somewhat 1nore ) than I supl)osed , in taking the value ramme radium per cubic centimetre as representative . Professor Milne expresses the opinion that a fairly abrupt transition occurs at a of miles , and that the matelial below that depth is fairly uniform the ) is entirely in rreement with the view put forward with to the earth 's interior . chemical nature of the interior is a difficult . It can scarcely consist mainly of iron , as has been very commonly supposed , from the analogy of meteorites . feteoric iron is ) lyfi.ee from radium , as shown above , and in this respect answers the requirements well enough . But if the stony exterior of the is but a small fraction of the whole volume , it cannot ve mnch influence on the mean density , which should be nearly equal to of the co1e . The density of earth is much less than the density of iron . 6 . of The of this paper have an interesting application to the moon . What we can observe of the moon 's surface ests that it consists of rock like that on the eartl ] . The moon is believed to have inally separated from the earth 's sul.face , and , therefore , consist of the same material as the latter . Moreover , the density of the moon ) does not differ much from that of rock . It seems leasonable to conclude from these facts that the moon consists almost of similar to that of the earth 's crust . On this view , the temperature radiant of the moon should be very great in comparison with that of the earth . The material of the mooll is taken to be some 30 times richer in radium than the ( mean ) material of the earth . Her volume is about one-fiftieth that of the earth . Thus the total heat production in the moon would be ) half of that in the earth . This heat has to flow out one-sixteenth the area of the ) surface . Thus the temperature adient at the moon 's surface should be reatert than at the earth 's . In addition to this , is very less on the moon . We conclude that the conditions which prevail there are more vourable to manifestation of the heat by volcanic upheaval . This fully volcanic features so much more prominent on the moon than on the earth . It has generalIy been supposed the lunar craters are extinct . But 1906 . ] , and the 's lnternal Heat . that view seems to rest chiefly on priori conviction that the moon has no internai heat . As Professor W. H. ering has pointed out , all those observers who have made a special study of the moon have believed in the reality of changes occurring there . * S 8.\mdash ; Sumr Conclusions . 1 . Radium can easily be detected in all igneous rocks . Granites , as a rule , contain most radium , basic rocks the least . 2 . This distribution of radium is uniform enough to enable a fair estimate to be made of the total quantity in each mile of depth of the crust . 3 . The result indicates that the crust callnot be much more than 45 miles deep , for otherwise the outflow of heat would be greater than is ) served to be the case . The interior consist of some totally different material . This agrees entirely with Professor Milne 's concluslon drawn from a study of the velocity of ation of earthquake shocks through the interior . 4 . The moon probably consists for the most part of rock , and if so , its internal temperature must be far greater than that of the earth . This explains the great development of volcanoes on the moon . . Iron meteorites contain little , if any , radium . Stony ones contain about as much as the terrestrial rocks which they resemble . In conclusion , I must thank Mr. A. Harker , Mr. Clement , and Mr. A. Hutchinson for their kindness in providing me with various specimens of rock , and for information on geological matters . 'Nature , ' January 5 , VOL. LXXyII.\mdash ; A.

rspa_1906_0043

0950-1207

On the dilatational stability of the Earth.

486

499

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Lord Rayleigh, O. M., Pres. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0043

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0043

10.1098/rspa.1906.0043

Fluid Dynamics

Tables

Fluid Dynamics

]\gt ; On the Stability of the Earth . By AYLEIGII , O.M. , Pres. Received March Read March evised The theory of elastic solids uSufdly proceeds upon the assumption that the body is initially in a state of ease , iree from stress and strain . Displacements from this condition , due to given forccs , or vibl'ations about it , are then ated , and they are subject to the limitation that Hooke 's law shall be applicable hout and that the strain shall everywhere be small . When we come to the case of the earth , supposed to be displaced from a of ease by the mutual ravitation of its parts , these limits are transgressed ; and several writers* have adopted this point of view cated the obstacles which inevitably present themselves . In his interesting Professor Jeans , in order to attain mathematical definiteness , the length of forces counteract the ravitation : " " That is to say , we must artificially nnul gravitation in the equilibrium configuration , so that this equilibrium furation may be completely unstressed , and each element of matter be in its normal state How wide a departure from actuality is here implied will be understood if we reflect that under such forces the inte1ior of the earth would probably be mobile as water . It appears to me that a satisfactory treatment of these problems must start from the condition of earth as actually stressed by its selfgravitation , and that the difficultics to be faced in following such a course may not reat as has been supposed . The stress , which is so enormous as to transcend all ordinary experience , is of the nature of a purely hydrostatic pressure , and as to this surely there can be no se1ious . After great compression the response to iurther stress is admittedly less at , but there is no reason to doubt that the reaction is purely elastic and that the material preserves its inCeglity . At this point it moy ) to relnark , in , upon the confusion often met with in and the ilure to uish b a one-dimensional three-dimensional , or hydrostatic , pressul.e . roc cast iron is said to be crnshed by such a pressure , it is the ' of , ' Phil. ] ] , . , ' , p. 1 1903 . it . , t . lbl . On tional Sbility of the Earth . former kind of pressure which is , or to be , meant . There is no evidence of crushing under purely hydrostatic pressure , however great . Not only is the intecovrity of a body unimpaired by hydrostatic pressure , but there is reason to think that the superaddition of such a pressure may preserve a body from rupture under stresses that vould otherwise be fatal . FitzGerald raises this question in a of Hertz 's ' Miscellaneous Papers . ' He writes : " " Ill , the crackin . of a material like glass , Hertz seems to thinlk its cracking will depend only on the tension ; that it will crack where the tension exceeds a certain limit . He does not seem to consider whether it not crack by with hardly any tension . It is doubtful whether a material in which there were sufficient eneral compression to prevent any tension at all , would crack . seem capal ) of being bent about and distorted to almost any extent without , and this might very well be expected if they were at a sufficient depth under other rocks to prevent their parts being under . It is an interesting question whether a piece of flass could be bent if it were strained at the bottom of a sufficiently deep ocean . On the other hand , there seems very little doubt that the parts of a body might slide past one another under the action of a shear , and would certainly crack unless there were a sufficiently great compression } stress to prevent the crack ; and that consequently a body might crack , evetl the tensions were not by themselves sufficiently great to cause separation , and where the shear was greatest , and not where the tensions were gl.eatest.\ldquo ; When we reflect that pieces of lead may be made to unite under pressure when the surfaces are clean , and upon what is implied when insufficiently lubricated journals , or slabs of lass under polish , ' we may well doubt whether it is possible to rate a material at all when subjected to enormous hydrostatic pressure . In the words of Dr. : " " The , conditions under which the deep-seated materials of the earth exist are fundamentally different from those we are familiar with at the surface . The enormous pressure , and the presumably high tempeJature , very likely combine to produce a state to which the terms solid , viscous , liquid , as we understand them , are alike inapplicable A study of the mechanical operations of coining and of ( in recent years , I believe , much developed ) would probably throw upon this question . We know that rod or tube may be " " squirted \ldquo ; from hot ( but solid ) lead . Is the obstacle to a similar treatment of nrder material purely practical ? In the laboratory I have experimented upon jellies of various 'Nature , ' November 5 , 1896 ; 'Scientilic Writings , ' p. 433 . 'Phil . Mag vol. 43 , p. 173 , 1897 . Lord [ Apr. 16 , of stiffness , on the ciple of the material to the appliances lathcr the appliances to the material . In the simplest ement a leaden budlet is imbedded in jelly contained in a strong lass tube which bullet nearly fits . the tube stand vertical for days , there is no descent . But if by rous longitudinal innpacts ainst pad the inertia of ) bullet be tht into play , movenlenCs several inches may be obtained . Here , although the deformations ctre very violent , there is no uptule visible , either before or behind the bullet . When an elastic body is slightly displnced from the condition of ease , ) potential is expressed by terms involving the squares and products of the displacements . If , however , we suppose finite to be constantly imposed , so that the initial condition is one of strain , the case is somewhat , not essentially , altered . It may be convenient to make a statement , once for all , in terms of generalised co-ordinates . If under the action of the forces , the co-ordinates assume the values , we have in of the potential of strain , etc. ( 1 ) If the forces permanently imposed be by the suffix ( 0 ) , they arc connected with the values of the co-ordinates , , etc. , ) the equations ' ' etc. ( 2 ) This strained condition is to be alded as initial , and displacements from it are denoted by to the -oldinates the altered values , etc. For the potential of strain we llavel , ( 3 ) which is of the ] order of small quantities is not now the whole potential . In ddition to the of strain to include of the steadily osed forces , ted by the . ( 4 ) potential is thus ( 5 ) to The total potential , is uo 1906 . ] On the tational Sbility of the L'arth . of the second order in , etc. , as is obviously required by the circumstance that the strained condition , etc. , is one of equilibrium under the proposed forces . The coefficients of stability are ) , etc. , and they may differ finitely from the values which obtainel previously to the application of the forces , etc. As an example having an immediate bearing upon the natter in , let us consider the case of a uniform body originally in a state of ease . If a small hydrost pressure upon it , the volume proportionally , and the ratio gives the } ility \ldquo ; of the body in this condition . Under the action of a finite pressure the volume may be greatly altered , especially if the body be , seous , the new condition is still one of equilibrium and be regarded initial . The compressibility now may be quite different from before , but it may be treated in the same way as depending upon the small of volume the imposition of a small pressure To those who , while the usual elastic theory bodies in a state of ease , repudiate the application to bodies subject to great hydrostatic pressure , I would that liquids and solids , as we know them , not really free from stress . In virtue of cohesional forces , there is every reason to believe , the interior of a drop of water is under pressure not nificant even in comparison with those inside the earth , and ) same may be of a piece of steel . The conclusion that I draw is that the usual equations may be plied to matter in a state of stress , provided that we allow for altered valnes of the elasticities . In general , these elasticities will not only vary from point to point , but be aeolotropic in character . If , veyer , we suppose that the body is naturally isotropic , and that the osed stress is everyw ere merely a hydrostatic pressure , so that by pure expansion a state of ease could be the case is much simpler and probably suffices for approximate view of the condition of the earth . But ] the initial state is one free of shear , not to conclude that the fidity is the as it vould be without the imposed pressure . On the contrary , there is much reason to that rigidity would be increased . If thele is any analogy to be i11 pile of mutually repellant hard spheres , it will follow an infinite prehsure will infnlite rigidity as well as infinite ] ) ibility . In the ( draft of paper I ) osed that it would be ] ) ssible upon ] ) lines find and for Jeanb ' analysis . correspondence with P convinced that this hope is destined to disappoint1nent , * To whom I am for correctiona Lord of the ) loscs nlUC ] ] of the ] ' at first I felt it . In Professor , if ) altered density is , radial } , the of a volumeibntion of ( ( ( a tioo of nsity - , the ents arc )jcct to , ( G ) two similar tion s to and are elastic constants of notation , and to initial condition . tionb ( and by 's eqnation , ( 8 ) . the constant of ation . Thus , ( 9 ) which is Professor Jeans ' The tion of these equations is loped by Profess Jeans the view of determining at what point instability in . Attcntion is mainly upon the solution of ( 9 ) explessc l a function of order that which bears upon the question of the evolution of the moon . I intended to indicate a tlnent , follo more closely the notation method 's melnoi , " " On the of Elastic Sphere ; \ldquo ; but as the lesults so do not those of , it to set ncnt in fuller detail , to cilitate c ticihlD . II ' in ( 9 ) we assume that is ) where : ( 11 ) ( solution of ( 10 ) , ) to of centre , is . . , ( 1 , :th ) , 1 . 1 ' . 1 . 1906 . ] On the Stability of the Earth . of order . As is well known , is expressible in finite terms ; in the case of ( hr ) may be replaced in ( 12 ) by , a constant factor . disregarded . Before going further it may be well to consider the particular case of a flnid for which . Here the solution for already given suffices to solve problem , and the condition of no pressure at surface ives at once , ( 13 ) which with ( 11 ) in terms an the elastic constant . The critel.ion of stability follows by . In the case of the displacements are symmetrical , beincro an . ; and we see that equilibrium is unstable for symmetrical ) if . ( 14 ) In general , by ( 8 ) and ( 10 ) so that ( 16 ) where satisfies hout the sphere . ( 17 ) Substituting the value of in ( 6 ) , we get with ro ( 11 ) ( 18 ) where . ( 19 ) Equation ( 18 ) and its companions may be treated as in Lamb 's classical paper . A solution is ' ' etc. , ( 20 ) where tisfies ( . In virtue of ( 17 ) these satisfy the relation : and the solution may be by the additi ) of , etc. , as well as the relation Professor Lalnb the general of ? , For our present Lord Rayleigh . [ Apr. 16 , purpose , with tion to one order of spherical , it suffices to take , ( 21 ) and two similar equations , where is a solid harmonic of : ; and is defined by the equation ve as to a constant multiplier is identical with , as employed in ( 12 ) . is thus associated ith solid in place of monics . The function possesses the following properties ; ; ( 24 ) . A formula in spherical harmonics frequently required is ( 26 ) The term of the order in is thus . and corresponding thercto do where is defined as above , , as well and , is a solid rlnonic of formation of tho conditions to be satisfied at the free csuli of the sphere proceeds most exactly as in Lamb 's investigation ( p. 199 ) , the only diflerence from the fact that has now valuc . The first of the synlllet]icnl surface con ditions Tl tcrms in ( 29 ) ) fs of found to ] ) 1906 . ] On the Stability of the where ( ) ; ( 31 ) ( ) . In manner Lamb finds for the terms in ( 29 ) arising from , ( 33 ) ; ( 34 ) We have now further an additional part from , which , it should be observed , makes no contribution to . In this : so that the additional part is ( 36 ) The two most important cases where and ] also simple , in that ( 36 ) disappears . It will be convenient to nsider first . When vanish : , since is constant , ( 28 ) reduces to where is proportlonal to . The motion is everywhere purely radial . Exactly as in Lalnb 's investigation of yibl.ations without gravity , the expression ( 30 ) educes to where is a constant , so that the surface conditions yield , or from ( 32 ) . ( 38 ) for ha , and for and their values , get ( 39 ) Lord Rayleigh . [ Apr. 16 , cept for tlifference of notation , this is the same as Lamb 's tion , and his results are therefore available . They are expressed by nteajls of 's elastic constant they as dependent on the of . To adapt them it is only necessary to Jcnlbcr t , as iven by ( 11 ) , herc different value from that which there is no gravitation . On the other hand , finite , still be equated to is the time occupied wave of vibration in a space equal to netel . of the sphere , and denotcs the of complete oscillation . The smallest values of to selected values of , as given ) exnlnplc , if 's value , the rion of stability Tf , the lnaterial is ) , and motiol ] of the kincl now under plation is excluded . When a diffcrent tson f The form of solution is lie the same if there were no tion . from , , ( 40 ) : ( 41 ) from , ) ) common no conditions ) ) of that . ( 44 ) lt that nltst balne f that tertns in { his 11 , ll ( .ally ) to the 1906 . ] On the Dilatational bility of the Eartl , . in which the values of to substituted from ( 40 ) , ( 41 ) , ( 42 ) , ( 43 ) . We find ; ( 46 ) or if , in accordance ) , we replace , -cept for the different of , this agrees with Professor Lamb 's equation ( S7 ) . In equation ( 46 ) there is no limitation upon the value of 1 If to find the criterion of we put or equal to zero , and equation reduces to . ( 48 ) The equation may also be written in of the Lessel functions . The relation between and is ; so that in ternls of becomes ; ( 49 ) or , if introduce the circular functions , . ( 50 ) Unfortunately ( 49 ) does not with the result iyen by ProfeRbor Jeans . In his notation , when ( from ) ( from ) and , give J. . . of processes is rendered cult by the occulrence of several elrors ( lnisprinls ) in Professor.1 ) ) does not seen colrect , and ( 41 ) , ( 42 ) do follo from ( :38 ) , ( 39 ) . Starting from ' equations just and of his , Lord [ Apr. 16 , ( 43 ) , ( 44 ) , ( 45 ) , ( 48 ) , ( 49 ) , I have ined a result in harmony equation ( 49 ) . ( 50 ) it is to calculate the value of corresponding to any tluc of . When , of which the first root is an of . ating for oles of find It seems that the value of is not very sensitive to variation of , and for alues of the ratio of as are to occur , especially under stlrc , almost content elves with the fluid solution . The simplicity of the cases so far considered , depends upon our having } ) necessity of value of values of greater than unity this function remains in the equations , which now demand a more oorate treatment . From ( 21 ) in which the second term becomes infinite whPn p O. In order to this , in ( 21 ) must be llade infinite of the order . Thus writing , we have in the eory of differential equations with equal roots , we have ( solid lonic ( , the nlcnt 1906 . ] On the Stability of the Earth . The boundary condition ( 29 ) requires a treatment . The terms on remain as in ( 30 ) , ( 31 ) , . From ) , ( 5 ) , we as appropriate for the present purpose Equations ( 33 ) , ( 36 ) now give , written as before for ) , which , when is made to vanish , is to be replaced by This is additional to ( 3U ) . The equations to be satisfied at the surface are thus . ( 5S ) When ) disappears , and the final condition is found by the ratio irom , ( 58 ) . This would conduct us to the results already arrived at for that case . In general we anothel ' equation with and For this purpose we must recur to the definition ( 16 ) of of A calculation is made by Jeans on the basis of cssioh ( of means of BesseFs functions . We have at the surface ( ha ) ( 59 ) In ordcl to expl.ess this in our present notation , see by comparison of ( 12 ) and ( 27 ) that . , ( 60 ) so that with use of ( 24 ) . ( 61 ) In Professor Jeans ' equations ( 5 ) , ) ) the of is positive , but appears to be error . Lord Rayleigh . [ Apr. 16 , Eliminating between this and ( 54 ) , we find . ( 62 ) The substitution for in now giyes This equation and ( 58 ) determine two values of , and the elimination of ratio ives the required final result . We will write ( 63 ) for evity as , ( 64 ) where by ( 31 ) , and reduction with the aid of , . ( 66 ) nilarly , if ( 58 ) be written , ( 67 ) we may take ; and the final result is , ( 70 ) iving the ratio in terms of and In results of calculation based upo11 the assumption of a uniform ibility to the case of the earth where the val'iatiou is likely to be very considerable , we must regard to the character of the function ( 12 ) which the dilatation is pressed . Vhen / or a eater nlmber , ( 12 ) vanishes at the centre and ( when ) at the surface . The values to be to the elasticities are thosc to an intermediate position , -way the centre and the sul.face . For a more complete we calculate the balance of the elastic and gravitational potentinl ) the of a displacement still . the same law 1906 . ] On the Dilatational Stability of the Earth . as has been found to apply to a uniform sphere . In accordance with a general principle the result , so calculated , will be correct as far as the first powers of the variations from uniformity . Another question , interesting to geologists , upon which our results have a bearing is as to the effect of denudation in altering the surface level . The immediate effect of the removal of material is . of course , to lower the level , but if the material removed is heavy and the substratum very compressible , the up of the foundation may more than neutralize the first effect and leave the new surface than the old one . So far as I am aware discussions have been based upon the elastic quality merely of the i1lterior without to self-gravitation ; but , as is easy to see , if the condition be one approaching instability , the effect of a pressure applied to the surface be immensely increased . VOL. LXXyII.\mdash ; A.

rspa_1906_0044

0950-1207

On the specific heat of, heat flow from, and other phenomena of, the working fluid in the cylinder of the internal combustion engine.

500

527

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Dugald Clerk|the Hon. C. A. Parsons, C. B., F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0044

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0044

10.1098/rspa.1906.0044

Thermodynamics

Tables

Thermodynamics

]\gt ; On the Speci.of , Heat Flow from , other Phenomena of , the Workvng Fluid in the Cylinder of the Internal Combustion Engine . By DUGALD CLERK , M.Inst . C.E. ( Communicated by the Hon. C. A. Parsons , C.B. , F.R.S. Received February 24 , \mdash ; Read Marcb 15 , 1906 . ) The present ttation was taken with the object of ) the specilic heat of , and heat-flow from , the why heated products of combustion which constitute the working fluid within the cylinder of an internal combustion engine , by a method which permitted direct observations to be l1lade ) an actual charge taken into the engine in the ordinary operations of its cycle . The method of expeliment is very simple , the writer believes it to be novel . It consists in subjecting the whole of the highly heated products of the combustion of a gaseous charge to alternate compression and expansion within the engine cylinder while cooling proceeds , and observing by the indicator the successive essure and temperature-falls from revolution to revolution , together with the temperature and pressure rise and fall to alternate compression and expansion . The set to at any given speed , and at the desired moment after the of gas and air has been drawn in , compressed , and nited , the exhaust yalve and charge inlet alves are prevented from , so that when the piston reaches the termination of its power stroke , the exhaust gases are retained within the cylinder , and the piston ompresses them to the minimum volume , expands them to the maximum volume , and so compresses and expands during the desired unber o strokes . Fig. 1 is an indicator diagram so obtained , and it will be noted that , in addition to the usual power , a series of lines are traced which show cooling of the hot contents of the cylinder the walls . The mode of dealing with these observations will be apparcnt the considerations:\mdash ; If a gas be compressed without gain or loss of heat from volume to and temperature rises from to , so that the work done upon the is , then the mean specific heat of the per unit volume at and 760 mm. at constant volume between the temperatures is where is a constant depending on the quantity of gas in the } linder . Phenomena in Cylinder of the Combustion . 501 FIG. 1 . It will be found more convenient to consider the specific heat per cylinder full of gas ; if this specific heat value be . ( 1 ) If different jases could be sufficiently compressed adiabatically , and the work of compression accurately measured , the value of could be obtained for any given temperature range . In actual apparatus , heat exchanges of course take place between the gas and its enclosing walls , so that this method cannot be experimentally applied without means of determining the law of heat flow to and from the gas . Assume , however , that in the case of an expanding gas the temperaturefall due to heat-flow through the walls is known , and its value for a given case is , while the temperature-fall during the yiven expansion is ; if the total work done by the expansion is , then the mean specific heat for the temperature range to is , ( 2 ) That is , by the temperature-fall due to heat-flow from the total temperature-fall , as shown by the expanding line , there is at once obtained the temperature-fall which is caused by the gas work upon the piston . It is therefore only necessary to determine the temperature-fall due to heat loss on any given expansion line to be enabled to at once calculate the mean specific heat of the gas for the temperature limits . The law of heat-loss cannot be ascertained by any consideration of Mr. D. Clerk . On the Phenomena in the [ Feb. 24 , compression or expansion curves separately , unless the specific heat values of the gas be known . By subjecting a cras , however , to alternate compression and expansion , at a relatively rapid , the law of heat-flow and its absolute yalue can be ascertained , and hence the mean specific heat determined , whether it constant or variable throughout the temperature range . Assume a ooas at a temperature than its walls to be alternately compressed from volume to , and expanding from to as illustrated in fig. 2 . The successive pressures at the volume are indicated at the points , and I , while those at volume are and J. The gas is thus compressed from A to to to to ; and I to ; and it is expanded from to to to ; and to I. Assume that the gas cooling but remains above the temperature of the walls during these compressions and FIG. 2 . During the first compression , work is done upon the gas equal to ; during the first expansion , to , work is done by the gas upon the piston equal to , and the pressure has fallen from the point A to the point , that is , the gas has been compressed from the volume to , and expanded back fain to the same volume , while heat is lost to the sides of the cylinder ; work also has been done upon the gas , and has passed away as heat , because is greatel than . If the absolute temperatures at and I be , and then the true temperature-fall due to heat-loss to the walls in the double operation is 1906 . ] linder of the Combustion . 503 being mean specific heat at constant volume in work units for the temperature between A and C. For the successive double operations between and I , the true tempel.ature-falls due to heat-loss through the walls are obtained in the same way . Taking temperature-falls between these points as , etc. , , etc. , ( 4 ) that is , the true temperatm.e-falls , etc. , greater than the apparent falls , , etc. , by temperature-fall equivalents of the respective work-areas ; etc. the first expansion from to work is done by the } upon the pistol equal to , and the second compression , to 1 ) , does upon the gas , and so on . the has fallen from the point to the point ; that is , the gas has been expanded from volunle to , and compressed back again from to , while heat is lost to the walls . Work , however , in this case has been done by the upon the piston , because is greater than . At the voltlme the successive points and indicate temperatul.e-falls due not only to heat-loss the walls , but also due to some work done upon the piston . If the absolute temperatures at and be as then the total or true temperature-falls due to heat-loss to the walls in the double operation of expansion and compression are ' ( 5 ) mean specific heat at constant volume for the temp r between and D. For the successive double operations uween D and , the temperature-falls due to heat-loss through the walls are obtained in the same way . Taking temperature-falls between those points as , etc. , , etc. , ( 6 ) that is , the true temperature-falls , etc. , are less than the apparent falls , , etc. , by the temperature equivalents of the respective work-areas , , etc. To calculate the specific heat from the expansion lines BC , DE , FG and HI , it is necessary to know the workareas and , as also the temperature-falls , , due to heat flow through the enclosing walls . All these values are given by direct from the diagrams , except the latter , , and to determine this it is necessary to convert the differences between the work-areas concerned into their Mr. D. Clerk . On the Phenomena in the [ Feb. 24 , temperature-fall equivalents . For this purpose the values , are required ; that is , the specific heats must be known before an accurate cooling curve can be prepared . This can be readily done with sufficient accuracy with two approximations . For a lirst approximation assume that , , etc. , correctly represent the temperature-falls due to heatflow the walls ; then construct a curve showing temperature-drop per reyolution , shown in black line at fig. 3 , which is taken No. ' 5 FIG. 3 . curve it will be seen that the temperature-drop assumed entirely due to heat-flow in one expansion stloke BC is equal to the ordinate ; let * The original enlarged indicator diagram cards are preserved for reference at ] ) Society . 1906 . ] linder of the Internal Combustion Engine . this be .(\fnof ; mn , then . ( 7 ) Values similar to are calculated from the losses on DE , , etc. , then these values are used to calculate , etc. , the temperature-fall equivalents of the areas ; etc. , etc. If then , etc. , be deducted from and , etc. , we values , etc. , which give successiye temperature-falls per revolution . These are used to construct a second temperaturefall curve . This curve is shown in fig. 3 in dotted lines . By the new values of the temperature-falls equal to the ordinates , etc. , another value of the specific heat is obtained for each expansion line , and a third temperature-fall curve is plotted . This curve , however , lies so close to the dotted that is indistinguishable ; and if the dotted curve be used the values so obtained of , etc. , are accurate within the error of experiment . By applying the same method to the points and I , adding the temperatnre-fall equivalent of ; ; etc. , temperature-fall curve is obtained calculated from the maximum volume , and such a curve is shown at fig. 4 in dotted lines . The specific heats on the different expansion lines are then obtained by ( 2 ) , etc. It is found , however , that calculations made from the in this manner are liable to considerable disturbance due to possible indicator errors so small as mm. It was therefore considered desirable to make the specific heat calculations from measurements relating to the upper part of the evrams , where the temperature differences to be measured are at a maximum . In order to determine the law of heat-loss at the upper ends of the diagram , it is necessary to investigate the curve more closely . If the true temperature-falls due to on the stroke be plotted with the mean temperatures of the working fluid during the double stroke , and the lines corresponding with the mean temperatures of the expansion stroke be drawn , cutting the curve so produced , it is foumd that the temperature-falls given by this curve at the mean temperatures of the expansion lines\mdash ; divided by two to give the correct value for a single stroke\mdash ; are the same as those found by the method above described from the dotted curve , fig. 3 . . D. Clerk . On the Phenomena in the [ Feb. 24 , - . . 4 shows such a curve ; it has been obtained by rement of meau peratures on the successive pairs of compression and expansion lines , and by taking values of -fall for the double stroke from the dotted curve , On the full vertical lines the curve are drawn points representing mean temperatures respectively on expansion and compression lines BC and Cl ) , DE and and , and HI and IJ . The vertical dotted lines refer to mettll temperatures or expansion lines , FG and HI only . The temperature-falls shown by the ordinates in full lines are taken from the dotted curve , Numerous curves of this ve been calculated , prove that the 1906 . ] of the Combustion Engine . temperature-fall may without eciable error be taken from the mean temperature curve in this way . This fact is applied to the determination of temperature-falls at the high-pressure part of the stroke as follows:\mdash ; eferring to fig. 1 , the vertical line marked 3/ 10 cuts the expansion and compression lines of the at three-tenths of the engine stroke . This is the part which is to be ated to determine specific heat . To the partial from the complete lines , the compression lines on fig. 1 are rked successively , etc. , and the expansion lines , etc. MEAN OOUBLE COMPLETE STROKES FIG. 5 . Work is done upon the gas equal to on the first compression line lc , and done by the gas on the piston by the first expansion line lc , the work . The heat lost during the partial compression and expansion is thus measured by the temperature-fall between and plus the temperature-fall equivalent of the area . By the specific heat value already calculated for the complete expansion line , the value of the total temperature-fall equivalent to the heat lost is obtained . The total temperature-fall has now to be divided between the compression and expansion lines . For this purpose the mean temperatures are calculated for lc and le , and a mean temperature-fall curve drawn for the upper threetenths stroke ( see 6 ) . On fig. 6 the full vertical lines cutting the curves are drawn through the mean temperatures respectively of the partial compression and expansion lines lc le , , and , and the dotted lines le , , and value , , for the temperature-fall on the expansion line le is taken from Mr. D. Clerk . On the Phenomena in the [ Feb. 24 , the curve , fig. 6 . The mean specific heat on the expansion line le is thus ' between the temperature limits and . The other expansion lines are calculated in the same manner . FIG. 6 . It was found that the specific-heat values obtained as above from the upper three-tenths diagram were lower than those obtained for the whole stroke . New temperature-fall curves were , therefore , drawn for diagram , taking the average specific-heat value found as above described , on the upper three-tenths stroke . One of these curves is shown in dotted lines in the diagram 6 . The final specifc-heat calculation was made , using these temperatule-fall curves in a similar manner to that described above . It was found that the temperature-faJl curves obtained by using the specific heat finally obtained 1906 . ] Cylinder of the Combustion Engine . do not differ appreciably from the curves obtained when the average specific-heat value on the upper three-tenths stroke is used . It was , therefore , unnecessary to make a further calculation . So much for the method of examination and calculation adopted . In what follows , the last described method of obtaining specific heat has been followed . Engine and other Apparatus for Experiments . engine used for the experiments was of the well-known four-cycle type , 14 inches diameter cylinder and 22 inches stroke , designed for a full load of 60 brake horse- power at 160 revolutions per minute . It was constructed by the National Gas Engine Company , Limited , and was used by the Thermodynamic Standards Committee of the Institution of Civil ineers , in conjunction with the present writer , for determination of data required for an ideal standard of comparison . It was carefully measured and calibrated by the Committee , the relevant matters being as follows:\mdash ; cub. Volume swept by piston-stroke 3390 Total volume 4164 Compression space 774 Compression per cent. of total volume Fig. 7 shows a vertical longitudinal section and part horizontal section . The indicator used was of the Casertelli type . It was caref.ully measured , and the calibrated , by the writer . The coal-gas drawn into the cylinder was measured by a meter which had been tested by the Committee , and the air supplied was also sured by anemometer , also calibrated by the Committee . During the experiments , observations were made of temperatures of gas , air , and water flowing into and out of the engine water-jacket . Analyses of the coal-gas used were made , and the heat of its combustion was determined by the Junker calorimeter . No leakage could be detected past either piston or valves during the experiments . Apparent -Heat Values.\mdash ; To determine the specific-heat values , tlJe engine was run without load , and the governor adjusted to keep the speed at about 120 revolutions per minute . The total revolutions were determined by counter ; the total number of explosions were also so determined . The water-jacket was kept cold by passing water through it at a sufficient rate . Gas consumption was taken , and barometer and thermometers 1ead . The rate of engine revolutions was also taken by neter . To make an vation the indicator cock was opened and a trigger operated , Mr. D. Clerk . On the in [ Feb. 24 , after a charge had been taken in , to liberate the springs , on the exh and inlet valve cam rollers . The springs displaced the rollers along their pins , them beyond the action of the cams . Consequently , the exhaust and inlet valves remained closed , so ) the electric spark produced the usual power-stroke explosion , the products of combustion produced were entirely retained in ) cylinder and alternately compressed and expanded behind the piston , the ) ) the energy of rotation of fly-wheel . FIG. The indicator pencil was htly held against the card a number of revolutions and traced a series of gradually ) lines . The tachometer was observed and made at the moment of explosion , and at the of last contact with the card . In this way the actual time of double operation was accurately known . 1)uring the first five revolutionls after explosion the speed dropped from about 120 oevolutions to 116 tions , so that the variation was only from 3 per cent. to 4 per cent. This variation , however , has been allowed for in the cooling curves . Indicator dia.rams were also taken with a to determine the pressure of tlJe charge within the cylinder on the completion of the stroke . It was found that the cylinder was entirely filled at this low 1906 . ] Cylinder of the Internal Combnstion Engine . speed , so that the pressure within was the same as that of the external atmosphere . Thirty indicator cards were taken at this speed for examination , and the proportions of the gas to air were varied within narrow limits to discover whether a slight change in composition changed the specific-heat values materially . The values of specific heat given are the mean values obtained from 21 cards , in which mixture was of nearly the same proportions . To facilitate measurement of the faint lines upon the cards , enlar . photographs were taken , doubling the scale . All measurements required for the calculations were made from these photographs . enlents Nos. 1 to 21 accompanying this paper ( see footnote , p. 504 ) , are those from which the apparent specific-heat values are deduced . In from the rams , the following assumptions have been made : ( 1 ) That constant for all temperatures and pressures of the experiments . ( 2 ) That constant for isothermal compression or expansion for all the experiments . ( 3 ) That no chemical contraction or expansion has taken place due to combustion . ( 4 ) That combustion is complete after seven-tenths of the first compression stroke . Five expansion lines were examined on each card , and the various values described were calculated from carefully-made measul.ements . The curve shown at fig. 8 was obtained from Cards 1 to 21 in this manner , so far as concerns the observed points , each of which points is the average value of the numbers calculated from 21 cards . These points carry the apparent instantaneous specific-heat values up to 92 C. The point was calculated in a similar manner from the upper one-tenth of the diagram , and the point was obtained by similar processes from explosion expansion line between one-tenth and three-tenths of the forward stroke . The observed points represent the average specific heats for the ranges of temperature of successive expansion lines , and the curve shown so drawn that the ge specific heats given by the , curve over the same temperature ranges are equal to the observed values . The value at C. is obtained by extrapolation , assuming all products to remain gaseous . The mean values from calculated from the usually accepted numbers are given , and it appears to be where curve shows . The specific heats are given in foot-pounds per cubic foot of working fluid Mr. D. Clerk . On the Phenomena in the [ Feb. 24 , Fr. SPEC . HEAT PER . CUB . Fr. , FIO . 8 . 1906 . ] Cylinde ? of the Combustion Engine . reduced to standard temperature and pressure C. , and 760 mm. mercury . The highest temperature measured for the purpose of this curve was 1450o C. , and the lowest 25 C. The mean composition by volume of the working fluid calculated from analysis of the coal-gas used at the works was Vols. Steam aseous ) Carbon dioxide Oxygen Nitrogen The mixture , however , was varied slightly between the extreme compositions , . :\mdash ; Vols. Vols. Steam assumed aseous ) and Carbonic anhydride , , Oxygen , , Nitrogen , , These two extreme correspond respectively to explosive mixtures containing before combustion 1 volume gas to volumes air , and 1 volume gas to volumes air . The composition by volume of the coal-gas used was of four analyses):\mdash ; Hydrogen Marsh gas Unsaturated hydrocarbons Carbon monoxide Nitrogen Carbon dioxide Table I shows the apparent instantaneous specific heats at different temperatures taken from the curve ; and Table II shows mean apparent specific heats for temperature ranges from C. up to 1500o C. From these numbers it is evident that the apparent specific heat of the Mr. D. Clerk . the in the [ Feb. 24 , working fluid consisting of products of colnbustion in the cylinder of the internal combustion increases considerably with temperature , so that at 1000o C. the value is 28 } ) cent. greater it is at 10 C. , while at C. the increase amounts to cent. The mean apparent specific heat between and 1000o C. is foot-pounds per cubic foot , or 15 per cent. greater than at , while at 1500o C. the increase amounts to over 20 per cent. Table I from Fig. 8.\mdash ; Table of Apparent Specific Heats ( Instantaneous ) in foot-pounds per cubic foot of Working Fluid at C. and 760 mm. Table II from Fig. 8.\mdash ; Table of Mean Apparent Specific Heats in foot-pounds per cubic foot of Working Fluid at C. and 760 mm. Inspection of the curve at once shows that while apparent specific heat increases more rapidly at first , it tends to a limit at upper tenlperatures , so that fro1n 1200o C. to 1500o C. the increase is less than half that from 90 C. to 1200o C. The appearance of the culve would a limit for the ap parent specific-heat value after no reat further increase in temperature . 1906 . ] Cylinder of the Internal Combustion Engine . Is this a real increase of specific heat ? If combustion be completed , then there appears to be no other explanation . Consider , however , the points of diHerence which arise between a real change of specific heat with changing temperature and an apparent change caused by continued combustio1l . If the continued combustion be due to dissociation , then it would be impossible to differentiate by any experiments of this kind ; but if it be combustion continuing at a given time rate , then discrimination is possible . With a real specific-heat change it is obvious that values calculated from any expansion line will show a fall along that line depending on temperature-fall only . No increase of specific heat could occur on the falling temperature expansion line . This is also true for change due to dissociation . If , however , combustion be continuing , then the apparent specific heat may vary from point to point of the line depending on the relations between the instantaneous values of the rates of heat addition to the working fluid and work performed by it , on the piston . If the rate of heat addition be less than tba of work performed , then the temperature will fall ; but if the work rate diminishes more rapidly than the combustion rate , then at a certain point of the expansion the rates may become equal and then the expansion line may become isothermal , and it is even conceivable that temperature might rise . In such a case specific-heat values calculated from to point of the supposed expansion line would show an increase with falling temperature , and at the isothermal point would become infinitely great . If combustion continues at a rate which becomes relatively greater than the work rate , it is evident then that specific-heat values will increase all along the expansion line as pressure and temperature falls . It has been already stated that this is found to be the , but numerous calculations been made from many diagrams which always show this interesting effect . To illustrate this point calculations have been made from Card No. 5 , expansion line BC for : first three-tenths of stroke ; first half of stroke ; second half of stroke ; and the whole stroke , as follows:\mdash ; Apparcnt Specific lfcat . First three-tenths of stroke-lbs . per cubic foot at C. and 760 mm. First half of stroke , , Second half of stroke , Whole stroke , Other cards show greater differences between he first three-tenths and the later parts of the stroke , some as much as 50 per cent. increase . It is true VOL. LXXVII . Mr. D. Clerk . the Phenoraen in the [ Feb. 24 that difficulties of reading and errors of indicator affect the lower ends of the more iously than the upper , and some allowance must be made for this ; but vithstanding this , the difference between the early parts of the stroke are so marked that it appears very improbable that they can be accounted for by any such errors . Combustion to be proceeding . Other indications are iven by varying the rate of revolution of the . If specific heat varies only with temperature , then obviously change in engine speed cannot alter specific-heat values . To test this matter four cards taken at 160 reyolutions , and four at 120 revolutions per minute , and calculations were made on expansion line BC for whole stroke , first half stroke and first three-tenths stroke . Results were obtained as follows:\mdash ; Apparent Spccific 160 revs . 120 revs . Whole stroke .-lbs . .-lbs . First half stroke1. . , , First three-tenths stroke 272 , , This experiment clearly indicates an increase of apparent specific heat with increasing speed as well as increased apparent value with falling pressure . The effect of increasing speed to some extent introduces opposing changes ; speed means less combustion completed when expansion on the line BC begins , but it also means performance of work on the piston at reater rate , so that the new factors cancel each other out to some extent . Still another indication is given by varying the temperature of the waterjacket of the engine , keeping the speed of the engine constant . The experiments were made with the running at 120 revs . per minute with the water-jacket cold , C. , and hot , C. Three expansion lines were calculated for the first three-tenths stroke . For cold , Cards 1 to 21 were taken ; the values given are mean values of the 21 cards . For the hot experiments eight cards were taken ; the values given are means of ei , . esults were obtained as follows:\mdash ; Appar Specific Water-jacket , C. Water-jacket , C. .-lbs . .-lbs . 25 . , 22.6 , 21.9 Obviously pparent slJccific heat is less with the hot . water-jacket . This could dlcct the mattel if the only change with is in specific 1906 . ] Cylinder of the Interned Combustion Engine . heat . The cause of the change mfty be due to the rise of the mean temperature of the chemical reaction which permits chemical action to be less affected by cooling walls which tend to remove a portion of the contents from the sphere of effective reaction by undue cooling . That is , combustion proceeds more quickly in a hot vessel than a cold one . This would produce the effect of lowered specific-heat value by less heat to be evolved when expansion line BC commenced . The experiments appear , therefore , to prove that some combustion is proceeding . The nature of the apparent specific heat also , as the rate of apparent change is much greater at the temperatures , the same portion of the stroke . Experiments made by the Thernlodynamic Standards Committee of the Institution of Civil ineers in conjunction with the present writer pear to support the contrary conclusion , because in this same engine a sheet was determined as follows for 100 heat-units given to the engine . Indicated work *Heat-loss to water-jacket and radiation *Heat passing away with exhaust determined by calorimeter This appears to account for the whole of the heat at the conclusion of the return or exhaust stroke . The writer considers , however , that the method used to determine radiation and the exhaust calorimeter introduce an error of 5 per cent. and possibly more . It is obvious that further experiment is required to settle the question . Values.\mdash ; Curves for temperature-fall values were prepared from the 21 cards used for the determination of apparent specific heat , each curve alTanged as described to show temperature-fall in terms of mean temperature of the valious expansion and compression lines studied . For convenience of calculation the temperature-fall values were expressed in isothermal units . The method of isothermal units consisted in all temperatures to an isothermal line calculated for the particular proportions of the cylinder and compression space . The corrections for temperature-fall were applied to the expansion lines of the same card . As the correct estimation of temperature- fall is important , and the accuracy of the specific-heat values depends upon It is known that part of the heat which should appear in the exhaust calorimeter passes into the water-jacket , so that the jacket loss value is too high , while the exhaust loss is too low . UICI Vi ' bVlllClltb bllC its knowledge , it has been thought desirable to study more closely the mode of heat-loss in the cylinder , and some features which call for explanation . Fig. 9 has been prepared with this object . Four curves are shown . The curves , represent the heat-losses incurred in complete revolutions , that is , in complete double strokes . Here the surface exposed and covered alternately is that due to the whole sweep of the piston . The curves represent losses incurred at the upper three-te1lths of the card ( see fig. 1 ) while the piston moves from three-tenths stroke to the end , compressing into the clearance space , and then moves out again to the point of three-tenths of the outward stroke . The ordinates give heat-loss in foot-pounds per second , and the abscissae mean temperatures per double stroke or double three-tenths stroke . FIG. 9 . Curves and are calculated Cards 2 , 3 and 5 , taken while the engine was running without load at 120 revolutions per minute with the jacket water kept at a mean temperature of C. Curves and are calculated from Cards Nos. 22 , 23 and 24 , taken while the engine running at about 160 revolutions per minute with a load of 50 B.H.P. , and the jacket water at C. Accordingly the curves are marked as engine cold and hot . The heat-loss values given are calculated from temperature-fall curves , assuming the apparent specific heats given at fig. 8 and at Tables I and II to be real specific heats ; but for the amounts of continued combustion believed to be present it appears probable that the heat-flow values calculated are also sufficiently close approximations within the errors of experiment . curve , it appears that the heat-loss is not proportional to temperature difference , but increases more rapidly as temperature ises . Further , the curve , when to the zero line representing no of heat , cuts that line at the temperature C. This appears to show that during complete engine strokes , ceases at that temperature , so that the mean temperature of the inner surface of the walls must be about C. , notwithstanding the fact that the water in the jacket is at C. Curve shows that the rate of heat-loss in time-units is greater for the first three-tenths of the engine stroke , even with equal mean temperatures . The curve cuts the zero line at a temperature of 16 C. , showing that the mean temperature of the wall surface is higher for the inner part than for the whole . This is to be expected for two reasons : the piston end , valves and caps are not water-jacketed , and their surface temperature is doubtless higher than the jacketed , so that the inner portion presents a larger proportion of hot surface ; also the mean temperatures of gases at the inner end are than those at the outer end , so that the surfaces must be hotter than those exposed at the outward end of the stroke . This fact explains the smaller heat-loss at the lower temperatures . The crossing of the line by proves the greater rate of heat-loss at the inner end ; this greater heat-loss appears to be due partly to the greater mean density of gaseous contents at the inner end , and partly to the larger proportion of the cooling surface of the admission port to the whole surface towards the inner end . Taking curve for whole stroke and hotter cylinder ttnd it with curve similar relations are apparent , but here the mean temperatures of the wall-surface are much C. for curve ( whole stroke ) , and C. for curve ( three-tenths stroke ) . The total surface exposed when the piston is full out is approximately square feet , and at tenths out about square feet . Calculating for equal temperature differences , it is found that the heat-flow per square foot per second at the three-tenths end is from to times that obtained for the whole stroke . From this follows the necessity of . the heat-flow separately for each part of the expansion curve investigated ; the quantitative law of heat-flow varies with surface exposed and density of working fluid , as well as with temperature . Every part of the stroke will give distinct heat-flow values . For three-tenths stroke , for example , a temperature difference of 70 C. causes a heat-flow of 8537 foot-lbs . per square foot per second , while Mr. D. Clerk . On the in the [ Feb. 24 , for the whole stroke 70 C. difference only gives 3340 foot-lbs . per square foot per second . is , increase of density and change of configuration are together responsible for the greatly increased rate of per unit surface in unit time . Calculation of the Total Heat given to Combustible from the Indicator rarn only.\mdash ; If the results given as to apparent specific-heat , temperature-fall , and heat-flow values be correct , then the total heat given to the combustible mixture may be calculated by diagram only . To test this , three diagrams were taken from the engine while it was running at 160 revolutions per minute under a load of 50 brake horse-power . The diagrams are numbered 22 to 24 . The heat-flow determinations were made as described , and plotted in work units per whole stroke . Fig. 10 shows the mean curve . The apparent specific-heat values were calculated for the proper ranges of temperature from the curve , fig. 8 . The charge temperature before compression was determined by a method which need not be described here ; it was C. Three balance-sheets were calculated from the data as follows:\mdash ; -lbs . Per cent. Heat-flow during explosion and expansion 12,480 Heat contained in gases at end of expansion. . 39,800 Indicated work 28,900 Total heat 81,180 i.e. , 104 B.T.U. Card .-lbs . Per cent. Heat-flow explosion and expansion . . 14,000 Heat contained in gases at end of expansion 40,500 Indicated work 27,700 Total heat B.T.U. -lbs . Per cent. Heat-flow explosion and expansion 13,100 Heat contained in CYases at end of expansion 40,600 Indicated work 28,260 Total heat i.e. , 106 B.T.U. 1906 . ] Cylinder of the Combustion Engine . KZAN FIG. 10 . Ihese values give the total heat accounted for by the indicator diagram of this particular internal combustion engine , and its distribution in indicared work , necessary exhaust-loss and heat-flow through the cylinder walis . The informs us that in all 104 to 106 British thermal units have been given to the gases in the cylinder for each power explosion . If this method be correct , then the total heat so found should corresl ) with that known to present from the measurement of gas supply . The present in the mixture per explosion was cubic foot . Its lower heat value B.T.U per cubic foot . B.T.U. Mr. D. Clerk . On the in the [ Feb. 24 , diagram thus accounts for the 105 B.T.U. known to be present in the form of Calculations from other indicator rams confirm the correspondence of the calculated heat values with those determined from the heat values of t , he gas known to be present . These apparent specific-heat and heat-flow valnes now make it possible for the first time to study the thermodynamic problems of the internal combustion motor from the indicator agram only , and this the writer believes will materially hasten the development of a complete theory of these motors by it possible to determine the principal properties of in the cylinder itself Many obscure phenomena are capable of ation by the method . Earlicr ations.\mdash ; Many chemists and physicists have experimented with c Hiru , Bunsen , Lfallard and Le Chatelier , erthelot and Vieille , Vitz , Dixon , Clerk , Grovcl , Petavel , and Bairstow tqnd Alexa]]der . All have observed a deficit of for heat of combustion to be available ; many explanations have been offered , loss to } alls , dissociution of steam and carbon dioxide , increase in specific heat , and combustion at a time rate . In present writer made expCl.iments with and explosions with air , and that " " the author 's experiments prove that the arrived at by chemists , the very slow chemical actions ated by them at low temperatures , hold equally in the case of rapid chemical combinations occurring at temperatures produciu explosion . In a rich mixture , where the acting gases are but little diluted -by neutral , the ation is at first exceedingly rapid , but becomes slower as it proceeds , because of the diluting effect of the products . In poor mixtul'e , when the molecules of the ases are widely separated by diluent , the combustion is slow from the first This position is now very generally accepted among investigators in chemical physics , and it is undoubtedly true of rapid as well as slo combinations . When the writer began the present investigation , he believed that these phenomena of slower chemical action furnished a complete explanation of the discord between the theoretical and observed results , and that there was no need to assume any considerable dissociation or variation of specific heat of the products of combustion . These experiments , however , appear to him to indicate real of specific heat as well as continuation of combustion . The experiments do not exclude dissociation or any other molecular change which by . the mance of work would specific heat . It appears improbable , however , that dissociation should be 1906 . ] of the Combustion material for temperatures so low as 6o C. It is not usual to suppose that either carbon dioxide or steam can be decomposed to any sensible extent at such temperatures . Mallard and Le Chatelier developed the theory of specific-heat change fully in 1883 from their experiments on explosion in closed vessels , and they give the following formulae for the mean specific molecular heat at constant volume for carbon dioxide , nitrogen , and oxygen:\mdash ; For and O. . Dividing respectively by 44 , IS , 28 , and 32 , the molecular of carbon dioxide , steam , nitrogen , and oxygen , we ) For O These formulae obviously show that the change of specific heat of the working fluid should be represented by a straight line , and this does not agree with the present experiments . These values , however , agree fairly with the apparent specific heat at 1000o C. and 1500o C. to Mallard and Le Chatelier 's ures , the mean } ) ecific heat of the working fluid used in the present experiments at 1000o C. would be foot-lbs . per cubic foot at C. and lllm . mercury . The value from Table II of this paper is foot-lbs . For 1500o C. , Mallard and Le Chatelier works out foot-lbs . , Table II foot-lbs . Mallard and Le Chatelier 's observations did not go below 1000o C. , as explosions became too slow near that temperature , so that they have estimated specific heats at the lower temperatures by extending the use of the formulae considerably below the points of observation . Holborn and Austin have determlned the specific heat of carbon dioxide , oxygen , nitrogen and air , at constant pressure , by means of a heating appliance , a thermo-couple , and a calorimeter ; but their values are considerably lower than those of Mallard and Le Chatelier , and show a much smaller proportion of increase for , and , but their numbers appear to be quite consistent with these experiments . Conclusions . The apparent specific heat of the fluid of the internal combustion engine ( consisting mainly of a mixture of nitrogen , carbon dioxide , steam and oxygen ) , when calculated from the first threeMr . D. Clerk . On the in the [ Feb. 24 , tenths of the engine stroke , undoubtedly increases between the observed temperatures C. and 1500o C. , but tends to a limit at the upper temperature . ( 2 ) The apparent in specific heat is not entirely due to a real change of specific heat , but requires in addition continuing combustion to account for all the facts . The rate of heat-flow from the working fluid to its enclosing walls for equal temperature differences varies throughout the stroke . Increased heat-flow accompanies increased mean density . ( 4 ) The mean temperature of the inner surface of the enclosing walls varies with the portion of the stroke examined from 19 C. for whole stroke to 40 C. for first three-tenths stroke under working conditions at full load . These mean te1llperatures , however , are not the highest mean temperatures by the walls . ( 5 ) The heat distribution during the operations of the working fluid can be determined with approximate accuracy from the apparent specific-heat values and heat-flow values obtained from the diagram only . The Casertelli indicator used by the writer for these experiments is one of the ) adapted to stand the rough of frequent heavy explosions rising above 400 lbs. per square inch ; but its indications at the lower pressures are not sufficiently accurate for the purpose of discussing the law of the variation of apparent specific heat throughout the stroke . For this purpose it is desirable to an indicator of a different type . The writer has examined the existing indicators , ding the optical instruments of Hospitalier , Carpentier and Petavel , but finds all unsuitable for the d work ired in order to attain further accnracy in this investigation . The writer has accordingly desi , a novel type of mechanical and optical indicator , with which he hopes to obtain rams which are sufficiently accurate at the low as well as the high pressures . When these farther experiments are made , he trusts that he will be able to distinguish with quantitative accuracy between the phenomena of . specific heat continuing combustion . The writer would point out that the method of specific heat , temperature-fall , and heat-loss here developed is applicable to determinations of the specific heat of gases , heated without combustion . These experiments on the compression of practically a mass of flame show that even at temperatures the heat-flow to a cylinder is lower on the ] the rate of addition of heat to the ss gns by performing upon it . For xample , in of these experiments one complete compression occupying second raises the temperature of tlJe contents of the cylinder from 1906 . ] Cylinder oj ' the lnternal Combustion Engine . 1000o C. to C. , showing that the rate of heat-flow from the gas , even at a mean temperature of over 1000o C. , is considerably less than the rate at which heat be added to the gas by work performed . From this indication it is evident that a simple gas , such as nitrogen , oxygen , or a compound such as carbonic acid , could be heated by compression alone , in a suitable apparatus , to at least 1500o C. It only requires a sufficiently powerful mechanical apparatus to stand the high pressure of about tons per square inch to get any desired temperatures . Such determinations will be entirely free from doubt due to possible combustion . The method described requires some modification , owing to the fact that where all the heat is added by compression , at one part of the stroke the gas would be absorbing heat , and at another part giving it out . My thanks are due to my assistant , Mr. W. Grylls Adams , M.A. , for his very aid in the laborious work of measurin the rams and making the numerical calculations . I have also had much pleasure in discussing with him the somewhat numerous points of difficulty which have arisen in the course of the ations . APPENDIX . eceived March 24 , 1906 . Tjmperature . the mean temperature during any expansion or compression stroke or part of a stroke is taken in relation to time , the obliquity of the connecting rod the motion of the piston being taken as simple harmonic motion . The error introduced by this asssumption is ible within the accuracy of the experiments . of Heat-Loss sion and Ccmpression \mdash ; It will be noticed that the temperature-fall due to heat-loss is divided between com- pression and expansion lines by drawing a curve whose abscissae represent mean temperatures , and whose ordinates represent the temperature-fall , and taking the temperature-fall on any expansion line from this curve at the mean temperature of that expansion line . This involves the assumption that heat-loss would be the same on an expansion line , and on a compression line for the same part of stroke if the mean temperatures of the two lines were the same . In considering the whole strokes , the temperature-fall due to heat-loss on an expansion line can be obtained by considering the expansion line with the compression line above it , and also with the compression line below it . This has been done , and it is found that the value thus obtained for the line BC ( fig. 2 ) is the same within the error of experiment , whether it be arrived at by considering the pair of lines AB , , or the . of lines , and similar results are obtained for the other lines . This shows that the Mr. D. Clerk . On the in the [ Feb. due to heat-loss on pairs of lines starting from the lower end of the diagram , can be taken from temperature-fall curve obtained by con- ring the pairs of lines starting from the upper end , and hence the value for an expansion line or compression line can also be taken from the curve . In the consideration of the upper end of the stroke , the case is somewhat more difficult , as the time periods dealt with are not there will be a diff'erence between compression and expansion strokes , in that on a compression stroke at the upper end of the the gases in contact with the cylinder walls have during the immediately part of the stroke been at a lower temperature , while on the expansion stroke they have been at a higher temperature . On the ) three-tenths stroke therefore the cylinder walls will be at a temperature at the of the part of the compression stroke considered than their temperature at the beginning of the part of the expansion stroke idered . The difference of temperature will not ) reat , and error neglecting the diffference is a very small one . This error also produces little effect on the apparent yalue ; an error of 10 per cent. dividing the temperature-fall due to heat-loss between the compression and expansion lines would not produce more than 3 per cent. error in the specific-heat value . Errors of , Indicator , .\mdash ; In the reduction to normal pressure and temperature 110 account has been taken of the change of volume due to combustion . This is small and only affects absolute values , and does not appreciably interfere with the deductions based on comparison of the various ures obtained . In calculating from the upper three-tenths stroke , an error of -inch on the icator card , and of -inch on the enlarged photograph , would introduce an error of 3 per cent. on the specific-heat value obtained on the first expansion line , and an increasing error on successive expansion lines amounting to 5 per cent. on the fourth expansion line . In calculating from the whole stroke an error of -inch on the indicator card , and -inch on the raph wouId introduce an error of 4 per cent. in the specific heat obtained from the first expansion line . In order to obtain the comparative results given from different parts of the stroke by errors of indicator , , it would be necessary to make an error to about 1/ 50-inch on indicator cards -inch on the raphs . There is nothing on the diaoramso to suggest such error as this , and the results are not of the kind that would be produced by indicator slack 1906 . ] Cylinder of the Internal Combustion Engine . or friction . This can be shown by the specific heat on the same expansion line , taking the heat-loss correction from the next upper and next lower compression lines respectively . It is found that the results are practically the same in the two cases . The effect of friction and slack is to keep the expansion lines uniformly higher than they should be , while the compression lines are kept lower than they should be . The result of this is that a temperature-fall measured on an expansion line will be too small , as the same height measured vertically will be equivalent to a greater temperature difference at the lower parts of the diagram ; and similarly a temperature-rise measured on a compression line will be too great . The result as ards the specific-heat value found from the upper three-tenths stroke is that frictional error on the expansion line is to a certain exteffl if not wholly balanced by frictional error on the compression line . This arises in the following manner:\mdash ; The error on the expansion line causes the gross temperature-fall on expansion to be too small , but to get the temperature-fall which is equivalent to the work under the expansion line we subtract from the gross temperature-fall a temperature-fall due to cooling , the determining part of which is the temperature difference measured between the compression and expansion lines on the ordinate at the three-tenths stroke . This temperature difference is thus taken small , and approximately too small by the same amount as the gross temperature-fall is too nall . In calculating the specific heat on a iven expansion line a different effect is produced by friction , according to the compression line which the correction is made for cooling . If an expansion line is considered in connection with the compression line immediately below it , friction causes these two lines to be too far apart instead of too near together . The temperature-fall measured on the expansion line is , as before , too small , but the temperature-fall due to cooling is in this case too ooreat , and therefore the friction will produce an accumulated effect . The fact that the value obtained for specific heat for the whole expansion line is the same whether that expansion line is considered together with the compression line above it , or with the compression line below it , therefore seems to show that friction indicator-slack could not be the cause of the results obtained .

rspa_1906_0045

0950-1207

The stability of submarines.

528

537

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir William H. White, K. C. B., F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0045

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0045

10.1098/rspa.1906.0045

Measurement

Fluid Dynamics

Measurement

528 The Stability of Submarines . By Sir William H. White , K.C.B. , F.R.S. ( Received April 4 , \#151 ; Read May 3 , 1906 . ) The purpose of this paper is to place on record the results of calculations made to determine the conditions of stability of submarine vessels in varying circumstances which may occur on service . Accidents have happened to many submarines , and in some instances have been accompanied by loss of life . After investigating possible causes of accident , the author was convinced that one of the chief was the singular variation in stability and buoyancy produced by changes in the draught of water and the " trim " of submarines . He was led , therefore , to undertake the detailed calculations of which the principal results are now stated and illustrated . Either by accident or intention , submarines may reach considerable depths below the surface and be exposed to severe external fluid pressures . Ample structural strength must be provided to meet these pressures and to prevent deformation of the vessels . In order to fulfil this object with moderate weights of structures , submarines are made " cigar-shaped , " with circular or nearly circular cross-sections . The cigar-shape is usually somewhat disguised by light superstructures built above tke upper surface of the hull proper , and carrying decks or platforms , which add to the comfort and convenience of the crews when the vessels are floating at the surface\#151 ; in the " awash " condition \#151 ; at their lightest draught . In that condition water is excluded from the spaces between the superstructures and the cigar-shaped hulls , and the buoyancy and stability are sensibly increased . The other extreme condition at the surface is that when a submarine has been " trimmed " for diving , and floats with a very small portion of her hull above water . This is effected by admitting water-ballast into tanks specially constructed for the purpose and of known capacity . The final adjustments of draught and trim during the process of trimming require great care . All openings into the interior are closed and secured in a watertight manner before trimming is commenced . Water is also allowed to enter the spaces between the superstructures and the cigar-shaped hull , and to remain in free communication with the surrounding water , so that the lightly constructed superstructures may sustain no external pressure when the vessel is submerged . Diving is accomplished by giving the submarine headway , and so manipulating horizontal rudders that the bow is depressed . The " stream-lines " The Stability of Submarines . developed in the water by the onward motion produce downward pressures on the upper surface of the hull towards the bow ; the vertical component of these pressures overcomes the vertical component of the rudder pressures and the small " reserve of buoyancy " which the submarine retains , and the vessel moves obliquely downwards until the desired depth below the surface is reached . The horizontal rudders must he then manipulated by a skilled steersman in such a manner that further motion ( although really along an undulating course ) is practically at a constant depth below the surface . When headway ceases , both rudder pressure and stream-line motions disappear , the small reserve of buoyancy reasserts itself and the submarine rises to the surface . This general statement may be illustrated by figures for an actual submarine , resting on official evidence given at the enquiry into the foundering of submarine A8 at Plymouth last year . In the awash condition , at the lightest draught of water , the reserve of buoyancy was about 13 tons ( excluding the conning tower ) , the corresponding displacement exceeding 200 tons ; so that the maximum reserve of buoyancy was about 6 per cent , of the displacement . The minimum reserve of buoyancy accepted for any class of war-ships at their deep-load draught has been about 10 per cent , in low-freeboard American " monitors , " many of which vessels foundered . For " breastwork monitors " in the Eoyal Navy the corresponding reserve was 30 per cent , of the load displacement ; for high-freeboard warships and passenger steamers it is from 80 to 100 per cent. ; for cargo steamers it varies from 25 to 40 per cent. The contrast between submarines at their lightest draught and other types of ships at their deepest draught , shown by these figures , indicates the acceptance of altogether exceptional conditions in submarines , and the necessity for their cautious management in the awash condition at the surface , when the apertures on the upper surfaces are kept open . These apertures are closed and secured before the vessels are trimmed for diving by admitting water-ballast . In the diving condition the reserve of buoyancy is extremely small . For submarine A8 it is said to have been 800 pounds , the corresponding displacement being about 220 tons . In other submarines of about the same displacement the reserve of buoyancy in the diving condition has been only 300 to 400 pounds . Consequently there is a necessity for extreme care in the final stages of trimming . The cigar-shape of the hulls involves very rapid changes in the areas and moments of inertia of the planes of flotation as the draught of water is increased in passing from the awash to the diving condition : the stability is greatly reduced , and every member of the crew has to remain in his station . Sir W. H. White . [ Apr. 4 , No weights must be allowed to shift . All the conditions , in fact , differ from those which prevail in ships of ordinary form as they pass from the extreme light draught to the deep-load , for in such ships the outlines of transverse sections approximate to the vertical , except near the bow and stern , over the range between these extreme conditions , and the areas and moments of inertia of planes of flotation do not vary greatly . These general statements may be illustrated by the comparison of a small cruiser of ordinary form with a submarine . The cruiser is about 260 feet long at the water-line , 37 feet broad , and 14 feet 6 inches mean load-draught , the corresponding displacement being about 2000 tons . The submarine has an extreme length of 150 feet , is 12*2 feet in extreme breadth , and has a displacement of 300 tons in the diving condition . In the light ( awash ) condition the submarine draws about 18 inches less water than in the diving condition , and has a displacement of about 284 tons . When awash the length at the water-line is 94 feet , and breadth extreme 8'2 feet ; when in the diving condition the corresponding measurements are 41 feet length and 3'6 feet breadth . These figures differ widely from the length of 150 feet over all and 12-2 feet maximum breadth . In the cruiser , within the corresponding range of draught ( 18 inches ) there is practically no change in length and breadth extreme at water-line , and these dimensions are practically identical with the extreme dimensions of the vessels . Fig. 1 illustrates the contrast TONS PER INCH IMMERSION . Fig. 1 . between the cigar-shape and the ordinary ship-shape . Horizontal measurements to the curves on that diagram , at any draught of water , measure the area of the corresponding plane of flotation , and the number of tons required to immerse the vessel one inch . It is obvious that the small area of the plane 1906 . ] The Stability of Submarines . of flotation at the lightest draught , its rapid diminution as the draught is increased , and the critical condition when trimmed for diving , all render possible the establishment of vertical dipping oscillations in submarines by comparatively trifling disturbances in the water-surface surrounding them . Fig. 2 shows the " metacentric diagrams " for transverse inclinations of the two vessels , constructed in the usual manner . MM shows the locus of the metacentre of the cruiser , and BB that of the centre of buoyancy as the draught of water varies . The curves m , m , m and b , b show the corresponding loci for the submarine . The intercept between these curves on any vertical ordinate represents the height of the metacentre above the centre of L-W-Land diving AWASH . SUBMARINE Fig. 2 . buoyancy at the corresponding draught of water . For the submarine in the awash condition this height is 032 foot , and in the diving condition it is OOl foot . Stability is obtained by disposing the weights so that the centre of gravity of the vessel and its contents lie below the axis ; and in some existing submarines in their diving condition the vertical distance between the axis and the centre of gravity , or metacentric height , is said to be about 9 inches . When submerged , this measure of stability , of course , applies to inclinations from the vertical in any direction . For the cruiser the height of the metacentre above the centre of buoyancy is 7*7 feet at the load water-line , and 8'6 feet for the water-line ( 18 inches VOL. lxxvii.\#151 ; a. 2 p Sir W. H. White . [ Apr. 4 , below the load ) corresponding to the awash condition of the submarine . The centre of gravity of the cruiser is about 2 feet below the metacentre and 5 f feet above the centre of buoyancy in the load condition ; the metacentric locus is nearly horizontal from the load to the light condition , and the centre of gravity rises a*few inches as coals and stores are consumed . Fig. 3 shows the metracentric diagrams for longitudinal inclinations . For the submarine awash the metacentre is 37 feet above the centre of buoyancy ; ORUI SE . R. ~g- L-W'L AND DIVING AWA5H . _ TSU v. . . Z - W. L. SUBMARINE . CRUISER . Fig. 3 . in the diving condition it is only 1/ 25 feet above . For the cruiser floating at a water-line 18 inches below the load draught , the height is 352 feet ; at the load draught it is 328 feet . Expressed in terms of the length over all , the heights of metacentres above centres of buoyancy are 0-25 and 0'0083 times the length respectively for the awash and diving conditions , as against 1'35 and 1'26 times the length for the cruiser at corresponding draughts . These 1906 . ] The ^Stability of Submarines . figures indicate the relatively small longitudinal stability of the submarine , and the necessity for avoiding any movements of weights when the vessel is in the diving condition or submerged . Reference has been made above to the effect upon stability produced by the addition of superstructures . Fig. 4 illustrates this effect for transverse inclinadiving . [ awash . Fig. 4 . tions , m m mbeing the metacentric locus without superstructure , and mi mi mi the locus with superstructure closed and water excluded from spaces between it and the cigar-shaped hull . In the awash condition the height of the transverse metacentre above the centre of buoyancy is increased about one-sixth by the superstructure . The effect of the superstructure upon longitudinal stability is much more marked , as will be seen from fig. 5 . In DIVING . Fig. 5 . the awash condition , closing the superstructure increases the height of metacentre above the centre of buoyancy by fully 50 per cent. It will be obvious from these diagrams that the maintenance of the full reserve of buoyancy is essential to the safety of a submarine when proceeding Sir W. H. White . [ Apr. 4 , at maximum speed at the surface . In the case of A8 , owing to special circumstances , this condition was not fulfilled , and the vessel proceeded at full speed on the surface with her ballast-tanks partly filled with water and with only 6 tons reserve of buoyancy as against the maximum reserve of 13 tons . In consequence of this deeper draught the longitudinal metacentric height was reduced from 12 feet to 8-Jr feet and the power of resisting changes in longitudinal trim was correspondingly diminished . Since that accident took place , definite orders have been given by the Admiralty that the maximum reserve of buoyancy shall always be secured before submarines are driven at full speed on the surface . The precaution is obviously necessary . When a submarine is in the diving condition with all apertures closed and crew stationed , the metacentric height ( as above stated ) is very small , and the trim may be sensibly and rapidly disturbed by small external forces . Consequently very moderate angles of helm given to the horizontal rudders by the operator will produce sensible changes of trim ; and , as the pressures on the rudders vary as the square of the speed of the vessel , increase in speed with consequent increase in rudder pressures demands greater skill and precaution on the part of the helmsman . A very small amount of trim " by the bow " in association with moderate speed when submerged will bring a submarine to a considerable depth below the surface in a very short time . Experience proves that with trained and disciplined operators at the helm , and with moderate speeds such as have been accepted hitherto , submarines can be worked at fairly constant depths below the surface . On the other hand , many cases have occurred where submarines have reached considerable depths and have touched bottom in consequence of slight accidents or failure in control . These considerations point to the conclusion that much higher speeds than have been obtained hitherto when submerged must be accompanied by greatly increased risk ; and it may be questioned if the gain in offensive power , obtained by increased speed , justifies the change in these circumstances . Eor large submarines it is universally agreed that automatic appliances for regulating depth below the surface are not to be trusted , although they are successful in locomotive torpedoes . Close approximations can be made to the pressures developed on the horizontal rudders of a submarine moving at a given speed , and to the corresponding changes of trim produced in the vessel . Similar approximations cannot be made at present to the pressures and inclining moments consequent on the stream-line motions in the water surrounding a submarine when she moves ahead . This , matter can only be dealt with by direct experiment on models and submarines . In the course of the enquiry into the foundering of A8 , this conclusion was universally accepted . Differences of opinion existed 1906 . ] The Stability of Submarines . as to the primary cause of that accident . It was obvious that the deeper draught , the lessened stability and the open hatch all conduced to the disaster ; but experienced witnesses asserted that they were not of opinion that the vessel could have been made to dive suddenly as she did if she possessed as much as 6 tons reserve of buoyancy . Others equally experienced entertained the opinion that this was the real cause of the accident . After a careful analysis of the evidence the author was convinced that the latter opinion was correct . It was stated at the time that the Admiralty proposed to have experiments made at their experimental tank and on actual submarines in order to settle this difference of opinion . Up to the present time no results of such Admiralty experiments have been published : if they have been made , this silence is much to be regretted on scientific grounds , and no reason is seen for refusing the information . It has been stated authoritatively that experiments of the kind have been made on models of submarines at the Experimental Establishment of the United States Navy at Washington , and that the results have confirmed the opinion expressed by the author . In connection with the enquiry into the loss of A8 it was made known that her commanding officer recognised the fact that lessened stability must accompany deeper immersion , and that he trimmed the vessel 4 ' by the stern ( lifting the bow about 4 or 5 feet ) in the belief that this change would make the vessel less liable to be driven under water by the stream-line action on the bow . In considering all the circumstances the author was consequently led to investigate the variations in stability accompanying changes of trim in submarines , and to compare them with corresponding changes in other ships . The technical term " trim " here used means the difference in draught of water at the bow and stern : it has no relation to " trimming " for diving . It was obvious , of course , that the cigar-shape must introduce variations in stability with change of trim much greater than those which would occur in vessels of ordinary form , and it was known that in ordinary vessels the changes of trim which occur in service are not of practical importance . Figs. 6 and 7 give the results obtained for the submarine awash and for the cruiser at load draught , when changes of trim take place by the bow and stern , up to 6 ' from the " even-keel " condition . In order to compare the two types more closely , the heights of metacentres above centres of buoyancy for the even-keel condition are treated as " unity " in both cases , although they differ widely , as above stated . Ordinates to the curves at any angle of trim measure the relative heights of the corresponding metacentre above the centre of buoyancy . Fig. 6 shows these heights for transverse inclinations and fig. 7 those for longitudinal inclinations . In both cases the effect of superstructures is omitted . Sir W. H. White . [ Apr. 4 , CRUISER . ( Load draught ) --- i Trimmed by stern . Trimmed by bow . Fig. 6 . 2s 4s Trimmed by bow . Trimmed by stern . Fig. 7 . Longitudinal stability is more important and the results may be briefly summarised . Taking 4 ' trim by the stern , the height of the metacentre above the centre of buoyancy in the submarine is only 45 per cent , of the height when the vessel is on an even keel . For the cruiser the corresponding figure is 100 per cent. : that is , there is practically no change in longitudinal stability within the limit of trim mentioned . If the superstructure came into play in the submarine the percentage of the metacentric height at 4 ' by the stern to the height on even keel would exceed 50 per cent. It will be seen , therefore , that for a cigar-shaped vessel departures from even keel are accompanied by serious decrease in longitudinal stability , and it may be doubted whether the depressing effect of the stream-line motions at the bow would be reduced to an equal extent , if at all , by raising the bow to the extent done in the case of A8 . The latter point , however , is determinable only by direct experiment . Fig. 8 represents three conditions of draught and trim for the submarine dealt with in the calculations . The foregoing statements lead to the conclusion that in the design of submarines the calculations for stability require to be worked out by naval architects to an extent which is not necessary for ships of ordinary form , and that each departure from precedent must be most closely scrutinised and exhaustively considered . It is true , no doubt , that for the diving and 1906 . ] The Stability of Submarines . Diving ^ condition . Lightest by the stern . Trimmed Fig. 8 . submerged conditions the essential point is to deal accurately with questions of weight and position of the centre of gravity , since stability all directions when submerged depends upon the relative positions of the centres of gravity and buoyancy , and moderate " metacentric heights " have to be accepted . On the other hand , it is certain that equal attention should be directed to the conditions of stability in the awash condition , and in the stages of immersion between it and the diving condition . Submarine design is not a task to be entrusted to amateurs or imperfectly informed persons . Skilled naval architects alone should undertake the work , and the results of their investigations should be put into the form of simple practical rules for the guidance of officers and men . From the nature of the case\#151 ; in consequence of the singular forms of the vessels , the small reserves of buoyancy , and the exceptional variations in stability which must be accepted in order to obtain the power of rapid submergence\#151 ; considerable risks must be taken . It is , therefore , the duty of all concerned to give all possible assistance to officers and crews in the form of information and instructions based on thorough investigation and experiment .

rspa_1906_0046

0950-1207

On a method of obtaining continuous currents from a magnetic detector of the self-restoring type.

538

542

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

L. H. Walter, M. A.

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6.0.4

http://dx.doi.org/10.1098/rspa.1906.0046

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0046

10.1098/rspa.1906.0046

Electricity

Measurement

Electricity

538 On a Method of Obtaining Continuous Currents from a Magnetic Detector of the Self-Restoring Type . By L. H. Walter , M.A. ( Communicated by Professor Ewing , F.R.S. Received March 28 , \#151 ; Read April 5 , 1906 . ) Magnetic detectors of electric waves can , for the purpose of considering their action , roughly be divided into two classes according as the magnetic mass or core to be acted upon by the electric oscillations set up in the receiving conductor upon the arrival of waves is situated outside the influence of the magnetising held at the time when such oscillations are acting , or is all the time in the magnetic field . In the first case , the energy available as a result of the action of the oscillations is limited to that represented by the remanent magnetism in the core , while in the second case it can be derived in part , though not wholly , from the external field . Detectors belonging to the first class have been designed which are capable of giving unidirectional currents\#151 ; practically continuously , as in the case of Fleming 's quantitative detector , * or intermittently , as unidirectional impulses , in Marconi 's more recent relay-operating detector . Although no details have been published relating to the latter , a cursory inspection of the instrument exhibited at the Royal Institution in 1905 showed it to belong to this class . Detectors of the second class , in which the magnetic mass is generally either taken through a slowly performed complete cycle of magnetism or else subjected to continuous reversals in a field of constant strength\#151 ; exemplified respectively in Marconi 's cyclic flux and moving band forms of detectors\#151 ; present other advantages , the chief among which are automatic action and the derivation of part of the energy from the externa ] field . No method of obtaining a continuous current from such detectors has , however , hitherto been devised , such as could be used for rapid recording work , although Tissot has described an arrangement of Marconi 's cyclic flux detector by which indications were received on a ballistic galvanometer.f For this reason the use of these self-restoring detectors has up to the present been limited to telephonic reception , the alternating impulses produced as a result of the action of oscillations prohibiting the employment of a relay or recording instrument . This drawback was pointed out by Marconi in his 1905 Royal Institution lecture . * * Roy . Soc. Proc. , ' vol. 71 , p. 398 , 1903 . t ' Comptes Rendus/ vol. 136 , p. 361 , 1903 . On a Method oj Obtaining Continuous , etc. 539 In view of the above it was considered that a description of a method by which the author has succeeded in obtaining continuous unidirectional currents from a detector of this type might prove of some interest . The method was arrived at as a result of experiments in connection with an instrument previously described , * to determine the cause of the increase of hysteresis loss as a result of the action of oscillations . It was found that the increase is due to a great extent if not entirely to the increase of induction produced , to which increased induction a largely augmented hysteresis loss corresponds at the field strength employed . Working on this basis , it was thought that such an increase of induction might serve as a means of furnishing continuous unidirectional currents , by generating a unidirectional ( commuted ) E.M.F. , i.e. , by making conductors cut the lines of force in a magnetic field , and causing the oscillations to act upon a magnetic mass undergoing reversals of magnetism in the magnetic field of the generator , whereby the E.M.F. generated should be augmented ; a second , equal E.M.F. being opposed to the first , so that normally there is no external potential difference . In such a case a continuous unidirectional current should be obtainable during the time that the oscillations are acting upon the magnetic mass . An experimental apparatus was accordingly made , a diagrammatic plan of which is given in fig. 1 . Two ebonite bobbins , BBi , mounted on the same spindle are rotated in the field of two horseshoe permanent magnets NS , N1S1 , these bobbins being wound , in a similar manner to those illustrated in connection with the pivoted bobbin detector previously referred to , with some feet of steel wire of suitable resistance . A winding of two coils , W , W ' , at right angles to one another , of a hundred turns , is placed on each bobbin , at right angles to the plane of the steel wire winding , as in a drum armature , corresponding coils , i.e. , W and Wi , W ' and W'i , being connected in such a way that the E.M.F/ s generated are equal and opposite . The ends of the windings are connected to the segments of a 4-part commutator C. ( For the sake of clearness only one pair of corresponding windings , of one turn each , is shown connected in fig. 1 . ) The steel wire windings of the two bobbins are exactly alike , the ends of one winding being insulated , while those of the other are connected to a pair of slip-rings , and brushes , by means of which the oscillations can be passed through the winding . On testing this apparatus in the normal condition , with the armature driven by a small electric motor , and no oscillations acting , there was no potential difference at the brushes , the zero of a sensitive Ayrton-Mather * Walter and Ewing , 'Roy . Soc. Proc.,5 vol. 73 , p. 120 , 1904 . 540 Mr. L. EL Walter . On a Method of Obtaining [ Mar. 28 , galvanometer connected to the terminals TT remaining undisturbed . On waves arriving , a steady deflection on the galvanometer was obtained , in a direction corresponding to an increase of E.M.F. generated by the armature ( bobbin ) acted upon by the oscillations . On the oscillations ceasing the galvanometer deflection returned to zero . The effect naturally was very small in the first experiments , but it has been found that by suitable designing the magnetic winding and proportioning the turns in the armature winding a quite considerable sensibility is obtained , and this is continually being improved upon . The usual speed employed is about five to eight revolutions per second ; higher speeds have been tried and give a larger effect , but the zero is not so steady . The model illustrated is not adapted to give the best results , this form having been chosen solely for convenience in construction . A considerable length of the winding on the armature is " dead " wire , and hence in a new model being constructed the armatures resemble small Gramme ring structures , in which the wire is more effectively utilised . The results obtained with the first form of the apparatus led to the idea that the magnetic mass might be located elsewhere in the magnetic circuit of M , such as at B in fig. 2 , undergoing slow continuous reversals at the most favourable speed , and an ordinary ring armature A be used , which latter could then be run at a much higher speed so that a proportionately greater external potential difference as a result of oscillations acting could be anticipated , two identical generators opposed to one another of course being employed as in the previous method . The few experiments made in this direction have , however , not given good results up to the present , but this is considered to be due rather to 1906 . ] Continuous Currents from a Magnetic , etc. 541 the experimental apparatus employed than to the inapplicability of the method . Fig. 2 . Since in many cases it may be desirable to receive signals or indications simultaneously by means of a telephone as well as recording them , a telephonic receiver may be connected so as to take off the current produced as a result of such signals , at some point before it is commuted into unidirectional current , as the alternating current is better adapted for actuating the telephone . When a relay alone has to be actuated , however , it may be advantageous to so arrange matters that the generated E.M.F. 's do not exactly balance , and a small initial current , insufficient to actuate the relay , passes all the time through it . By this means the impulse resulting from the action of oscillations has only to supply little more than the current required to effect the actual movement of the relay tongue or coil , the steady current always passing being sufficient to almost start it from its position of rest . The change can be rapidly effected by a very slight shift of the brushes . While the author 's method of passing the oscillations directly through the magnetic winding leads to a very simple mechanical construction , there is nothing to prevent the older , more general method being made use of , in which they are passed through a separate copper wire winding on the outside of the magnetic core ( co-directional oscillations ) . Since this paper was written the author has seen a proof of a paper giving the results of recent experiments by J. Bussell* on the effect of co-directional and of transverse electric oscillations on the magnetism of sheet iron . These * ' Boy . Soc. Edinburgh Proc. , ' vol. 26 , No. , 1 , 1905-6 . Mr. R. Threlfall . On a Static Method of [ Apr. 3 , results tend to show , if applied without discrimination , that the iron at the low field employed is more sensitive to the co-directional oscillations ; but the experimental conditions as regards the transverse oscillations , which latter are produced in a solid mass of metal , and hence are nearly entirely dissipated in the form of eddy currents , are so entirely different from the circular magnetisation obtained by the author 's method , in which the value of the magnetisation at the surface of the magnetic wire carrying the oscillations varies inversely as the radius of the wire , that a comparison cannot be made . A combination of the two methods appears to offer additional advantages , but has not yet been tried . On a Static Method of Comparing the Densities of Gases . By Bichard Threlfall , M.A. , F.B.S. ( Beceived April 3 , \#151 ; Bead May 3 , 1906 . ) The measurement of small differences of pressure to a fairly high degree of accuracy is not difficult . I have indicated a construction of a micromanometer* which in its ordinary commercial form has a range of 3 or 4 cm . of height of a liquid column and reads to OOOo mm. direct . Dr. Stantonf describes a manometer constructed on Professor Chattock 's principle , having a reading sensitiveness of 0-0015 mm. of water , but the range is not stated . Lord Bayleigh , observing the contact between mercury surfaces and sharp points , obtained a sensitiveness of 0'0005 mm. of mercury with a range of about 15 mm4 The idea of employing the micro-manometer for the determination of the relative densities of gases first occurred to me in 1901 in considering the corrections to a set of Pitot tube observations taken in a gas pipe situated some 20 feet above the manometer , and though a rough trial was carried out at the time it is only recently that I have had an opportunity of making an adequate test of the method . Beferring to the figure , Ai A2 are the two limbs of the micro-manometer\#151 ; the liquid ( coloured water or oil ) being in communication by the syphon B. The gases whose densities are to be compared are allowed to pass into the long tubes Ci and C2 , through the openings at Di and D2 , where there are * ' Inst , of Meehan . Engine . Proc. , ' February , 1904 , p. 273 . t Minutes of 'Inst , of Meehan . Engine . Proc. , ' vol. 156 , session 1903\#151 ; 1904 , part 2 . f ' Phil. Trans. , ' A , vol. 196 ( 1901 ) , p. 205 .

rspa_1906_0047

0950-1207

On a static method of comparing the densities of gases

542

545

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Richard Threlfall, M. A., F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0047

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0047

10.1098/rspa.1906.0047

Thermodynamics

Measurement

Thermodynamics

542 Mr. R. Threlfall . On a Static Method of [ Apr. 3 , results tend to show , if applied without discrimination , that the iron at the low field employed is more sensitive to the co-directional oscillations ; but the experimental conditions as regards the transverse oscillations , which latter are produced in a solid mass of metal , and hence are nearly entirely dissipated in the form of eddy currents , are so entirely different from the circular magnetisation obtained by the author 's method , in which the value of the magnetisation at the surface of the magnetic wire carrying the oscillations varies inversely as the radius of the wire , that a comparison cannot be made . A combination of the two methods appears to offer additional advantages , but has not yet been tried . On a Static Method of Comparing the Densities of Gases . By Bichard Threlfall , M.A. , F.B.S. ( Beceived April 3 , \#151 ; Bead May 3 , 1906 . ) The measurement of small differences of pressure to a fairly high degree of accuracy is not difficult . I have indicated a construction of a micromanometer* which in its ordinary commercial form has a range of 3 or 4 cm . of height of a liquid column and reads to OOOo mm. direct . Dr. Stantonf describes a manometer constructed on Professor Chattock 's principle , having a reading sensitiveness of 0-0015 mm. of water , but the range is not stated . Lord Bayleigh , observing the contact between mercury surfaces and sharp points , obtained a sensitiveness of 0'0005 mm. of mercury with a range of about 15 mm4 The idea of employing the micro-manometer for the determination of the relative densities of gases first occurred to me in 1901 in considering the corrections to a set of Pitot tube observations taken in a gas pipe situated some 20 feet above the manometer , and though a rough trial was carried out at the time it is only recently that I have had an opportunity of making an adequate test of the method . Beferring to the figure , Ai A2 are the two limbs of the micro-manometer\#151 ; the liquid ( coloured water or oil ) being in communication by the syphon B. The gases whose densities are to be compared are allowed to pass into the long tubes Ci and C2 , through the openings at Di and D2 , where there are * ' Inst , of Meehan . Engin . Proc. , ' February , 1904 , p. 273 . t Minutes of 'Inst , of Meehan . Engin . Proc. , ' vol. 156 , session 1903\#151 ; 1904 , part 2 . f ' Phil. Trans. , ' A , vol. 196 ( 1901 ) , p. 205 . 1906 . ] Comparing the Densities of Gases . V* fD taps . The tubes Ci and C2 are formed of ordinary composition gas pipe and are kept at the same temperature by being placed in an outer iron pipe , not shown\#151 ; through which a current of water passes\#151 ; the temperature of the water being ascertained by sensitive thermometers . It is obvious that since the upper openings of the tubes Ci and C2 ( bent downwards for gases less dense than air ) are in the same horizontal plane , the gaseous contents are exposed to the same external pressure , while the pressure in the limbs Ai and A2 corresponds to the external pressure , together with the " pneumostatic " pressure due to the height and density of the columns of the gases in the composition pipes . Let the density of the gas in the pipe Ci be pi and of the gas in the pipe C2\#151 ; p'2 , and let H be vertical distance between the free ends of the composition pipes and the surface of the liquid in the manometer when both pipes are filled with the same gas . Let a be the density of the liquid in the manometer and hthe manometer reading , i.e. , the difference of level of the liquid in the two limbs due to the density of the gases being different in the two limbs . If h is very small compared with H , then it is easy to see ( small corrections being omitted ) that h P2 pi jj ! D. \#151 ; -4p ... i. \#151 ; in the case where the pressure at the foot of the tube Ci is the greater . The practical limit of accuracy is fixed by the determination of h , and since in the micromanometer the actual error is independent of the magnitude of h , the experiment must be arranged in such a manner that h is as large as possible . In the actual experiment a height of nearly 20 metres was available for the gaseous columns . The accuracy of a comparison is thus easily estimated : suppose that the gases to be compared have about the density of air , that \lt ; r=l , that h\#151 ; 0'005 mm. and H = 20 metres , we have 0-0005 pi\#151 ; p2 'H 2 x 103 2-5 x 10"7 . Mr. R. Threlfall . On a Static Method of [ Apr. 3 , The density of air , however , is about 0'00129 gramme per cubic centimetre under standard conditions , so that the smallest difference of density observable by this method is T93 x 10-4 of the actual density or , say , 1/ 5000 part . Lord Eayleigh and Sir William Ramsay* state that the mean of their determinations of the density of " chemical nitrogen " is L2511 and of " atmospheric nitrogen " L2572 in grammes per litre . The difference is thus about 1/ 2100 of the density of the lighter gas . It appears , therefore , that the static method on the scale described should be able to show the difference between the density of " chemical " and of " atmospheric " nitrogen . Producer gas being lighter than air , it is advantageous to lead it into the column from the top , so that the air in the pipe may be displaced with as little mixing as possible . A preliminary experiment with a rough and ready piece of apparatus has shown that when hydrogen was passed in from the bottom it was very hard to get the column free of air . It is necessary to protect the free ends of the columns from draughts . In practice , producer or other gas , after passing a suitable drying system , first displaces the air from a large flask which is in communication both with the column and a loosely plugged test-tube\#151 ; the connection to the latter being by means of about 1 metre of glass tubing of 2 or 3 mm. bore . After a time the flow to the test-tube is stopped and the column filled\#151 ; the bottom being left open to the air by slipping the rubber tube off the manometer . The column itself was erected in the angle of a square brick tower , and the height was measured by means of a steel tape\#151 ; not a method for a classical experiment , of course , hut sufficient for the purpose . The water supply was from a large tank at the top of the tower and the water first passed down the tower so as to attain the temperature of the tower as nearly as possible before entering the jacket of the columns . The composition pipes were \#163 ; inch internal diameter , and were strengthened and soldered to the flanged plate where the}7 passed through it . The manometer was at such a height that the free surface of the manometric fluid was at practically the same level as the bottom of the water column . Similarly the open ends of the columns are practically at the level of the top of the water\#151 ; but as the water and tower were at substantially the same temperature , it was not necessary to be very particular . The comparison of the densities of producer gas and air appeared to offer no difficulty\#151 ; everything proceeding " according to arrangement . " A set of 20 settings of the micro-manometer showed a probable error of the total of * ' Phil. Trans. , ' A , vol. 186 , p. 189 . 1906 . ] Comparing the Densities of Gases . 545 about 0-00077 mm. , and of a single setting 0-0034 mm. ; in satisfactory-agreement with the opinion formed on instrumental grounds that the error of a single setting might be about 1/ 200 mm. at most . The value of It , deduced for the sample of gas used\#151 ; air filling the other column\#151 ; was 0-3458 cm . , the manometer fluid being distilled water coloured by a trace of aniline blue . Other data were:\#151 ; Height of barometer , corrected for temperature ... ... ... 748-6 mm. Mean temperature both of water jacket and of tower ... . 18 ' C. Height of columns of gas above undisturbed level of micromanometer ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 1956-8 cm . Height of manometric column ... ... ... ... ... ... ... ... ... . 0-3458 cm . Density of manometric fluid ... ... ... ... ... ... ... ... ... . 0-9987 Hence density of producer gas 0-001195-0-9987 = 0-0010185 , 1956-8 or , reduced to 0 ' C. and 760 ' mm. , the producer gas density is 0'001102 gramme per cubic centimetre . The gas was most carefully analysed several times and the density calculated from the composition ; the result was :\#151 ; Density = 0*001089 gramme per cubic centimetre , which agrees with the absolute density as nearly as could be expected from an analysis made with commercial apparatus . Three days later a second experiment was made on the gas which was being manufactured at that date , and a manometer reading of 0*3550 cm . was observed . This remained constant for several fillings of the columns , and even after they had remained at rest for several hours . The resulting density in this case was 0*001098 gramme per cubic centimetre . I have pleasure in acknowledging my indebtedness to my assistant , Mr. Bradbury , who carried out the experiment described above .

rspa_1906_0048

0950-1207

A variety of thorianite from Galle, Ceylon.

546

549

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Wyndham R. Dunstan, M. A., LL. D., F. R. S.|B. Mouat Jones, B. A. (Oxon.)

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6.0.4

http://dx.doi.org/10.1098/rspa.1906.0048

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0048

10.1098/rspa.1906.0048

Chemistry 2

Atomic Physics

Chemistry

546 A Variety of Thorianite from Ceylon . By Wyndham B. Dunstan , M.A. , LL. D. , F.R.S. , and B. Mouat Jones , B.A. ( Oxon . ) , Assistant in the Scientific and Technical Department of the Imperial Institute . ( Received April 11 , \#151 ; Read May 10 , 1906 . ) In a previous paper* an account has been given of the composition and properties of a new mineral from Ceylon , chiefly composed of thorium dioxide ( 78 to 79 per cent. ) , to which the name thorianite was given . The mineral was shown to contain , besides thoria , a certain proportion of oxides of uranium varying in the three specimens analysed between 11 and 15 per cent. , the uranium being present partly as dioxide and partly as trioxide , that is to say , in the same condition as in uraninite or pitchblende . It was shown that the evidence strongly supports the conclusion that thorianite and uraninite possess the same crystalline form and that they are isomorphous minerals . It is interesting to note that the new mineral naegite , from Japan , which is essentially a silicate of uranium containing thorium , appears to be isomorphous with thorite ( thorium silicate ) . It was suggested that the intimate association of thoria with oxides of uranium in thorianite is to he regarded as a case of isomorphous mixture . Such a mixture , or perhaps " solid solution , " might result from the crystallisation of thorianite from a fused mixture or magma containing the oxides of both elements . We have now obtained important confirmation of this view through the analyses of some unusually large crystalline fragments of thorianite received from the Gall District of Ceylon , which show that a still wider variation may occur in the proportions of the two oxides present in the mineral . This variety is composed of black lumps , usually of indefinite crystalline form , some of the pieces being apparently cubic . They are often partially covered with a brownish yellow substance containing a considerable amount of silica and probably derived from the associated rock . Some of the pieces weighed over 50 grammes , and were evidently portions of much larger masses . The fractured surfaces often showed a slightly less lustrous and more pitchy appearance than ordinary thorianite . The appearance of the mineral is thus intermediate between the small separate and cubical crystals of thorianite and the large masses without definite crystalline form , which are usually characteristic of uraninite . A small amount of material from Hinidumpattu in Gall consisted of small cubic crystal almost indis* Dunstan and Blake , { Proc. Roy . Soc. , ' A , vol. 76 , 1905 . A Variety of Thorianite from Gall , Ceylon . tinguishable in appearance from ordinary thorianite . In hardness , optical properties , density and general physical characters this variety of thorianite closely resembles the ordinary form of the mineral . Analysis by the methods described in the previous paper* on thorianite shows , however , that it contains a much larger proportion ( from 27 to 32 per cent. ) of oxides of uranium and less oxide of thorium , whilst the minor constituents of the two forms of the mineral are seen to be similar in nature and quantity . It appeared possible that the masses might consist of uraninite crystallised on a nucleus of thorianite or vice or that the two minerals might be separately crystallised within the masses . Analyses of different portions of one and the same piece have , however , given nearly identical results , and the oxides of the two elements appear to be uniformly distributed through the mineral , although there is some variation in the composition of specimens obtained by different collectors . It may be noticed in the following table that the Analysis I of the small crystals from the Gall District shows rather more uranium and less thorium than that of the larger lumps ( II to YI ) . If the uranium is calculated as U02 , the molecular ratio of Th02 to U02 in the small crystals is almost exactly 2 to 1 , but there is no evidence that this is more than a coincidence . No. YII was a large crystal , 8 mm. cube , of ordinary thorianite from Balangoda . The fact that thoria in thorianite is naturally associated with quantities of oxides of uranium varying from 11 to over 30 per cent. , confirms the conclusions , indicated in the previous paper , that the oxides of thorium and uranium are present in thorianite in that intimate association known as " isomorphous mixture . " Different specimens of thorianite from the Gall district have furnished 58*84 , 62*16 , 62*30 , 63*36 and 66*82 per cent , of thoria , whilst common thorianite from other localities has furnished from 76 to 79 per cent , of thoria . The relations of thorium and uranium in minerals is a subject of some importance in connection with the present developments of the theory of the chemical elements . Attention has been directed recently to the subject by the Hon. It . J. Strutt.*]* It may be noticed in this connection that the percentages of thoria recorded by Mr. Strutt in his paper have been calculated from the observed radio-activity of the minerals , and not directly determined by chemical analysis . A comparison of the two series of percentages shows differences which in some cases are considerable . The calculated results are , however , only to be regarded as roughly approximate . * Loc . cit. t 'Proc . Roy . Soc. , ' A , vol. 76 , p. 88 1905 . VOL. LXXVII.\#151 ; A. Prof. W. R. Dunstan and Mr. B. M. Jones . [ Apr. 11 , The Galle variety of thorianite , as was to be expected , is radio-active , and it contains helium . Mr. Strutt has kindly examined the radio-activity of this variety , and compared it with ordinary thorianite . The method of comparison was as follows:\#151 ; " The quantity taken in each case was about one-tenth of a gramme . It was dissolved in strong nitric acid , and most of the excess of acid driven off by evaporation . The solution was diluted and exactly neutralised with ammonia , to prevent any injurious effect of the acid fumes on the apparatus . The solution was then made up to a standard volume . The solutions of the two minerals were placed in exactly similar test-tube wash-bottles . These vessels were selected to have exactly the same diameter , and the inner tube in each case dipped to exactly the same depth in the solution . A continuous current of air could be drawn through either of them alternately into an electroscope . A two-way stop-cock made it easy to exchange one wash-bottle for the other . Constant suction was secured by the obvious device of letting in air through a deeper wash-bottle attached to a T-piece on the other side of the electroscope . The pressure driving the air through the electroscope was thus equal to the difference of depth between this bottle and the wash-bottle containing the active solution . The current was regulated once for all by a stop-cock , and was not sufficiently rapid to appreciably disturb the gold leaf of the electroscope . In making the comparisons , air was first drawn through the solutions long enough to expel all accumulated radium emanation . Three measurements of the rate of leak due to the first solution were taken , then three with the other solution ; then three more with the first , and so on . The mean of each of these sets was compared with that of its successor . The mean ratio so obtained was corrected for the slight difference in the quantities of material taken . The correction ( or normal leakage of the electroscope ) was too small to be worth applying . Two samples of each mineral were weighed out , and compared in the manner above described in every combination . Four values for the ratio of thorium activities in the two minerals were thus obtained . They were as follows:\#151 ; B/ A = 119 , 112 , 1-10 , 1-24 . Mean , 116 . The specimen of thorianite B used in this comparison contained 78*86 per cent , of thoria and 151 per cent , of uranium oxides . The specimen of the Galle variety A used was that numbered I in the table of analyses . The results of the radio-activity determinations are in fair accordance with the proportions of uranium and thorium determined by analysis . " 1906 . ] A Variety of Thorianite from , Ceylon . In the following table of analyses , I represents the composition of the small crystals from Hinidnmpattu , Gall District ; II to VI represent the compositions of the large lumps from the same locality ; II , III , and IV are analyses of different parts of the same crystal , III being that of the outer layer ; VII is an analysis of a large crystal of ordinary thorianite from Balangoda . Table of Analyses . I. II . III . IV . V. VI . VII . ThO , 58 -84 62 -16 1 fin -89 J _ 62 -32 63 -36 78 -98 ( Ce , La , Di)203 0-85 1-84/ y)\j o\#163 ; s \#151 ; 2 '24 1 -16 1 -47 y2o3 \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; -U0.2 uos }82 -74 j 10 -32 1 18 -88 J 28 '24 28 *68 27 -02 27 -99 13 -40 PbO 2-56 2-29 2-29 2*50 2-99 2 -90 2 -54 FeoO-j 1 31 1 11 1 22 2*43 2 -28 1 -27 0-87 CaO 0 -19 0-59 0-54 \#151 ; 0-50 0-85 0 . 91 H.,0 1 -26 1 '05 1 -oo \#151 ; 2 -16 1 -32 1 -28 Insoluble in nitric acid ... 0-45 0-77 0 ; 56 0*54 0-87 0-77 0 '47 He \ coj present present present present present present present Mineralogists have often assigned a new name to a mineral found in a new locality when it has differed essentially in composition from the previously known mineral . It does not , however , seem desirable , in the light of present knowledge , to regard this variety of thorianite from Gall as a new mineral species , especially when it is remembered that the oxides of thorium and uranium in thorianite are not chemically combined and that from the probable mode in which the mineral has been formed , it is to be expected that considerable variations would naturally occur in the proportions of the two oxides in the mineral found in distinct localities which have therefore crystallised under different conditions . In fact , it is probable that further examination of other specimens from distinct localities may reveal the existence of a series of substances intermediate between the hypothetical pure uraninite , consisting of uranium dioxide , and the pure thorianite , consisting of dioxide of thorium .

rspa_1906_0049

0950-1207

Some stars with peculiar spectra

550

553

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir Norman Lockyer, K. C. B., F. R. S., LL. D., Sc. D.|F. E. Baxandall, A. R. C. S.

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10.1098/rspa.1906.0049

Atomic Physics

Astronomy

Atomic Physics

550 Some Stars with Peculiar Spectra . By Sir Norman Lockyer , K.C.B. , F.B.S. , LL. D. , Sc. D. , and F. E. Baxandall , A.RC . S. ( Received May 5 , \#151 ; Read May 17 , 1906 . ) In a paper on the chemical classification of the stars* communicated to the Royal Society on May 4 , 1899 , it was pointed out that it was then possible to classify the stars according to their chemistry . In a later publicationf the spectra of the brighter stars were arranged in groups according to the suggested classification . In the course of this work it was found that in the case of a few stars the spectra show certain peculiarities , and do not altogether conform to any common type . The most notable of these stars are a Andromedm , 6 Aurigse , a Canum Venaticorum , and e Ursae Majoris . These are all on the descending side of the Kensington curve of stellar temperature , the first three being of the Markabian type and the last of the Sirian type . The present paper contains a short account of their spectra . More minute discussion will be reserved for a subsequent memoir . a Andromedce . This star has been recently found by Slipher , of the Lowell Observatory , to be a spectroscopic binary . In the published statement* to that effect , the period is given as about 100 days . This result has been based on measures of the displacement of the Hv and Mg 4481 " 3 lines from their normal position . The Lowell publication does not give an account of the -general nature of the stellar spectrum , and there is no mention of any changes in the relative intensity of any of the lines . Prior to this announcement of Slipher , an investigation of various spectra of uAirtlromedae , taken between the years 1900\#151 ; 1904 at Kensington , appeared to indicate slight changes in the relative intensity , position , and definition of some of the lines in the various photographs . In the classification a Andromedse was placed in the Markabian group , the accepted type star for which is \#171 ; Pegasi ( Markab ) . The Markabian stage is on the descending side of the temperature curve immediately higher than the Sirian stage , and below the Algolian ( / Persei ) . Although placed in the Markabian group , \#171 ; Andromedse , as determined by the behaviour of the * ' Roy . Soc. Proc. , ' vol. 65 , p. 186 . t ' Catalogue of 470 of the Brighter Stars , ' published by the Solar Physics Committee . f 'Lowell Observatory Bulletin , ' No. 11 . Some Stars with Peculiar Spectra . 551 helium lines in its spectrum , represents a slightly higher stage , but it approaches more closely to the type star of the Markabian group ( a Pegasi ) than to that of the higher temperature Algolian group ( / 3Persei ) . Its acceptance as a Markabian star was based on the behaviour in its spectrum of the lines of hydrogen , helium , magnesium , silicium , etc. Next to the lines of hydrogen and helium , the most prominent lines which have been traced to known terrestrial elements are those of silicium Group II ( XX4128*20,4131*04 ) , proto-magnesium X 4481 '3 , and proto-calcium ( X 3933-83 ) . The strongest enhanced lines of iron , chromium , carbon , and titanium are present , but only occur as comparatively weak lines . In addition to these lines of known origin there occur several strange and well-marked lines , not found in the spectrum of any other star yet examined , and for which no satisfactory terrestrial origin has yet been found . Of the strange lines , those at XX3943-9 , 3984-1 , 4137*0 , 4206*3 and 4282*4 are the most prominent . All except X 4206*3 agree closely in position with fairly strong solar lines , one ( X 3944*1 ) ascribed by Eowland to Al , the others to Fe , but there is no evidence obtainable from the Kensington Laboratory spectra that these lines of aluminium and iron behave specially under varying conditions and the approximate agreement in wave-length is possibly a fortuitous one . As the strongest stellar lines , apart from those of hydrogen , are all enhanced lines of certain metals , it would also appear probable that the strange lines mentioned are due to some element or elements not yet found terrestrially or for which , if found , tlj^re is yet no record of enhanced lines . The records of other celestial spectra , such as those of nebulae , bright-line stars , and novae , have all been searched for possible identification of some of their lines with the strange lines in a Andromedae , but with no success . Although , as has been stated , there appear to be slight changes in relative intensity , position or definition of some of the lines in the a Andromedae spectrum , there does not seem to be any regularity in the changeSj either in the lines themselves or in the manner in which they are affected , so that at the present stage it is not possible to come to any conclusion as to their real significance . Whether the changes have any relation to the period established by Slipher cannot be settled from the existing photographs , and additional photographs of the stellar spectrum at extended intervals will be necessary to throw more light on this point . 6 Aurigce . Like aAndromedse , this star has , in the Kensington classification , been placed in the Markabian group , the type of which is a Pegasi . Its spectrum Sir N. Lockyer and Mr. F. E. Baxandall . [ May . 5 , resembles that of a Pegasi more closely than that of either / 3 Persei , the type star of the Algolian , the next higher group , or Sirius , the representative of the next lower group ( Sirian ) . The 0 Aurigse spectrum , however , lacks the helium line 447l"7 and its real position is intermediate to a Pegasi\#151 ; in which the helium line mentioned is weakly represented\#151 ; and Sirius , in which the helium lines are lacking . Apart from the hydrogen lines , the chief feature of the spectrum of #Aurigse is the prominence of the lines of silicium Groups I and II , the behaviour of which in the silicium spectrum has been discussed in a previous paper.* The proto-magnesium line 448P3 is moderately strong , but the lines of proto-calcium , proto-iron , proto-titanium , proto-strontium , proto-chromium , although present , are comparatively weak . In addition to the lines of known origin , there are a few which appear to be special to this spectrum . The stronger of these are near 3954-3 ( 3\#151 ; 4 ) , 4076-3 , 4191-8 ( 2\#151 ; 3 ) , 4200-7 ( 2\#151 ; 3 ) , and 4377-0 ( 3 ) . These lines form an entirely different set from the strange lines in the spectrum of i\ndromedse . Reference to records of terrestrial spectra has afforded no satisfactory results as to the origin of these lines . One of them 4200'7 ) apparently agrees in position with one of the series of lines discovered by Professor Pickering in the spectrum of \#163 ; Puppis . In the absence of the other lines of the series , however , it is scarcely likely that the line is of identical origin in the two cases . a Canum Venaticorum . This star has also been placed in the Markabian group in the Kensington classification , and its general spectrum is very similar to that of 6 Aurigse , one of the stars previously discussed . Of this stellar spectrum , Pickering remarks that the K line of calcium is extremely faint , and the lines 4128-5 , 4131-4 ( subsequently traced to silicium Group II ) are stronger than in the normal spectra of the same class . Some of the fainter lines , he says , appear to be of " peculiar wave-length . . All these abnormalities have been confirmed by an investigation of the Kensington spectra of this star . The lines in the spectrum are , in general , only faint , the most prominent , apart from those of hydrogen , being the silicium lines previously mentioned and the enhanced magnesium line 4481 3 . The more pronounced enhanced lines of iron , titanium and chromium , aie present , but weak . The ordinary metallic arc lines , which occur prominently in the lower type stars , are lacking . * i Roy . Soc. Proc. , ' vol. 67 , p. 403 . 1906 . ] Some Stars with Peculiar Spectra . Some of the strange lines\#151 ; that is , lines not in the normal spectrum of the same general type\#151 ; appear to be identical with those in 6 Aurigse . Thus there are lines whose wave-lengths are approximately 3954*3 , 4076*5 , 4136*3 , 4192 0 , and 4376*8 , which occur in Aurigse , but not in the normal spectrum . There are no lines of considerable intensity special to a Canum Venaticorum , though some of the fainter lines seem to be peculiar to this spectrum . e Ur see Majoris . This star has , in the Kensington classification , been placed in the Sirian group , the type star of which is Sirius . From the intensity of some of the metallic lines it is apparently somewhat lower on the temperature curve than the Sirian , coming between that and the Procyonian type . Its spectrum , however , resembles the Sirian more than the Procyonian . The spectrum has been carefully compared with that of Sirius , and any differences in intensity or position of the lines noted . These will be given in detail in a future paper . What peculiarities there are , however , are chiefly confined to alterations in relative intensity of certain lines , very few lines having been found which do not occur in the Sirian spectrum . The spectrum does not , therefore , diverge from the normal type so much as in the case of a Andromedse and 6 Aurigse . The most noticeable features of the comparison of this spectrum with the Sirian spectrum are the weakening of the Group II silieium lines at X4128\#151 ; 4131 , and the strengthening of the enhanced lines of chromium in the former spectrum . Certain of the enhanced lines of titanium and iron seem to be affected , but , as a class , the lines of neither of these elements are affected so much as those of chromium . There are a few cases of lines occurring in e Ursse Majoris which appear to be lacking in Sirius , but these are nearly all weak lines . The photographs of the stellar spectra were all taken with one 6-inch Henry objective prism of 45 ' angle . The dispersion is such that the distance between He and Hp is 1*85 inches or 4*6 cm . The various photographs involved in the discussion were obtained by Messrs. Baxandall , Butler , Kolston , and Moss .

rspa_1906_0050

0950-1207

Erratum

554

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Measurement

Biography

Measurement

554 ERRATUM . Page 289 , line 20 from the top , instead of " 10 , 15 , 20 , " read 20 , 15 , 20 . "

rspa_1906_0051

0950-1207

A note on the theory of directive antenn\#xE6; or unsymmetrical hertzian oscillators.

1

8

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

J. A. Fleming, M. A., D. Sc., F. R. S.

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Fluid Dynamics

Electricity

Fluid Dynamics

]\gt ; PROCEEDINGS OF THE ROYAL SOCIETY . SECTION A.\mdash ; MATEEJrATICAL AND PEYSICAL SCIENCES . A Note on the Theory of Directive or Unsymmetricat Hertzian Oscillators . By J. A. FLEMING , M.A. , D.Sc . , F.B.S. Received March Read March Received form The employment in wireless telegraphy of antennae or wires which have part of their length vertical and part horizontal , and possess the power of radiating unequally in various horizontal directions , draws attention to the particular qualities of bent electric oscillators when used as diators or transmitters . * The objecc of the note is to sho that the properties of such radiators can be deduced from accepted principles , experimental results so far obtained are in rveneral accordance with theory . The nature of the field of electric and magnetic force round a shorC straight electric oscillator or doublet has been expressed analytically ) delineated graphically in well-known memoirs by Hertz , earson and Lee , and others , and that around a not very short rod or linear oscillator has been * See G. Marconi , .D . , D.Sc . , " " On Methods whereby the Radiation of Electric Waves may be mainly confined to certain Directions , and whereby the Receptivity of a Receiver may be restricted to Electric Waves tting f certain Directions ' Soc. Proc vol. 77 , p. 413 , 1906 . H. Hertz , ' Wied . Ann vol. 36 , p. 1 , 1889 , or ' Waves , ' English translation , p. 137 . Pearson and Lee , ' Phil. Trans , vol. 193 , p. 169 , 1900 . VOL. LXXVIII.\mdash ; A. Prof. J. A. Fleming . Theory of tive [ May 24 , ated by M. Abraham*and depicted by F. Hack . In these cases we have perfect symmetry of radiation round the axis of the oscillator . This equality is , however , destroyed by bending the oscillator , and it then radiates unequally in different directions taken in the equatorial or sylmetrical plane of the oscillator through its centre , being somewhat greater or stronger on the convex side of the oscillatol The analytical treatment of subject presents , however , enormous difficulties unless we limit consideration to the case in which the current in the oscillator is assumed to have the same value at all points at the same time , and also that the dimensions of the oscillator are small compared with the distance from it of the points at which the field is considered . One . form of bent oscillator of the above kind may be considered to be made up by the superposition of three Hertzian electric doublets placed at right angles to each other , the poles being so arranged that at the two corners poles of opposite sign are superimposed , the oscillations in all being synchronous and similarly directed ( see fig. 1 ) . Hence , to obtain the field 01 the bent \ldquo ; we need merely to calculate those of the components and add them together . FIG. 1 . Let a single electric oscillator or doublet be placed with centre at the and axis coinciding with the axis . Let oscillations exist in it of period , and radiation be emitted of waye-length . Suppose the length of the oscillator to be denoted by , the electric charge at either pole at any instant by , the uniform current in the axis by , whilst and I are the maximum values of and which vary so that and . Also let be the maximum electric moment of the * M. Abraham , ' Ann. der Physik vol. 66 , p. 435 , 1898 . F. Hack , 'Ann . der Physik vol. 14 , p. 539 , 1904 . 1906 . ] Ante , nnoe or Unsyrmetrical Hertzian Oscillators . oscillator . We have , therefore , or , and , the velocity of propagation of the radiation through space . The scalar potential at any point whose distance from the origin is is given by ( 1 ) where is the dielectric constant of the medium , and Also , if , and are the components of vector potential at , we have in this case , and . ( 2 ) If we employ the symbol to stand for , we can write the above expressions ( 1 ) and ( 2 ) in the form . ( 3 ) If we suppose this doublet to be moved parallel to itself in the ative direction so that its centre is displaced by a distance , the scalar and vector potentials at become\mdash ; , ( 4 ) . ( 5 ) Consider , then , other similar doublets of length , and maxinnum moment , placed with poles . in opposite directions and axes parallel to the axis of , the doublets having centres at distances from the origin and poles as in . The scalar and vector potentials at the point of these last two doublets ether a double-doublet criven by\mdash ; , ( ) . ( 7 ) Hence , if three such short , straight oscillators , having equal curreuts and charges , are placed round the origin so as to create a doubly-bent the scalar and vector potentials of this oscillator at a point thu distance of which from the origin is large compared with linear dimeusions of the oscillator , are iven by\mdash ; . ( 8 ) Prof J. A. Fleming . Theory of Directive [ May 24 , ( 9 ) where The electric and magnetic forces at the point , of which the axial components are , and , can be obtained from equations ( 8 ) and at once by the aid of the relations\mdash ; ' ( 10 ) It is obvious that if the electric circuit is completed by placing a pair of double-doublets of moments and at right angles to each other with poles directed in like sense all round the , the free charges cancel each other pair and pair , and we are left with a closed electric circuit of area traversed by a maximum current I. This quadruple doublet creates potentials such that where 1906 . ] Antennoe or Oscillators . Such a completely closed circuit or magnetic doublet creates , therefore , periodic electric and magnetic forces in its field when current oscillations are set up in the circuit . * For the purposes we require only the electric and magnetic forces perpendicular to the radius vector , taken at its extremity , when that radius is taken in the plane , which is normal to the plane in which the oscillator is situated . Hence we need only calculate the value of , and for the case in question . If we write for I and call this the netic moment of the bent oscillator , so that , we have the following equations for the potentials and forces in the field at points not very near the oscillator\mdash ; , ( 12 ) Performing the necessary differentiations on the function and collecting . terms in and mr \mdash ; , which for shortness will be written and , also putting for or , where are the permeability and dielectric constant of the medium , we have the following expressions for , and * In the discussion on Mr. Marconi 's paper read at the Royal Society on March 22 , 1906 , Professor J. Larmor , Sec. R.S. , pointed out that the bent antenna employed by Mr. Marconi was equivalent in effect at distant points to the combination of a magnetic doublet or bi-pole magnetic oscillator of the kind investigated , in advance of Hertz 's discovery of electric radiation , by Professor G. F. Fitzgerald ( see The Scientific Writings of the late Professor G. F. Fitzgerald , ' edited by Professor J. Larmor , p. 128 ) , and a straight Hertzian doublet or bi-pole electric oscillator . It is obvious that if a straight electric oscillator is placed in contiguity to one side of a closed rectangular circuit or magnetic oscillator , the currents being of the same value and directed in an opposite sense in the open and adjacent side of the closed circuit , the resultant electromagnetic effect must be of a doubly bent oscillator of the type considered in the text . The equations 8 ) , , ( 6 ) , and ( 11 ) are consistent with this mode of viewing the facts . Prof. J. A. Fleming . Theory of Directive [ May 24 , ( 13 ) . ( 14 ) Suppose we limit attention to the value of the electric force and the magnetic force at right angles to the extremity of the radius vector , the former being parallel to the -axis and the latter being drawn in the plane of magnetic force in this direction is equal to . Hence we obtain its value by muItiplicabion of the values of and by and and subtraction . Then putting in the above equations and writing for we have , ( 16 ) If we denote the amplitudes of and by and , we have finally ( 18 ) where is the amplitude of the electric force perpendiculal to the radius vector and to the equatorial plane , and is the amplitude of the magnetic force perpendicular to the radius vector and in the equatorial plane . Hence , since is always much greater than , it is clear that when is 18 the values of and are both greater than when 1906 . ] Antennoe or Unsymmetrical Hertzian Osciltators . If we put in the above equations they reduce to the values given by Hertz for the electric and magnetic forces of the short straight oscillator or doublet taken in the equatorial plane , the electlic force being parallel to the axis and magnetic force at right angles . When is large compared with unity we have , showing that the energies of the magnetic and electric components of the wave then become equal . Also there is a minimum value of and corresponding to a value of , such that , The above expressions are numerically small when is large compared with the wave-length of the radiation . Hence a minimum value of the forces at the extremity of the radius vector is found , corresponding to some azimuthal angle rather less than reckoned from the direction in which the free ends of the bent oscillator point . A reference to the records of observations made by Mr. Marconi* on the radiation from a bent antenna shows that the above deductions from theory agree with his observed facts . Hence we conclude that whereas a straight vertical oscillator earthed at the lower end radiates equally in all horizontal directions or azimuths , the result of bending the antenna over to one side , so that a portion of it is horizontal , is to cause it to radiate less orously in the direction in which the free end points than in the opposite direction , and to create a minimum radiation in two other directions equally inclined to the ection of maximum radiation . The degree of this fore-and-aft inequality in the plane of the oscillator will depend upon the ratio of the magnitude of the quantities SMmr and , or upon the ratio of to , that is upon the ratio of to , i.e. , to where is the total length of the bent oscillator . The greatest inequality between the fore and aft radiation in the plane of the oscillator will exist when times the ratio of the sum of the of the two horizontal parts of the oscillator to its total length is as nearly as possible equal to the product of the ratios of and . The ratio is iixed by the geometrical form of the oscillator , hence the inequality in radiative power in the fore and aft directions for a given oscillator essentially depends upon the ratio of wave-length to the distance of the point at ) observations are made , and at large distances will only be sensible when long wave- * See ' Roy . Soc. Proc , vol. 77 , p. 415 , 1906 . 8 On Directive Antennoe or Uns . ? Oscillators . lengths are employed . This result also agrees with the observations of Mr. Marconi , who " " I have observed that , in order that the effects should be well marked , it is necessary that the length of the horizontal conductors should be great in proportion to their height above the ground , and that the wave-lengths employed should be considerable , condition which makes it difficult to carry out such experiments within the walls of a laboratory . " " I have found the results to be well marked for wave-lengths of 160 metres and over , but have not been able to obtain as well-defined results when employing much shorter waves , the effects following some law which I have not yet had time to investigate The above theoretical examination of this operation of a bent oscillator shows clearly that its unsymmetrical radiation in the equatorial planle depends not upon absolute wave-length , but upon the ratio of wave-length to the distance of the receiving point and upon the proportion between the length of the vertical and of the horizontal portions of the oscillator . The theory is thus supported by the observed facts . If necessary , it would be possible from the equations given above to delineate the lines of electric force in the field of the bent oscillator for various epochs . Thus if and are the components of the electric force in the plane , the differential equation to the lines of electric force in that plane is . The substitution of the values of and and integration of this equation would furnish the equation to the lines of electlic force in the plane from which they might be delineated , but its complexity does not make the task of actually delineating the lines of force for the bent oscillator an inviting one . . cit. , p. 420 .

rspa_1906_0052

0950-1207

Erratum.

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Biography

Atomic Physics

Biography

VI No. A. 526.\#151 ; February 2 , 1907 . Calcium as an Absorbent of Gases for the Production of High Vacua and Spectroscopic Research . By Frederick Soddy , M.A. , Lecturer in Physical Chemistry in the University of Glasgow . Communicated by Professor J. Larmor , Sec. R.S ... ... ... ... ... ... ... ... ... ... ... ... . . The Theory of the Compositions of Numbers.\#151 ; Part II . By Major P. A MacMahon , F.R.S. , etc. ( Abstract ) ... ... ... ... ... ... ... ... ... The Theory of Photographic Processes , Part III : The Latent Image and its Destruction . ( Abridged Account . ) By S. E. Sheppard , D.Sc . , and C. E. K. Mees , D.Sc . Communicated by Sir William Ramsay , K.C.B. , F.R.S. . The Relation between Breaking Stress and Extension in Tensile Tests of Steel By A. Mallock , F.R.S ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . An Examination of the Lighter Constituents of Air . By Joseph Edward Coats , B.Sc. Wales . Communicated by Sir William Ramsay , F.R.S ... ... ... . The Photo-electric Fatigue of Zinc . By H. Stanley Allen , M.A. , B.Sc. Senior Lecturer in Physics at King 's College , London . Communicated by Professor H. A. Wilson , F.R.S ... ... ... ... ... ... ... ... ... ... . . The Effect of Temperature on the Activity of Radium and its Transformation Products . By Howard L. Bronson , Ph. D. Communicated by Professor E. Rutherford , F.R.S ... ... ... ... ... ... ... ... ... . Index ... ... ... ... . . OBITUARY NOTICES OF FELLOWS DECEASED . ERRATUM . Page 212 , line 8 , fo 1896 read 1906 . PAOE

rspa_1906_0053

0950-1207

The law of distribution in the case in which one of the phases possesses mechanical rigidity: Adsorption and occlusion.

9

22

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Morris W. Travers, D. Sc., F. R. S.

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10.1098/rspa.1906.0053

Thermodynamics

Tables

Thermodynamics

]\gt ; The of Distribution in the Case in which one of the Phascs possesses Rigidity : Adsorption Occlusion . By MORRIS W. TBAVEBS , D.Sc . , F.R.S. , Professor of Chemistry in University College , Bristol . ( Received Apri123 , \mdash ; Read lIay 10 , 1906 . ) oduction . The teru ] " " occlusion\ldquo ; has been applied somewhat indiscriminately to denote the state in which a gas exists in a solid , by which it has been absorbed , or from which it is evolved on , and no doubt the term includes phenomena of a totally different character . Similarly , the term " " adsorption\ldquo ; is commonly used to differentiate between ] cases of solution and the removal of substances from solutions by solids in contact with them . It is the object of this paper to point out rities which exist between certain cases , which may be included in these two groups , and to make some gestions as to the classification of the phenomena . In the first place we may dispose of certain instances in which solids evolve gases when they are heated , the change being irreversible . In 1898* I succeeded in showing that the evolution of such gases as and carbon monoxide from minerals on heating did not require the assumption of their previous existence in the minerals at all ; hence , there was no need to introduce term occlusion to explain it . I proved the gases were produced by the interaction of water vapour and carbon dioxide with such substances as ferrous oxide , the change followed quantitatively . Later , I put forward an explanation of the evolution of helium from minerals , in which it cannot be supposed to be present in a state of chenlical combination . Ramsay and Soddy had shown that helium was one of the products of radio-active change , and had ested that its presence in the minerals was due to the decay of some radio-active substance which they had formerly contained . This explanation did not , however , account for the retention of the gas in the mineral , and the clue to the solution of this part of the problem was given by Jaquerod 's that heliunl would pass through the walls of a quartz bulb at a comparatively low temperature , though this material is quite impermeable to it in the cold . It follows that the gas may be present in the mineral in a state of supersaturation , may 'Roy . Soc. Proc vol. 64 , p. 131 . 'Nature , ' January , 1905 . ' Comptes Rendus , ' , vol. 139 , p. 261 . 10 Prof M. W. Travers . of Distribution uhere [ Apr. 23 , remain in that state for an indefinite time , if the temperature is moderately low . When , however , the mineral is heated , the gas can diffuse freely through it , and there is a tendency to establish equilibrium between tho two phases . Many cases in which solids , or at least substances which are apparently solids , absorb and evolve gases reversibly have been investigated , and the experimental data are , in some of them , sufficient for the purpose of comparison . However , I only intend to consider the absorption of gases by palladium , platinum , and carbon , and as in the last case the measurements of the pressure-concentration relationships for small concentrations did not seem to be of sufficient accuracy , or to cover a sufficiently wide range of temperature , for my purpose , I have made some measurements quantity of hydrogen and carbon dioxide absorbed by , between 10 C. and C. , and at pressures up to one atmosphere , for myself . I shall refer to the work of others as I come to discuss it , but I can state here that Dewar 's demonstration of the very complete absorption of gases by carbon at low temperatures made it clear that the results obtainable with this substance would prove of high interest . * Experimental Part\mdash ; The Apparatus . The apparatus ( fig. 1 ) employed in this investigation was very similar to the gas thermometer , described in the paper by Senter , Jaquerod , and myself , on the vapour pressures of liquid and liquid oxygen . As , however , it was considerably modified for this purpose I shall be obliged to give a brief description of it . The carbon was contained in the bulb , which was about cm . in diameter , and cm . long . For convenience in filling it with carbon , the part of the stem for the first centimetre next to it was about cm . in diameter . After the carbon had been introduced , and covered with a plug of asbestos to prevent it from rising into the capillary stem the latter was sealed to it . The first quantitative investigation of the absorption of gases by charcoal appears to have been carried out by Th. de Saussure ( Gilbert 's ' Annalen der Phvsik , ' 1814 , vol. 47 , p. 112 ; Thomson 's ' of Philosophy , ' 1815 , vol. 6 , ) . He showed that Henry 's law , which he verified by means of his apparatus , did not apply to this phenomenon . His values for the relationships between the pressu1e and the volume of oxygen absorbed at about F. are fairly well reproduced by the expression we have been considering . Thus\mdash ; ( inches of mercury ) . 27 . 0.072 Phil. Traus , vol. 200 , p. 142 . one of the Phases possesses Mechanical Rigidity . The tube which formed the dead-space was calibrated before it was sealed to the rest of the apparatus . The volume of the space above the surface of the mercury , when the latter was in contact with the point , 12 Prof. M. W. Travers . of Distribution where [ Apr. 23 , was determined . and also the volume of 1 mm. of the tube below it ; so that if the distance of the surface of the mercury from the point was known , the volume of the space above could be calculated . The pressure exerted by the gas in the apparatus was measured by bringing the mercury in close to the point , and observing the height to which the column rose in the barometer tube . The volume of mercury in the apparatus was adjusted by means of a reservoir connected through a rubber tube and stop-cock at ; bubbles of air were caught in the tube The gas was introduced , and the apparatus exhausted , through a stopcock , to which were connected a syphon , for drawing the gas out of tubes in which it was contained over mercury , and a tube , leading through an arrangement for catching drops of mercury to the pump . The Preparation of the Carbon . The carbon was prepared by calcining the soft part of the cocoanut , at a temperature not above a dull red heat , till vapour ceased to be evolved , and then cooling the product as quickly as possible . After it had been introduced into the bulb , and the latter sealed to the stem and dead-space , it was heated to C. in vacuo for some hours , by surrounding the bulb with a bath of sulphur vapour , and maintaining a vacuum in the apparatus by means of the pump . The mass of the carbon was determined at the end of the experiments by transferring the contents of the bulb to a closely-covered platinum crucible , drying it at 15 C. , hing , and afterwards determining the loss of weight on combustion in air . The Preparation and Method of Measurement of the Intending to investigate the absorption of a number of gases by carbon , I selected , as two extreme cases , and carbon dioxide , for the first experiments . Soon after I commenced my work , however , I heard from Sir W. Ramsay that he and Miss I. Homfray , B.Sc. , were engaged on a similar research , so I decided to limit my own investigation to the two gases mentioned above . In either case the gas was obtained from a Kipp 's apparatus , which had been in use so long that the gas delivered from it might be considered to be free from air . The gases were dried by passing through tubes containing pentoxide of phosphorus , and were collected in tubes over mercury . Successive volumes of gas , each of about 5 , were delivered into the apparatus , and after the addition of each quantity , a series of measurements of the , relationships was made . These quantities of gas were measured 1906 . ] one of the Phases Rigidity . in a constant-pressure gas-burette , such as I have described in " " Experimental Study of Gases\ldquo ; . The temperature of the water and the height of the barometer were observed simultaneously . In the whole of the calculations involved in this research the coefficient of expansion of carbon dioxide is taken to be and that of hydrogen to be 1/ 273 ; it has also been assumed that , within the limits of the pressures investigated , the product could be taken as constant . The Method of Calculating the Results . To obtain the relationship between the pressure exerted by the gas in the apparatus and its concentration in the carbon , it was necessary to obtain the ollowing d ( a ) The mass of the carbon : this amounted to grammes . and was associated with gramme of ash . * ( b ) The mass of toas introduced into the apparatus , a factor which could be deduced directly from the burette , the temperature , the pressure , and the density of the gas . ( c ) The volume of the dead-space , and of that portion of the stem which remained at the air temperature . 'this is given by the formula , where is the distance of the surface of the mercury from the point . ( d ) The volume of the bulb , and of that part of the stem which was at the same temperature , was determined by an indirect method . Two . successive quantities of hydrogen , previously measul.ed in the burette , . were introduced into the apparatus , and while both bulb and dead-space were at the air temperatul.e , the pressure and the temperature vere . carefully observed . Now from the formula:\mdash ; where are the pressure , volume , and temperature of the in the burette , and and are the pressnre and temperature in the apparatus , it is possible to calculate the ] of the gas in the bulb . Thus : C. C. The result shows that at the higher pressure the bulb contains more hydrogen than at the lower pressure , as of course it should do , since gas is slightly soluble in the carbon . However , as we shall see14 Prof. M. W. Travers . Law Distribution where [ Apr. 28 , later , it is probable that at this temperature the amount absorbed can be taken as proportional to the pressure , so that we can calculate the true volume of the free space in the bulb , which works out at The formula given above may be used to calculate the quantity of gas in the bulb , which must be subtracted from the quantity introduced into the apparatus in order to calculate the quantity absorbed by the carbon ; it then takes the form : where and are the temperature of the bulb and dead-space respectively . As a matter of fact , no correction was made for the change of volume of the bulb , for the expansion of the carbon , or for the volume of the gas . So long as the pressures remained low and the correction , which is the product on the left-hand side of the equation , small , this could have but little effect upon the result , but it obviously vitiate results dependent on the measurement of rher pressures , and which , as will appear presently . must be very exact , if they are to be of any value at all . Method of Conducting th eriments . The object of each experiment was to determine the relationship between the pressure and the quantity of absorbed at a particular temperature . The temperatures at which experiments were made corresponded to , and , in the case of hydl.ogen , to about \mdash ; 190o . The first three } ) were obtained by water , chlorofolm , and ether , respectively , in a vapour jacket surrounding the bulb . corrections were not applied , as the small variation of temperature with pressure did not materially affect the results , and to apply corrections would have entailed a great deal more experimental work . The ice-point was of course obtained by immersing the bulb in ice . A mixture of solid carbon dioxide and alcohol in a vacuum vessel will , if the latter is well exhausted , remain at for some hours ; and liquid air , contained in a two-litre globular vacuum vessel , will only be reduced to about half its volume in hree days , and the temperature will not have risen more than The time which elapsed before equilibrium was established varied considerably under different conditions . In the case of the absorption of hydrogen by carbon at the temperature of liquid air it was often some hours before the column of mercury came to rest . the case of carbon dioxide equilibrium was always most rapidly established at the lower tempera1906 . ] one of the Phases possesses Rigidity . tures . Thus , working at , the bulb of the apparatus was allowed to remain in the bath of solid carbon dioxide and alcohol for about three hours Experiment . when it was noticed that the pressure did not vary after the first few minutes of the experiment . After reading the pressure the bath was removed , and when the bulb had ained the temperature of the air it was again coolsd . In a few minutes the was identical with that observed at the first } . At 10 equilibrium was more slowly established , the pressure appearing to rise at first and then to fall slowly . So as to eliminate errors arising from such a source , the bulb was usually allowed to remain at the temperature of the vapour for at least three hours , or , in fact , till equilibrium appeared to be established . ? nith Carbon Dioxide . The following experiments were carried out in the manner described above , and form one continuous series , successive quantities of the gas being added after each set of measurements at the four temperatures . The results are plotted on the accompanying diagram , and it may be said that there is at least some internal evidence that they are satisfactory . 16 Prof. M. W. Travers . Law of Dist.ibution where [ Apr. 23 , The mass of carbon contained in the bulb was , as has already been stated , 1400 grammes ; the volume of the bulb and of the dead-space have beeu given on p. 13 . with Hydrogen . A similar set of experiments WftS made with hydrogen , but only at the teluperature of liquid air . For at higher temperatures it appears that the pressure-concentration curve is nearly linear , and results would only be of value if they were of a sufficiently accurate character to enable one to distinguish between the linear relationship and deviations from it . The results when plotted give a curve very sinlilar to that obtained for carbon dioxide at the ice-point . In each experiment the ttus was left at rest with the bulb immersed in liquid air for 24 hours before a reading was taken , and it will be observed 1906 . ] one of the Phases possesses Rigidity . that , even with this precaution , the results are not so satisfactory as those obtained in the case of carbon dioxide . The slight irregularities which occur at 12 to 14 mm. cannot be attributed to the inconstancy of the temperature . Discussion of the Results . On examining the results , one is at once struck by the similarity between the pressure-concentration curves for the gases hydrogen and carbon dioxide in solution in carbon and those which have been obtained by Hoitsema*and by Ramsay , Mond , and Shields , for the absorption of gases by palladium and platinum . The curves are in each case represented by the formula constant , where is the pressure of the gas corresponding to the concentration in the " " solid\ldquo ; phase , and increases as the temperature falls . Thus we have for carbon dioxide . The formula does not apply so well to the pressure-concentration curve for C. , a fair approximation is obtained by calculating the values of It vould appear , then , that is almost exactly equal to 3 for the isothermal at C. , and to 2 for the isothermal at 10 C. It follows that at higher eratures it probably reaches the limiting value , unity , when carbon dioxide will dissolve in carbon in strict accordance with the law of distribution . If we apply the same method to the results obtained with hydrogen . 'Zeit . Phys. Chem 1895 , vol. 17 , p. 1 . 'Phil . Trans vol. 186 , p. 657 ; vol. 190 , p. 120 ; vol. 191 , p. 105 . VOL. LXXVIII.\mdash ; A. 18 Prof M. W. Travers . of Distribution where [ Apr. 23 , we find that this gas at C. behaves similarly to carbon dioxide at C. Hoitsema*ated the pressure-concentration relationships for hydrogen and palladium , at temperatures between and C. The curve he obtained for the isothermal C. is similar to that for carbon dioxide and carbon at C. , and the isothermal for C. is not to be distinguished from it at low pressures . The isothermal for C. , and those at higher temperatures , consist of three portions ; that corresponding to low pressures , at which , as in the of carbon dioxide and carbon , increases more rapidly than ; a horizontal portion , where increases without increase in ) , corresponding to the condensation of a gas ; and a portion which is nearly perpendicular , where hardly increases at all with increase of . It is the first portion , corresponding to small concentration , which is of interest to us at the moment . Hoitsema points out that this portion of the curve is represented by the same formula which we have found to represent the pressure-concentration curves for carbon dioxide and carbon , he states his results in terms of the volume occupied by two ammes of hydrogen . The following table contains a summary of his results:\mdash ; It will be observed that while is constant for the values obtained for and at C. over the whole ange investigated , and for comlioc . 1906 . ] one of the possesses Rigidity . paratively low pressures at temperatures , there is a tendency under the latter conditions for the product to attain a more constant value , particularly at the higher pressures . Hoitsema gests that his results indicate that hydrogen , in solution in palladimn , is dissociated into atonls , but that as the concentration increases association takes place , and the solution contains complexes of the formula . This hypothesis finds support in Nernst 's of the distribution of such substances as'benzoic acid between water , which it appears to exist as simple molecules , and benzene , in which it appears to exist as complexes of the formula . It appears , howevcr , that this is highly improbable , for , if it were so , it would necessarily follow that this gas , dissolved in amorphous carbon at C. , must be supposed to be dissociated into fractions of an atom . Mond , Ramsay , and atsd the absorption of by palladium and came to the conclusion that the gas was absorbed with the formation of a mixture of oxides . The substance formed appears to be a brown powder , totally different from palladimn , and no oxy could be removed from it at a red heat . They considered that if it were possible to leave the metal enough in contact with oxygen it be completely converted into the oxide , . Thermochemical lrements supported this view . They also investigated the absorption of hydrogen by platinum , and though their work deals chiefly with the effect of temperature on the evolution of hydrogen from the metal , they determined the pressul.econcentration relationships for pressures up to mm. at C. The curve their results is very similar to the pressure-concentration curve for carbon dioxide carbon at . or for palladium and hydrogen at C. ; 13 . of gas were absorbed before any rise in pressure was observed , the curve at first slowly and then rapidly . It appeals then that these three cases present marked nilarities . Discussion of the Rcsults . has shown that when animal charcoal absorbs iodine from solution the distribution of the solute between the solid and liquid phases is iven by the formula olid)( solution ) constant , 'Zeit..Phvs . Chem 1891 , vol. 8 , p. 110 . 'Zeit . Phys. Chem vol. 15 , p. 60 20 Prof. M. W. Travers . of Distribution ? where [ Apr. 2:3 , an expression which is identical in form with the one which we have ] to the distribution of a gas between a solid and a liquid phase . He also calls attention to the fact that the general formula , olid)( solution)constant , represents the condition of equilibrium , not only between charcoal and such substances as acids , etc. , but between dyes and textile materials in contact with solutions of them . Zacharias* carried the matter further , and in a paper entitled " " Uber den Zustand und die Eigenschaften dcr Kolloide\ldquo ; not only discusses the abso1ption of dyes by textile materials , but points out the connection between such phenomena and the absorption of hydrogen by palladium . He considers that in such cases the condition of equilibrium may be arrived at by that when the solid , or colloid as he considers it to be , is into contact with the gas or solution , the gas or solute diffuses into it , and forms a diffusion column , so that the concentration of it in the solid phase decreases as the distance from the surface increases . There appears , however , to be no ground for the assumption that the modification of the simple law applies only to colloidal substances ; rather it appears capable of application to any system in which one phase is rigid . and in which , in consequence , the law of distribution may be determined in some way by diffusion . Zacharias 's analysis relates to a state of steady flow across a surface , and not to a condition of equilibrium , and does not furn ish mathematical proof that under the latter condition the logarithmic relationship would apply . As phases possessing rigidity we can describe crystalline solids , super-cooled liquids , and probably for this purpose colloidal , or jelly-like , masses , though the latter may , in themselves , consist of more than one phase . In my opinion such solid phases as we have considered fall under the second heading , and may be considered as without discontinuity iu their properties from the liquid phase . No analogous case of a crystalline solid appears to have been investigated . It need scarcely be pointed out that such cases as that of the distribution of iodine between liquid and solid follow the simple law of distribution , the case in which in the eneral expression , for the reason that iodine does not diffuse into the solid benzene , but that the solid is formed directly from the liquid solution . It is probable that the absorption of gases by the platinum which is " " splashed off\ldquo ; from the electrodes of a vacuum-tube during the passage of the discharge takes place in a similar manner , each layer becoming saturated as 'Zeit . Phys. Chem vol. ) , p. 468 . , . 478 . Bylert , ' Zeit . Phys. Chem vol. 8 , p. 343 . 1906 . ] one of the Phases possesses Rigidity . it is deposited . On , the gas is evolved , and as the metal appears to change at the same time from the amorphous to the metallic condition , the chano.eo is practically irreversible . One give man other examples of phenomena to which the terms adsorption\ldquo ; and " " occlusion\ldquo ; have been applied , and which be explicable without the introduction of any principle other than that which have been . To take one final example : value of in the genel'al expression , at any particular temperature , increases with the molecular complexity of the gas or substance ill solution . Hence it is not to find that when animal charcoal absorbs " " matters\ldquo ; from solutions of organic substances , the quantity of the latter which is removed from the solution appears to be proportional to the quantity of charcoal only , the latter being capable of re1moving practically the whole of the colourin matter if it is present in sufficient quantity . Further , if the charcoal has been too heated it loses its power of absorbing colouring matters and , indeed , substances generally , either in the gaseous state or in solution , and this may be explained by the fact that the action of heat results either in the partial conyersion of the carbon into a more stable crystalline phase , into which substances diffuse less readily , or in causing it to become more compact , in which case the surface is limited , and each\ldquo ; diffusion column\ldquo ; becomes longer . [ Note added May , 1906.\mdash ; Within the last few weeks a paper entitled " " Vapour Pressure in Equilibrium with Substances Moisture \ldquo ; been published by Prof. Trouton , and as it may appear that he and I differ in the explanation of apparently identical phenomena , I have thought it advisable to append this brief explanation . Prof. Trouton 's are similar to those obtained by Hoitsema and referred to on p. 18 . The lower portion of the PX isothermal curve for the system water-cotton appears to have the form represented by the equation const . , and so far as it is concerned Prof. Trouton ests that ' there is distinct indication of some further action or law coming into operation that is to say , some law distinct from that which he has established for the upper portion of the curve . The fact is , that while I have been considering the condition of equilibrium consequent on the formation of a diffusion column within the material of the " " rigid phase Prof. Trouton is concerned with the phenomenon of surface condensation , which implies the formation of a new phase . This new phase does not appear till a certain concentration of the component which suffers 'Roy . Soc. Proc vol. 77 , p. 292 . . cit. , p. 229 . Prof. E. Wilson . [ May 9 , distribution is reached in the phase , and the new phase , as . Prof. Trouton has shown , must be considered as bivariant till the lilm has attained a certain thickness . It would be interesting to speculate as to the subsequent course of Prof. Trouton 's curves , and I hope that his further researches will throw light on the subject . ] Effects of Self-induction in Iron Cylinder . * By Professor ERNEST WILSON , King 's , London . ( Communicated by Sir William H. Preece , K.C.B. , F.R.S. Received May 9 , \mdash ; Read June 7 , 1906 . ) If a solid cylindrical conductor be divided into imaginary concentric tubulal conductors , the ordinary self and mutual induction theory shows that ] the conductor is subjected to an alternating potential difference , the interior shells carry electric currents of snlaller density than the exterior ones , and the currents suffer a phase displacement greater the nearer the centre of the cylinder . The theory shows that the permeability and conductivity of the material play an important part , the effects nlentioned being increased in magnitude with increasing permeabiIity and conductivity . When , however , the material of the conductor has variable permeability the problem becomes more complicated , and it is the object of this paper to examine more closely what on in an iron cylinder when electric currents are reversed in it , and maintained steady after reversal . A second part of this research will deal with alternating currents of varying frequency and wave-form . The cylinder employed is of mild steel and has a diameter and length each equal to 10 inches cm It is provided with holes drilled in a plane containing its axis of figure in such a manner that exploring coils can be threaded to enclose certain portions of that plane . The coils are three in number . They are each 2 inches wide in a direction parallel with the axis of figure and midway between the ends of the cylinder . Their depths in a radial direction are 1 , 2 , and 2 inches , and their average radii are , 2 and 4 inches respectively . These coils are referred to as Coils Nos. 1 , 2 , and 3 , No. 1 near the centre of the cylinder . The cylinder has been already described , but for the purpose of * In mection with this research , I wish to acknowledge a grant voted to me by the Council of the Royal Society out of the Government Grant Fund . 'Roy . Soc. Proc vol. 69 , p. 440 .

rspa_1906_0054

0950-1207

Effects of self-induction in iron cylinder.

22

27

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Professor Ernest Wilson|Sir William H. Preece, K. C. B., F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0054

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0054

10.1098/rspa.1906.0054

Electricity

Tables

Electricity

22 Prof. E. Wilson . [ May 9 , distribution is reached in the rigid phase , and the new phase , as Prof. Trouton has shown , must be considered as bivariant till the film has attained a certain limiting thickness . It would be interesting to speculate as to the subsequent course of Prof. Trouton 's curves , and I hope that his further researches will throw light on the subject . ] Effects of Self-induction in Iron Cylinder* By Professor Ernest Wilson , King 's College , London . ( Communicated by Sir William H. Preece , K.C.B. , F.R.S. Received May 9 , \#151 ; Read June 7 , 1906 . ) If a solid cylindrical conductor be divided into imaginary concentric tubular conductors , the ordinary self and mutual induction theory shows that when the conductor is subjected to an alternating potential difference , the interior shells carry electric currents of smaller density than the exterior ones , and the currents suffer a phase displacement greater the nearer the centre of the cylinder . The theory shows that the permeability and conductivity of the material play an important part , the effects above mentioned being increased in magnitude with increasing permeability and conductivity . When , however , the material of the conductor has variable permeability the problem becomes more complicated , and it is the object of this paper to examine more closely what goes on in an iron cylinder when electric currents are reversed in it , and maintained steady after reversal . A second part of this research will deal with alternating currents of varying frequency and wave-form . The cylinder employed is of mild steel and has a diameter and length each equal to 10 inches ( 25'4 cm . ) . It is provided with holes drilled in a plane containing its axis of figure in such a manner that exploring coils can be threaded to enclose certain portions of that plane . The exploring coils are three in number . They are each 2 inches wide in a direction parallel with the axis of figure and midway between the ends of the Cylinder . Their depths in a radial direction are 1 , 2 , and 2 inches , and their average radii are 0'5 , 2 and 4 inches respectively . These coils are referred to as Coils Nos. 1 , 2 , and 3 , No. 1 being near the centre of the cylinder . The cylinder has been already described , f but for the purpose of * In connection with this research , I wish to acknowledge a grant voted to me by the Council of the Royal Society- out of the- Government Grant Fund . t ' Roy . Soc. Proc. , ' vol. 69 , p. 440 . 1906 . ] Effects of Self-induction in an Iron Cylinder . the present research has had a hole ^-inch diameter drilled through it coinciding with the axis of figure . At each end of the cylinder are two massive gunmetal projections , which in the present research serve to conduct the electric current into the cylinder . The conductors attached to these projections are connected to a reversing switch so constructed that at its mid position it short-circuits the circuit of the cylinder and its conductors , which were arranged in the form of a circle about 6 feet diameter . The electric current was supplied by storage cells through an adjustable resistance and the shunt of an ampere-meter . The potential difference of the cells and the adjustable resistance were such that on reversing the current in the cylinder its value in the main circuit remained constant . In fact , the reversal of the main current was practically instantaneous . The epoch of reversal was noted on a seconds clock and at two-second intervals after reversal the deflections of the dead-beat galvanometers in circuit with the exploring coils were noted . The deflections have been reduced to volts per turn per square centimetre of the coils from which they were obtained , and plotted in terms of the time . Figs. 1 , 2 , and 3 give the results obtained from Coils Nos. 1 , 2 , and 3 respectively , and each curve is numbered to correspond with the total amperes reversed when it was observed . The curves have been integrated in order to find the maximum average value of the induction density B for the respective coils . The average values are set out in Table I. Current Density . \#171 ; . If the current density over the cross-section of the cylinder was constant , the force H would vary as the radius . If the values of B for Coil No. 3 in Table I be plotted in terms of the total currents reversed in the cylinder , it will be found that the resulting curve resembles the BH curve of a piece of mild steel . If the values of B for Coils Nos. 2 and 1 be plotted in terms of the total current multiplied respectively by 0*5 and 0T25 ( to correspond with their radii ) , it will be seen that , although similar , the three curves do not lie on one another . To make them do so the coefficients with which to multiply the total currents are 0*75 and 0'28 respectively . This suggests that under steady conditions the current density is greater near the centre of the cylinder than near the surface . The average relative densities appear to be : ( 1 ) over the area of the cylinder within the average radius of Coil No. 1 , 0-56 ; ( 2 ) over the annulus between the average radii of Coils Nos. 1 and 2 , 0'36 ; ( 3 ) over the annulus between the average radii of Coils Nos. 2 and 3 , 0'21 . A total current of 950 amperes corresponds to an average force H of about 6 C.G-.S . units for Coil No. 3 , and the BH curve for mild steel is well Prof. E. Wilson . [ May 9 , represented by the results of the experiments . The relation between the average value of H for each of the coils and the total current is given in Table I. Table I. Total current in cylinder . Coil No. 1 . Ay . H. 1-68 1*18 0-924 0-75 0-627 0-426 0-372 0-283 0-218 0-141 0-079 Max. ay . B. Coil No. 2 . Ay . H. 4-5 3T5 2-48 2-01 1-69 1 -14 0-998 0-758 0-583 0-379 0-213 Max. av . B. Coil No. 3 . Ay . H. .68 .25 .52 .33 .01 0-777 0-505 0-284 Max. ay . B. Comparison of E.M.F. Curves . * The E.M.F. curves are given in figs. 1 , 2 , 3 , to which reference will be made . Coil No. 3 experiences its maximum rate of change at once , although after reversal of about 400 amperes there is slight evidence of a second maximum at about 20 seconds after reversal . After about 400 amperes it will be seen that as the total current increases the curves cross one another at shorter intervals , indicating that the effects penetrate more rapidly after the maximum average induction density has passed the value at which maximum permeability occurs . \#163 ; o O ' CQ ec \#163 ; . F , '\amp ; \#166 ; 1 Is C* ^ \ ^8 70 Co il 1 . \#163 ; \#163 ; S / 240 7/ 80 \l ^634 ^621 ^360 0 10 20 30 4 0 SO00 70 80 90 100 110 120 TIME AFTER REVERSAL . IN SECONDS . 1906 . ] Effects of Self-induction in an Iron Cylinder . Coil No. 2 shows the effect of a second maximum more markedly . When the total current in the cylinder is small there is no second maximum . At about 200 amperes the second maximum shows signs of being developed , and with larger currents its development is such as to make it the most important feature of the curves . As in the case of Coil No. 3 , the E.M.F. curves cross one another at earlier intervals after about 420 amperes has been reached . TINE AFTER REVERSAL , IN SECONDS . Coil No. 1 shows similar effects , but its E.M.F. 's have a still later maximum for a given current . Moreover , the time between the first and second maxima is greater than in the case of Coil No. 2 . These results are in keeping with what has already been observed in the case of the reversal of currents in a copper coil surrounding cylinders of 4 and 12 inches diameter , * and in the present cylinder when rotated in a magnetic field.'f It is difficult to say exactly how long the effects take to die away owing to the ultimate want of sensibility of * 'Phil . Trans. , ' A , vol. 186 ( 1895 ) , pp. 93\#151 ; 121 ; also 'Journ . Inst. Elec . Eng. , ' Part 116 , vol. 24 , p. 194 . t ' Roy . Soc. Proc. , ' vol. 69 , p. 435 , and vol. 70 , p. 359 . Prof. E. Wilson . [ May 9 , Coil 3 . 10 20 30 TIME AFTER REVERSAL IN SECONDS . the instruments , but a comparison of the times taken to practically die away is of interest . In Table II are given the times taken to reverse the magnetism at the centre of 4- and 12-inch diameter cylinders when the currents in their magnetising coils are instantaneously reversed , and then maintained steady . The times in these two cases roughly vary as the square of the diameters of the cylinders . The results obtained in the present experiments are also included in Table II . Table II . 4-inch magnet . 12-inch magnet . 10-inch cylinder . Duration Duration Duration in seconds . Total in Max. H. in Max. H. \#151 ; current in seconds . seconds . Coil No. 1 . Coil No. 2 . Coil No. 3 . cylinder . 40 1 -7 360 1 -2 20 45 45 3 0 420 2 -4 20 28 15 80 33 4-96 180 6-0 30 48 30 160 10 16 -0 80 11 *0 58 80 50 210 5 37 -0 50 24 -0 75 100 \#151 ; 240 116 112 60 356 120 120 50 424 190 90 , \#151 ; 522 90 75 40 670 90 65 30 950 1906 . ] Effects of Self-induction an Iron Cylinder . Upon integrating the E.M.F. curves it was found that the average magnetic flux , for total currents up to about 240 amperes , was reversed in sign for Ooil No. 2 after Coil No. 1 . For currents greater than 240 amperes the % curves cross the axis of time in the order 3 , 2 , 1 . In all cases , however , the total interior average currents , as obtained from the magnetic hysteresis loops , reversed in the order 3 , 2 , 1 . Application of Results to other Sections . Comparing two cylinders whose diameters are as 1 : the value of H at similar radii will be the same when the total currents are as 1 : n. Considering unit length of the two cylinders , the total magnetic induction up to similar radii varies as n , and the electric resistance of ' similarly placed longitudinal paths varies as 1 / n2 . Therefore to induce n times the current in those paths the E.M.F. 's must vary as If the time varies as 2 the E.M.F. 's will vary as 1/ n , thereby giving rise to the same value of the magnetic force H at similar radii . A paper recently published* dealt with the self-induction of bull-headed , railway rails , weighing 70 lbs. per yard . It was there shown how greatly the self-induction varies with the frequency for a given current , and with the current for a given frequency . The head of one of these rails is roughly equivalent to a cylinder of 2 inches diameter . A current of 100 amperes in such a cylinder corresponds to 500 amperes in our 10-inch cylinder if the forces at similar radii are to be the same . We infer roughly that an alternating current of 8 seconds periodic time and approximately rectilinear wave-form would permit of practically the whole section being made use of as regards conduction for a small fraction of the time of each half period . The frequencies employed in practice are of the order 25 periods per second , and are enormous by comparison . In railway work a _FL-shaped rail would obviously be more suited from the standpoint of electric conduction of alternating currents . A current of about 0'5 ampere in an iron wire of 0T inch diameter would give rise to a force of about 0'3 near the surface . Changes of magnetism in our 10-inch cylinder were observed 20 seconds after reversal of about 50 amperes . A frequency of 250 would allow of the full section of the wire being made use of during a small fraction of the time of each half period with 0*5 ampere , but not with a current of 5 amperes . In conclusion , I wish to thank Mr. A. E. O'Dell for his patience and care in working out results , and Mr. H. W. Franks for his assistance in the experimental part of the paper . * ' The Electrician , ' February 23 , 1906 .

rspa_1906_0055

0950-1207

Some physical constants of ammonia: A study of the effect of change of temperature and pressure on an easily con\#xAD;densible gas.

28

42

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Edgar Philip Perman, D. Sc.|John Hughes Davies, B. Sc.|Principal E. H. Griffiths, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0055

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0055

10.1098/rspa.1906.0055

Thermodynamics

Chemistry 2

Thermodynamics

]\gt ; Some Physical Constants of Ammonia : a Study of the Effect of Change of and Pressure on an Easily Condensible Gas . By EDGAR PHILIP PERMAN , D.Sc . , Assistant Professor of Chemistry , and JOHN HUGHES DAVIES , B.Sc. , University College , Cardiff . ( Communicated by Principal E. H. Griffiths , F.R.S. Received Apri124 , \mdash ; Read May 17 , 1906 . ) This work was originally undertaken in order to obtain an accurate value for the density of ammonia , the only determination that appeared reliable that of Le Duc . * While the experiments were in ress , the result of a determination by Guye was published ; the number differed from that of Le Duc and made a fresh determination still more desirable . We ]lave now determined the density at temperatures ranging frum \mdash ; 20o C. , also the density at half an atmosphere pressure at C. From these data the coefficient of expansion and the compressibility be calculated . In addition to this , measurements of the pressure , of vapour-pressure , and of the density of ammonia in the presence of air , have been made . Vapour-den.sity of Ammonia . Two methods were employed:\mdash ; ( 1 ) The ammonia was pumped from the lobe in which it was contained into concentrated sulphuric acid contained in -tubes , and so weighed . The globe remained in position during each iment . ( 2 ) In a few experiments the ammonia was weighed directly . Apparatus , Method ( l).\mdash ; The apparat , us may be divided into three parts : ( a ) the ammonia supply , ( b ) the globe and bath , ( c ) the absorption apparatus : The ammonia was contained in an iron tube cm . long and cm . in diameter , closed by a valve , obtained from the Scotch and Irish Company . The outlet tube was connected by means of lead pipe ( about 1 foot ) and junctions of fusible alloy to the drying tubes and containing limy and recently fused sodium hydroxide respectively . The tube then divided into two branches , one leading to the escape tube , about 900 mm. long , dipping under mercury , and the other to the globe G. Any 'Comptes Rendus , ' 1897 , vol. 125 , p. 571 . 'Comptes Rendus , ' ) , vol. 141 , p. 61 . Some Physical Constants of ammonia bubbling through the mercury was absorbed by dilute sulphuric acid contained ) the wash-bottles F. ( b ) The globe of about 18litres capacity was placed in ( 1 ) a thermostat containing an Ostwald toluol regulator of special pattern , in an ice bath , ( 3 ) in a bath of alcohol and solid carbon dioxide , according to the temperature required . was ordinary stop-cock , and a three-way tap leading to two sets of bulbs , containing strong uric acid . ( Only one set is shown in the diagram . ) The temperatures above were measured accurately to by means of a thermometer made by Fuess , of Berlin , and standardised at the Reichsanstalt . For temperatures below a mercury thermometer was used which had been previously standardised by comparison with an air thermometer . to the difficulty of maintaining the oonstancy of these low tenlperatures , we cannot claim that they were accurate to less than ( c ) The absorption apparatus consisted of three -tubes , , connected ether by thick rubber and were stoppered . was connected with a tube from the globe by the round joint the -tube being eld in place by a rubber band . The tube was connected with the gauge and a water air-pump not shown in the diagram . and were stop-cocks . Method of Work . Filling the Globe . Every n position , the globe and connecting tubes were exhausted to mm. by means of a Topler pump . The valve was then opened until ammonia bubbled through the mercury in , the taps and were opened , and left open until the ammonia began to escape , when was immediately closed . The main part of the ammonia was then } ) umped out by the water airpump through , and the remainder by the mercury pump through R. It should be mentioned that the drying tube of the pump contained strong sulphuric acid , which immediately absorbed the ammonia thus admitted . The globe was again filled as before . The temperature of the bath was carefully regulated , and the excess of ammonia allowed to escape into the air , the stop-cock being turned on from time to time . Owing to the cooling caused by the expansion , some little time was required for the gas to acquire the exact temperature and pressure . From half an hour to an hour sufficed . order to indicate when the pressure was equal to that of the 'Roy . Soc. Proc 1903 , vol. 72 , p. 74 . Dr. E. P. Perman and . Mr. J. H. Davies . [ Apr. 24 , atmosphere , a small mercury gauge was connected with ; it showed finally no on turning R. In some of the earlier experiments the water air-pump was used in the filling ; in that case the globe was exhausted to 1/ 10 atmosphere and filled with ammonia , the process being carried out six times . Absorption of the \mdash ; The tubes , includin , were freed from ammonia and moisture by repeated exhaustion and admission of air L. The -tubes containing sulphuric acid and glass wool soaked with it ( see fig. I ) were then connected up , and having been weighed . was a guard tube to prevent the access of moisture from the pump . connections were tested by exhausting . the -tubes and noting any change in the on standing . Leaks having been shown to be absent , air was admitted through , and the -tubes were connected with the globe through and R. The apparatus was then exhausted very slowly to about 1/ 10 atmosphere , very nearly all the ammonia being absorbed by the sulphuric acid in ; air was admitted through , and the apparatus again exhausted . This was done { ive times in all . Next , air was admitted through , and in order to make the pressure inside the tubes exactly that of the atmos.phere , connection was made through a calcium chloride tube fixed to and were closed and then removed and carefully . The barometer was read immediately after the ammonia 1906 . ] Some Constants of in the globe had ceased to blow off , the readings being made accurately to 0.1 mm. Volume of the Globe.\mdash ; The globe was full of dry air at known temperature and pressure , and again full of vater at known temperature . From these weighings the capacity of was calculated . Correction was made for the displacement of air by the weights , and the used in this part of the work were compared with those used in the ammonia ( both sets ( been compared with a ) . The coefficient of expansion of was found by experiments with a weight thermometer made from a broken globe . Between and the coefficient was Jfethod ( 2).\mdash ; The ammonia was directly in a of about litre capacity . The hings were made on a short beam Oertling balance , and were carried to ramme . The were standardised with the same accuracy . In this case the globe was attached to the rest of the apparatus by means of a ground glass joint above the stop-cock ; it was exhausted by a Fleuss pump to mm. , the read on a mercury gauge by means a cathetometer . The empty globe was bed , then filled with onia and detached . The excess of mmonia was allowed to escape , and the globe was again weighed , the usual precautions taken throughout . A globe was used as a counterpoisc . The volume of the globe was found by it , completely exhausted ; ( b ) full of dry sir at known temperature and pressure ; ( c ) full of water at known tenlperature . These measurements gave two closely concordant values for the capacity of the globe . The contraction of the globe on exhaustion was measured as follows:\mdash ; The globe was nearly filled with water , about 5 . of air in the upper part . This air was then out and the stop-cock closed . The was next suspended in water and to ramme . It was opened to the air and , when it was found to lost ramme . The weight of air admitted was igible . Testing for Possible Errors . Adsorption of Ammonia by has been usually supposed that a considerable quantity of ammonia is orbed ' by glass , the adsorption ressing for some time . If so adsorbed , it be again evolved on exhausting the globe , or it might be held permanently by the lass . An experiment was made in which the bolobe was filled with nmmonia ) the atmospheric pressure , and allowed to stand 12 hours ; the of Dr. E. P. Perman and Mr. J. H. Davies . [ Apr. 24 , ammonia was then allowed to escape , and the usual number for the density was obtained . It is thus proved that if ammonia is adsorbed it is not given off on exhausting the globe . As a further test a globe was filled with ammonia , exhausted to and allowed to stand . The pressure was then read at intervals for some days by means of a cathetometer , but it remained constant . Further , in determining the pressure coefficient , the same conclusion was arrived at , the pressure of the ammonia in an ammonia thermorneter was not found to alter after the lapse of a month . From these experiments we are forced to the conclusion that , with carefully dried ammonia and glass , adsorption ( if it takes place at all ) is inappreciable . Condensation on the Surface of the Glass.\mdash ; It has been thought that ammonia will condense in the same way as water vapour on the surface of glass , and so would cause an error in density determinations in glass globes . If this were the case , different densities should be obtained if }obes of different sizes were employed . We have found , however , that globes of litre and litres capacity respectively gave the same result . The surfaces of these are as 1 : , whilst the volumes are as 1 : The only conclusion to be is that when the ammonia and the glass are carefully dried , tihere is no appreciable condensation of ammonia . Loss of Am nonia ; Incomplete Absorption.\mdash ; The ammonia pumped out of the globe passed into two -tubes concentrated sulphuric acid ( including four plugs of ( flass wool soaked with acid ) , but as in all the exhaustions , except the first , the ammonia was mixed with a large proportion of air , it was thought possible that traces of ammonia might nevertheless escape absorption . This was tested by allowing the mixture of air and amtnonia at the second and the fourth exhaustions to pass through two -tubes into an exhausted globe . The contents of the globe were then tesCed for ammonia by Nessler 's solution ; but not a trace was found . Moisture from the Air.\mdash ; The air made to expel the ammonia was first passed through two ' potash bulbs\ldquo ; containing strong sulphuric acid , and the bulbs were recharged every day . On 5litres of air the weight of the -tubes remained unaltered , thus showing that none of the moisture escaped absorption . Evaporation of Sulphuric Acid.\mdash ; In order to test whether any sulphuric acid was lost by evaporation , about 8litres of dry air were passed the first -tube , the sulphuric acid contained in it being heated to about the same temperature as it acquired during the absorption process . The weight constant to milligramme . 1906 . ] Some Physical Constants of Dispfacemont of Air owing to Change in Volume of Sulphuric Acid caused by of Ammonia . After the completion of an experiment , the density of the contents of the -tube was determined , also that of the original sulphuric acid : grammes . 20- . specific gravity bottle bottle after expt . . . . filling bottle . bottlefresh Fresh filling bottle If no change in volume of acid had taken place , weight of mixture filling bottle would be grammes grammesweight of absorbed ) , Change in volume produced by absorption of . approximately . The correction for air displaced is therefore gramme . Preparcction of jbonia . Ammonia from various sources was employed : ( 1 ) Commercial anhydrous ammonia from an iron der . ( 2 ) Commercial ammonia was passed through a tube containing red-hot lime into pure hydrochloric acid ; the ammonium chloride formed was heated with solution of sodium hydroxide , and the ammonia evolved was thoroughly dried by over quick lime and sodium vdroxide . This method was used by Guye . * In our early ents t was condensed in a glass tube placed in a mixture of ether and solid carbon dioxide ; later an iron tube was used . In order to prove the efficacy of this method of preparation in destl'oying pyridine , a slow stream of hydl.ogen was bubbled liquid contained in a small wash-bottle , and then passed over -hot lime . No pyridine could be detected in the gases the hard-glass tube . A sample of ammonium chloride made by the above-mentioned method was very kindly subjected to spectroscopic examination by Dr. J. J. Dobbie , who reported that he found no indication of the presence of pyridine . ( 3 ) Dobbie has shown that ammonium oxalate freed from pyridine by repeated recrystallisation . Some ammonium oxalate was made 'Chem . Soc. Journ , Trams . , vol. 77 , p. 318 . VOL. LXXYUI . Dr. E. P. Perman and Mr. J. H. Davies . [ Apr. 24 , from commercial oxalic acid and ammonia and recrystallised 10 times ( another sample six times , which proved sufficient ) ; the ammonia was set free by heating with potash , and condensed in a glass tube . ( 4 ) Sodium nitrite was reduced with aluminium and sodium hydroxide solution ; the ammonia was absorbed by hydrochloric acid , and again liberated by sodium hydroxide . The main part of the ammonia used was made by method ( 2 ) , and was condensed in the iron tube ( see diagram ) placed in ether and solid carbon dioxide . The tube was fitted up like a wash-bottle , the ammonia passing in through the long tube . To the short tube was connected a drying-tube to prevent the entrance of moisture from the air . When a sufficient quantity of ammonia had condensed , the tube was removed from the freezing mixture , placed in a vice , and the valve immediately screwed on , a leather washer being placed between the tube and the valve . The valve was fully opened , and left for about 5 minutes in order to expel the air from the top of the tube by the rapid stream of ammonia . After some preliminary experiments the following results were obtained:\mdash ; Method ( 1 ) . Commercial Ammonia.\mdash ; Temperature . Capacity of globe 17738litre . Temperature Capacity of globe 17738litre . *Left for 12 hours to test adsorption . 1906 : ] Some Physical Constants of Method ( 2 ) . Capacity of globe . Temperature The results now available for the vapour-density of ammonia at GuyeLeDuc . Reduced t Perman and Davies ( 1 ) We may venture to say that Le Duc 's number is erroneous , owing to the use of unpurified ammonia . Our final result is ( giving the greater weight to series ( 1 ) ) , which differs only by about one part in 15,000 from that obtained by Guye , and may be taken , we believe , as the most accurate value yet obtained for this constant . Density of Ammonia at \mdash ; Capacity of globe litres . Mean finaMe } Demity of at \mdash ; Capacity of globe ( new ) ] litres . Dr. E. P. Perman and Mr. J. H. DavieS . ; Density of Ammonia at \mdash ; The temperature was obtained by shaking solid carbon dioxide into a bath of alcohol surrounded by thick felt and thoroughly stirred . temperature was read on a mercury thermometer and was maintained constant within by adding solid carbon dioxide in small quantities as required . The thermometer was standardised by means of an air thermometer . Capacity of globe Coefficient of Exparosion of Ammonia.\mdash ; From the results just given the specific volumes Temperature . Volume of 1 gramme . 119575litres 1.2973 From these numbers the coefficients of expansion for different ranges of temperature have been calculated:\mdash ; Temperature . Between and\mdash ; 20o Coefficient of expansion . The coefficient is seen to be much greater than that of the less easily condensible ases , and decreases with rise of tenlperature . Attempts were made to calculate values of and in van der Waals ' equation from these data ; it was found , however , to be impossible , the equation not representing the facts with sufficient accuracy . Taking the simple equation is found to vary about 2 per cent. between and 190.6 . ] Some of monia . Temperature . is here expressed in atmospheres and in litres . Compressibility of Ammonia.\mdash ; By comparing the density at half an atmosphere with that at one atmosphere , the compressibility of ammonia may be determined . The globe was filled with ammonia in the usual way , then connected with a pressure-gauge . and about half the ammonia pumped out . Next the ammonia was allowed to blow off until equilibrium had been attained , when the pressure was immediately read . The readings were made on a mirror scale , the barometer standing in the same trough being read at the same time ( see fig. II ) . to the difficulty of reading the pressure and maintaining its constancy , no great accuracy was attained ; the probable error is about mm. Dr. E. P. Perman and Mr. J. H. Davies . [ Apr. 24 , Density of Ammonia at Half an \mdash ; Capacity of globe litres . Temperature From these results As before stated , we cannot claim any great accuracy for this result . and we prefer to make use of Lord Bayleigh 's number in proceeding to calculate the molecular weight of ammonia , the method and apparatus used by him specially adapted to the purpose . * Lord Rayleigh found at , which , corrected in the way indicated by him , becomes at This gives , and the correction factor Molecular weight of ammonia Taking , the atomic weight of nitrogen is deduced as thus closely . confirming the number obtained recently by several investigators . Density of Ammonia in the Presence of Air.\mdash ; Experiments were made to test the effect of admixture with air on the density of ammonia . Determinations were first made of the density of air freed from moisture and carbon dioxide by means of phosphorus pentoxide and soda-lime respectively . Temperature . Volume of globe Zeits . fur Phys. Chem 1905 , vol. 52 , p. 705 . 1906 . ] Some Constants of Ammonia . The globe was exhausted and weighed , about half filled with ammonia , and again . It was then surrounded with ice , and air carefully admitted un til the mixture had attained the atmospheric pressure . Another weighing was then made . The following are the data : Temperature . Volume of globe mmonia a The density calculated from 's value for the compressibility is . The partial pressure of the ammonia in the above table is tained by subtracting the partial pressure of the air ( calculated from its weight ) from the total pressure . It will be seen that the density is nearly one part in 1000 higher than that calculated from ths compressibility , and this represents the deviation Dalton 's law of a mixture of approximately equal volumes of ammonia and air . The normal value of the density of ammonia , calculated from its molecular weight and the density of oxygen , is ; consequently the density of ammonia is still about 1 per cent. above the normal value , even when diluted to the extent mentioned . Pressure-coeffici of simple form of constant volume airthermometer , with a globe of about S litre capacity , was filled with pure ammonia at about C. , and atmospheric pressure . In order to test if there were any inaccuracy caused by adsorption , successive readings were taken at an interval of 48 hours , of 24 hours at , and of a month at but the readings in each case agreed within the limits of expel'imental error . Allowance was made ior the expansion of the globe with rise of temperature . The correction for the tube connecting the globe and the gaugc was inappreciable . The following are the results ( see p. 40 ) . It will be seen at once that the numbers show a considerable deviation from van der Waals ' equation , which may be written in the form where and are constants : is proportional to the pressure-coefficient and varies , therefore , by nearly 6 per cent. over the range of temperature employed . The values of the pressure-coefficient are , as ] be expected , very close to those obtained for sulphur dioxide , and than those for carbon dioxide or-nitrous . oxide . : E. P. Perman and . J. H. Davies . [ Apr. 24 , Summary . ( 1 ) The vapour density of ammonia at has been found to be mass of llitre in grammes at latitude ) , previous results being by Guye and by Le Duc . ( 2 ) When the ammonia and the ylass vessel were thoroughly dried no preciable adsorption of ammonia by glass , or condensation of ammonia on the surface of glass , was found to take place . ( 3 ) From density determinations at different temperatures , the coefficient of expansion of ammonia has been deduced as between and , and between . and ( 4 ) From Rayleigh 's determination of the compressibility of ammonia and our own value for the density , the molecular weight of ammonia has been calculated as , and the atomic weight of nitrogen as ( 5 ) Incidentally the density of air free from water vapour and carbon { lioxide has been determined as ( lat. ) . ( 6 ) The deviation from Dalton 's law for a mixture of approximately equal volumes of air and ammonia has been found to be about 1 part in ( 7 ) The pressure-coefficient of ammonia has been determined , the pressure being atmospheric at . Between and the coefficient was , and between and it was The expenses incurred in the above research have been defrayed by a grant from the Royal Society . 1906 . ] Constants Pressurc of Liquid Ammoni and the of its Boiling Point . By JOHN HUGHES DAVIES . It was suggested to me by Dr. Pcrman , to whom I am much indebted for kindly advice nd assistance , that I should repeat the determination of the vapour pressure of liquid ammonia at some of the lower temperatures , using pure ammonia , in order to obtain accurate value for its point . Apparatus . This consisted 1 . The bath , which was a cylindrical zinc pot about 10 inches high and 6 inches diameter , covered completely on the outside with a of very thick felt . It contained alcohol and solid carbon dioxide , and was provided with a stirrer worked by a hot-air motor . 2 . The iron tube , which contained the liquid ammonia . This differed from the tube previously described only in having a narrow stem . 3 . The pressure gauge . Two forms of gauge were used , one for the lower temperatures , i.e. , temperatures at which the pressure was less than atmospheric , and the other for the crher temperatures and pressures . The former is indicated in the by and the latter by . The pressure was read on a millimetre scale . is a movable glass mirror of rectangular shape with a horizontal line drawn across it ; by sliding it along the edge of the scale , and behind the glass tubes of the gauge , the pressure could easily be read to 1/ 10 mm. 4 , The thermometer . A pentane thermometer was employed ; it was gladuated in single degrees , so that the temperature could be read accurately to . It was standardised by means of an air thermometer . Method of Procedure.\mdash ; The apparatus being in position with the suitable pressure gauge attached and the steel valve shut off , the leading tubes were exhausted to 1/ 10 mm. by means of a Fleuss pump , exhaustion taking place through th stop-cock in the case of the and through the side tube in the case of F. The stop-cock was then turned off , or the side tube drawn out and fused , as the case might be . The bath was brought down to the required temperature by the addition of solid carbon dioxide , the valve turned on , the pressure indicated by the gauge read , and the temperature of the mercury in the gauge taken . Results.\mdash ; Determinations were carried out over the range of temperature to Some of From these results the values of the vapour pressures at equal intervals of from to have been obtained by graphical interpolation . Those pressures marked have been obtained from the curve , whilst the others were actually observed . From this curve the boiling point of liquid ammonia at 760 mm. pressure is given as C. The results obtained are found to be in very good agreement with those obtained by Regnault*and Pictet , whilst they differ considerably from those obtained by Faraday and Blumcke . S Also the value obtained for the boiling point , viz. , , is in close agreement with the value obtained by H. D. Gibbs Vide ' Landolt und Bornstein Tabellen , ' 1897 edition , pp. 77 , 78 . Vide xbid . 'Phil . Trans 1845 , p. 166 . S 'Wied . Ann vol. 34 , p. 10 , 1888 . 'Amer . Chem. Soc. Jour vol. 27 , p. , 1906 .

rspa_1906_0056

0950-1207

Barometric variations of long duration over large areas.

43

60

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

William J. S. Lockyer M. A., Ph. D., F. R. A. S.|Sir Norman Lockyer, K. C. B., LL. D., Sc. D., F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0056

en

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0056

10.1098/rspa.1906.0056

Meteorology

Tables

Meteorology

43 Barometric Variations of Long Duration over Large Areas . By William J. S. Lockyer , M.A. , Ph. D. , F.R.A.S. , Chief Assistant , Solar Physics Observatory , South Kensington . ( Communicated by Sir Norman Lockyer , K.C.B. , LL. D. , Sc. D. , F.R.S. Received May 8 , \#151 ; Read June 21 , 1906 . ) [ Plates 1\#151 ; 5 . ] In a paper* communicated to the Society in the year 1902 , Sir Norman Lockyer and I pointed out the existence of a barometric see-saw of short durationf ( about 3'8 years ) occurring between two large regions , nearly antipodal to each other , the centres of which were approximately India and Cordoba ( South America ) . A continuation of the research indicated that this barometric see-saw was of greater extent than was at first supposed , and in a further communication ! in the same year observations extending over new regions were discussed and the results published . Still further inquiry indicated that this see-saw was almost world-wide in its extent , and the result of a later investigation , which included the examination of pressure observations at 95 stations scattered over the earth 's surface , was communicatedS to the Society in the year 1904 . During the progress of this work it was noticed that many of the curves representing barometric changes over a great number of years in various widely distributed areas exhibited variations of much longer duration which were neither coincident in their epochs of maxima or minima or even in the lengths of their oscillations . It seemed to me therefore quite possible that if a distinct pressure change of short duration could occur simultaneously , but of opposite phase , in anti* ' Roy . Soc. Proc. , ' vol. 70 , p. 500 . + The use of the word period previously employed in these investigations did not necessarily imply that the curves discussed were perfectly " " but that the meteorological variations which they represented showed oscillations which , when more will be known about them , may possibly be found to be dependent on a periodic cause or causes . The sun-spot variation , for instance , is generally described as being periodic , with a period of 11T years . As a matter of fact this is only a mean value of the intervals , minimum to minimum , the departures from this mean amounting sometimes to two years . Such differences from the mean may be due to other underlying periods , one of which of about 35 years in length was suggested in my paper entitled " The Solar Activity 1833\#151 ; 1900 , " communicated to the Royal Society in 1901 , ' Roy . Soc. Proc. , ' vol. 68 , p. 294 . | 'Roy . Soc. Proc. , ' vol. 71 , p. 134 . S ' Roy . Soc. Proc. , ' vol. 73 , p. 457 . Dr. W. J. S. Lockyer . Barometric [ May 8 , podal parts of the earth it was not unreasonable to expect variations of long duration to behave in a like manner . The question was , however , well worth inquiring into , and the object of this communication is to present to the Society the first results of the investigation . In the present instance the survey does not extend over the whole world , but is restricted to the areas which include India , the East Indies , Australia and South America . It may be stated further that , for such an investigation as this , as long a series of homogeneous observations as possible for each station is desirable . The available data are , however , not so numerous as would have been wished , but in spite of this I think that the results deduced are sufficiently consistent to serve as a first approximation to the barometric changes in operation in these areas . The paucity of barometric data is most conspicuous in the South American region , so that for this part of the world the change of long duration has to be deduced from several portions of series of observations made at various stations . This I am aware is not a very satisfactory procedure , but failing this no other means is available . In a previous communication* curves have been published representing barometric changes of short duration for Bombay , Cordoba and Adelaide , commencing in the years 1873 , 1873 and 1876 respectively . Since the curves for Bombay and Adelaide can be carried much further back than the above dates , namely to 1847 and 1857 respectively , I have considered it necessary and advantageous to bring together in the first instance a series of curves 'representing the short period variation for the regions dealt with in this paper . Further , two or more independent curves are given for each area investigated , in order to demonstrate the real nature of such variations . Plate 1 gives seven curves exemplifying the variations of the mean annual pressure changes from year to year . Madras and Bombay represent India , Batavia the East Indies , Melbourne and Adelaide are typical of Australia , and Cordoba and Santiago show the changes in the South American region . Since the barometric variation of short duration of the last two mentioned places is of opposite phase to that occurring in the Indian area , these two curves representing their changes have been inverted in the plate . The curves are all drawn on the same scale , so that a quantitative as well as a qualitative idea may be obtained of the amplitudes of the variations in these different and widely distributed regions . It is only necessary to take a rapid glance at this series of curves to form an idea of the very close relationship that exists between the barometric * 'Roy . Soc. Proc. , ' vol. 73 , Plate 13 . 1906 . ] Variations of Long Duration over Large Areas . changes in these parts of the world . As the curves indicate , the changes are of the greatest magnitude . in the Australian area , while in the East Indies , India and South America , they are more or less of the same order of intensity . This magnitude , although for a great part dependent on the geographical positions of the areas as regards latitude , is not apparently entirely so , since there is a great difference between the values for the Cordoba and South Australian stations , the latitudes of which are approximately the same . In a subsequent paragraph reference will be made to the effect of latitude on the percentage values of the amplitudes of the variation of short duration in terms of the mean annual swing . To determine approximate relative magnitudes of the largest amplitudes of these changes of short duration for these regions , the five most prominent rises in the curves from a minimum to a succeeding maximum have been selected and the differences of the readings determined . In the case of Madras and Bombay the means are respectively 0*033 and 0*036 inch , which give for the Indian area a mean maximum amplitude of 0*035 inch . The individual years taken ancf1 the corresponding barometric readings were as follows Station . Year . Minimum . Year . Succeeding | maximum . Difference . inches . inches . Bombay 1862 29 -778 1864 29 -827 1875 29 -812 1877 29 -848 1878 29 -801 1881 29 -825 1886 29 -812 1888 29 -836 . 1898 29 -795 1899 29 -830 Mean ... 29 -800 ... 29 -833 0*033 Madras 1862 29 -806 1864 29 -851 1875 29 -814 1877 29 -866 1882 29 -806 1884 29 -840 1887 29 -810 1888 29 -836 1898 29 -805 1899 29 -828 Mean r - 29-808 | 29*844 0*036 For three stations in Australia the values for the amplitudes , derived in a similar manner , are 0*076 inch for Melbourne , 0*077 inch for Adelaide and 0*071 inch for Sydney , the mean value for Australia being 0*074 inch . The values from which these means have been derived are as follows ( see p. 46 ) . Comparing the means for the Indian and Australian regions , it is seen that the ratio of amplitudes is as 35 to 74 , that is as 1 to 2 nearly . Dr. W. J. S. Lockyer . Barometric [ May 8 , Station . Year . Minimum . Year . Succeeding maximum . Difference . inches . inches . Melbourne 1863 29 -896 1866 29 -954 1875 29 -886 1877 29 -993 1878 29 -905 1881 29 -966 1882 29 -902 1885 29 -996 1890 29 -924 1891 29 -985 Mean ... 29 -903 ... 29 -979 0-076 Adelaide 1863 30 '006 1865 30 -073 1875 30 -028 1877 30 -144 1879 30 -052 1881 30 -107 1882 30 -047 1885 30 -121 1890 30 -036 1891 30 -111 Mean ... 30 -034 ... 30 -111 0-077 Sydney 1867 29 -872 1868 29 -933 1875 29 -803 1877 29 -896 1879 29 -816 1881 29 -874 1882 29 -829 1885 29-920 1893 29 . 829 * 1894 29 -885 Mean ... 29 -830 ... 29-901 0-071 General mean ... \#151 ; ... 1 ... 0-074 This fact seems to me of very great importance , because , if these barometric changes of short duration are on so much larger a scale in Australia than they are in India , a study of the Australian conditions may materially assist Indian Meteorologists . The amplitude for the South American region is of about the same order as that of India , the mean for five stations derived in the above-mentioned manner being 0'38 inch . The individual stations and corresponding values are as follows- ( see opposite page ) . The first step taken to render more apparent the changes of long duration involved in all these curves was to eliminate as far as possible the prominent short variations of about four years ' duration . This was to a great extent accomplished by grouping the years in sets of four and employing the mean values of each of these groups . Thus the means for the years 1873 to 1876 1874 to 1877 , 1875 to 1878 , and so on , were determined , and curves were drawn through each of these points after they had been plotted on squared paper . Each mean point was actually plotted on the time scale at the end of the second year of the group of which it was the mean . Thus the mean for 1873 to 1876 was plotted at the end of 1874 . The curves first dealt with in this manner were those showing the pressure changes for India . Although one curve would have been sufficient to 1906 . ] Variations of Long Duration over Large Areas . illustrate the variation over this area , a second curve is added to serve as a check on the accuracy of the first . For this region the barometric observations made at Bombay and Madras were utilised since they go back so far as 1847 and 1842 respectively . Station . Year . Minimum . Year . Succeeding maximum . Difference . inches . inches . Cordoba 1873 28 -494 1875 28 -534 1884 28 -498 1886 28 -532 1888 28 -499 1890 28 -531 1891 28 -508 1893 28 -552 1902 28 -487 1903 28 -522 Mean ... 28 -497 ... 28 *534 0-037 Curityba 1887 27-008 1888 27 -043 1891 27 -028 1894 27 055 1899 27 -031 1900 27 -055 1902 27 -031 1903 27 -057 Mean ... 27 -025 ... 27 -053 0-028 Goya 1877 29 -782 1878 29 -832 1888 29 -805 1890 29 -840 1891 29 -828 1893 29 -858 Mean ... 29 *805 ... 29 -843 0-038 San Juan ( Buenos 1868 29 -892 1871 29 943 Airs ) 1873 29 -930 1874 29 -979 1877 29 -906 1878 29 -946 1887 29-880 1889 29 -923 1891 29 -908 1893 29 -954 Mean ... 29 -903 ... 29 -949 0-046 Santiago 1871 28 -235 1872 28 -269 1877 28 -185 1879 28 -235 1888 28 -217 1890 28 -238 1900 28 -176 1901 28 -232 1902 28 -182 1903 28 -230 Mean ... 28 -199 ... 28 -241 0-042 General mean ... ... ... ... ... 0-038 These two curves are reproduced on Plate 2 and it will be seen that they are very nearly identical in every respect . They exhibit , further , variations of a periodic nature , but this periodicity becomes muoh less apparent after the year 1880 . The next curve examined was that of Batavia ( East Indies ) . Unfortunately the observations do not go back further than 1866 , but where the curve overlaps those of India the close similarity of the changes is very apparent . 4.8 Dr. W. J. S. Lockyer . Barometric [ May 8 , Going still further away from India , the Australian continent was then examined . Here the curves representing the variation of long duration begin to present a new aspect . Fortunately three excellent series of barometric observations are available for this region , namely , those for Adelaide , Melbourne , and Sydney , commencing respectively in the years 1857 , 1859 , and 1858 . The changes atj Perth are also included here , as there is a set of observations commencing ' iji 1875 which represent the variations taking place well to the west of this continent . ... ... . All these four curves are reproduced on the scale in Plate 2 . It will be seen in the first instance that the Adelaide curve resembles in a general way that of Bombay and that the maximum about the years 1877 and 1878 is almost equally pronounced in Adelaide . Attention is specially drawn to this particular maximum , as it will be observed when examining the curves for Melbourne , Sydney , and Perth , that during these years it becomes of quite secondary importance . If for the moment the curves at this epoch be left out of consideration , it will be seen that the remaining portions of all the curves are not only very like each other , but bear a general resemblance to those of the Indian region . Before dealing with the possible origins of these barometric variations of long duration in the eastern hemisphere , attention will first be directed to ai part of the western hemisphere , namely , that of South America , to see whether similar changes are in operation there , and if so , to study their \#166 ; nature . It ; will be remembered that the barometric change of short duration in this region behaved in an inverse manner to that of the Indian and Australian areas ( see Plate 1 ) . Unfortunately for this part of the world data are not numerous , but still , I think they are sufficient on the present occasion not only to demonstrate that a long barometric variation does take place , but that the epochs of maxima and minima are not those of either India or Australia as deduced in this paper . Employing the same method as above described , four-year means were determined and curves drawn for the five stations , Cordoba , Goya , and San Juan ( Argentine Republic ) , Santiago ( Chili ) , and Curityba ( Brazil ) . All these curves are reproduced in Plate 8 , and are drawn on the same scale as those of the Indian and Australian curves in Plate 2 . Although the South American curves extend over different periods of time , there is sufficient overlapping in all cases to connect up one series with another . . . _ : L906 . ] Variations of Long Duration over Large Areas . 49 The Cordoba curve undoubtedly indicates that a long barometric change is taking place , but the shortness of the period over which the observations extend , namely , from 1873 to 1904 , renders it unserviceable for the determination of its possible periodicity . A neighbouring station , Goya , corroborates in a general manner , so far as the observations extend , the Cordoba variation , with perhaps the exception of the first three points on the curve . To carry back these pressure changes to an earlier date , the observations at San Juan ( Buenos Airs ) were employed ; the available data for this station extend from 1867 to 1889 . Here we find the fall of pressure at Cordoba from 1875 to 1882 well corroborated , followed by a subsidiary maximum similar to that at Goya in 1885 . So far as these observations extend , there seem to be two prominent maxima at about the epochs 1874 and 1893 , each of which is followed by minima at about the years 1882 and 1901 . The curve for Santiago , a station to the west of the Andes , indicates also very clearly these two principal maxima and the second of the two minima at the same epochs , but the minimum about the year 1882 occurs somewhat earlier . At a station in Brazil , Curityba , in which only a short series of observations is available , this long variation is also in existence ; the second principal maximum , however , falls a little later than at the previously mentioned stations . In order to indicate generally the approximate dates of the occurrence of the points of maxima and minima in these four-year mean curves , the following table has been drawn up . In this the large type figures represent the years of the most prominent maxima and minima , while those in smaller type indicate those of a subsidiary or uncertain nature:\#151 ; Years of maxima . Years of minima . India . Batavia . Adelaide . Perth , Melbourne , Sydney . South America . India . Batavia . Adelaide . Perth , Melbourne , Sydney . South America . 1845 . 1857 - _____ 1849 \#151 ; \#151 ; \#151 ; \#151 ; 1867 1867 1868 1862 \#151 ; 1862 1863 \#151 ; 1877 1877 1878 1878 1874 1871 1872 1871 1875 \#151 ; 1886 ? 1884 ? 1887 1887 1881 1881 1881 1881 1882 1901 ? 1901 ? ( 1901 ? ) \#151 ; 1893 1894 1894 1894 1894 1901 VOL. lxxviii.\#151 ; A , E 50 Dr. W. J. S. Lockyer . Barometric [ May 8 , Generally speaking , the above figures indicate that while the Indian and Batavian ( and Adelaide ) curves show a variation , the duration of which is somewhere about 11 years , the curves for the other Australian stations and those of South America present a change in which the maxima and minima are about 19 years apart . Reference to these changes will be made more fully in subsequent paragraphs . It is important further to note , as was done in the case of the variation of short duration , the very great difference between the amplitudes of these long changes in the Indian , Australian , and South American regions . If for instance the difference between the readings of the several maxima and minima of the curves plotted for Bombay and Madras be determined , it is found that they are 0*026 and 0'026 inch respectively , the mean of which is 0*026 inch . For Adelaide , Melbourne , and Sydney the differences for each are 0*054 , 0*043 , and 0*058 inch respectively , the mean of these three being 0*052 inch . The actual values from which the above figures have been derived are given in the following tables , but since in this instance the points on the Bombay . Madras . Year . Minima . Mean . 1848\#151 ; 49 1861\#151 ; 62 1870\#151 ; 71 inches . 29 -808 29 *808 29 *804 29 *807 Maxima . 1856\#151 ; 57 1865\#151 ; 66 1876\#151 ; 77 29 *832 29 *837 29 *830 29 *833 Difference ... ... 0*026 Tear . Minima . Mean . 1861\#151 ; 62 1871\#151 ; 72 1893-94 inches . 29 *789 29 *797 29 *805 29*797 Maxima . 1875\#151 ; 76 1886-87 1900\#151 ; 01 29 *821 29 *824 29 *823 29 *823 Difference ... ... 1 0 *026 1 General mean difference 0 *026 inch . Adelaide . Melbourne . Year . Minima . Mean . 1861\#151 ; 62 1870\#151 ; 71 inches . 30 -023 30 *035 30 *029 Maxima . 1877\#151 ; 78 1886\#151 ; 87 1895\#151 ; 96 30-082 30 *093 30 -073 30 *083 Difference ... ... 0-054 Year . Minima . Mean . inches . 1862\#151 ; 63 29 -914 1873\#151 ; 74 29 *921 1893\#151 ; 94 29 -915 29 *917 Maxima . 1867\#151 ; 68 29 -947 1886\#151 ; 87 29 *973 29 *960 Difference ... ... 0*043 1906 . ] Variations of Long Duration over Large Areas . 51 Sydney . Year . Minima . Mean . 1862\#151 ; 63 1874\#151 ; 75 1880\#151 ; 81 inches . 29 -842 29 -829 29 -837 29 -836 Maxima . 1857-58 1886\#151 ; 87 1895\#151 ; 96 29 -896 29 -902 29 -883 29 -894 Difference ... ... 0-058 General mean difference 0*052 inch . curve are derived from means of four years , the years given refer to the two middle years of each four . In the case of Australia then this long variation has an amplitude twice as large as that of India , a feature which I think has not been pointed out previously . The magnitude of the amplitude of this long barometric swing must have a great effect in changes in Australian weather , and most probably is responsible for the marked secular weather changes which have been previously shown to exist in this region of the world . To determine the amplitude of the oscillation in South America , differences between the readings of the maxima and minima points on the four-year mean curves were also determined . The mean of the values for Cordoba ( 0-032 inch ) , Santiago ( 0-045 inch ) , and San Juan ( Buenos Airs ) ( 0-039 inch ) was 0'039 inch . This value is intermediate between the Indian ( 0"026 inch ) and the Australian ( 0'052 inch ) amplitudes . The values for the individual stations were as follows:\#151 ; Cordoba . Santiago . Year . Minima . Mean . 1881\#151 ; 82 1900\#151 ; 01 inches . 28 -499 28 -492 28-495 1875\#151 ; 76 1893\#151 ; 94 Maxima . 28 -521 28 -524 28 -527 Difference ... ... 0-032 Year . Minima . Mean . 1876\#151 ; 77 1900\#151 ; 01 ' inches . 28 -215 28 -192 28 -203 Maxima . 1872\#151 ; 73 1893\#151 ; 94 28 -252 28 -244 28 -248 Difference ... ... 0-045 e 2 Dr. W. J. S. Lockyer . Barometric San Juan ( Buenos Airs ) . [ May 8 , Year . Minima . Mean . 1881\#151 ; 82 1887\#151 ; 88 inches . 29 -911 29 909 29 -910 Maxima . 1873\#151 ; 74 29 -949 29 -949 Difference ... 0-039 General mean difference 0 *039 inch . It may be of interest here to summarise in tabular form the amplitudes of the mean annual and the short and long variations of barometric pressure for the stations used in this enquiry which have been found to be most conspicuous . Two columns of figures , the third and last , indicate the percentages of the amplitudes of the short and long changes in terms of the mean annual variations determined from a long series of years in each case:\#151 ; Amplitudes of Pressure Variations . Stations . Mean annual variation . Short variation . Percentage of annual . Long variation . Percentage of annual . Bombay 0-283 0-033 11 -7 0-026 9-2 Madras 0-297 0*036 12 -1 0-026 8-8 Adelaide 0-226 0-077 34-0 0-054 23 1 Melbourne 0-204 0-076 37-2 0 043 21 -1 Sydney 0-212 0-071 33 -0 0-058 27-3 Cordoba ... .* 0-177 0-037 20 -9 0-032 18 -1 Curityba 0-188 0 -028 14 -9 \#151 ; \#151 ; Goya 0-248 0-038 15 -3 San Juan ( Buenos Ayres ) 0-236 0-046 19 -5 0-039 16 -5 Santiago 0*128 0 042 32 -7 0-045 35 -1 The values shown in this table are very striking . In the case of Australia , for example , the fact is made apparent that the amplitude of the variation of short duration amounts , in the mean to as much as 35 per cent , of that of the mean annual variation , while that of the variation extending over about 19 years reaches nearly 25 per cent. Considering the great magnitudes of these changes in relation to those of the mean annual variations , no doubt can remain as to the important rdle which must be played by them in bringing about changes in the seasons from year to year . 1906 . ] Variations of Long Duration over Large Areas . 53 In a previous paragraph it has been mentioned that the amplitudes of the variation of short duration , expressed in percentage of the annual swing , suffers a change on account of the position of the stations as regards latitude . To illustrate this for the region including India and Ceylon , the pressure observations at several stations have been analysed , and the result is given in the following table . The stations are arranged in order of latitude , so that the increase in latitude will be seen to correspond generally with a decrease in the values of the percentages mentioned above:\#151 ; \#151 ; Lat. N. Mean annual variation . Short variation . Percentage . Colombo o / 6 56 inch . 0-094 inch . 0-027 28-7 Coimbatore 11 0 0-200 0 036 18 -0 Madras 13 4 0-297 0-036 12 1 Bombay 18 54 0-283 0-033 11 -7 Nagpur 21 9 0-436 0-036 8-3 Allahabad 25 26 0*555 0-031 5 -6 Jaipur 26 55 0-498 0-025 5-0 Jacobabad 28 24 0-647 0-031 4-8 Lahore 31 34 0 -574 0 039 6-7 D. Ismail Khan 32 0 0-620 o-oio 6-4 This percentage change is not so much due to the variation of the amplitude of the change of short duration as to the increase with the latitude of that of the mean annual variation as shown in the second column of figures above . The question now arises : how does the long South American variation compare with those shown to exist in the Indian and Australian areas ? In the first instance it will at once be seen that the South American curve is of a type conforming more , in length of swing , to the Australian variation than to that in India . Further , there is no doubt about the non-coincidence of the principal epochs . In order to make a closer comparative study of these variations , hypothetical curves embodying the main features of these changes have been drawn at the bottom of each of these two series of curves illustrated in Plates 2 and 3 . These are intended to indicate in curves the general nature of the variations as regards their epochs of maxima and minima . In Plate 2 the epochs of the two principal maxima for the Australian area are seen to occur at about 1868 and 1887 , while three subsidiary maxima are suggested at about the years ( 1858 ? ) 1878 and ( 1898 ? ) , but the epochs of the first and last of these are very uncertain , as the curves do not extend over a sufficiently long period of time . Nevertheless , it may here be 54 Dr. W. J. S. Lockyer . Barometric [ May 8 , remarked that the interval between the two chief maxima is 19 years , while those between the successive secondary maxima are about the same length . Forming a hypothetical curve in exactly the same way for the South American region ( see Plate 3 ) , the two principal maxima here fall in the years 1874 and 1893 , while a subsidiary maximum occurs somewhere between 1880 and 1885 . Here again the interval between the two main maxima is 19 years . In both of the hypothetical curves those portions representing the fall from and the rise to a principal maximum have been connected by a dotted line as if a subsidiary maximum did not exist , thus forming a principal ( but really non-existent ) minimum . The object of doing this is to indicate that in the Australian area the rise to the principal maxima seems to be more abrupt than the fall from them , while in the South American area the opposite feature seems to be the case . An unsymmetrical curve seemed in both cases to represent the main features better than one drawn symmetrically . In fact , in the Australian area there is suggested an 8-year rise and an 11-year fall , while in the South American region an 11-year rise and an 8-year fall is indicated . Particular attention is called to this unsymmetrical peculiarity of the curves , since a similar feature was found to be present in the curve representing the barometric variation of about four years ' duration , * in operation in India and Cordoba . It was there stated that for Cordoba " the points of maxima of the hypothetical curve at the top of the plate do not lie midway between the minima on either side of them , but nearer the preceding minimum . " In order to be able to make a direct comparison between these two hypothetical curves representing the barometric changes of long duration in the Australian and South American areas Plate 4 has been added . In this the South American curve is placed directly above that for Australia , and below the latter is given the South American curve inverted . The first striking fact which this comparison indicates is the remarkable similarity of the nature of the variation in the two cases . Both curves seem to have principal maxima occurring at intervals of about 19 years , while situated between these is another maximum of a subsidiary nature . The second point of importance is that the epochs of these maxima in these two areas are not coincident . Further , we are not here in the presence of a barometric see-saw , or opposite pressure variation , because the Australian maxima do not occur simultaneously with the South American minima ; there seems to be a general time difference of phase amounting to about * 'Boy . Soc. Proc. , ' vol. 76 , A , p. 503 , 1905.\#151 ; Note . 1906 . ] Variations of Long Duration over Large Areas . six years , the epochs of the Australian high pressures preceding those of the South American region . In the case of the barometric variations of short duration existing between India and South America , the inversion of the latter curve corresponded exactly with the direct curve of the former . In order to make a similar comparison , the South American curve representing the curve of long duration has here also been inverted and it will be observed that the curves are not the inverse of each other . The above discussion of barometric changes occurring over large areas shows , I think , clearly that the type of variation taking place in South America is closely similar to that existent in Australia , but unlike that in operation in the Indian area . With so short a length of time covered by the observations it is difficult to say , especially with regard to Australia , whether the recurrence of the maxima and minima is of a regular periodic nature or not . Judging by the curves and figures which have been referred to in this paper , there seems to be a general indication that the intervals between the maxima or minima in the case of India are , on the average , approximately 11 years in length , while in the case of the Australian and South American regions the principal maxima are 19 years apart . I have previously indicated that the Australian pressure change of long duration is undoubtedly very closely associated with that in India , but that the reduction of the intensity of the maximum about the year 1877 in most of the Australian stations alters very considerably the aspect of the Australian curves . It seems , therefore , probable that if a satisfactory cause be found which is producing the fluctuations in one of these areas , then those in the other area will be subject to the same influence , but will be modified by some cause due possibly to a different geographical position . In comparing such regions as India and Australia it is as well , in this connection , to bear in mind the continental condition of the former and the insular condition of the latter , each of which has its own special effects on meteorological changes . In looking for the cause of these barometric changes which extend over several years , it seems as if the solar changes , as exhibited by the frequency or areas of sun-spots ( the only indication of solar activity extending over a long period of time that exists ) , are responsible for the Indian fluctuations . To indicate this relationship the sun-spot curve ( inverted ) is placed at the top of Plate 2 . This curve represents the variation from year to year of the mean daily areas of sun-spots deduced from both hemispheres of the sun . 56 Dr. W. J. S. Lockyer . Barometric [ May 8 , Perhaps different solar data handled in another manner might indicate a closer relationship than is at present suggested . Although the existing relationship may be considered of too approximate a character to indicate clearly a cause and effect , there is undoubtedly a general similarity between the sun-spot variation curve and that representing barometric changes in India from 1844 to 1903 , a period of 59 years . Years of average high pressure are years of few sun-spots , and vice versd , but there is a marked exception to this about the epoch of sun-spot maximum in 1883 , which maximum , it may be remarked , was much smaller in intensity than those of 1870 and 1860 . If India be thus dominated by the solar changes , then the curves for Australia and South America become of secondary importance from the solar point of view and may be considered as a modification of the Indian variation , due possibly to some terrestrial cause . How this modification is brought about I am not yet prepared to say , but I do not think we need be driven to explain the Australian or the South American barometric changes as depending either on lunar influence or a solar variation of about 19 years . The similarity of the curves representing the pressure changes in India and the sun-spot curve is not pointed out here for the first time . In fact , so striking was the resemblance between curves representing these changes in years previous to 1880 that the attention of several meteorologists was drawn to the close association of these two phenomena . Thus F. Chambers , writing in 1878 , * concluded that the curves " support each other in showing a low pressure about the time of sun-spot maximum and a high pressure at the time of sun-spot minimum . " He further stated:\#151 ; " The range of the variation of the year by mean pressure from the minimum of 1862 to the maximum of 1868 is 0042 inch and the mean range of the barometer from January to July is 0291 inch , from which it appears that the variation of pressure produced by the absolute variations of the sun 's heat are , in comparison with the usual seasonal changes , by no means insignificant . " J. A. Brown , f S. A. Hill , J Sir John Eliot , S H. F. Blanford , || E. Douglas Archibalds and others have all corroborated in a general manner this relationship between pressure change and sun-spot variation ; Douglas * ' Nature , ' vol. 18 , p. 568 . t 'Nature , ' vol. 19 , p. 7 , 1878 . f 'Nature , ' vol. 19 , p. 432 , 1878 . S 'Indian Meteorological Keports , ' p. 170 , 1877 . || 'Nature , ' vol. 21 , p. 479 , 1880 . IT ' Indian Meteorological Memoirs , ' vol. 9 , p. 543 , 1897 . 1906 . ] Variations of Long Duration over Large Areas . Archibald used data which extended up to the year 1893 and his deductions , which I think are the most recent , were:\#151 ; " The mean anomalies present all the characteristics of a true period , rising to a maximum of 0'0132 inch about the epoch of minimum sun-spot , and , with an exception in the sixth year , falling to a minimum of O'OIOO inch coincidently with that of maximum sun-spot , the former barometric epoch slightly preceding , and the latter slightly following the corresponding solar epoch as is usual in all other sun-spot comparisons . . " Still the figures from the other years , and the repetition in each cycle , show that there is a cyclical tendency to high pressure at the time of few spots and low pressure at the time of many spots . . . the amplitude of the variation amounts to 0'02 inch . . By utilising in this inquiry observations made up to the most recent date possible , 1905 , it will be seen ( Plate 2 ) that the sun-spot maximum of 1893 corresponded with an epoch of mean low pressure about that epoch ; while up to 1901 , a year of about sun-spot minimum , the pressure had steadily risen . It is thus evident that the same relationship is still in operation , only the amplitude is much smaller than was the case in the earlier years of observation So far as I am aware , the long barometric swing of 19 years in Australia has not been pointed out before ( Bruckner omitted the Australian area in his pressure investigation* * * S ) but the existence of a 19-year period of rainfall change has often been mentioned . One of , if not the earliest record of it is in " Notes on the Climate of New South Wales , " 1870 , by Mr. H. C. Bussell , and in a later paper which he published in 1876 , f he more strongly advocated this rainfall cycle . In a still later paper which he published in 1896 , Mr. Bussell collected information of a miscellaneous kind and extended his 19-year rainfall cycle both over a greater period of time and a wider area . In fact Australia , India , Europe , Asia , Africa , North and South America , all tended to give him general ideas relating to droughts , which he marshalled and from which he deduced that this cycle was occurring over the whole earth , epoch for epoch , nearly simultaneously . Mr. Bussell was finally led to give up the idea of the sun-spot cycle as influencing rainfall . In place of solar action he regarded the moon as the origin of this cycle , a suggestion which he made in 1870S and again in 1896.|j * ' Klimaschwankungen seit 1700 , ' Eduard Bruckner , p. 194 , 1890 . + 'Journal of the Royal Society of New South Wales , ' vol. 10 , p. 151 , 1876 . t 'Journal of the Royal Society of New South Wales , ' vol. 30 , p. 70 , 1896 . S ' Notes on the Climate of New South Wales , ' 1870 . || 'Journal of the Royal Society of New South Wales , ' vol. 30 , p. 90 , 1896 . Dr. W. J. S. Lockyer . Barometric [ May 8 , It may , in conclusion , be stated that while the present investigation fully endorses the results of Indian meteorologists as regards the relationship between pressure and sun-spot variation , and agrees with regard to length of period with Mr. Russell 's long period cycle in Australia ( so far as the observations since 1857 permit ) , it does not corroborate his view that this cycle is world-wide in extent , with similar epochs of occurrence of the maxima and minima , or is dependent necessarily on lunar influence . On the completion of this paper I took the opportunity of submitting it to Dr. W. 1ST . Shaw , F.R.S. , and I should like here to express my thanks to him for kindly reading it through and making valuable suggestions . Owing to the shortness of the time covered by the observations discussed in this paper I refrained from entering into any of the possible barometric changes which were visible in the curves other than those to which mention has already been made . Dr. Shaw suggested , however , that as I had eliminated the variation of about four years ' duration to render apparent the changes of 11 and 19 years , I should proceed a step further and eliminate the 11-year change from the curves , since both the Indian and Australian pressure values exhibited changes of about thi3 length . The object of this procedure was to find out whether the 19-year variation was a possible harmonic of the 4- and 11-year changes or a separate variation independent of these two shorter oscillations . If the former , then it should be absent after the observations had been freed from these two variations . To accomplish this , 11-year mean values were formed , that is , the value for each year plotted was composed of the combined mean for that year with the addition of the five years each side of this date . Such an operation not only eliminates any periodic change of 11 years , but at the same time disposes of the variation covering about 4 years . Plate 5 shows the resulting curves for India , East Indies , and Australia after the above-mentioned treatment . The South American would have been similarly handled if the series of observations at each station ( excepting Santiago ) had been longer . An examination of these curves shows that distinct variations still remain , and they are most marked in the Australian area , being specially prominent in the curve for Sydney and a little less so in that for Melbourne . The variation at Adelaide is almost as strong as at Sydney , but , as before in the case of the 11-year change , is not quite of the same nature . At Bombay a variation of much longer duration seems to be in operation , while the curve for Madras suggests maxima about 19 years apart , which in this respect conform with those of the Sydney curve ; the amplitude , however , is very 4- ana n-year Variations . Cn 4- and 11-year Variations . Oi 1860 0 5 18700 P -O * , l00U , y 5 l8buu 5 IB/ O 5 18800 5 18900 s 19000 hs Lurves to illustrate the Pressure Changes in India and Australia after the Elimination of the | 4- and 11-year Variations . o* 18600 s 18700 Curves to ittust'1 ate \900'0 . 18900 5 , m/ U . 18800 \#174 ; Elimination of 5 '* India and Austraha Changes tn I\#171 ; * ( { ons . C-V- \lt ; s\gt ; uyouu tM o c* :S Curves to illustrate the Pressure Changes in India and Australia after the Elimination of the 4- and 11 -yearVariations . Roy . Soc. ProcA . vol. 78 , Plate 1906 . ] Variations of Long Duration over Large Areas . much less . The observations at Calcutta have been treated in a similar manner , but the resultant curve seems to represent a variation which differs from both those of Bombay or Madras . The time dealt with in these curves is , however , so short that any reference to the possible periodic nature of these curves for the present is out of the question . The variations exhibited are , however , very suggestive , and when further observations have been accumulated , a more definite idea of these barometric changes will be gleaned . I take this opportunity to express my thanks to the Director of the Solar Physics Observatory , Sir Norman Lockyer , for permitting me to prepare this paper for the Society . I am indebted also to Messrs. W. Moss and T. F. Connolly , computers in the observatory , for the abstraction , reduction , and drawing of the curves of the observations . Conclusions . Summing up the results arrived at regarding the behaviour of the curves representing these long barometric changes , it may be stated:\#151 ; 1 . The Indian variation is nearly the inverse of the 11-year ( about ) sun-spot cycle , that is , years of mean high pressure are generally those of small spotted area . 2 . The Australian variation is allied to , but in part a modification of , the Indian variation . 3 . The interval between the Australian 'princmaxima is about 19 years . 4 . The interval between the South American principal maxima is about 19 years . 5 . The South American variation is not the inverse of that of Australia , but there is a time-phase difference between the maxima of about six years , the Australian maxima preceding those of South America . 6 . There seems evidence to suggest that the 19-year variation is due to solar action modified by some terrestrial cause . 7 . So far as the research has gone , no explanation has been found of the cause of the modification of the prominent 11-year variation in India into those of the pronounced 19-year changes which occur both in the Australian and South American regions . [ Addendum , June 8 , 1906.\#151 ; Since this communication was sent to the Royal Society I find a still earlier reference to the 19-year cycle in Australia . In an article on the " Development of Meteorology in Australia , " by Mr. Andrew Noble , of the Sydney Observatory , it is stated\#151 ; " Australian meteorology is greatly indebted to the Rev. W. B. Clarke for his untiring 60 Prof. G. Quincke . Transition from the Liquid to [ June 6 , efforts in its behalf during those early years , beginning with his observations at Paramatta in the year 1839 and continuing long after the inauguration of the New South Wales service under Government auspices in the year 1858 . . . . The 19-year cycle theory , elaborated by Mr. Russell in more recent years , was advanced by Mr. Clarke in the * Sydney Morning Herald ' of May 1 , 1846."* This reference is of great interest , since it indicates that this 19-year variation was evidently quite a prominent feature of Australian weather before the observations discussed in the present communication were made . ] The Transition from the Liquid to the Solid State and the Foam-Structure of Matter . By G. Quincke , For . Mem. R.S. , Professor of Physics in the University of Heidelberg . ( Received June 6 , \#151 ; Read June 21 , 1906 . ) 1 . On June 19 , 1905 , I laid before the Royal Society the results of my researches on ice-formation and glacier-grains . The further prosecution of these researches has shown that phenomena similar to those observed in the freezing of water occur in all bodies in nature , and are in agreement with the structure of metals as observed by myself and also by other investigators , who in some cases have described their results in the ' Philosophical Transactions . ' Solid bodies , then , are never homogeneous , but always exhibit a foam-structure . 2 . For brevity 's sake I use the word " oily " to describe any liquid that tends to make its surface as small as possible , and exhibits surface tension at the boundary separating it from another liquid . All liquids in nature resemble water in forming , as they cool , oily foam walls , which may be very thin and invisible . The shape and position of these foam walls become visible on freezing or thawing in the following ways:\#151 ; ( a ) By fissures or fractures at the surface of the foam walls , whenever the liquid contents of the foam cells contracted on solidification , or when the walls and the contents of the foam cells contracted differently as they cooled . * 'Monthly Weather Review , ' vol. 33 , No. 11 , November , 1905 , p. 480 . Washington , U.S.A. , Weather Bureau .

rspa_1906_0057

0950-1207

The transition from the liquid to the solid state and the foam-structure of matter.

60

67

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

G. Quincke, For. Mem. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0057

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0057

10.1098/rspa.1906.0057

Biology 3

Thermodynamics

Biology

60 Prof. G. Quincke . Transition from the Liquid to [ June 6 , efforts in its behalf during those early years , beginning with his observations at Paramatta in the year 1839 and continuing long after the inauguration of the New South Wales service under Government auspices in the year 1858 . . . . The 19-year cycle theory , elaborated by Mr. Russell in more recent years , was advanced by Mr. Clarke in the * Sydney Morning Herald ' of May 1 , 1846."* This reference is of great interest , since it indicates that this 19-year variation was evidently quite a prominent feature of Australian weather before the observations discussed in the present communication were made . ] The Transition from the Liquid to the Solid State and the Foam-Structure of Matter . By G. Quincke , For . Mem. R.S. , Professor of Physics in the University of Heidelberg . ( Received June 6 , \#151 ; Read June 21 , 1906 . ) 1 . On June 19 , 1905 , I laid before the Royal Society the results of my researches on ice-formation and glacier-grains . The further prosecution of these researches has shown that phenomena similar to those observed in the freezing of water occur in all bodies in nature , and are in agreement with the structure of metals as observed by myself and also by other investigators , who in some cases have described their results in the ' Philosophical Transactions . ' Solid bodies , then , are never homogeneous , but always exhibit a foam-structure . 2 . For brevity 's sake I use the word " oily " to describe any liquid that tends to make its surface as small as possible , and exhibits surface tension at the boundary separating it from another liquid . All liquids in nature resemble water in forming , as they cool , oily foam walls , which may be very thin and invisible . The shape and position of these foam walls become visible on freezing or thawing in the following ways:\#151 ; ( a ) By fissures or fractures at the surface of the foam walls , whenever the liquid contents of the foam cells contracted on solidification , or when the walls and the contents of the foam cells contracted differently as they cooled . * 'Monthly Weather Review , ' vol. 33 , No. 11 , November , 1905 , p. 480 . Washington , U.S.A. , Weather Bureau . 1906 . ] the Solid State and the Foam-Structure of Matter . 61 ( b ) By the bounding surfaces of the doubly refracting crystals ( glacier- grains ) which are differently orientated in neighbouring foam cells . ( c ) On illumination with sunlight or electric light , or on warming , when the doubly refracting contents of the foam cells melt and are transformed into singly refracting liquid . ( d)By lens-shaped masses , foam flakes or air bubbles , suspended in the foam walls . ( e ) By the furrows , or network of lines on the solidified surface formed by the intersection with that surface of the foam walls in the interior of the solidified mass . ( / ) By polishing or etching the natural or artificial surface , in cases when the walls and the contents of the foam cells differ in hardness , or in the rapidity with which they are attacked by chemical reagents . 3 . Pure benzene , slowly frozen in glass flasks , shows foam walls and fissures ( normal to the glass surface ) inclined to one another at 120 ' . The totally reflecting planes in the interior bound foam cells ( glacier-grains ) or hexagonal tables , each of which contains a crystal , differently orientated in the different foam cells . In the case of quickly frozen benzene , the foam walls are often warped or twisted , and the bounding surfaces of the benzene-grains exhibit waves , folds , or furrows , or parallel fibres . The light from an arc lamp developed in the clear contents of the separate foam cells a row of parallel bands of " dendrites , " or fir-tree formations , the needles of which changed in daylight into tubes with rounded heads and totally reflecting walls , and swelled up . The tubes formed bulbous enlargements and fell into strings of bubbles , some rounded , and some elongated . Benzene , slowly frozen in a rectangular glass trough , appeared clear between the white diagonal planes , which had frozen last and contained rounded air bubbles . Illumination for a few seconds with the arc light developed in the clear benzene fine dividing walls ( normal to the surface ) which bounded hexagonal prisms , 3 mm. wide and 8 mm. long . Beneath the sides of the prisms the solid benzene surface showed , on illumination , furrows like those of an ice-block exposed to radiation , corresponding in fact to Porel 's bands in glacier ice . Pressure with a steel point caused the solid block of benzene to cleave along the diagonal planes with a fibrous fracture , the fibres being normal to the surface , just as in an ice-block . The phenomena presented by benzene and water when freezing and thawing are extraordinarily similar . The air-filled tubes in the diagonal planes are , in the case of water , thinner and more numerous than in benzene , which contains more spherical air bubbles . Water is thus more viscous while solidifying than is benzene . 62 Prof. G. Quincke . Transition from the Liquid to [ June 6 , There is an essential difference between water and benzene in the fact that , on freezing , water expands , whereas benzene contracts . In the case of benzene , therefore , the walls of the foam cells become visible through the totally reflecting surfaces between the glacier-grains . 4 . Water , benzene , acetic acid and glycerine , when exposed in the form of clear solid blocks to the electric light , exhibit liquefaction figures of various shapes at the places where , as the cooling proceeded , traces of impurities had separated out at periodic intervals . These correspond to the liquefaction figures observed by Tyndall in natural ice . 5 . Bromine , frozen in a test tube and illuminated with the arc light , showed on the surface a network of fine furrows inclined to one another at 120 ' , and in the interior totally reflecting fissures ( normal to the surface ) at the places which had been occupied by invisible layers enclosing hexagonal prisms 2 to 3 mm. long . 6 . Bed hcematite has a surface like a mass of soap bubbles , and is bounded by spherical surfaces 10 mm. in diameter , in which are distributed small lens-shaped masses , 02 mm. in size . The spherical surfaces cut at angles of 120 ' , 90 ' , and so on , and are inclined at 120 ' to the cleavage planes that terminate in the lines of intersection of these spherical surfaces . On these cleavage planes can be distinguished fibres normal to the surface , as in melting ice . In the outer , quickly solidified layers , the fibres are 006 mm. thick , but in the interior , where the solidification occurred more slowly , they are 0*36 mm. thick , thus resembling the fibrous foam cells in quickly and slowly frozen ice . 7 . Malachite and chalcedony exhibit forms similar to those of red haematite , save that there are no lens-shaped masses in the spherical surfaces . 8 . The light-coloured veins that traverse the darker ground mass of marble and sandstone are twisted screw-surfaces , conical tubes swollen out at some places , pinched in at others , and spirally twisted , in the walls of which are distributed hollow lens-shaped spaces and smaller foam cells . These veins exhibit , therefore , the forms assumed by an oily viscous liquid under the influence of its surface tension . 9 . Pure molten salts\#151 ; NaCl , KC1 , KBr , KI , iSra2C03 , Na2S04 , Na^O ; \#151 ; when dropped on to platinum foil and allowed to solidify , show , like solidified benzene , many totally reflecting fissures , or plane layers , 0-05 to 025 mm. wide , which are bounded by straight lines or arcs of circles , and are inclined to one another at 120 ' or other angles . These plane layers , as the cooling proceeded , had contracted differently from the contents of the foam cells enclosed by them . In the surface of these layers or foam walls there lay lens-shaped masses , O01 to 0'02 mm. in size , arranged singly or in 1906 . ] the Solid State and the Foam-Structure of Matter . 63 two intersecting rows of 8 or 10 each . Sometimes these intersecting rows have the same orientation in several neighbouring foam walls ( totally-reflecting surfaces ) . Molten Na2S04 showed zig-zag fissures normal to the surface , and inclined at 120 ' . In the corners of the zig-zags three oily layers had met . The thinnest invisible layer had had , it is true , the same surface tension as the two others , but the tension caused by the thermal contraction had been insufficient to produce a fissure . In freshly melted drops of Na^COs there were foam walls , normal to the surface and inclined at 120 ' to one another , which bounded hexagonal prisms . At the points of intersection of the edges of the foam walls there lay occasionally , as in the case of thawing ice , a tetrahedron bounded by spherical surfaces . 10 . The surfaces of solidified drops of pure molten metals\#151 ; such as I used in 1868 and 1897 for measuring the surface tension of these metals\#151 ; show a network of straight lines or arcs of circles ( usually inclined to one another at 120 ' or 90 ' ) , or foam walls with embedded lens-shaped masses . This is so in the case of gold , silver , platinum , palladium , iridium , indium , copper , zinc , iron , nickel , cobalt , bismuth , sodium , kalium , mercury . Similar phenomena are to be observed on the surface of solidified drops of sulphur and selenium , or on the surface of carbon which has been distilled with the electric arc in a magnetic field , and deposited on the cathode . The more quickly a metal has solidified , the smaller are its foam cells . 11 . On account of the volume changes which occur when metals solidify , the shapes and mutual inclinations of the foam cells are somewhat deformed . 12 . Ewing and Eosenhain ( 1900 and 1901 ) , and Osmond and Cartaud ( 1901 ) have published fine photographs of the surfaces of metals solidified on glass . In the case of lead these photographs show metallic grains or hexagonal foam cells with angles of 120 ' , and , near the edge , of 90 ' . The foam walls are identical in shape and inclination with the 300 times larger foam walls which I saw forming in the median plane of a slowly thawing prism of ice . Parallel cylindrical tubes , already partially transformed into strings of spheres , can be followed through many neighbouring foam cells , just as in ice . The tubes and strings had therefore been formed before the walls of the hexagonal foam cells . Hexagonal foam cells similar to those in lead , together with rounded lens-shaped masses in the middle of the foam cells , are visible in the photographs of the solidified surfaces of tin and zinc . On the surface of a zinc drop can be recognised radially-arranged straight and twisted fibres , with 64 Prof. G. Quincke . Transition from the Liquid to [ June 6 , swellings , and foam cells inside , as in a sphero-crystal . Many of these fibres have already fallen into rows of spheres . In Ewing and Eosenhain 's photographs of cadmium castings on glass , one recognises a network of straight lines and arcs of circles ( mostly with mutual inclinations of 120 ' ) which bound metallic grains or foam cells 0*02 to 0*07 mm. in size , and have gas bubbles at the boundaries of the foam cells . The metallic grains easily suffered mutual displacement . The surfaces at which such displacement or slipping took place were thus the walls or bounding surfaces of the foam cells , precisely as in the case of the glacier-grains of ice . Molten tin formed smaller foam cells the more quickly it had been cooled . The metallic grains of cadmium and lead grew larger at temperatures below the melting points of the metals . In my opinion this enlargement occurred , as with the glacier-grains of ice below 0 ' , by the bursting of some of the foam walls , and the running together of the contents of the foam cells . Holborn and Henning ( 1902 ) experimented with thin strips of iridium , rhodium , platinum , palladium , gold and silver foil , which they heated nearly to melting point by means of an electric current . They obtained on both sides of such strips the same network of straight lines and arcs of circles inclined at 120 ' , but often also at other angles . In the network of lines there are also frequently to be recognised closed circles , 0*02 to 0*1 mm. in diameter , containing rows of very small lensshaped objects or bubbles . Thin strips of electro-iron were heated in vacuo by Sir W. Eoberts-Austen ( 1896 ) to a temperature of 1500 ' by means of an electric current , and carbonised with diamond , starting from one end . Osmond 's photograph of this strip shows linear and curved foam walls , 0*001 to 0*005 mm. thick , inclined at 120 ' , and enclosing dark foam cells 0*08 mm. across . 13 . The shapes of the bounding surfaces of molten metals , and the circular arcs in the network of lines on the surface of metals raised to red or white heat prove , in my opinion , that these bounding surfaces must be regarded , not as they have hitherto been , viz. , as crystalline faces , but as solidified oily foam walls , which , as in the glacier-grains of ice , enclose foam cells with contents differing from the walls . Just as the glacier-grains of ice run together and enlarge by the bursting of the foam walls , so also larger foam cells with fewer foam walls are formed in metals heated nearly to melting point . 14 . The electrically heated metal appears softer , because of the lack of the foam walls , whose surface and surface tension increase the rigidity of the metal , as I proved in 1868 . 1906 . ] the Solid State and the Foam-Structure of Matter . 65 15 . A network of lines or foam walls similar to that on the natural surface of solidified metals comes to light also on artificial surfaces of metal castings when these are polished , or suitably etched by acids or other liquids . The foam walls are attacked or dissolved either more easily or less easily than the contents of the foam cells . If the foam walls are not normal to the artificially produced surfaces , then , of course , the mutual inclinations of the lines on these surfaces are different from those of the foam walls . 16 . Sorby , A. Martens , Osmond and Werth , Osmond and Sir W. Roberts-Austen , Osmond and Cartaud , Th. Andrews , Ewing and Rosenhain , Beilby , Humfrey , E. Heyn , and C. Benedicks have given drawings of these networks of lines and etched figures for iron and steel , gold , platinum and lead . In general the etched figures of the artificial surface correspond to the network of furrows on the natural surface of the same metal . Figures of sections parallel and perpendicular to natural cleavage planes of the crystals of spiegeleisen , given by A. Martens , show parallel tubes , which lie parallel to the cleavage plane and fall into separate drops . Often there are visible two intersecting systems of parallel tubes ( which show bulgings , or are resolved into strings of drops ) , or " fir-trees " with branches normal to the main trunk . These branches show several bulgings and rounded heads , occasionally having in their interior spheres lying side by side , transverse walls and foam masses . At times the branches of the " fir-trees " also fall into separate spheres . There are also cracks 0'04 mm. wide , normal to which lie numerous parallel layers or fibres , as in ice . This structure has since been named perlite . Breakage surfaces , and ground and etched surfaces of Bessemer steel exhibit , in the figures given by Martens and by Osmond and Werth , straight and twisted fibres normal to the surface . Steel gives breakage surfaces showing folds , and wave-like and zig-zag markings . On the crystal faces of spiegeleisen there lie dendrites . Heyn has photographed etched surfaces of slowly cooled iron containing varying amounts of carbon . Iron with 0*05 per cent , of carbon shows fine circular foam walls of carbide of iron , FesC ( cementite ) , which enclose foam cells 004 to 0*1 mm. in diameter , filled with iron ( ferrite ) , and meet at angles of 120 ' , 90 ' and so on . In the partly invisible foam walls are suspended islets of perlite . In the case of iron containing more carbon , the carbide of iron separated periodically in parallel layers , or as parallel cylindrical tubes with bulgings and rounded heads , or as spherical foam walls enclosing " foam lenses " and foam cells , 0-001 to ( V003 mm. in diameter . The tubes , lenses and foam cells are filled with iron , and surrounded by iron . The greater the percentage of carbon , and the more quickly the molten iron is VOL. lxxviii.\#151 ; A. F I 66 Prof. G. Quincke . Transition from the Liquid to [ June 6 , cooled , the less is the distance of the layers from one another and the smaller are the foam cells , just as in the case of ice containing any salt . The shapes of the microscopic structures in solidified iron containing carbon are the same as in ice containing salt . The carbide of iron corresponds to the oily salt solution in freezing water . Other foreign substances in iron\#151 ; carbon in the form of graphite and temper-carbon , silicon , phosphorus , sulphur , air or other gases , and other metals such as manganese and nickel\#151 ; even if present only in small quantities are able ( like the traces of salts in ice ) considerably to modify the surface tension , melting point , and viscosity of the foam walls and of the contents of the foam cells , and the size and shape of the foam cells or glacier grains of the iron . In quickly cooled steel the etched surfaces figured by C. Benedicks show fissures on the circumference of spirally twisted conical tubes . 17 . Pure molten metals after solidification exhibit on artificial polished and etched surfaces a network of lines or foam cells ( similar to the glacier-grains of ice ) , which are bounded by thin foam walls . These thin foam walls themselves contain still smaller foam cells , as is proved by the visible lensshaped masses embedded in them , and the wave-like furrows on their surface , which are capable in reflected light of giving diffraction colours like mother-of-pearl . This foam structure of pure metals when solidified after fusion has been demonstrated in the case of:\#151 ; 18 . Molten metals solidify on cooling to a liquid jelly , and later to a solid jelly . The walls and contents of the foam cells of such a jelly still consist of viscous liquid , i.e. , the jelly itself is still liquid\#151 ; like ice\#151 ; at temperatures lower than the melting points of the respective metals . The welding of two pieces of metal corresponds to the running together of the cell walls and cell contents of two lumps of jelly , or the regelation of ice . 19 . All the other substances in nature behave like these metals . The soft , plastic condition , which all bodies assume for a larger or smaller interval of temperature on the transition from the solid to the liquid state , Bismuth Cadmium Cobalt Copper Iridium Lead Manganese Mercury Nickel Palladium Platinum Potassium Rhodium Sodium Tin Zinc Gold Iron Indium 1906 . ] the Solid State and the Foam-Structure of Matter . 67 proves the presence of jelly , i.e. , of oily , visible or invisible foam walls , over this interval of temperature . 20 . Presumably all liquids on cooling form , before they pass into soft jelly with continuous oily foam walls , a turbid solution containing visible and invisible spheres , bubbles and foam flakes of oily , half-solidified substance , suspended side by side . 21 . The heterogeneous oily liquid , which as solidification occurs becomes visible in all substances in nature in the form of thin foam walls of different surface tension , must also appear as a thin liquid skin on the surface of solidifying drops . This explains the variations in the measurements of the surface tension of molten metals and salts , and of liquids in general . 22 . The walls and contents of the foam cells consist of heterogeneous substance . That foreign matter in very small quantities\#151 ; 1 / 1000000 per cent , and even less\#151 ; does form oily layers and foam walls in pure liquids , is proved by my observations on ice and benzene . Traces of foreign matter ( gases , carbon , metals , etc. ) too small to be shown in any other way are present even in the purest liquids , and are sufficient to explain the observed foam structure of all solidified substances in nature . 23 . As however in every liquid , even the purest , the number of the foam cells increases and their size diminishes as the velocity of cooling and solidification increases , it is in my opinion necessary to assume that , even in perfectly pure liquids , oily heterogeneous liquid can separate out on cooling . Every liquid , before it solidifies , becomes for a longer or shorter time a turbid solution . A liquid does not possess constant and unchangeable properties at the same temperature and pressure . All liquids in nature form allotropic modifications , such as have long been known in the case of sulphur , phosphorus , iron , etc. Such an allotropic modification is formed in larger quantity , the more quickly the liquid is cooled , and exhibits surface tension at the common boundary with the original liquid .

rspa_1906_0058

0950-1207

On the osmotic pressures of some concentrated aqueous solutions.

68

68

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Earl of Berkeley|E. G. J. Hartley|W. C. D. Whetham, F. R. S.

abstract

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0058

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0058

10.1098/rspa.1906.0058

Biochemistry

Thermodynamics

Biochemistry

68 On the Osmotic Pressures of some Concentrated Aqueous Solutions . By the Earl of Berkeley and E. G. J. Hartley . ( Communicated by W. C. D. Whetham , F.R.S. Received May 28 , \#151 ; Read June 7 , 1906 . ) ( Abstract . ) This communication gives an account of measurements of osmotic pressures of aqueous solutions of cane sugar , dextrose , galactose , and mannite . The method adopted is that briefly outlined by us in Yol . 73 , ' Roy . Soc. Proc. ' A gradually increasing pressure is placed upon the solution ( which is separated from the solvent by a semi-permeable membrane ) until the solvent , which at first flows into the solution , reverses its direction and is squeezed out . The pressure , when there is no movement of the solvent , is considered to be the osmotic pressure . Owing to the difficulty of determining the exact point at which no movement takes place and for other reasons , the experiments are carried out so as to enable an observation to be made of the rate of movement of the solvent , both when the pressure on the solution is just below and when just above the turning point pressure . The osmotic pressure is deduced from these rates . The range of pressures covered by the experiments is from 12 to 135 atmospheres . A description is also given of the methods adopted for making the copper ferrocyanide membranes , and it is pointed out that with the best membranes , in most cases , a small quantity of solution comes through during the experiment . It is shown that even a small leak causes a considerable lowering of the observed pressure ; hence the final results accepted are those where the leak was least . Attention is drawn to the fact that the osmotic pressures of cane sugar solutions when measured directly and when calculated from their vapour pressures agree to within 3 per cent.

rspa_1906_0059

0950-1207

An apparent periodicity in the yield of wheat for eastern England, 1885 to 1905.

69

76

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

W. N. Shaw, Sc. D., F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0059

en

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0059

10.1098/rspa.1906.0059

Tables

Agriculture

Tables

]\gt ; An Apparent Periodicity in the Yield of Wheat for , 1885 to 1905 . By W. N. SHAW , Sc. D. , F.R.S. , Director of the Meteorological Office . ( Received May 7 , \mdash ; Read May 17 , 1906 . ) In a paper contributed to the Hann celebration volume of the Neteorologische Zeitschrifl , I endeavoured to account for a curious relation between the yields of wheat for sive years in the eastern district of England by referring the variation to periodic components . The relation referred to will be understood from an inspection of the table of yields on p. 75 , or the diagram which illustrates it . The yields for the years 1896 , 1897 , and so on , taken in order , apparently " " compensate\ldquo ; respectively those for 1895 , 1894 , and so on , taken in reversed chronological order . Each pair of years at equal intervals , one before and one after 1895\mdash ; 6 , gives a mean value approximating very closely to bushels per acre , the average yield for the 20 years 1885 to 1904 . This relation is further illustrated by the yield for 1905 , which was not ascertained when the paper referred to was written ( November , 1905 ) . The data have been issued since then by the Board of Agriculture , and the yield for 1905 comes out at bushels per acre , which " " compensates ' ' the yield for 1886 , bushels per acre , the mean being , surprisingly near to The work of the paper referred to was based upon the supposition that a reversal of the kind indicated points to the yield being represented by the combination of a number of simple harmonic components , each having a node , ascending or descending , at the epoch . At first I did not suppose that the components belonged to a harmonic series , and I tried to evaluate them by eliminating components of specified period , two years , four years , etc. , by numerical process . * The simplification produced by , the mean of consecutive years , and thus eliminating the simple periodic term of two years ' period was considerable , and , in my contribution to the " " Hann\ldquo ; volume , I dealt with the curve thus simplified . When I had selected periodic terms to give the best representation I could make of the curve of two-year means , one of the terms had a period of 11 years , and I could draw no practical distinction between the others and the harmonic components of a fundamental period of 11 years . In the result it was shown that the average yield for two consecutive years ' * I owe this method , which is very useful in dealing with complex periodic variations of unknown periodicities , to the suggestion of Professor G. Crystal , of Edinburgh . Dr. W. N. Shaw . Periodicity in the Yield of [ May 7 , yield of wheat in the eastern counties of England between 1885 and 1904 was represented with remarkable fidelity by the equation where is the number of years , counting backwards or forwards , from the point representing the mean for 1895\mdash ; 6 . The process of taking means of consecutive years not only eliminates the oscillation of two years ' period , but it alters the amplitude and phase of all other periodic oscillations . It is also to be noted that an apparent oscillation of two years ' period may correspond with a combination of the fifth and sixth terms of the harmonic series with a fundamental period of 11 years . These two terms have periods of 11/ 5 or years , and 11/ 6 or years respectively . I have now extended the calculation to get , from what I will call the ascertained components of the curve of two-year means , the corresponding components of the curve of original values . It is a matter of simple trigonometry to show that if are the amplitudes of the first four components in the original curvs , the amplitudes of the components of the same periods in the curve of means for two successive years , then The phase of each component is altered by half a year , and thus the components remain concurrent in a common node if they are so in the original . The equation to the first four components in the original curve is therefore To get the values for successive years we have now to put equal successively to 3 , . . , on the positive and negative sides of the node , which in the actual curve is betweeu 1895 and 1896 . These values were computed for each year and a curve of residuals plotted . It is an irregular curve , for the values are necessarily affected to some extent by accidental circumstances and the residual variations are not very large . In order to represent the residual curve I took two equal components , each having an amplitude of 1 bushel per acre for the fifth and 1906 . ] Wheat for Eastern England , 1885 to 1905 . sixth terms of the series , and an node at the epoch 1895\mdash ; 6 . The final representation of the annual sequence of the yield of wheat for Eastern is by a periodic variation of 11 years ' period with its five harmonic components , as follows:\mdash ; Period years . Amplitude bushels per acre . The indicates that the component has an ascending node at the epoch 1895\mdash ; 6 , the sign a descending node . The values computed from this combination of components are shown in the table ( p. 75 ) side by side with the actual values . The agreement may fairly be called surprising ; the differences are large for three years , 188 1888 , and 1903 , in those cases to and bushels respectively , but the error does not reach 2 bushels in axly other year , and in 11 out of the 21 years it is less than a bushel . When the amplitudes of the components were evaluated the yield was unknown , the computed value was bushels , the actual value turns out to be 32 bushels , thus showing a very striking agreement between calculation and actuality . The relation between the computed values and the actual values is shown best by the diagram ( fig. 1 ) . It appears therefrom that the direction of the actual variation is the same as that of the computed variation for every step of consecutive years , the amount of the variation is different to the extent indicated in what has been said above . FIG. I.\mdash ; YIELD 0F WHEAT , ENGLAND EAST , 1885\mdash ; 1905 . The line represents the combination of the harmonic components\mdash ; Period 11 years . Amplitude [ 31 ] bushels per acre . Each has a node ascending , descending ) at 1895\mdash ; 6 . The crosses denote the actual yields of the several years . Dr. W. N. Shaw . Periodicity the Yietd of [ May 7 , The curious reversal in the variation of yield with reference to the epoch is thus satisfactorily accounted for by regarding the variation as the result of a simple periodic oscillation of 11 years ' period with its five harmonic components of suitable amplitude . Objection may be raised to the method adopted to obtain the amplitudes of the components . It is partly by numerical calculation and partly by trial plotted residuals , and thus does not follow a strictly orthodox process . As a matter of fact , I was not prepared to find 11 years as the fundamental pe1iod , and the result has been extorted from me somewhat ainst my will by a long manipulation of the numbers having the reversal with reference to 1895\mdash ; 6 as the governing consideration . When I first took the matter up , although I considered the reversal to be obvious evidence of periodicity , I did not consider that I was entitled to assume any period as fundamental and I did not therefore regard the ordinary processes of harmonic analysis as applicable to this particular case . * But at the time when my evaluation of the six components was completed I had the advantage of the assistance of Mr. H. E. Wood , Chief Assistant in the Transvaal Service , who was working in the Meteorological Office for a period preparatory to his taking up his appointment in South Africa , and he was good enough to undertake the treatment of the figures for the yield of wheat on more orthodox methods . He analysed harmonically the 11 years ' period from 1891 to 1902 with the following results:\mdash ; Mean value bushels . Period years . Amplitude bushels . Node ( nearest year ) 1896 1895 1896 1896 1895-61895-6 ( ) ( ) ( ) ( ) means ascending , \mdash ; descending . It will be seen that except for the amplitudes of the fifth and sixth components the result is not very different from that which I obtained by less regular process from a study of the values for the whole twenty years . When the calculation derived from the analysis is extended to give * The advantage of supposing that the components do not belong to a harmonic series is that any group of non-harmonic components , if persistent , must ultinlately concur in a node , but the node and consequent reversal need not recur until after the lapse of what Professor Chrystal calls a " " configuration period which may be very long . 1906 . ] Wheat for Eastern , 1885 to 1905 . values for comparison with the whole series of 21 years , the errors are somewhat greater and the two-year oscillation is too conspicuous in the calculated values . The amplitude depends upon a number in the harmonic computation and is therefore not capable of very accurate evaluation . The calculated value for 1905 is bushels and is therefore a little further from actuality than the figure derived from my computation . Mr. Wood also calculated the periodogram for the observations according to the method indicated by Professor Schuster . The periods dealt with were of 2 , 3 , 4 . . . up to 14 years and thereafter 16 years and 18 years . The method is from the nature of the case not very effective with data of such limited extent . Moreover , as there is only one wheat value for a whole year the components of 11 years cannot be well represented . Still the periodogram shows a prominence for a variation of an 11 years ' period ; 11/ 2 is less marked , 11/ 3 is very prominent , 11/ 4 is just indicated . One point in connection with the affords , as I understand it , a strong confirmation of the views represented in this paper . The ordinate representing the amplitude for the period of two years is This result surprised me at first because the fluctuations from year to year are a most conspicuous feature of the line representing the actual values . My estimate of the amplitude of the fifth and sixth components which combine to give an oscillation of two years ' period is 1 bushel ; Mr. Wood 's value , calculated from the data for 1891 to 1902 , is 2 bushels . But the disappearance of the two-year oscillation from the periodogram deduced from 20 years ' values is easily explained if the fluctuation is really the result of the " " beat\ldquo ; of two connponents , one htly greater and the other slightly less than two years . If the two components are equal in amplitude , the fluctuation , which is the combination of the two , changes its phase to the opposite in five and a-half years , so that the fluctuation taken over 11 years should show no two-year oscillation at all ; similarly , on the average of 22 years there should be no two-year oscillation , and the combination of the figures for 20 years , to give the periodogram ordinate for the two-year oscillation , shows that this inference is borne out by the actual numbers . The periodogram , therefore , confirms the result that the two-year oscillation which is very conspicuous at some parts of the cycle is really a combination of two oscillations of nearly equal period which alters its phase within 20 years in such a way that on the average of the whole period there is no oscillation of two years ' period at all , in other words , the even years are on the average neither better nor worse than the odd years . Dr. W. N. Shaw . Periodicity in the Yield of [ May 7 , The singular agreement between the actual figures and those derived from the periodic values for 11 years with its harmonic components may be attribuved to chance by those who desire to adopt that explanation . It is certainly difficult to see how wheat can have much to do with variations which are periodic in a fraction of a year , even } the fraction be an improper one . But here again a curious point is disclosed . Those terms are most accentuated of which the periods come nearest to an exact number of years ; the amplitudes and periods are ( taking my own estimates ) :\mdash ; Amplitudes Periods The least conspicuous component is that of five and a-half years , which has its maximum alternately in summer and winter , or other opposite periods of the year . The fourth component is stronger than the third ; it is more nearly periodic in an exact number of years . The fifth and sixth components together when they are in concurrence give a result greater than that of the third , and the period of the combined effect is of two years . Thus there are subsidiary points which seem to discredit to a certain extent the doctrine of chance as an explanation of the fact from which the investigation started , namely , that the excesses and defects of the yield balance one another about the years 189.\mdash ; 6 . Nor can I myself regard it as a matter of chance that a law of sequence derived observations of a number of years continues to hold for extrapolations both in the past and in the future . I cannot see any other conclusion consonant with the facts but this\mdash ; that during the 21 years\mdash ; 1885 to 1905\mdash ; the yield of wheat in Eastern England has been very nearly identical with the sequence given by a periodic variation of 11 years and its five harmonic components . When one considers the vicissitudes to which the wheat crop is exposed , before the yield is estimated for the Board of Agriculture , it must be regarded as very remarkable not that there are exceptions to the law of sequence , but that there are so few of any importance . Whether the law of sequence will continue to be that indicated by the composition of the curve for 21 years is another matter . The fundamental period may not be exactly 11 years ; components may prove to be after all not exactly the harmonics of the 11-year fimdamenta ] . Presumably we must wait until additional data have . It does not follow that the law , if true for the particu ] are district I have chosen , the " " England East\ldquo ; of the Meteorological Office , is necessarily true for every 1906 . ] for England , 1885 to 1905 . county or every field . data for two years taken at random indicate that the counties are differently affected in different years:\mdash ; On that account I have not attempted to trace the relationship in the data compiled for different localities for longer periods . A variation of about 11 years ' period has been ested for various solar and terrestrial phenomena , but I know of no case in which the sequence of phenomena is so completely accounted for in magnitude and direction as in the case of the yield of wheat for Eastern England . If it is not a matter of chance , and that seems too improbable , it must be a matter of considerable importance . Table : Yield of Wheat for Eastern England . 76 in the Yield of for England . This study arose out of the consideration of the relation between the autumn rainfall and the yield of wheat of the subsequent year . The relation as concerning the yield of wheat for Great Britain was the subject of a preliminary note to the Royal Society in February , 1905 . The corresponding relation for the East of England is\mdash ; where is the yield in bushels per acre and the rainfall of the previous autumn . The figures from which this relation is computed are given in the table on the previous page , and a column of values derived from the formula is also given . It is clear that the rainfall is subject to no such rigorous law of sequence as the wheat crop . A relation between the autumn rainfall and the wheat crop is sufficiently manifest , but evidently the fall of rain is subject to disturbances of an irregular character which have little counterpart in the curve of wheat values .

rspa_1906_0060

0950-1207

The electrostatic deviation of \#x3B1;-rays from radio-tellurium.

77

79

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

W. B. Huff|Professor J. J. Thomson, F. R. S.

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en

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10.1098/rspa.1906.0060

Atomic Physics

Electricity

Atomic Physics

]\gt ; The Deviation of from Radio-Tellurium . By W. B. HUFF , Associate Professor of Physics , Bryn Mawr College , Pa. , U.S.A. ( Communicated by Professor J. J. Thomson , F.R.S. Received June 27 , \mdash ; Read June 28 , 1906 . ) A determination of the electrostatic deviation of the -rays from radiotellurium was suggested to the writer by Professor J. J. Thomson , as a continuation of the work on -rays done by Professor A. S. Mackenzie . * The general plan of the work was to let a beam of the rays pass between two charged plates , and then fall upon a glass plate coated with a thin layer of zinc sulphide on the side receiving the radiation . A photographic plate in contact with the other side of this fluorescent screen would be affected by the scintillations and thus mark the position of the beam . The arrangement of the apparatus used is shown by the fram . The radiation from the disc at , passing through the brass slit-tube , and between the charged plates , reaches the fluorescent screen D. A copper disc , coated with radio-tellurium by Sthamer , served as the source of the rays . The slits were mm. and 8 mm. apart . Over the outer slit was a sliding magnet ( not shown on the diagram ) , which made it possible to shield the screen from the rays when no field was on . Quartz rods supported the condenser plates , which were of thin steel , 4 cm . long and cm . wide . The ends of these plates were cm . and cm . from the slit-tube and fluorescent screen espectively . These parts of the apparatus were supported by a long split-ring , which fitted closely in a glass tube cm . in diameter . This tube was vertical , the lower end being waxed into a larger tube which contained phosphorous pentoxide , and connected with the mercury pump . The wires from the 'Phil . Mag vol. 10 , 1905 . 78 Prof W. B. Huff The Electrostatic Deriation of [ June 27 , Wimshurst machine were soldered to the steel condenser plates , and sealed into glass side tubes . The fluorescent screen was 2 cm . square and mm. thick . The coated area was 5 mm. square . This plate was waxed to a brass cap , the latter being waxed to the upper end of the large glass tube , which contained the condenser plates , slit-tube , etc. The vacuum was as good as could be got with a mercury pump . After the tube was exhausted , the scintillations could be seen with a lens , but they were too few to make eye-measurements possible . Even when using the most sensitive photographic plates , exposures of 40 or 50 hours gave lines which were extlemely hazy . Scintillations , and therefore photographs , can be obtained when the rays traverse considerably greater distances than those indicated in the figure ; but with narrow slits the time required is very long ; with wide slits , the lines are too broad to be of use . When the rays are allowed to fall directly upon the photographic plate , an impression , of about the same density as that got with a screen , is considerably wider . This effect , due to a screen , suggested using a very thin one over the photographic plate , the combination being sealed into the vacuum tube . A screen mm. thick was tried in this way . When no field was on a good plate was obtained , but with the field on the plate invanably fogged , even when the tube was allowed to stand for several days after being pumped out , and when the electrometer had given no evidence that had occurred . Plates showing the double deviation were obtained , but fog rendered them worthless . It was finally decided to fasten a metal frame to the outside of the brass cap over the upper end of the tube , and to fit photographic plates accurately into this . By choosing plates with smooth edges it thus became possible to measure the distance of a single line from the edge of the photograpluc plate parallel to it . By using wider slits denser lines were got , and this , it seemed probable , would more than compensate for the errors introduced by having to compare separate plates . this method , several plates have been obtained . Exposures of 60 hours each gave three fairly clear lines . Using these plates , the following measurements were taken for the double deviations . mm. mm. 1 . 1 . 1.35 1.40 mm. , or mm. for the deviation one way . 1906 . ] from Radio-Tellurium . The variations in the separate measurements indicate the difficulty in setting on lines which are , at best , extremely hazy . and using the relation we obtain Since we derive the values\mdash ; in electro-magnetic units . This result is considerably less than the corresponding quantity for radium . The chief source of possible error lies in the difficulty of making accurate settings on a broad hazy line . I desire to record my thanks to Professor J. J. Thomson for to me the privileges of the Cavendish Laboratory , and for advice and suggestions always generously given . * Maxwell , 'Electricity , ' S202 . . J. Thomson , ' Conduction of Electricity through Gases , ' S50 . Mackenzie ,

rspa_1906_0061

0950-1207

An investigation of the influence of electric fields on spectral lines: preliminary note.

80

81

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Professor G. F. Hull|Professor J. Larmor, Sec. R. S.

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10.1098/rspa.1906.0061

Atomic Physics

Fluid Dynamics

Atomic Physics

80 An Investigation of the Influence of Electric Fields on Spectral Lines :Preliminary Note . By Professor G. F. Hull , Dartmouth College , U.S.A. ( Communicated by Professor J. Larmor , Sec. R.S. Received and read June 28 , 1906 . ) In general the electrical fields used were those concomitant with the luminous electric discharge . An interferometer of the Michelson form and an echelon spectroscope of 18 plates were used to analyse the radiations . The results may be summarised as follows:\#151 ; ( 1 ) End-on discharge tubes of special design , in which the light-source was a uniform column of luminous mercury vapour viewed in the direction of discharge , showed no change of wave-length as great as 1 part in 4,000,000 when the direction of the discharge was reversed . The pressure in the tube was varied from a few millimetres to a vacuum so high that there was but little luminosity . ( 2 ) The passage of Rontgen rays through the tube did not alter the wavelength nor the width of the mercury lines , to an extent sufficient to affect the visibility of interference fringes formed with a difference of path of 400,000 waves . When the luminous column was viewed at right angles to the direction of the discharge no polarisation effects in the radiation from it , due to the passage of the Rontgen rays , could be detected by a sensitive Savart plate and Nicol prism . ( 3 ) When the discharge passed in air between electrodes formed of an amalgam of cadmium and mercury , no variation of the wave-lengths of the strong Cd , Hg , lines greater than 0002 tenth-metres was obtained , by changing the line of sight from a direction along the discharge to one at right angles to that direction . Approximately the same result held good when a small capacity was inserted in the circuit , but in this case the discrepancies in the readings were larger . This result shows that the luminous particles do not acquire a velocity in the direction of the discharge greater than 150 metres per second . Hence the curving of the image of the discharge produced by a rotating mirror , as in the Feddersen experiment , and as recently studied by Schuster and Hemsalech for individual spectral lines , appears to be due not so much to motion of luminous particles as to the propagation along those particles of a condition of luminosity . ( 4 ) Doppler effects in the canal rays , as announced by Stark during the course of the present investigations , were found for the strong hydrogen Influence of Electric Fields on Spectral Lines . 81 li .es . In some cases they appeared also in mercury lines . The velocities r. resented by the displacements of the lines were of the order of 4x 105 metres per second for the hydrogen particles and 2'5 x 104 metres per second for those of mercury . But it was found that , in general , the luminous mercury particles in the canal rays did not move , at any rate with a velocity greater than 100 metres per second . In these cases the canal rays appear to he due to non-luminous particles streaming through the mercury vapour and producing luminescence in the latter , probably by bombardment . ( 5 ) A glass tube was sealed on to a canal-ray tube , at right angles to the direction of the rays . This tube was covered by a piece of optical glass as free as possible from strain . A very sensitive combination of Savart plate and Nicol prism was used to detect , if possible , any polarisation that might exist in the light from the rays in hydrogen . After eliminating reflections from the walls of the tube no polarisation could be recognised . ( 6 ) The light produced by electrical discharge , in uniform tubes 3 or 4 cm . in diameter , was examined perpendicular to the direction of discharge , at various points between the electrodes and also behind the perforated cathode . It wTas found that the principal hydrogen lines were greatly broadened in those parts wThere the electric field is known to be of great intensity . For example , the luminous layer covering the cathode ( the dark space being 0'5 to 4 cm . ) gave hydrogen lines 04 Angstrom units in width , but the lines of the second hydrogen spectrum and certain air lines were not appreciably broadened . This broadening seems to be due mainly to motion of the particles rather than change of free periods , for it is found to the same extent behind the cathode in the canal rays . The broadening is so great that it is not possible with the instruments at the writer 's disposal to determine the shift of these lines except to fix a superior limit of OT A.U. to its possible magnitude . The amount is probably considerably less than this . On the other hand , the shift of the lines of the second spectrum of hydrogen is so small as to approach the limits of error , viz. , 0-005 A.U. The mercury lines show no shift but a slight broadening . The experiments thus show that any electrical analogue of the Zeeman effect is , under the above conditions , largely masked by a widening of the lines . The work was carried out at the Cavendish Laboratory , Cambridge , during the past winter ; and the writer 's thanks are due to Professor J. J. Thomson and to Professor Living for the facilities kindly accorded to him . vol. lxxviii.\#151 ; a. G

rspa_1906_0062

0950-1207

The affinity constants of amphoteric electrolytes. I.\#x2014;Methyl derivatives of para-aminobenzoic acid and of glycine.

82

102

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

John Johnston, B. Sc., A. I. C.|Professor James Walker, F. R. S.

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10.1098/rspa.1906.0062

Chemistry 2

Biochemistry

Chemistry

]\gt ; The Affinity Constants of Amphoteric ctrolytes . I.\mdash ; Methyl Derivatives of Para-aminobenzoic Acid and of Glycine . By JOHN JOHNSTON , B.Sc. , A.I.C. ( Carnegie Research Scholar ) . ( Communicated by Professor James Walker , F.R.S. Received May 21 , \mdash ; Road May 31 , 1906 . ) ( From the Chemical Laboratory , Lniversity College , Dundee . ) The following investigation was undertaken in order to determine the influence on the basic and acidic constants of successive introductions of a methyl group into an amino-acid , including the effect of changing the acid into corresponding methyl ester . Two series of compounds were investi- gated , namely , the methyl derivatives of -aminobenzoic acid and of glycine . Constants for aminobenzoic acid , glycine , and some of its methyl derivatives had already been determined by Wiukelblech . * Methods . Whenever practicable the basic constant was determined by means of the catalysis of methyl acetate , using the comparison method of Walker and Wood . The end point was determined in a separate experiment with decinormal hydrochloric acid ; and it was found that the same result was obtained whether or not the bottle containing the reaction mixture had been opened to admit of intermediate readings being taken . In every case 1 at a time was withdrawn and titrated with caustic soda , which had been prepared from sodium and conductivity water ; and unless otherwise stated , phenolphthalein was used as indicator . In the tables refers to the dilution of the solution after mixture , A is the total of the reaction , and is the constant for a monomolecular reaction . In cases where the catalysis method was inapplicable , recourse was had to the Lovenherz solubility method , which was carried out as follows : A flask a known weight of substance mixed with a known volume of standard hydrochloric acid was kept in the thermostat for at least a day , being shaken from time to time . The liquid was then filtered through a tared paper , and the paper and contents\mdash ; the amount left undissolved\mdash ; were dried until of constant . The solubility in water was determined by a similar method . ' Zeit . fur physikal . Chem vol. 36 , p. 546 , 1901 . 'Journ . Chem. Soc vol. 83 , p. 484 , 1903 . Compare Wood , ' Journ. Chem. Soc vol. 83 , p. 572 , 1903 . The Affinity of Amphoteric Electrolytes . In one case , owing to the impracticability of either of the above methods , the basic constant was determined by the distribution method of Farmer and Warth . * Known of substance were shaken up with known volunles of benzene and water , and of benzene and standard hydrochloric acid . The amount of free base present in the benzene layer was determined by experiment , allowance being made for the mutual solubility of benzene and water ; the amount of base in aqueous layer was obtained by difference . From the data obtained in this way , the basic constant , calculated . The acidic constant was determined by means of conductivity measurements or by the ] -hydrolysis method of Shields The conductivity measurements were effected in the usual way , but it was found that in most cases unplatinised electrodes gave better results than platinised electrodes , owing , apparently , to a certain amounG of absorption of the substance by the latter . The water used had a conductiviCy not greater than at . no correction was made for the conductiyiGy of the water . From the measurements the acidic constant was calculated by means of the equations established by Walker . The symbols used have the same as in those papers . The solution for the hydrolysis method of Shields was prepared as follows . To a measured volume of a standard solution of pure soda was added the equivalent quantity of the substance . Wheu this solution had reached the temperature of the thermostat , the equivalent amount of a solution of methyl acetate\mdash ; also at \mdash ; was added . After shaking , 5 . of the mixture was immediately withdrawn and titrated with hydrochloric acid , using nitrophenol as indicator . When tlJe reaction proceeded very rapidly , this initial titre was obtained by calculation . At suitable intervals , other portions of withdrawn and titrated ilarly . As equivalent concentrations of salt and methyl acetate were enlployed , the calculation is somewhat simpler than that given by Shields . If is the original concentration of methyl acetate and of the salt , the amount transformed in time the constant the equilibrium between the hydrolysed and unhydrolysed portions of the salt , and the saponificatiou constant for caustic soda , then ' Journ. Chem. Soc vol. 85 , p. 1713 , 1904 . ' Zeit . physikal . Chem vol. 12 , p. ] , 1893 . 'Roy . Soc. Proc vol. , p. 155 , vol. 74 , p. 2/ 1 , 1904 . S Cf . Shields , . cit. Mr. J. Johnston . [ May 21 , which on ration between the proper limits gives The value of is o'otained from the equation , in which is the dissociation constant of water , and is equal to at . The of the above formula is inadmissible when the degree of hydrolysis is reat . This is the case with the betaines investigated . These were compared directly with a similar solution of pure caustic soda ; and the rates 01 reaction in the two cases proved to be almost identical . The experiments throughout the investigation were carried out at a temperature of Methyl Ester of Acid , A solution of the acid in absolute methyl alcohol was saturated with hydrochloric acid gas , and boiled under a reflux condenser for five hours . On cooling , crystals of the ester hydrochloride separated , which , on recry-stallisation from methyl alcohol , yielded plates of a slightly yellowish colour . Chlorine found I , per cent. requires Cl , . . The amount halogen was in this and in all similar cases determined by Volhard 's method . On a solution of the hydrochloride with ammonia , the ester was precipitated , and was recrystallised from methyl alcohol as white plates melting at Comparison Solutions . Cl solution cent. cent. , . Hydrolysis in ; in II per cent. per cent. Now if is the hydrolysed proportion , the dilution , and the dissociation constant for water , * Compare Einhorn , ' Liebig 's Annalen , ' vol. 311 , p. 158 , 1900 . 1906 . ] The Affinity of Amphoteric Electrolytes . Hence 1 . II . ; Mean value for Determination of Basic Constant\mdash ; Catalysis Method . ramme hydrochloride in 15 . water , 1 MeAc , I. Titre . Mean II . Mean 1 ' Ethyl Ester of inzoic Acid , This substance was prepared by a method analogous to that adopted for the methyl ester . The hydrochloride , when recrystallised from methyl Mr. J. Johnston . [ May 21 , alcohol , separated in shining white plates , which melted at to with decomposition . Chlorine found per cent. COOC H requires Cl The ester was liberated by treatment of the hydrochloride with ammonia . It recrystallised from aqueous alcohol in the form of fine white needles at Determination of Basic Constant\mdash ; Catalysis Method . gramme hydrochloride in 20 . water , 1 MeAc , I. II . Comparison Solutions . Cl solution cent. cent. , \ldquo ; Hence , 236 ; II , 240 . Mean value of 1906 . ] The Affi , nity Constants of Amphoteric tectrolytes . Methylam whenzoic Acid , Twenty-five grammes of -aminobenzoic acid were dissolved in the equivalent quantity of an aqueous solution of caustic soda of about 8 per cent. . To the cooled solution , one equivalent of methyl sulphate was added , and the mixture was kept cool , and shaken from time to time . After one and a half hours the reaction was practically complete , the mixture become quite pasty . The solid was filtered off on the pump , dried and recrystallised from boiling water . The yield of crude substance was almost quantitative . When recrystallised , it consisted of small white needles , which on drying turned slightly yellow , at to 14 ; and this melting point remained unchanged after recrystallising twice from water , alcohol , or benzene . gramme substance gave gramme and gramme T. gave . moist , measured at and 764 mm. II . , , , , , , , , 15 , , 773 C. H. per cent. per cent. per cent. Found 1 , II , COOH)requires As the direct dete1mination of nitrogen in the case of the aminobenzoic acids tends to give low results , the percentage of rogen was redetermined by Kjeldahl 's method . ammonia equivalent to gramme per cent. The same product was also obtained by the action of methyl iodide on -aminobenzoic acid , but the yield was much smaller , and the isolation and purification of the acid were more troublesome . zoic acid has an reaction to ordinary indicators , and can be roughly titrated by means of changes colour when about 94 per cent. of the acid present has been neutralised . It is soluble in alcohol and benzene , though not very soluble in cold water , and is to a slight extent volatile in steam . The alkali salts are freely soluble in water ; and from their aqueous solutions the free acid can be recovered by the cautious addition of hydrochloric acid , excess of which must be avoided , since it redissolves the acid with formation of the hydrochloride . Mr. J. Johnston . [ May 1 , Determination of the Basic Constant\mdash ; A. Catalysis Method . I. gramme acid in HC1 and 22 . water , 2 Cl solution cent. cent. Therefore relative concentration of free HC1 0.487 salt 0.663 free base COOH whence II . gramme acid in HC1 and 20 . water , 2 MeAc , Cl solution cent. cent. , 1906 . ] The Affi of Amphoteric Electx.olytes . B. Lowenherz Solubility fethod . Amount dissolved by . water grammes . Whence concentration of base in nbility ) N. Amount dissolved.by 50 gramme . Whence total concentration of base COOH N. Therefore concentration of salt And concentration of free HC1 N. General mean of Determination of the Acidic Constant ctiyity Method . of the Sodium Salt.\mdash ; As the salt does not crystallise well , the solutions were made up by adding the calculated quantity of acid to a standard solution of soda , made from sodium -free water . , I II The figures under I and II were obtained from distinct solutions : from the above , which is about the normal value for nonhydrolysed sodium salts . The speeds of the and sodium ions are ively : so tlJat and For the method of obtaining the value of compare l of the Acid.\mdash ; Sample I was recrystallised from water , sample II from benzeue . The solution at each dilution was made up separately , as the use of pipettes is not advisable when dealing with solutions of such feeble Mr. J. Johnston . [ May 21 , It is evident that the Ostwald " " dissociation constant\ldquo ; has here no real application , since it rises by 50 per cent. in the comparatively small range of dilutions studied . Conductivities calculated from Walker 's equations . The divergence between the experimental and the calculated values of does not exceed the conductivity of the solvent water . Ester of -Methylarnunobenzoic Acid , was prepared by an method to that iven on p. 84 . In this case , however , the hydrochloride did Jlot separate out , and the ester was precipitated by means of sodium . It crystallised from roin in the form of small white plates , to per cent. gramme unmonia equivalent to ramme N requires N This substance is soluble in benzene , alcohol , and ether , it does not crystallise well from them , but it is almost insoluble in water . Determination of Basic Constant\mdash ; Distribution Method . 1906 . ] The Affinity of nphoteric Electrolytes . From I\mdash ; Concentration of free base in water N. Concentration of total base N. Whence concentration of salt is , and of acid N. Therefore 182 . Similarly , from II\mdash ; 164 . Mean value of p-Di , , laminobenzoic Acid , By the action of methyl sulphate upon the crude -methylaminobenzoic acid the process of methylation can be carried step further . The mode of procedure is identical with that described for the preparation of the monomethyl acid . By recrystallising the } ) roduct from 50 per cent. aqueous alcohol , -dimethylaminobenzoic acid separates out in fine white needles , which melt at 230 to , and are identical with the product tained by the action of on dimethylanilin The yield is practically quantitative . DimethylaminobeIlzoic acid , though soluble in alcohol , is not very soluble in ether or benzene , and is almost insoluble in water . Determination of Basic Constant\mdash ; Solubility Method . Solubility in Water . A. Solution superheated\mdash ; I , ramme per litre } B. , , not superheated\mdash ; I , , II , . I. Solubility in HCI gramme per N. II . , , , , , , N. From I\mdash ; And from II\mdash ; Mean value of * Michler , ' Berichte , ' vol. 9 , p. 401 , 1876 . Mr. J. Johnston . [ May 21 , Determination of the Acidic Constant.\mdash ; The only practicable way of this was by conductivity measurements , and this could only be done at one dilution . The Shields method was tried , but the insolubility of the acid prevented accurate titration , and rendered the method invalid . Conductivity of the Sodium Salt . The difference , , is again nearly nol'mal , showing that there is not much hydrolysis . as on p. 89 , and Conductivity of the Acid . I , II , and III were distinct solutions . Conductivity calculated from ) , , and from the above values fur lJster of obenzoic Acid , This ester was prepared in the same as the ester of the omethyl acid ; it recrystalli es from ethyl alcohol in white plates , melting at Determination of the Basic \mdash ; The distribution method was tried , but proved unsatisfactory , owing to the excessive magnitude of the distribution-ratio between benzene and water . The constant was determined by the solubility method . . Bischoff , ' Berichte , ' vol. 22 , p. 343 , 1889 . 1906 . ] The Affinity of Amphoteric Electrol . Solubility in water gralnme per litre N. I. , , , , , , II . , , , , , , N. From I\mdash ; And from II\mdash ; Mean value of Acid This substance was prepared by the action of methyl iodide on either -aminobenzoic acid or its derivativ The iodide was recrystallised from water , and decomposed by the action of moist silver hydroxide the cold . If the mixture is heated , a basic substance is obtained , which has not yet been ated . The benzbetaine was purified by recrystallisation from absolute alcohol , from which it separated in cubes , at Iodine found per cent. COOH reqnires I Determination of Basic Constant\mdash ; Catalysis Method . gramme iodide in . water , 1 MeAc , I. * Compare Michael and Wing , ' Amer . Chem. Journ. , vol. 7 , p. ) . Mr. J. ohnston . [ May 21 , solution cent. cent. , From I\mdash ; And from II\mdash ; Mean for Determination of the Acidic Constant\mdash ; Salt Hydrolysis . A.\mdash ; 25 NaOH , MeAc , B.\mdash ; As , but with gramme 50 . water . -benzbetaine added . It is here evident that reaction proceeded almost as quickly as reaction , a fact which shows that the sodium salt of ) etaine is almost entirely hydrolysed in solution . Now if 4 per cent. remained unhydrolysed , that would correspond to a value of less than 3 ; so it may with certainty be st , ated that the value of cannot be greater than The smallest value of deduced from conductivity measurements 1 between and ; it was , therefore , useless to attempt the further purification of the substance by crystallisation , on account of its great solubility and its small inherent conductivity . 1906 . ] Affinity Constants of Amphoteric Electrolytes . -Benzbetainc Iodide , This salt was by heating equivalent quantities of methyl iodide and the methyl ester of -dimethylaminobenzoic acid at 10 for five hours in a sealed tube . On cooling and opening ) tube , the mixture was extracted with water . After filtration , the aqueous solution was evaporated down , when iodide separated . Colourless crystals were by recrystallisation fro1n aqueous alcohol:\mdash ; Iodine found per cent. requires I A decinormal solution had an acid reaction to azolitmin , but did not affect methyl orange or congo red . The catalytic action of an aqueous solution of the iodide on nlethyl acetate was too slow to yield a definite value for the basic constant of the substance . Methyl Ester of cine , This was prepared in an analogous nner to the other methyl esters . On , crystals of the hydrochloride separated in the form of white ] ates . After recrystallisation from methyl alcohol , the hydrochloride melts at to 17 with decomposition . Chlorine found per cent. requires Cl Determination of Basic Constant\mdash ; Catalysis Method . I. gramme hydrochloride in 15 . water , 1 Mr. J. Johnston . [ May 21 , II . Cl solution cent. cent. , From I\mdash ; AIId from II\mdash ; Mean value for ? . In these experiments nitrophenol was found to be the best indicator , but was 1lot satisfactory . Jthlyl Est of cine , COOC H A specimen of the hydrochloride obtained from Kahlbaum was tallised from absolute alcohol . Chlorine found ) per cent. Cl A methyl acetate catalysis experiment with the.hydrochloride showed that the ethyl ester of glycine was a stronger ] ) than the meth.yl ester , but the action proceeded too slowly to admit of an calculation of the basic constant . COOH . This substance was prepared to the method given by Eschweiler . * Equivalent quantities of a 33-per-cent . aqueous solution of and of formaldehyde-cyanhydrin mixed . Afber for 24 hours the resulting nitrile was extracted with ether , and , after removal of the ether , was saponified with baryta . barium was removed by means of onic anhydride , and the solution was evaporated to dryness . The residue was dissolved in absolute alcohol , from which it afterwards separated in exceedingly hygroscopic crystals , which melted to ' Liel) 's Annalen , ' , p. 44 , 1894 . 1906 . ] The Affinity of Arnphoteric Electrolytes . gramme gave ammonia equivalent to gramme N per cent. N A sample of the hydrochloride was prepared by with hydrochloric acid . On recrystallising it from alcohol , it was obtained in the form of white hygroscopic crystals , at 19 with decomposition . gramme gave an1monia equivalent to gramme per cent. Chlorine found .COOH . HCI reqniresN , Cl Determination of Basic Constant\mdash ; Catalysis Method . I. gramme hydrochloride in 15 . water , 1 MeAc , Cl solution cent. cent. , Ir . gramme hydrochloride in 15 . water , 1 MeAc , Cl solution cent. cent. , VOL. LXXVIII.\mdash ; A. 98 Mr. J. Johnston . [ May 21 , In II the temperature of the thermostat increased slightly during the course of the reaction ; the comparison solution was going simultaneously , and wtffl similarly affected . Mean value of mination of the .\mdash ; The conductivity method was tried , but , owing to the very slight conducting power and to the difficulties ; recrystallisation , it gave too hjgh results ; the smallest value of obtained by this means was Shields ' Method . gramme dimethylglycine , 25 soda , 10 MeAc solution , Whence , and Betaine hydrochloride was obtained by the saponification of betaine ethyl ester hydrochloride , which was effected by boiling for four hours with dilute hydrochloric acid . After partial evaporation of the water , beautiful white crystals of betaine hydrochloride out , and were dried in a desiccator:\mdash ; Chlorine found per cent. requires 1906 . ] The Affi olytes . Determination of the Basic Constant\mdash ; Catalysis Method . I. , ramme hydrochloride in 10 . water , 1 c.c. MeAc , II . gramme hydrochloride in 15 . water , 1 MeAc , litre . Mean Cl solution cent. cent. , Whence and from II\mdash ; Mean value for Bredig*from the electrical conductivity calculated the value Determination of the Acidic Constant.\mdash ; In carrying this out , the hydrochloride was used along with two equivalents of , on account of the difficulty in pure betaine . This , however , answered the purpose equally well , for Shields states that the presence of a neutral salt exerts practically no influence on the velocity of the reaction:\mdash ; ' Zeit . physikal . Chem vol. 13 , p. 323 , 1894 . 100 Mr. J. Johnston . [ May 21 , A.\mdash ; 25 NaOH , gramme betaine hydrochloMeAc , . water . ride , 50 NaOH , MeAc , . water . As in the case of -benzbetaine , it is evident that cannot exceed , Betaine Ethyl Ester Chloride . This salt was prepared by adding an equivalent of methyl chloracetate to a solution of trimethylamine in absolute alcohol . After standing some time the alcohol was partially evaporated off , and on cooling , the substance separated out as white extremely hygroscopic crystals , which melted at to , with decomposition:\mdash ; gramme gave ammonia equivalent to gramme , per cent. Chlorine found requires , Cl , , , Cl The substance by its composition and melting-point was thus proved to be the ethyl ester chloride , the formation of which was due to the choice of ethyl alcohol as solvent . * Determination of Basic Constant\mdash ; Catalysis Method . I. gramme substance in 15 . water , 1 MeAc , * Compare Koeppen , ' Berichte , ' vol. 38 , p. 167 , 1905 . 1906 . ] The Affinity Constants of Amphoteric Electrolytes . 0.2945 gramme substance in 15 . water , 1 MeAc , Cl solution cent. cent. , From I\mdash ; And from II\mdash ; Mean value for This value can only be regarded as approximate , owing to the length of time over which the action extended . Summary of Results . * The values pel.taining to the substances marked with an asterisk are derived from Winkelblech 's measurements . cit and , except in the case of -aminobenzoic acid , are not strictly comparable with my results . 102 The Constants of Amphoteric Electrolytes . * The values pertaining to the substances marked with an asterisk are derlved from Winkelblech 's measurements ( loc. and , except in the case of -aminobenzoic acid , are not strictly comparable with my results . \mdash ;

rspa_1906_0063

0950-1207

The affinity constants of amphoteric electrolytes. II.\#x2014;Methyl derivatives of ortho- and meta-aminobenzoic acids.

103

139

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Alexander Charles Cumming, D. Sc.|Professor James Walker, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0063

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rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0063

10.1098/rspa.1906.0063

Chemistry 2

Biochemistry

Chemistry

]\gt ; The , of Electrolytes . II.\mdash ; Methyl of Ortho- and obenzoic Acids . By ALEXANDER CHARLES IING , D.Sc . ( 1851 Exhibition Scholar ) . ( Communicated by Professor James Walker , F.R.S. Received May \mdash ; Read , 1906 . ( From the Chemical Laboratory , University College , Dundec . ) The investigation by Winkelblech* of various amphoteric electrolytes , and the subsequent application to his experimental figures of the theory of electrolytic dissociation and the of mass action , showed that the aminobenzoic cids exhibit their amphoteric character in a marked mannel The following paper contains the esults of au vestigatio of methyl derivatives of ortho- and meta-aminobenzoic acids to ascertain the eHect of successive introductions of a methyl oroup on the of these substances both as acids and as bases . In to obtain all the possible methyl derivatiyes of -aminobenzoic and of anthranilic acid , it was necessary to new substances and to revise some preyious wolk . Since this pol.tion of the research is only incidentally connected with the more physical part , it has been kept sepal'ate , and placed belore the account of the physico-chemical measurements . COOMc loride of Nethyl Estcr of ? ? The method of prepal.ation was found by trial to good yields and was used throughout in the prepal'ation of the esters and their hydrochlorides of both the ortho and meta chloride was passed through a methyl alcoholic solution of the acid , was contained in a flask fitted with an inverted condenser . On cooling the solution , it was found that the ester hydrochloride usually separated in . In some instances crystals separated when the chloride had ssed for a few minutes , but this was due to the insolubility of the hydrochloride of the acid , and as the action these crystals dissolved again . When the hydrochloride of the ester proved to be soluble in alcohol , it necessary to concentrate the solution before Cl.ystals would separate . The 'Zeit . . physikal . Chem vol. 36 , p. 546 , Walker , ' Boy . Soc. Proc vol. 73 , p. 155 , and vol. 74 , Dr. . C. Cumming . [ May 21 , esters of the meta series formed much more slowly than those of the ortho series . A convenient method of finding roughly how far the action had gone at any was to take a small sample of the solution , boil off most of the hydrochloric acid , and then add some aqueous solution of sodium acetate , which caused the ester to separate as an oil . If the acid was insoluble , it also was precipitated . The hydrochloride of the methyl ester of -aminobenzoic acid was made in this manner , and the action was found to be complete at the end of five hours . The crystals ltelted at to , with decomposition , and the melting point remained the same after two crystallisations from alcohol . The amount of chloride in ths recrystallised salt was estimated with the following result:\mdash ; gramme of the salt contained gramme chlorine . Found Cl per cent. Calculated for The methyl ester of -aminobenzoic acid separated as a fragrant oil when sodium acetate solution was added to a solution the hydrochloride . COOH Monomethyl -Aminobcnzoic cid , Equivalent quantities of -aminobenzoic acid and methyl iodide were heated together in a sealed tube for about three hours at , when it was found that combination had occurred , the resulting compound being the hydriodide of monometh.yl -aminobenzoic acid . This was crystallised from alcohol to remove any of the original acid , appeared as a white crystalline substance , which melted with decomposition at , and was soluble in hot water and alcohol , but much less so in the cold solvents . It did not crystallise well from water , as it underwent slight decomposition . Estimation of the iodine present resulted as follows:\mdash ; gramme of the substance contained gramme iodine . Iodine found per cent. Calculated for The iodide dissolved readily in aqueous potash , and on addition of acetic acid , -anu1lobenzoic acid separated in sHlall crystals , which , after crystallisation from water , were free froUl colour and melted at ( The dimethyl acid melts at ) 1906 . ] The Affinity of Amphoteric Electrolytes . Estimation of the by Kjeldahl 's method gave the ving results:\mdash ; gramme contained gramme of per cent. , , , , , , , , Calculated for per cent. The substance was acid to litmus and to hthalein . gramme neutralised with phenolphthalein as indicator . of sodium hydroxide . The combining weight calculated from these is 149 , while that required for the formula is Monomethyl -aminobenzoic acid was found to be very soluble in alcohol , chloroform , and acetone when hot , but much less so in the cold . It was somewhat soluble in hot water and almost insoluble in cold water , ether , and ligroin ; soluble in dilute mineral acids , but not in acetic acid . The same substance was also prepared iu the following manner , though the yield in this case was very small , on account of the number of operations . When an aqueous tion of the sodium salt of -aminobenzoic acid was treated with an equimolecular amount of methyl sulphate , an orange-coloured acid substance was obtained which melted at about , and retained the same point and appearance after crystallisation from seyeral solyents . Analyses showed that this was a mixture of the mono-and di-methyl acids , and variations in the method of preparation failed to give a pure product , whilst numerous attempts at separation by crystallisation were also unsuccessful . The substitution of methyl iodide for methyl sulphate also yielded orange-coloured substance , which , as far as it was examined , appeared to be the same mixture . The mixture was separated into its components by methylation with boiling methyl alcohol and dry hydrochloric acid , when the hydrochlorides of the methyl esters of the respective acids were formed . hese were readily separated , as the hydrochloride of the nlethyl ester of methyl / -aminobenzoic acid is insoluble in cold alcohol , while that of the dimethyl acid is very soluble . The two hydrochlorides obtained in this way possessed the same perties as those of the mono- and -llethyl acid esters made by other methods , as described below . The monomethyl -aminobenzoic acid was readily from its ester hydrochloride by boiling with excess of aqueous caustic soda . The addition of acetic acid to the solution thus obtained precipitated the monolnethyl Dr. A. C. Cumming . [ May 21 , -aminobenzoic acid , which does not forlll an acetate stable in aqueous solution . The acid so prepared was quite from any pink colour . P. Griess*obtained a pink substance from -benzcreatine , and described it as monomethyl -alninobenzoic acid , but hc gave neither analysis n.or melting point . The result of the work detailed above indicates that Griess ' substance was probably a mixture , since the coloured substance which I obtained was proved to be a mixture , although both mono- and di-methyl -aminobenzoic acids are free from colour when pure . It was found that this pink colour could be produced by a solution made from a mixture of the pure , colourless monomethyl and dimethyl acids , . on one occasion , for some unknown , the resulting colour was boreen . It is probable that the colour is due to oxidation . From the failure to effect a separation of the mixture by crystallisation it was considered that the solubilities of ] cids in the various solvents tried must be very similar , and by erinlent with the pure substances it found that this was the case , the list of solubilities for the dimethyl acid being exactly the same as that given for onomethyl -aminobenzoic acids . rochloride of the m-Arninobe ? 7 zoic Acid , COOMe After treatment of a boiling aleohnl solution of monomethyl -aminobenzoic acid with dry hydrogen chloride for . hours , crystals separated on cooling . These were dried on the , and found to melt to . It must be mentioned that none of the melting points iven for these hydrochlorides are true points , but are more or less definite decomposition temperatures . Estimation of the chloride present resulted as follows:\mdash ; gran ) of the salt contained )rnmmc chlorine . Chlorine found ) cent. Calculated for This hydrochloride was also prepared , dil)cd , as a step in the preparation of monomethyl anthranilic acid . It be ] made from the ester by passing dry hydrochloric acid [ ethereal ] ution of vol. 8 , ] ) . 1906 . ] The Affinity Constants of photeric Electrolytes . the ester . However prepared , it is unstable , as it loses hydrochloric acid by simple exposure to the air . COOMe Ester of Monom obcnzoio Acid , This substance was prepared by washing its hydrochloride with water , whereby all the hydrochloric acid was removed and the ester obtained as a white solid . The methyl ester of monomethyl -aminobenzoic acid was found to possess a faint pleasant odour , and was obtained crystals by slow evaporation of its ethereal solution . It was very soluble in ether , htly soluble in alcohol , and extremely insoluble in water . It melted at , and thus differed in a manner from the esters of -amillobenzoic acid and of the dimethyl acid , since both of these oils . The preparation of this ester and its hydlochloride in nother way has been described under the preparation of monomethyl The -coloured mixture , obtained , as previously described ( p. 105 ) , by the actiou of methyl sulphate and caustic soda minobenzoic acid , was dissolved in just sufficient aqueous sodium hydroxide aill teatedo with methyl sulphate . The resulting crystalline precipitate was free from any pink colour , and proved to be dimethyl -aminobenzoic acid . The yield was 30 per cent. of the calculated quantity , but could probably be much increased , since no attempt was made to find the best conditions . The separation of the dimethyl acid from the mixture by of its methyl ester oride h as already been described under monomethyl -aminobenzoic acid . This method involyed too many operations to give other than a very small yield . P. Griess*prepared this acid from its methyl ester , which he obtained by melting -benzbetaine ; a quantity was prepared in this way to his directions . Another new method of dimethyl -aminobenzoic acid was discovered after sufficient for use had been obtained by the above three methods , but it appeared to be the easiest method of preparation . Some hydrochloride of ) -benzbetaine was cautiously lnclted , when hydrochloric acid was evolved , and a yellow oil , the methyl ester of dinethyl Bel.iohte , ' vol. 6 , p. 587 . Dr. A. C. Cumming . S [ May 21 , -aminobenzoic acid , remained behind . From the ester , the acid was readily prepared by boiling for a few minutes with potash solution , and then adding acetic acid , when the dimethyl acid separated in small crystals . As the hydriodide of -benzbetaine proved to be one of the easiest derivatives to prepare , the same action was then tried with it . Like the hydrochloride , it also yielded the ester of the dimethyl acid on heating . The samples obtained by the above methods were each found to agree with ' description . drochloride of Methyl Est of Dimjthyl Acid , COOMo Some -benzbetaine was placed in a tube in a metal bath and the tube exhausted . The temperature was kept at , until all the water from the deliquescent betaine was removed , and was then raised for 15 minutes to , at which temperature Griess showed* that benzbetai changes into the isomeric methyl ester of dimethyl -aminobenzoic acid . The ester was dissolved in ether , and dry hydrochloric acid was passed through the solution . The resulting crystalline precipitate , after several washings with ether , was dried on the . This hydrochloride was found to be a pure white crystalline salt , which melted at 17 to , and contained the amount of chlorine:\mdash ; gramme contained gramme of chlorine . Chlorine found per cent. Calculated for -Aminobenzoic acid was dissolved -per-cent . methyl alcohol and to the solution were added three equivalents of methyl iodide , together with one equivalent of potassium hydroxide . The solution was then allowed to stand for several days , with addition of more potash whenever it was found to have become acid , until three equivalents of potash had been used . Thus far the method used was similar to that employed to obtain p-benzbetaine , by Michael and but the subsequent treatment was different . Amer . Chem. Jouru vol. 7 , pp. 196 1906 . ] The Affinity Constants of Amphoteric Electrolytes . Michael and first evaporated the so.lution to dryness , and then went through several operations to remove the potassium iodide , after which the betaine was precipitated as the hydriodide by addition of hydriodic acid . The nlethod I adopted was to concentrate the solution sufficiently to remove most of the alcohol , and then add a little acetic acid to precipitate any mono-or di-methyl acid present . After filtration , hydrochloric acid was added , whereby all the -benzbetaine present was precipitated as hydriodide , since the solution contained plenty of potassium iodide . The -benzbetaine hvdriodide was found to be almost entirely free from chloride , methiodide and periodide , and was readily purified by crystallisation from water . It melted at , and estimation of the iodine present the following result:\mdash ; gramme of the iodide contained nlme of iodine . Iodine found . cent. Calculated for -Benzbetaine was prepared from the hydriodide by treatment with moist silver oxide or lead hydroxide , and was purified by several crystallisations from alcohol . It was very deliquescent , and at to wftS Lransformed into the methyl ester of dimethyl -aminobenzoic acid . * -Benzbetaine was successfully obtained by the use of the same process , so it may be of general applicability in the preparation of benzbetaines . COOH Eydrochloride -Benzbetaine , This was prepared by mixing the betaine with ochloric acid . The salt is almost insoluble in concentrated hydrochloric acid and only slightly soluble in water . It was found to be white and not deliquescent ; it melted at , and contained the of chlorine:\mdash ; gramme contained gramme of chlorine . Chlorine found per cent. Calculated for The hydrochloride was recrystallised from alcohol , and the again estimated :\mdash ; gramme contained gramme of chlorine . Chlorine found . . per cent. * Griess , . cit. Dr. A. C. Cumming . [ May 21 , The hydrochloride was then suspended in alcohol and dry hydrochloric acid led . The crystals were then off , dried on a the , not in a desiccator:\mdash ; granne contained } ralnlne of chlorine . found per cent. This sample was used at once in a catalysis experiment , as it contained the right proportion of chlorine . COOMe thiodide of the Esterof Dim Acid , This substance was readily obtained by the action of methyl iodide on the methyl ester of dimethyl -aminobenzoic acid , as described by inter and Kalm . * These authors drew attention in their paper to the ease with which betaines of this class yielded , by internal rearrangement , the isomeric methyl ester of the dimethyl acid , and showed this property to be well marked in the case of -benzbetaine . In this connection the following new mode of obtaining the quaternary iodide is of some interest , though it offers no as a method of preparation:\mdash ; Some dry -benzbetainc was kept in a closed tube with methyl iodide at to for 24 hours , when it was found that lnosb of the betaine had been used up with formation of the quaternary iodide . That this reaction is simply a combination of the betaine with methyl iodide does not seem probable . It is more probable that the change of -benzbetaine into the ester proceeds even at low temperatures , but reaches an equilibrium , unless the ester is removed as it is formed . In this case we know that methyl iodide combines quickly and readily with the methyl ester of m-aminobenzoic acid . The ester would thus be removed as it was produced , and the reaction would therefore proceed steadily to completion . The application of this hypothesis to the similar ortho compounds would require the reaction between -benzbetaine and methyl iodide to proceed much more slowly , as the interaction of the methyl ester of dimethyl anthranilic acid and methyl iodide is known to be very slow . By experiment it was found that only a small yield of the quaternary ortho iodide was obtained when a mixture of methyl iodide and -benzbetaine had been kept in a warm place for two weeks . 'Berichte , ' p. 411 , 1904 . 1906 . ] Affinity of nphoteric Ftes . of th . All the methyl deriyatives of this series have been described , and the samples used were prepared mainly by the lmethods of inter and ICah There is a uity in a of their which conveys the impression that the compound which they obtained by the action of methyl sulphate on anthranilic acid was the methyl ester of monomethyl-anthranilic acid instead of the acid itself . It may be mentioned that in an abstract of their it is stated that they obtained the methyl ester in this wRy and not the acid . To prevent the possibility of any mistake , the substance , prepared to their directions , was nalysed , with the result : \mdash ; gramme of the on combustion lnlne of watel and amme of carbon clioxide . Found , Calculated for monomethyl-anthranilic acid ) OOEt Ester of Acid , This was prepared from monomethyl-anthranilic acid by the action of boiling ethyl alcohol and hydrogen chloride for 10 . The solutionl was evaporated almost to dryness , and then excess of dilute caustic was added , whereby the ester separated as an oil , which was removed by extraction with ether . The ethereal solution was washed with dilute alkali , dilute acid , and then several times with water , after which the ether was evaporated . The ethyl ester of monomethyl-anthranilic acid was found to be a colourless oil with a pleasant odour of jasmine . It was solid below to , and , , closely resembled the methyl ester in both odour and melting point . It was somewhat soluble in alcohol , freely soluble in ether , and so extremely insoluble in water and acids that it was not found possible to determine its strength as a base . The hydrochloride was prepared as a white slalline salt by dry hydrogen chloride into a solution of the ester . It was soluble in alcohol , insoluble in ether , and mixing it with water caused instantaneous 'Berichte , ' p. 401 , 1904 . Chem. Soc. Journ 86 , I , p. 236 , 1904 . Dr. A. C. Cumming . [ May 21 , separation of the ester from the hydrochloric acid . Analysis of the amount of chlorine this result:\mdash ; gramme of the hydrochloride contained gramme of chlorine . Found chlorine Calculated for Methiodide of th JTethyl Ester of Dimethyl-anthrandic Acid , This compound prepared in the manner recommended by Willsta , tter and Kahn , *namely , by the interaction of methyl iodide and the methyI ester of dimethyl-anthranilic acid , and it was found that the yield became almost theoretical if the mixture was kept for lnany days at about The above authors state that this combination does not occur in ethereal solution , but this is not strictly correct , the action does take though with extreme slowness . Ether , however , is a poor solvent for the purpose , and it was found that if alcohol or acetone were employed , the rate of rea , ction approximated to that observed in the absence of any solvent . However , as a method of preparation it is best to use no solvent . of the Acid and Constants . Except where it is specifically stated that some other temperature was employed , the experiments detailed in the were performed in a thermostat , which was kept at to within one-tenth of a degree . Basic Constants.\mdash ; There are a number of methods available for the determination of the strength of weak bases , and of these the methyl acetate catalysis method was found to be the most enerally applicable . The comparison method , details of which may be found in the paper of Walker and Wood , was employed as being the most accurate and , as the figures below will show , these amphoteric electrolytes as good results as those obtainable with ordinary electrolytes . As a general rule the hydrochloride was used , but in a few cases the hydriodide was more readily prepared in a state of purity and was therefore substituted for the chloride . One naturally expecc the hydrolysis of a chloride and of an iodide to be equal , but as there was no experimental evidence as to the action of hydriodic acid and iodides on methyl acetate a few experiments were tried . . cit. 'Chem . Soc. Journ vol. 8.3 , p. 484 . 1906 . ] Tloe Affinity Constcmts of Electrolytes . Solutions were prepared , one of which was for oric acid and for potassium chloride , while the other was for hydriodic acid and for potassium iodide . The experiments were in duplicate , and the constant found for the chloride solution was as against for the iodide . Both acids were standardised in the same manner and against the same soda solution . To eliminate any error in determining the strength of the ncids , the following experiments were nexb performed:\mdash ; Solution A was made from 10 . of hydrochloric acid , . grammes of potassium chloride , and 10 c.c. of ater , and was , therefore , for acid and for total chloride . found Solution was made from 10 . of hydrochloric acid , grammes of potassium bromide , and 10 . of water , and was , therefore , for acid and for total bromide contents . found Solution was made from 10 . of hydrochloric acid , rammes of potassium iodide , and 10 . of water , and was , therefore , for acid and for total iodide contents . found Since an equal quantity of the same acid was used in all cases , the difference can only be due to the difference between chloride and iodide . It will be noticed that the bromide and chloride , and that the error arising from the use of an iodide is that too low a yalue is obtained for the hydrolysis , and consequently too high a value for . The cause is most probably oxidation of the hydriodic acid , since the solution , which at the start was almost colourless , always darkened the experiment . Other methods for determining the basic constant were also tried , but were mostly unsatisfactory on account of the readiness with which the substances oxidise in solution . Acid Constants.\mdash ; In some cases an attempt was made to determine the acid dissociation constant by direct measurement of the hydrion concentration by the interesting new method of Bredig and Fraenkel , have found that extremely small concentrations of hydrion can be measured by the rate at which the catalysis of diazo-acetic ester occurs . Details of the method as applied in this research will be found under anthranilic acid ( o-amino- benzoic acid ) . The acid dissociation constants for the stronger acids were obtained by ' Zeit . Elektrochem vol. 2 , p. 626 , 1905 . VOL. LXXVIII . 114 Dr. A. C. Cumming . [ May 21 , calculation from the conductivities by Walker 's method . As most of these substances possess a tendency to oxidise in solution , the conductivity was always determined in a cell with unplatinised electrodes , but as they are all feeble electrolytes , this did not diminish the accuracy of the readings . The water used for the conductivities was prepared as recommended by Walker and Cormack , none was used with a conducoivity greater than at The sodium hydroxide used in the preparation of the sodium salts was made by exposing metallic sodium to a wet atmosphere in a vessel protected from the atmosphere until it was completely hydrated , and the hydroxide was then dissolved in pure " " conductivity\ldquo ; water . Platinised electrodes were , of course , available for the sodium salts . Saponification of Methyl cetate ( Shields ' Method ) Where the C011ductivity of any substance proved too small to be of any use , the strength of the acid was found by the rate at which the sodium salt saponified a methyl-acetate solution . Several attempts were made to prepare the sodium salts in the solid state to insure that exactly equivalent proportions of acid and base were present . Addition of alcohol and ether precipitatea1 the sodium salt from a strong aqueous solution , but in such a gelatinous form that it was not capable of purification . Corlsequently , all the sodium salts mentioned in this paper were prepareci by solution of a weighed quantity of acid in a standard solution of pure sodium hydroxide . For a methyl-acetate saponification experiment so much of the acid , sodium hydroxide , and methyl-a jetate solutions were mixed as to make the solution the same strength for all constituents . The equation for the reaction is then , , where is the initial titre , and the amount in any time . The constant for sodium hydroxide in the same units at is about From we obtain by means of the relation Anthranil Acid , Basic Constant and Dilution Law.\mdash ; It has been assumed that the dilution law for simple holds true also for amphoteric electrolytes , but there Chem. Soc. Journ vol. 77 , p. 8 , 1900 . Shields , ' Phil. Mag vol. 35 , p. 365 , 1893 . Arrhenius , ' Zeit . physikal . Chem vol. 5 , p. 16 , 1890 . 1906 . ] The Affinit.of Amphoteric Electrolytes . has been no experimental justification by the catalysis method for this * assumption . The hydrolysis of the hydrochloride of anthranilic acid was therefore determined at several dilutions , by the comparative methyl acetate catalysis method of Walker and Wood . * If the dilution law is true , then the ratio should be the same , whatever the dilution at which the experiment is performed , since by this law the formula holds true for all dilutions : \mdash ; The results for anthranilic acid hydrochloride were as follows , the amount hydrolysed:\mdash ; It will be seen that the dilution law does not trictly true , but the error introduced by calculation from one dilution to another is only a minor one , if the two dilutions be reasonably near one another . Hydrion Concentration.\mdash ; One of the most striking facts in connection with amphoteric electrolytes is that the conductivity does not give a direct estimate of the hydrion concentration . Bredig and Fraenkel have recently deyised a simple 1nethod for the estimation of hydrion in small concentrations by the catalysis of diazo-acetic ester , the rate of the reaction , which is monomolecular , being followed by observing the amount of nitrogen evolved . The experiments with this method which are given in this paper were all performed in a thermostat at . The same volumes were used in all cases to render the experiments comparable , namely 20 c.c. of the solution hydrion , . of diazo-acetic ester , and 2 . of ethyl-alcohol . The diazo-acetic ester was also as a check . No reading was taken for the first few minutes after . cit. . cit. . A. C. Cumming . [ May 21 , Anthranilic Acid . As a standard of comparison , acetic benzoic acids were investigated under the same conditions . benzoic acid , which has a hydrion concentration of , gave a constant of in the same units . acetic acid with a hydrion cuncentration of gave a constant of lrion concentration of anthranilic acid , if the benzoic acid be taken as the standard of comparison , ) , while if the acetic acid be used as the standard it is Walker*has calculated the hydrion concen tration in anthranilic acid solutions from the experimental data of Winkelblech , ftnd according to his equations it should , in solution , be , whilst a simple acid of similar conductivity would have a ydrio concentration of . The result is thus in excellent accord with Walker 's tion . Ester of For the determination of the of the ester as a base the twice crystallised hydrochloride was used . This was from anthranilic acid , and melted at . Estimation of the chlorine resulted as follows:\mdash ; gramme contained ) of chlorine . Found chlorine Calculated for . cit. Erdmann and Erdmann , ' Berichte , ' vol. 32 , p. 1215 . 1906 . ] The Affinity of Amphoteric Electrolytes . Methyl Acjtate Catalysis . gramme of hydrochloride of methyl estcr of anthranilic acid in 20 . of water . otution . for total chloride , for free , hydrolysis in solution per cent. Ethyl Ester of Acid , The hydrochloride of this ester was prepared like the similar compou n and crystallised from alcohol . The melting point was , and analysis of the amount of chlorine gave the following result:\mdash ; gramme of the hydrochloride contained ramme of chlorine . Chlorine found per cent. Calculated for Methyt hydrochloride of this ester is so much hydrolysed in solution , and the ester itself so insoluble , that it was not found possible to work with a solution stronger than , and the satisfactory estimate obtained at this dilution shows the wide applicability of the method . ramme of the hydrochloride of the ethyl ester of anthranilic acid in 20 . water . Dr. A. C. Cumming . [ May 21 , Comparison Solution . for chloride , for free hydrochloric acid , hydrolysis in solution Monomethyl-anthranilic Acid , Two samples of this were prepared by different methods:\mdash ; ( A ) A quantitative yield was obtained by the use of methyl sulphate ( Willstatter and Kahn ) . Reference has already been made to this method and an analysis given of the sample , which was crystallised from alcohol and then three times from water before use in the following experiments . ( B ) Another sample , which was used only for a conductivity determination , was made by the action of methyl iodide and potash on anthranilic acid . Before use the sample was crystallised six times from water . Basic Constant.\mdash ; Monomethyl-anthranilic acid is so insoluble that it was found necessary in the methyl acetate talysis e to take more hydrochloric acid than corresponded to the amount of base , and to use supersaturated solutions , in order that the experiments not be unduly As this diminishes the accuracy of the method , two expel.iments were performed with different ratios of acid to base . Methyl Acetate atalysis . gramme of monomethyl-anthranilic acid in 50 . of hydrochloric acid . for base for Titre . O Mean C'ompurison Solution . for total chloride , for free hydrochloric acid , mean * Schultz and Flachslander , abstract in ' Chemisches Centralblatt , ' ( 2 ) , 448 , 1902 . 1906 . ] The Affinity of Amphoteric Electrolytes . II . A solution was made from gramlne monomethyl-anthranilic acid and 10 hydrochloric acid , diluted to 110 . with water . These irregular quantities were taken because they were the smallest amounts of acid and water in which the base would remain dissolved , when the solution was cooled from the high temperature used to obtain the solution . for base for acid parison Solution . for total chloride , for free hydrochloric acid , mean method of calculation used to find in an experiment such as the above is as follows:\mdash ; Base taken Free acid Total acid taken Salt present Free base present Mean of I and II Acid Constant.\mdash ; Monomethyl-anthranilic acid possesses marked acid properties , as was shown by the fact that it could be accurately titrated against soda with phenolphthalein as indicator . Its strength as an acid was found from the conductivity determinations , which were done on solutions prepared separately by dissolving quantities acid in llitre of water in a bottle of " " \ldquo ; Dr. A. C. Cumming . [ May 21 , The conductivity of the sodium salt of monomethyl-anthranilic acid was also determined . 68 . 80 was taken as the value at infinite dilution , and this gave for monomethyl-anthranilic acid , . Turning to the acid constant to be deduced from these figures , examination of the tables given in Walker 's paper show that where is small , and are practically identical at high dilutions , such as were employed here . The value of for monomethylanthranilic acid may be taken then as Ester of milic Acid , Basic Constant.\mdash ; The hydrochloride of -anthrsnilic acid was prepared from the acid by the combined action of alcohol and chloride . It was a salt which crystallised from alcohol in fine , colourless needles , was very soluble in water , in ether , and melted at The sample used was crystallised twice alcohol and analysed for chlorine . gramme contained ramme of chlorine . Chlorine found per cent. Calculated for Methyl Acetate Catalysis . gramme of the hydrochloride of methyl ester of monomethyl-anthranilic acid was dissolved in 20 . of water . Mean Comparison Solution . for chloride , for free hydrochloric acid mean 1906 . ] The Affinity Constants of Amphoteric Electrolytes . Dim ! Acid , Basic The method of preparation was that given by Willstutter and . The acid was purified by three crystallisations from ether , and formed transparent ] which melted at . Its as an acid was sufficient to prevent titration of acetic acid by phenolphthalein in its presence , but it not strong enough to be titrated itself by the use of that indicator , so that it was found necessary to -nitrophenol as indicator in the catalysis experiment . atalysis . of dimethyl-anthranilic acid in 20 . of hydrochloric acid . Titre . Titre . Titre . Mean Comparison Solution . for chloride , free hydrochloric acid , mean in ) cent. Acid \mdash ; Dimethyl-anthranilic acid crystallised so well from ethel that an attempt was made to determine its strength as an acid by the conductivity , but with each rec1ystallisation the conductivity steadily diminished , until it was too near that of pure water to value . last determination made with water of conductivity , in a cell with electrodes , gave the following result . That the acid dissociation constant was not negligibly small was shown 1oy the action on indicators , and also by the conductivity of the sodium salt , which exhibited evidence of but a small amolmt of hydrolysis . Dr. A. C. Cumming . [ May 21 , Conductivity of sodium salt of dimethyl-anthranilic acid . 67 . 80.8 This experiment showed , however , that , though there was hydrolysis , it was very slight . The diazo-acetic ester method for the estimation of hydrion was also tried with a solution of dimethyl-anthranilic acid , but no measurable amount of was evolved in two hours . This is a conclusive proof that the acid is extremely weak . Acetate Saponification.\mdash ; The methyl acetate saponification method of Shields did not adapt itself well to the case of dimethyl-anthranilic acid , since the only indicators with which one could estimate the acetic acid were more or less affected by the dimetbyl acid . As the best available , -nitrophenol was used , but it was not vely satisfactory . The solution was ma by dissolving gramme of dimethylanthranilic acid in 25 . of sodiunl hydroxide and addition of 25 of methyl acetate solution . Mean x The saponification constant for soda and methyl acetate is , so that Physical Properties and Ring will be seen that there is a very marked drop in the acid dissociation constant when we introduce the second methyl group in the anthranilic series . In the meta series , on the other hand , it was found that the mono- and di-methyl acids agreed closely in all their physical properties , such as bility , appearance , and the acid and basic constants . The summary of the physical properties of dimethyl-anthranilic 1906 . ] The Affinity Constants of Amphoteric Electrolytes . acid , in comparison with the allied substances , leaves little doubt that the diflerence is stereochemical , and that this acid is more closely related to the betaines , possessing a tendency to ring formation , which would naturally be most marked in the ortho series . In the first place , dimethyl-anthranilic acid resembles in external appearance -benzbetaine much more closely than it does anthrauilic or monomethyl-anthranilic acid , since it forms soft , transparent crystals , which are characteristic of both ortho-and meta- benzbetaine . It dissolves also very readily in water and alcohol and slightly in ether , thus agreeing with the betaines , but not with the other substances . The point of anthranilic acid is 14 ; the mono derivative melts at , whilst the dimethyl derivative melts at . In the meta series the mono-and di-methyl derivatives melt within of one another . The similarity to the etaine sests ring formation in the molecule , and this would at once explain the low acid dissociation constant , since extensive ring formation and pronounced acid properties are incompatible . fllethyl Ester of Di Acid , Basic Constant.\mdash ; This ester was prepared by the method of Willstatter and Kahn , purified by distillatio1 ] , and its strength as a base determined by a ethyl acetate catalysis with the hydrochloride . The hydrochloride was prepared by passing hy chloride through an ethereal solution of the ester , when the salt separated as a white crystalline solid , which was purified by several washings with ether . The hydrochloride of the methyl ester of dimethyl-anthranilic acid , which has not been previously described , melts with decomposition at to is very soluble in wat , er , soluble in alcohol , insoluble in ether , and is slightly deliquescent . Its identity was confirmed by analysis of the amount of chlorine . gramme of the hydrochloride contained gramme of the chlorine . Chlorine found per cent. Calculated for Jfethyl Acetate Catalysis . gramme of the hydrochloride of the methyl ester of dimethyl-anthranilic acid was dissolved in 20 . of water . Dr. A. C. Cumming . [ May 21 , for chloride , for free hydrochloric acid , mean It will be seen that is here only approximately a constant , as it showed a steady increase with time . It was found by repetition of the experiment that this was a real variation and not due to experimental error . In another set of experiments , in which the readings were taken at an earlier stage of the reaction , the value obtained for was somewhat higher , viz. , 4200 . The explanation is , doubtless , that the methyl ester of dimethyl-anthranilic acid undergoes hydrolysis ( sapouihcation ) itself during the course of the reaction , and the hydrolysis of any of this ester irvolves the liberation of an equivalent quantity of hydrochloric acid , since at such a reat dilution any hydrochloride of -anthranilic acid would be almost completely hydrolysed . The influence of such a secondary action would be very small if the ester hydrochloride were much hydrolysed , but when we are dealing with a comparatively strong base , such as we have here , the effect on the apparent is at its maximum . As an instance , we may consider an ester whose real is 7800 , and suppose that in the ester is itself hydrolysed 1 per cent. before the readings are taken ; the apparent will then be 3100 . for the methyl ester of dimethyl-anthranilic acid may , therefore , be taken as not below 4000 , and from a consideration of the rate at which the constant falls off with time , it is probable the real lies between 5000 and 6000 . Basic Constant . -benzbetaine , prepared by the method of Willstatter and Kahn , was repeatedly crystallised from alcohol , and in this manner obtained in large transparent crystals , which melted at . The basic dissociation 1906 . ] The Affinity Constants of Amphoteric Electrolytes . constant was found by a methyl acetate catalysis with a solution of the hydrochloride prepared from the pure betaine and an equivalent quantity of hydrochloric acid . Acetate Catalysis . gramme of -benzbetaine in 20 . of hydrochloric acid . Comparison olution . for clllorides , for free hydrochloric acid , . mean , hydrolysis of -benzbetainle hydrochloride in solution per cent. Acid bstant.-benzbetaine , which had been several times crystallised from alcohol , was found to possess an appreciable conductivity , but further careful crystallisation produced a steady , until the last conductivity obtained from a solution was only three times that of pure water . The method of SlJields was therefore used , and , as a preliminary showed the hydrolysis to be very , a solution of pure caustic soda was employed as a comparison:\mdash ; ( A ) gramme of -benzbetaine was dissolved in 20 . of sodium hydroxide and diluted to 100 . This was mixed with 100 . of of methyl acetate , so that the final dilution of all constituents was 128 . ( B ) sodiunl hydroxide solution was with 100 . of methyl acetaoe , and was here also 138 . Dr. A. C. Cumming . [ May 21 , It is evident that all the caustic soda is free , and the conclusion is , therefore , that -benzbetaine possesses no measurable acid properties . The Eydroxide of the JTethyl Ester of -Benzbetaine , Willstatter and Kahn have shown that if an aqueous solution of the uuethiodide of the methyl ester of dimethyl-anthranilic acid is acted on by Qilver oxide at zero , a strong base is obtained , which quickly disappears , and the solution is found to contain only the -benzbetaine . The base is undoubtedly the hydroxide of the methyl ester of -benzbetaine , and the methiodide the the same base . This iodide is quite stable in aqueous solution and it was , therefore , prepared and purified by two crystallisations from water . It melted at , and analysis for iodine gave the following result:\mdash ; gramme of the iodide contained gramme of iodine . Iodine found per cent. Calculated for Basic Strength of the Hydroxidc.\mdash ; An attempt was made to find the extent olysis of the iodide in solution by catalysis of methyl acetate , but it too small to detect in this manner . By the delicate method of Bredig and Fraenkel extremely minute concenlrations of hydrion can be readily recognised , but a solution of the iodide of the methyl ester of -benzbetaine , when mixed with diazo-acetic ester in the usual manner , caused no evolution of nitrogen at all . This proved con clusively that there was no appreciable hydrolysis . of the Hydroxide of the Ester of An ice-cold solution of the methiodide of -benzbetaine , was mixed with a measured volume of ice-cold water in which excess of freshly prepared and thoroughly washed silver oxide was suspended . After for two or three minutes , the solution was filtered off from the silver oxide and iodide . If the temperature was kept very near zero throughout , an almost quantitative yield of the tetramethyl derivative was obtained , provided that the solutions were very dilute . The hydroxide of the methyl ester of -benzbetaine is a substance of peculiar interest , since it is at the same time a strong base and an ester . The experiments with its iodide showed the base to be a very strong o1le , and it was found that even in very dilute solution it quickly decomposed . Since the end products were neutral , this reaction could be readily followed by 1906 . ] The Affinity Constants of Amphoteric Electrolytes . titration , and it was conclusively proved that the decomposition was due to the tion of the ester part of the molecule by the hydroxidion which the same substance in virtue of its p1operty as a base . Rate of Decomposition . . of tetramethyl iodide solution was shaken with 100 . of water excess of silver oxide , and immediately filtered . Precautions taken to keep the temperature as near as possible , and the solution after filtration was kept in a vessel sulrounded by finely crushed ice . The solution was found by the first titration to be 0.00995 N. should be a constant if the action were monomolecular , whilst if we take the action as bimolecular we should , et where A is the total change expressed in terms of a normal solution , and is the amount changed in any time The reaction is evidently bimolecular , as it should be if it were an action an ester and the hydroxidion prodnced by the electrolytic dissociation of the basic group . Rate of nposition in Presence of Sodium obtain a comparison between the strength of the base and that of sodium hydroxide , similar experiment was performed under identical conditions , except that the solution was made not only for the ester-base , but also for sodium hydroxide . Dr. A. C. Cumming . [ May 21 , : The constant is calculated as before from the equation\mdash ; From this ib appears that the rate at which the ester-base saponified itself is roughly half that at which the saponification occurred when an equivalent amount of sodium hydroxide was also present . Strictly the above equation should have been replaced by one taking account of the two reactions . , where A is the . concentration of the ester-base and also of the sodium hydroxide , and and the amounts hydrolysed by the ester-base and the sodium hydroxide respectively in any . The data are not sufficiently accurate to test this equation , but the evidence supports the assumption that and are approximately equal , i.e. , that the ester-base supplies as much hydroxidion as the sodium hydroxide . Rate of Decomposition in Presence of Tethyl Acetate.\mdash ; Perhaps the most convincing proof that the hydroxide of the methyl ester of -benzbstaine is really a strong base , and yields hydroxidion , was afforded by its action on methyl acetate . A solution of the ester-base- was prepared from the iodide with silver oxide , and sufficient methyl acetate solution added to make the mixed solution for both constituents . The solution was at once filtered , and titrated at intervals , being kept at zero as in the previous experiments . The equilibrium in the above solution is so complex that no attempt has made to calculate the constant for the reaction , but a comparison of these figures with those given for the auto-saponification of the ester-base at the same temperature and dilution show that the methyl acetate was rapidly saponified by the ester-base , which thus possesses basic properties comparable with those of sodium hydroxide . Conductivity of the droxide of the iMethyl Ester of -Benzbetainc.\mdash ; The conductivity of the tetramethyl derivative in comparison with that of 1906 . ] The Affinity Constants of Amphoteric Electrolytes . sodium hydroxide of some interest . The constant of the cell was determined at , and measurements were then made at about that temperature with sodium hydroxide and hydroxide of the methyl ester of -benzbetaine , under conditions as nearly identical as possible . The hydroxide of the methyl ester of -benzbetaine was prepared frolu its iodide interaction with washed silver hydroxide , and filtered at once into the measuring . From the amount of iodide used and the volume , the strength of the tion should have been N. From a titration made immediately after the filtration , it was found to be N. Conductivity of the Hydroxide of the Methyl Ester of -Benzbetaine . Conductivity of Sodium Hydroxide under the same Conditions . The.agreement is sufficiently close to show that the dissociation and ionic velocities must be of the same order of magnitude . It may be remarked that it would be possible to follow the self-saponification of the ester-base by means of the conductivity , since the ester-base is a strong electrolyte , while the products -benzbetaine and methyl alcohol are non-electrolytes . In the above experiment the conductivity fell about 1/ 6 in one hour . obenzoic Acid , Hydrion Concentration.\mdash ; The diazo-acetic ester method for the estimation of hydrion was tried at various dilutions . VOL. LXXVIII.\mdash ; A. 130 Dr. A. C. Cumming . [ May 21 , The constants for acetic and benzoic acids have already been given under anthranilic acid . If benzoic acid be taken as the standard , the hydrion concentration in -aminobenzoic acid is . With acetic acid as standard it is . Walker 's calculated value is , while that of a simple acid with a conductivity equal to that of -aminobenzoic acid would be Mean 1906 . ] The Affinity Constants of photeric Electrolytes . There are several causes which may contribute to the discrepancy between the calculated and the observed value , for instance , the influence of ionised salt on the diazo-acetic ester . According to Walker 's theory there must be ionised salt present , since -aminobenzoic acid possesses marked acid and basic properties . Further , we have no positive knowledge of the of unionised molecules , or of the addition of alcohol to an aqueous solution of an amphoteric electrolyte . There is , however , a method of comparison which is open to less uncertainty , namely , to ascertain the effect of dilution on the hydrion concentration . In this case the influence of disturbing factors should be regular throughout . It was by experiment that the hvdrion concentration of benzoic acid was double that of a tion , as shoul be the case with a simple acid , according to Ostwald 's dilution law . The divergence of an amphoteric electrolyte from the simple law is clearly shown in the following table , in which the hydrion concentration with has been called 100 , the figures for the other dilutions being calculated on this basis : Methyl Ester of -Aminobenzoic Acid , Basic Constant.\mdash ; The strength of this ester as a base was found by a methyl acetate catalysis with the hydrochloride , the preparation of which has already been described . Methyl cetate Catalysis . grammes of the hydrochloride of the methyl ester of -aminobenzoic acid were dissolved in 20 . of water . Comparison Solutions . for chloride , for free hydrochloric acid ; ( 2 ) for chloride , for free hydrochloric acid ; mean Monomethyl -Aminobenzoic Acid , Basic Constant . Whenever possible it is preferable to use a crystalline salt in making up a solution for hydrolysis purposes and , accordingly , methyl acetate catalysis was performed with the thrioe crystallised hydriodide of monomethyl -aminobenzoic acid , the preparation and analysis of which will be found in the first part of this paper . 1906 . ] The Affinity Constants of Amphoteric Electrolytes . Mjthyl Acetate gramme of the ydriodide of monomethyl -aminobenzoic acid in 20 . of water . Comparison Solution . for chloride , for free hydrochlorie acid , mean , hydrolysis in solution per cent. These results appeared to fix the basic strength of 1nonomethyl m-aminobenzoic acid with fair certainty , but when it was found that an iodide is . liable to give too high a result , the chloride was tried . It was not found possible to obtain the chloride in a pure crystalline state , so hydrochloric acid was added to weighed quantities of monomethyl -aminobenzoic acid . The first two experiments gave the hydrolysis in solution as 16 per cent. and per cent. respectively , which would mean that the was about 350 , as ainst 1850 from the experiment with the iodide . There seemed a possibility that the acid had oxidised in the chloride expel.iments , and an experiment was therefore performed in a flask from which the air was expelled after each titration with The result was as follows : \mdash ; Methyl Acetate boramme of monomethyl -aminobenzoic acid in 20 . of h.ydrochloric acid . Comparison Solution . for chloride , for free are , id , mean , hydrolysis in solution per cent. Dr. A. C. Cumming . [ May 21 , The difference between the values obtained from the chloride and iodide is still , and there seems no means of determining the exact value . As that from the chloride is probably too low , and the iodide value too has been taken as 1000 in the calculation of the acid constant from the conductivity . Conductivity and Acid monomethyl -alninobenzoic colourless . Conductivity of the Sodium Salt.\mdash ; free.from conductivity wmostacid wised , ound pbtain i , so that a Conductivi o which were known not to alter the conductivity . In view of the uncertainty as to the exact value of , the agreement between the experimental and calculated vahues of the molecular conduotivity may be regarded as satisfactory . Nethyl Ester of rn-A ? m nobenzoi Acid , Although both the ester and its hydr ( Jchloride were prepared , no value can be given for the basic constant of this ester on account of its extreme insolubility . On addition of water to the hydrochloride , the hydrochloric acid all dissolves , but none of the ester . The Lowenherz solubility method was tried , but a litre of hydrochloric issolved , ofChem Sster. . Farmer's* 1906 . ] The ffinity of Amphoteric Electrolytes . method was also tried , using benzelle as the non-aqueous solvent , but the whole of the ester dissolved in the benzene and none in the water . Dimeth ? y-Aminobenzoic Acid , Basic Constant\mdash ; The specimen used for the physical determinations was prepared from m-benzbetain crystallised once from alcohol and twice from water . The strength as a base was found by catalysis of methyl acetate . Methyt Acetate Catalysis . gramme of dimethyl .-aminobenzoic acid was dissolved in 10 . of lydrochloric acid , and 5 . of water . olution . for chloride , for free hydrochloric acid , A repetition of this determination with a sample of dimethyl acid prepared by the new method gave , the experiment performed in solution in the same manner as the above . Acid Constant.\mdash ; The preparation of this substance has already been described . The sample used was several times crystallised from water . The conductivity of the sodium salt at was , and the figures used for and were , therefore , , and respectively . The value of used in the calculations was 1580 , water used had a conductivity of Dr. A. C. Cumming . [ May 21 , The reason for the discrepancy in this case between the theoretical and experimental numbers is not apparent . It is probably connected with the high value of Methyl Ester of Dimethyl -Aminobenzoic Acid , Methyl Acetate Catalysis . gramme of the hydrochloride of the methyl ester of dimethyl -aminobenzoic acid was dissolved in 25 . of water . Comparison for for free hydrochloric acid , ; the constants were , 111 , 112 , 112 . Basic Constant.\mdash ; ? -Benzbetaine is deliquescent and hydrochloride was therefore prepared for the methyl acetate catalysis , which was performed also with the hydriodide . Acetate Catalysis . granlme of hydrochloride of -benzbetaine in 20 . of water . 1906 . ] The Affinity Constants of Electrotytes . Comparison Solution . for chlorides , for free hydrochloric acid , mean , hydrolysis of betaine hydrochloride in solution per cent. A similar experiment with ? -benzbetaine hydriodide showed it to be per cent. hydrolysed , or with a of 3060 . Probably the lower value is the more correct , as it has already been mentioned that iodides show less than the true amount of hydrolysis . Acid Constant . -Benzbetaine crystallised from alcohol , but on account of its great solubility and deliquescence it was not found possible to reduce the conductivity to a minimum , as it continued to fall with each recrystallisation . Saponification of methyl acetate , in the same manner as described under -benzbetaine , was performed with three solutions which were all for sodium hydroxide , but contained respectively no betaine , one equivalent of betaine , and two equivalents of the betaine . The results are iyen in this table : 20It is evident that -benzbetaine , like the similar ortho , is practically devoid of acid properties . The Hydroxidc of the Ester of Basic Strength.\mdash ; The iodide of this base was faintly acid to azolitmin , but neutral to other dicators . No hydrolysis could , however , be detected in solution with diazo-acetic ether , and base was evidently very strong . Addition of moist silver oxide to a cold solution of the iodide gave a strongly alkaline solution which became neutral in a few minutes . This hydroxide , like the corresponding ortho compounld , has a basic constant of the same order of magnitude as caustic soda . Dr. A. C. Cumming . [ May 21 , :1 Sulnmary of NHMeN . . . 1 . 0 . 3 . 1906 . ] The Affinity Constants of Amphoteric Electrolytes . 43 . ca . great

rspa_1906_0064

0950-1207

The affinity constants of amphoteric electrolytes. III.\#x2014;Methylated amino-acids.

140

149

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Professor James Walker, F. R. S.

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6.0.4

http://dx.doi.org/10.1098/rspa.1906.0064

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0064

10.1098/rspa.1906.0064

Biochemistry

Chemistry 2

Biochemistry

140 The Affinity Constants of Amphoteric Electrolytes . III.\#151 ; Methylated Amino-acids . By Professor James Walker , F.B.S. ( Received May 21 , \#151 ; Read May 31 , 1906 . ) ( From the Chemical Laboratory , University College , Dundee . ) The main object of the present communication is to discuss the results obtained by Johnston and Cumming* in their investigation of the affinity constants of methylated amino-acids . Before entering on the discussion of these amphoteric electrolytes , however , it is necessary to refer to certain general principles applicable to the affinity constants of simple electrolytes , in particular of simple bases . Amino-bases and their alkyl derivatives are supposed to exist in aqueous solution to a greater or less degree in the hydrated form , and it is this hydrated form winch we conceive to give rise to the characteristic ion OH ' of soluble bases . Thus the alkalinity of ammonia solution is attributed primarily to the ionisation of ammonium hydroxide , according to the equilibrium equations NII3+ H20 n NH4OH r NH4 ' + OH ' . Now , when we calculate the dissociation constant kb of such a base from measurements of conductivity , catalysis , or salt hydrolysis , the constant obtained is not the constant for the equilibrium between the non-ionised hydroxide and its ions , but one which is a function of this ionisation constant and of the hydration constant in addition.^ Thus a stoichiometrical comparison of the values of kh for such bases is not so simple as the corresponding comparison of ka for acids , since in general for acids no effective hydration is involved . The value of the constant kbthen , depends not only on the direct effect of a substituent on the ionisation equilibrium , but also on the effect of the same substituent on the hydration equilibrium . It is , of course , reasonable to expect that a substituent which increases the dissociation constant of an acid will , ccetparibus , diminish that of a base , and vice versed ; and this we see to be in general the case in the comparison of the acidic and basic constants given in the subjoined table :\#151 ; * See preceding papers , pp. 82 and 103 . t Compare Walker , 'Chem . Soc. Journ. , ' vol. 83 , p. 182 , 1903 . The Affinity Constants of Amph Electrolytes . 141 X = COOH X = NH3OH or NH2 + H20 H.X Jca X 10 ' . 21-4 kb x 10 ' . 2*3 HO . X 0-03 \#151 ; CH3.X 1-8 52 CH2Me . X 1-34 56 CHMe2.X 1-44 53 CMe3.X 0-98 32 C6H5.CH2.X 5-6 2-4 C6H5.X 6-0 0-00005 On the one hand we have the group of acetic acid and its methyl derivatives , on the other the group of methylainine and its O-methyl derivatives ; in each of these groups the constants vary but little . Compared with formic acid and phenylacetic acid , the constants of the first group are considerably smaller ; compared with the corresponding bases , ammonia and benzylamine , the constants of the second group are considerably greater . As no change in the hydration takes place in the acids considered , we may take it , from the general regularity displayed , that no change , or at least no great change , takes place in the hydration of the corresponding bases . Consider , now , carbonic acid , HO . COOH , the second member in the list of acids given above . Generally speaking , the substitution of hydroxyl for hydrogen in the case of fatty acids effects a marked increase in the value of the acid constant . The degree of hydration remaining the same , we should therefore expect that the acid constant of carbonic acid , HO . COOH , should be decidedly greater than that of formic acid , H.COOH , of which it is the hydroxyl derivative . We find , instead , that it has only 1/ 700 of the value of the constant for formic acid . The conclusion may therefore be drawn that in the aqueous solution of carbonic acid by far the greater portion of the dissolved substance exists as the anhydride C02 . Similar reasoning may be applied to the bases . From the fact that the acid constants of benzoic acid , CeHs . COOH , and of phenylacetic acid , CeH5.CH2.COOH , are nearly equal , we conclude that the carboxyl group may be attached directly to the benzene nucleus , or indirectly through the group CH2 without any decided change in the ionisation of the resulting acid taking place . It is , therefore , probable that little change in the ionisation proper will result from the direct or indirect nature of the attachment of the basic group NH2 ( or NH3OH ) to the benzene nucleus , i.e. , we might expect aniline , C6H5.]SrH2 , and benzylamine , CeH5.CH2.NH2 to have nearly equal basic constants , the former perhaps slightly lower 142 Prof. J. Walker . [ May 21 , Instead of this relation we find that the basic constant of aniline is only 1/ 50000 part of that of benzylamine . We consequently attribute the smallness of the basic constant of aniline , and other derivatives in which the basic group is attached directly to the benzene nucleus , to a great diminution in the degree of hydration as compared with that of the bases in which the basic group is not in direct union with the benzene nucleus . That the great diminution of the constant in the former case is not directly due to the influence of the phenyl group is sufficiently attested by the powerfully basic character of the compound C6H5.NMe3OH . Here the formation of an anhydride is impossible , and although the basic group is directly united to the benzene nucleus , the base is as powerful as those in which the union is indirect . Since the alkyl derivatives of aniline have values of fa of the same order as aniline itself , it seems not unsafe to deduce that all these substances as a group have approximately the same degree of hydration . The bases considered above are all primary . Bredig* has shown that secondary bases have greater constants than the corresponding primary bases , when the substituting groups are alkyls , but that , contrary to expectation , the tertiary bases are considerably weaker than the secondary bases , being roughly of the same order of strength as the primary bases to which they correspond . Here , again , we probably have , owing to stereochemical influence , diminution in the hydration of the tertiary bases . The nature of the variation may be illustrated from ammonia and its methyl derivatives:\#151 ; Tcb x 105 . Ammonia , NH3 ... ... ... ... ... 2'3 Methylamine , NH2Me ... ... ... . 50 Dimethylamine , NHMe2 ... ... . . 74 Trimethylamine , NMe3 ... ... . 7'4 In the quaternary bases the hydration is necessarily complete , and the basic constant is incomparably greater , tetramethylammonium hydroxide , NMe4OH , being as strong a base as caustic potash . When we consider the effect of a substituent in an amphoteric electrolyte , the question becomes still more complicated , because we have to deal with it from the point of view of acid as well as of base , and because there is , in addition to the possibility of dehydration of the basic group in the ordinary sense , the possibility of ring-formationf which affects both acidic and basic * ' Zeit . physikal . Chem. , ' vol. 13 , p. 299 , 1894 . t Compare Sakurai , 'Chem . Soc. Proe . , ' p. 90 , 1894 ; p. 38 , 1896 . 1906 . ] The Affinity Constants of Amphoteric Electrolytes . 143 TSTTT constants * Thus the amphoteric amino-acid , generally written R\lt ; qqqjj\gt ; may exist in the non-ionised state in the solution as R\lt ; qqqjj\gt ; / NH3 and K\lt ; \ , without our being able to distinguish directly between these COO various forms . The further complication of a " hermaphrodite ion " ( Zwitterion ) , ^^qqq-\gt ; nee(^ scarcely be considered , as in the present state of our knowledge concerning amphoteric electrolytes its assumption is unnecessary to explain the known phenomena . In discussing the constants of amphoteric electrolytes , therefore , we must bear in mind that ring-formation will diminish the value of both acidic and basic constants , and prepare to encounter this disturbing factor in . the comparison of constants of derivatives of the amino-acids . I have already stated , with numerous examples , f that the primary effect of replacing a hydrogen atom by a methyl group is in general to diminish the constant of an acid . This may be seen to be the case for the methyl derivatives of acetic acid tabulated on p. 141 . Conversely , the methylation of ammonia , up to the stage of dimethylamine at least , is accompanied by increase in the value of the basic constant . One might consequently imagine the direct effect of the introduction of a methyl group into the basic radical of an amino-acid would be to increase the value of the basic constant and perhaps slightly diminish the value of the acid constant . If , however , the introduction of the methyl group increased the extent of ring-formation or brought the acidic and basic radicals into closer approximation , then the secondary stereochemical effect would be a diminution of both acidic and basic constants.| Since the introduction of a methyl group into a primary amine is not associated with any great increase in the value of the basic constant , we should not expect the primary effect of a similar substitution in an amphoteric electrolyte to be any great variation either of ka or of The secondary effect of the stereochemical approximation of the active radicals might , however , be many times greater , since we know that in the case of dibasic acids the reinforcement of each carboxyl group by the other is in general much increased by the stereochemical influence of the introduction of methyl groups . S * R. Wegscheider , ' Sitzungsber . d. kaiserl . Akad . d. Wiss . in Wien , Matli.-naturw . Kl . , ' vol. 114 , Abt . ii , b. , 1905 . + 'Chem . So . Journ. , ' vol. 77 , p. 397 , 1900 . + Compare Winkelblech , ' Zeit . physikal . Chem. , ' vol. 36 , p. 588 , 1901 . S Compare Bone Sudborough , and Sprankling , ' Chem. Soc. Journ. , ' vol. 85 , p. 540 , 1904 . 144 . Prof. J. Walker . [ May 21 , Now in the three aminobenzoic acids we should expect the influence of each active radical on the other to be greatest in the case of the ortho-acid , and least in the case of the para-acid . The following table gives the constants for these substances and their methyl derivatives . Ortho . Para . ka X 105 . kbx 1012 . Tca X 105 . kb x 1012 . A minobenzoic acid 1 -4 1 -3 1 -2 2-5 Monomethyl derivative 0-46 0-9 0-92 1-7 Dimethyl derivative 0 00023 0-28 0-94 3 -2 The derivatives of the para-acid show a slight fall of the acid constant , and , from the first to the last member , a slight increase of the basic constant . Here the stereochemical effect ( including change of ring-formation ) seems to be almost absent , and the primary influence of the methyl groups is apparent . In the ortho series , on the other hand , we have a very distinct falling off of the acid constant in passing from the first to the second member , and an enormous diminution in passing from the second to the third . The fall of the basic constant is less well marked and more regular . The very small value of Jca for dimethylortho-aminobenzoic acid is probably to be attributed to ring-formation.* A similar diminution in the basic constant by ring-formation need not be looked for , since the basic radical involved in the ring-formation must already , when directly attached to the benzene nucleus , be almost wholly anhydrous ( compare p. 142 ) . The meta derivatives resemble those of the para series more closely than those of the ortho series:\#151 ; ka X 105 . kb x 1012 . Meta-aminobenzoic acid 1-6 13 Monomethyl derivative 0-8 12 Dimethyl derivative 0-8 19 The peculiarity which they exhibit is the comparatively great value of all the basic constants . In the case of glycine ( amino-acetic acid ) we should expect the acidic and basic radicals , owing to their proximity , greatly to affect and neutralise each other . This we find very pronouncedly in the acklic constants , which have only about 1/ 50000 of the value of the corresponding constants of the aminobenzoic acids . * Compare Cumming , loo . . , p. 122 . 1906 . ] The Affinity Constants of Amphoteric Electrolytes . X 105 . kb x 1012 . Amino-acetic acid ... ... ... ... ... 0000034 2'9 Monomethyl derivative ... ... ... . 0R00013 1-8 Dimethyl derivative ... ... ... 0'000014 1*1 From this table it will be seen that the values of the acid constant of the amino-acetic series are even smaller than that of ortho-dimethyl-amino-benzoic acid , pointing to even more extensive ring-formation . The primary effect of the introduction of a basic radical into acetic acid could scarcely produce this reduction of the acidic constant from 1*8 x 10-5 to 3-4 x 10-10 , for the introduction of an amino group into the ortho position of benzoic acid only reduces the acidic constant to about one-fourth of its former value , namely , from CeHs . COOH = 6'0 x 10-5 to NH2.C6H4.COOH = 1*4 x 10-5 . It need scarcely be pointed out that the comparatively slight diminution of the constant of benzoic acid by the introduction of an amino group indicates the presence of little or no ring-formation in the amino-benzoic acids . A consideration of the esters of amino-acids is , to some extent , helpful in dealing with the effect of hydration and ring-formation on the basic constants of these acids . If the carboxyl group of an amino-acid is esterised , no ringNH formation is possible , i.e. , ^\lt ; QQQ]\pe is n't convertible by solution in water into R\lt ; ^ \ NH2Me COO By comparison , then , of the basic constants of the aminoacid and of its ester , we may obtain some information as to the state of the acid in solution . The probable effect of the substitution of the group COOMe for the carboxyl group CO OH may be ascertained from the consideration of the same substitution in dibasic acids . I have shown elsewhere* that the substitution of COOEt or COOMe for one CO OH group in a dibasic acid reduces the acid constant of the latter to approximately half its original value , provided that there is no great stereochemical influence of the two carboxyl groups in the original acid . Wegscheider , f in a theoretical treatment of the subject , deduced the relation K = 2 h for a symmetrical dibasic acid , K being the observed acidic constant of the acid , and Jc the constant for each carboxyl group singly . If , therefore , the constant of the ester-acid is half that of the dibasic acid we conclude that the * ' Chem. Soc. Journ. , ' vol. 61 , p. 696 , 1892 . t ' Monatshefte fur Chem. , ' vol. 16 , p. 153 , 1895 ; ibid. , vol. 23 , p. 346 , 1902 . VOL. LXXVIII.\#151 ; A. L Prof. J. Walker . [ May 21 , influence of the COOMe group or the COOH group on the other carboxyl group is precisely the same . From another point of view the matter appears as follows . If the two carboxyl groups of a dibasic acid are sufficiently far apart to exert no stereochemical influence on each other , the double value of the constant of the dibasic acid is simply due to the double number of ionisable carboxyl groups in the solution , since the concentrations ( or dilutions ) used in calculating the dissociation constants are molecular and not equivalent concentrations ( or dilutions).* In short , if we calculate with equivalent dilutions , instead of molecular dilutions , the dissociation constant of a symmetrical dibasic acid will be the same as that of a monobasic acid of the same structure . The constant of suberic acid , COOH . CH2.CH2.CH2 CH2.CH2.CH2.COOH , is ka = 0-0000296 . That of butyric acid , CH3.CH2.CH2.COOH , is 0-0000149 . How , in the expression m2/ ( l\#151 ; m)v = 0-0000296 for suberic acid , let us substitute the equivalent dilution , v ' = 0-5 v , for the molecular dilution v , and we obtain m2/ ( l\#151 ; m)v/ = 0"0000148 , practically identical with the acidic constant of butyric acid . We may take it , then , that the carboxyl groups in suberic acid do not reinforce each other at all . The dissociation constant of succinic acid , COOH . CH2 ; CH2.COOH , is 0*000068 ; that of acetic acid , CH3.COOH , is 0-000018 , when molecular dilutions are reckoned . The constant of succinic acid , when reduced to equivalent .dilution , is 0-000034 . It is thus greater than that of the monobasic acetic acid , and we may legitimately infer , therefore , that the carboxyl groups in succinic acid reinforce each other considerably . Coming now to the ester-acids , we have for hydrogen ethyl suberate , COOEt . CH3.CH2.CH2.CH2.CH2.CH2.COOH , k = 0-0000146 . This is almost equal to the value for an equivalent solution of suberic acid , as we might expect , since we have seen that the carboxyl groups of suberic acid do not reinforce each other , except in as far as each neutralises the slight positive effect of the extended hydrocarbon radical . This latter neutralising effect is equally well produced by the COOEt group . * For purposes of comparison it would be better to refer throughout to equivalent instead of molecular concentrations , at least when the poly basic acids are symmetrical , or nearly so . Thus the Ostwald affinity constants of dibasic acids should be divided by 2 those of tribasic acids by 3 , etc. , for effective comparison with monobasic acids . 1906 . ] The Affinity Constants of Amphoteric Electrolytes . 147 In succinic acid we have just seen that the carboxyl groups reinforce each other . It is therefore to be expected that in the ester acid , COOEt . CH2.CH2.COOH , the group COOEt should exert an influence on the remaining COOH group . Comparing equivalent concentrations , we have the constants : Acid . Tc x 105 . H.CH2.COOH ... ... ... ... ... . 1-8 COOEt . CH2.CH2.COOH ... ... . . 3-0 |(.CH2.COOH)2 ... ... ... ... . 3-4 The influence of the group COOEt is here less than that of the COOH group , but only slightly less . In general , we may say that when the carboxyl groups do not very strongly reinforce each other , the COOEt , COOMe , or COOH groups have practically the same effect on a carboxyl group . When there is very strong reinforcement , as in the case of malonic or maleic acids , the effect of the ester group is much less than that of the carboxyl group.* Applying these results now to the consideration of amphoteric electrolytes , we should expect that when there is no great stereochemical influence of the acidic and basic radicals on each other , the esterisation of the acid should produce little or no change in the value of the basic constant , provided , of course , that there is no change in the extent of hydration . We have already deduced that the reciprocal influence of the acidic and basic radicals in the para-aminobenzoic series is slight . There should be little difference , therefore , in the basic constants of these acids and their methyl esters . Para Series . Acid . Ester . * Jcb x 1012 . kbx 1012 . Aminobenzoic acid 2-5 2*4 Monomethyl derivative ... 1*7 21 Dimethyl derivative 3-2 3-3 It is evident from these figures that the theoretical requirements are closely fulfilled , and that the extinction of the acidic radical has little effect on the basic portion of the molecule . Take , now , the ortho series , in which the stereochemical influence is greater . * Compare Wegscheider , ' Monatshefte , ' loc. cit. Prof. J. Walker . [ May 21 , Ortho Series . Acid . Ester . Tcbx 1012 . Tc0 x 1012 . Aminobenzoic acid 1-3 17 Monometliyl derivative ... 0-94 33 Dimethyl derivative 0-28 60 In the methyl derivatives the differences between acid and ester are great , but , since for anthranilic acid itself the difference is small , we should be inclined to refer the greater differences observed with its derivatives rather to increased hydration than to the direct effect of the substitution of COOMe for COOH . As far as can be judged from the data available , the meta series takes up . with regard to the ratio between acid and ester , a position intermediate between the ortho and para series . Meta Series . Acid . Ester . Tcb x 1012 . hbx 1012 . Aminobenzoic acid 133 43-6 Monomethyl derivative 121 \#151 ; Dimethyl derivative ... 19-4 72-6 The data for the glycine series are somewhat scanty , as it was not found possible to prepare the esters of sarcosine and dimethylglycine by the methods which proved successful for the preparation of the esters mentioned above . There is little doubt , however , that here the esterisation greatly increases the value of the basic constant . Thus for glycine itself we have Acid . Ester . Tcbx 1012 . Tcb x 1012 . Glycine 2-9 220 The theoretical deductions , then , with regard to the relation between the constants of amino-acids and their esters , are thus satisfactorily concordant with the experimental results . When we come to consider the betaines , we find that whilst the basic properties are still in some cases almost entirely disappeared :\#151 ; well marked , the acid properties have Betaines . ha X 1012 . hb X 1012 . Betaine ca . 001 0-87 Ortho-benzbetaine . . ca . O'Ol 0-28 Meta-benzbetaine . . ca . O'Ol 33-9 Para-benzbetaine . . ca . OOl 32-3 1906 . ] The Affinity Constants of Amphoteric Electrolytes . 149 Here , again , the stereochemical influence is evident in betaine and ortho-benzbetaine , which are much more weakly basic than meta-benzbetaine and para-benzbetaine . The hydrated form of a betaine is hi which the basic group is quaternary and , therefore , very powerful ; the acid group , on the other hand , is of the usual comparatively feeble type . Even then , though ring-formation has become so nearly complete as to bring about the practical disappearance of acid properties , the basic properties will still persist in a measurable degree , owing to the inherent strength of the free basic group . The powerfully basic character of the quaternary group is rendered evident by Dr. Gumming 's observations on the autosaponification of the ester o-CeH*\lt ; \lt ; ^0()an\lt ; ^ ^ie ac^on this ester on methyl acetate , * which it saponifies at a rate comparable to that attained by an equivalent solution of caustic soda . The chlorides and iodides of these betaine-esters were all found to possess a slightly acid reaction to azolitmin . This is at first sight surprising , since the substances themselves have no acid group , and since , with bases of such great strength , there can be no appreciable hydrolysis of their salts in aqueous solution . It must be borne in mind , however , that the substances , being esters , are liable to become hydrolysed ( saponified ) when dissolved in water , with production of minute quantities of the corresponding acid ( betaine salt).f Now , this is the salt of such a feeble base that at small concentrations it is practically all hydrolysed into the betaine and the strong mineral acid . The traces of mineral acid thus produced would sufficiently account for the feebly acid reaction of the solutions . Probably the methyl acetate catalysis observed with betaine ethyl ester chloride^ is attributable to the same cause , in part at least , the observed value of kb , viz. , 10"u , being probably much smaller than that of the real basic constant of betaine ethyl ester hydroxide . * Loc . cit. , p. 127 . t Cumming , p. 124 . X Johnston , p. 100 .

rspa_1906_0065

0950-1207

On the distribution of radium in the Earth's crust.

150

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Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

The Hon. R. J. Strutt, F. R. S.

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10.1098/rspa.1906.0065

Geography

Atomic Physics

Geography

150 On the Distribution of Radium the Earth 's Crust . By the Hon. R. J. Strutt , F.E.S. , Fellow of Trinity College , Cambridge . ( Received June 20 , \#151 ; Read June 21 , 1906 . ) Part II.\#151 ; Sedimentary Rocks . In a paper read before the Society on April 5 , I gave determinations of the quantity of radium in igneous rocks . Similar data for sedimentary deposits will now he given to complete my survey of the radium content of the earth 's crust . The limestones examined ( oolite , chalk , marble , etc. ) were simply dissolved in hydrochloric acid , and the emanation extracted from the solution . All other rocks ( including sandstones , clays , slates , gravel ) were first fused with sodium carbonate , in exactly the same way as the igneous rocks dealt with in the former paper . I believe that in some cases , clays for instance , this is unnecessary ; for determinations made on clay simply treated with hydrochloric acid gave the full quantity of emanation.* But to avoid any doubt , fusion was always resorted to . The results for sedimentary rocks are given in Table I. Table I. Rock . Oolite ... ... ... ... . Oolite ... ... ... ... . Marble ... ... ... ... . Kimmeridge clay ____ Oil-bearing sandstone Roofing slate ... ... Silicified gritty slate . Grault clay ... ... . . Clay ... ... ... ... ... . Red sandstone ... ... G-ravel ( fine siftings ) . Red chalk ... ... ... . Flint ( large nodules ) White marble _______ Marble ... ... ... ... . Chalk ... ... ... ... . . Chalkf ... ... ... ... . Locality . Radium per gramme , in grammes . Bath 5*84 x 10"12 St. Alban 's Head 4-05 x 10~12 East Lothian 3-87 x 10-12 Ely Gallicia Whales ( ? ) 3-77 x 10-12 3-04x10-12 2-57 x 10-12 St. Ives , Cornwall 2-50 x 10"12 Cambridge 2*13 x 10"12 Terling , Essex 1-73 x 10-12 East Lothian 1-68 x 10-12 Terling , Essex 1-42 x 10-12 Hunstanton 1-07 x 10~12 Terling , Essex 1-06 x 10"12 Deccan , India 0 54 x 10-12 East Lothian 0 52 x 10-12 Bottom of pit , Cherry Hinton , Cambridgeshire . . Top of same pit 0-78 x 10"12 0-25 x 10-12 * The emanation cannot be quantitatively extracted from clay by merely boiling it with water . + This determination was made on 500 grammes of material , in order to get a sufficient leak for measurement . On the Distribution of Radium in the Earth 's Crust . 151 On comparing these figures with those given in my former paper for igneous rocks , * it will be observed that the average radium content of sedimentary deposits does not differ appreciably from that of igneous rocks . This is what might be expected on the received view that sedimentary rocks derive their material from the disintegration of igneous ones . It appears then that the examination of sedimentary rocks for radium gives no reason for altering the estimate of the radium content of the earth 's crust formerly arrived at . I have examined a few other materials which cannot be properly described as rocks , but which are of interest in the present connection . The results are given below :\#151 ; Table II . Material . Deposit from hot springs , Bath ... ... ... . . Cambridge tap-waterf ... ... ... ... ... ... ... Sea-salt ( approximate determination only ) Boiler crust , Cambridge ... ... ... ... ... ... . Radium per gramme in grammes . . . 828 xlO"12 . . 0-78 xlO"12 . . 0T5 x 10~12 . . 0-078 xlO-12 It will be noticed that the deposit from the Bath spring is 100 times as rich as any rock . The materials transported by cold water , sea salt , and boiler crust are , on the other hand , much poorer in radium than any of the rocks . Part III.\#151 ; Rock-forming Minerals . Igneous rocks are aggregates of many distinct minerals . It was felt that the enquiry as to the distribution of radium in such rocks would be incomplete without some attempt to determine in which of these minerals that element chiefly resides . Most of the rock-forming minerals can be obtained in large well developed crystals . Such crystals occur for the most part in exceptional localities where crystallisation has been extremely slow , and where the structure of the rocks is on a large scale throughout . In these cases it is easy to obtain any desired quantity of the pure mineral for investigation . I have examined a number of such specimens of rock-forming minerals for radium . The results are given in Table III . In some cases the quantity of material taken for the experiment proved insufficient to give a satisfactory quantitative measure of the amount of radium in the mineral . This is * ' Roy . Soc. Proc. , ' vol. 77 , A , p. 479 , last column but one of the table . t This is the quantity of radium which corresponds to the emanation dissolved in 1 c.c. of the water . The radium is not itself present in the water . Hon. Tt . J. Strutt . [ June 20 , indicated by a note of interrogation . In other cases no radium at all was detected . In all probability some traces would have been found if more of the mineral had been taken , but the object was to determine whether the mineral made any important contribution to the total radium in the rock . Thus it was not thought worth while to push the examination of accessory minerals , such as ilmenite or rutile , which only occur in small proportions , very far . The quantities of material taken for these experiments are given , so that the quantitative significance of a negative result may be judged . Table III . Mineral . Zircon ... ... . . Zircon ... ... . . Zircon ... ... . . Zircon ... ... . . Perofskite ... . Spliene ... ... Apatite ... ... Apatite ... ... Hornblende Tourmaline Labradorite ... White felspar White mica Brown mica , Brown mica White quartz Butile ... ... . Ilmenite ... . Locality where found . Quantity taken , grammes . Ural Mountains ... ... . . North Carolina ... ... . Brevig ... ... ... ... ... Kimberley ... ... ... ... Magnet Cove , Arkansas p Sweden ... ... ... ... ... California ... ... ... ... ? Devonshire ... ... ... . . Labrador ... ... ... ... . Nellore , India ... ... . Nellore , India ... ... . Deccan ... ... ... ... ... ? Nellore , India ... ... . ? ? 0*690 1-17 4-7 7*5 11 -3 17 20 10 10 10 30 1 1 Badium per gramme , in grammes . 865 x 10"12 658 x 10"~12 139 x 10"12 74 *8 x 10-12 197 x 10"12 102 x 10"12 29 -7 x 10"12 11 -0 x KT12 4 *27 x 10-12 3 -32 x 10"12 1 -1 x 10~12 ? 0 *6 x 10"12 ? 1 *0 x 1CT12 ? 1 *0 x 10~12 ? Nil . Nil . Nil . Nil . It will be observed that certain of the accessory minerals , i.e. , zircon , sphene , pero.fskite and apatite , which occur in granite , are rich in radium . The hornblende , micas , tourmaline and felspars examined contain much less , while in quartz none could be detected . Although these experiments throw a certain amount of light on the subject , they are in some respects inconclusive . It is not safe to take these exceptional cases where large crystals occur , as typical ; for slow crystallisation is likely to result in more perfect separation of the constituent elements . Moreover , it is difficult to form any idea of the proportion in which the various minerals occur , especially when there has been no opportunity of examining them in situ . One cannot tell , for instance , whether enough zircon occurs to account for any large fraction of the radium contained in the whole rock . I have accordingly made some experiments by separating the constituents of an ordinary rock . For this purpose Cornish granite was 1906 . ] On the Distribution of Radium the Earth 's Crust . 153 selected , as being comparatively rich in radium , and coarse enough to allow of easy separation of the constituent minerals . Sixty-five grammes of Cornish granite was powdered just so far that each particle was seen to be composed of one mineral only , when examined with a magnifier . Bromo-form was used to separate the dense minerals from the light ones . The dense minerals , which sank , weighed only 7-5 grammes . The rest of the powder , consisting of quartz and felspar , floated on the liquid . The dense portion consisted mainly of brown mica , but may have contained some zircon enclosed between the flakes , the separation of which by mechanical methods would be impracticable . The dense portion was accordingly digested with hydrochloric acid until the flakes had lost all their colour , nothing but silica remaining . This treatment would leave the zircon behind , as it is not appreciably acted on by hydrochloric acid . The rock was thus divided into three portions . The quantity of radium in each of these portions was determined by the usual method . The result was that 1 gramme of Cornish granite contains :\#151 ; In the light portion ( quartz and felspar ) ... ... ... ... ... In the heavy portion , soluble in HC1 ( brown mica ) ... In the heavy portion , insoluble in HC1 ( zircon ? ) ... ... Total ... ... ... ... ... ... ... ... ... Radium . o'85 x 10~12 gramme . 4-27 x 10~12 T02 x 10-12 9T4 x 10~12 It appears therefore that more than half of the radium is contained in the heavy minerals , though these are only 1/ 8 of the whole mass of the rock . Although the separation by means of bromoform was not perfect , it was , I think , good enough to make it certain that a considerable portion of radium is really contained in the light constituents . As to the heavy minerals , it would not seem that there is enough zircon to account for much of the radium , which chiefly resides in the brown mica . It appears that radium , or rather its parent , uranium , is not perfectly separated from a rock magma by the crystallisation of the heavy constituents , though considerable concentration in these constituents occurs . '

rspa_1906_0066

0950-1207

On the ultra-violet spectrum of ytterbium.

154

156

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir William Crookes, D. Sc., F. R. S.

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rspa

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10.1098/rspa.1906.0066

Atomic Physics

Chemistry 2

Atomic Physics

I On the Ultra- Violet Spectrum of Ytterbium . By Sir William Crookes , D.Se . , F.R.S. ( Received June 21 , \#151 ; Read June 28 , 1906 . ) The rare earth , ytterbia , was discovered in 1878 by Marignac.* In 1880 Wilson , f in purifying Marignac 's ytterbia , found that it contained another earth which he named scandia . Cleve , and more recently his daughter Astrid Cleve , have worked much on ytterbia , and within the last few years M. Urbain has taken up the subject , and has succeeded in purifying ytterbia in larger quantities . During my own work on the fractionation of the rare earths I also have prepared and worked with ytterbia . Marignac , Wilson , Cleve , and Urbain have each presented me with some of their ytterbia . Wilson 's earth , sent in 1886 , appears very pure . Unfortunately , there was only sufficient to enable me to photograph the part of its spectrum between wave-lengths 2400 and 2580 . Ytterbia is one of the least basic oxides of the yttria group ; the order being yttria , erbia , thulia , ytterbia , and scandia ; yttria being the most basic and scandia the least . The atomic weight of ytterbium , taking the formula of the oxide , the only one known , as Yb203 , is , according to Wilson , 173'01 . Miss Astrid Cleve obtained the number 173Y1 . The salts of ytterbium are colourless and show no spectrum bands by transmitted light . My ytterbia was prepared from the mixed yttria earths by the old method of partial decomposition of the nitrates by heat . The chief difficulty is to free the ytterbia from the last traces of thulia . The fractionation of the nitrates must go on until a considerable thickness of the fused nitrate shows no trace of the thulium absorption bands at wave-lengths 4700 and 7000 . A trace of scandia may still be present , but this earth is very seldom met with . All my tests have failed to show its presence , and Miss Cleve , working with several kilogrammes of ytterbium earths derived from different minerals , also was unable to find scandium in them . In April , 1904 , M. Urbain gave me sufficient of his purest ytterbia to enable me to photograph its complete ultra-violet spectrum . His earth was prepared by the fractional crystallisation of the ethyl-sulphates of crude gadolinite earths.^ The subsequent separation is by the fusing nitrate method . This after 20 series of fusions gave in the least basic portions a mixture of * ' Comptes Rendus , ' vol. 87 , p. 578 . t ' Ber . , ' vol. 12 , p. 554 . + 'Comptes Rendus , ' vol. 132 , p. 136 . On the Ultra-Violet Spectrum of Ytterbium . ytterbia and thoria , which are easily separated by Wyrouboff and Verneuil 's method . This is the ytterbia of which I have photographed the spectrum . It still contains traces of thulia . M. Urbain 's more recent method of preparing ytterbia is by fractionally crystallising the nitrates from a slightly diluted nitric acid . In this way he tells me he has succeeded in getting ytterbia free from thulia . The examination for absorption bands in a strong solution is a fairly good test for an earth , such as erbia and thulia , giving absorption spectra , but it is not so delicate as an examination of the spark spectrum photographed through a quartz train , for dominant lines , which most elements show in some part of their spectrum . For instance , the dominant lines of yttrium are at wave-lengths 36009 , 3710-4 , 3774-5 , 4177*7 , and 4375-1 . The dominant lines of erbium are at 3499-3 , 3692-8 , and 3906"5 . They are , however , not strong , and fortunately the absorption bands of this element are striking and characteristic . The spark spectrum of thulium has only been slightly examined by me , and 1 do not think it has any strong lines . Its absorption spectrum , as with erbium , is a very characteristic one . The spark spectrum of ytterbium has strong dominant lines at 3289-5 and 3694-4 . Scandium has dominant lines at 3572'7 , 3614-0 , 3630"9 , 3642-9 , and 4247*0 . The spark spectrum of ytterbium was first examined by Thalen , but only in the visible portion . Exner and Haschek have published a set of measurements of the spark spectrum of ytterbium from wave-lengths 2116\#151 ; 4726.* I have found them to be very accurate , and in my photographs I have generally adopted their figures . Occasionally lines are in their list which appear to belong to other elements , and in some cases lines given by them cannot be distinguished in my spectrum . My photographs were taken with the quartz apparatus already described , the spectrum of pure iron being used as a standard . The ytterbium spark was taken from a strong solution of the nitrate betwepn platinum poles , sufficient self-induction being introduced to eliminate nearly all the air lines . The ytterbium , by this very severe spectrum test , is seen to be not absolutely free from impurities\#151 ; thulium , f copper and calcium , being present . Thulium * ' Wellenlangen-Tabellen fur Spektralanalytische Untersuch ungen , ' F. Deuticke , Leipzig und Wien , 1902 . t M. Urbain writes , under date May 5 , 1906 :\#151 ; " The ytterbium , of which you have taken the spectrum , was prepared some years ago . It is impossible to affirm that it does not contain thulium , and the experience I have acquired since these already ancient researches leads me to think it does contain traces . Thulium is very difficult to separate completely from ytterbium , and I have only recently succeeded in doing so . Do not fail to mention that this preparation was obtained by fusion of the nitrates of the rose-coloured yttric earths obtained in the tails of the crystallisation of the ethyl-sulphates . " 156 On the Ultra-Violet Spectrum of Ytterbium . is seen by its lines at 30207 , 3131*4 . 3425*2 , 3441*6 , 3462*4 , and 3848*2 . Copper is seen by its dominant lines at 3247*7 and 3274*1 , and calcium by its dominant lines at 3933*8 and 3968*6 . The platinum lines which are present are easily recognised , and are useful as an additional measure of identification . Besides these , a number of fainter and indistinct lines are seen . These may be due to ytterbium or to traces of hitherto unrecognised impurities . The wave-lengths of all the recognisable lines of ytterbium are given on the photograph , and also those of thulium , calcium , and copper , but the platinum lines are not marked .

rspa_1906_0067

0950-1207

A method for determining velocities of saponification.

157

160

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Professor James Walker, F. R. S.

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6.0.4

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10.1098/rspa.1906.0067

Biochemistry

Tables

Biochemistry

157 A MetJiod for Determining Velocities of Saponification . By Professor James Walker , F.R.S. ( Received July 10 , 1906 . ) ( From the Chemical Laboratory , University College , Dundee . ) A possible method of following the progress of a reaction in which electrolytes are involved is to measure the electrical conductivity of the solution at stated intervals . This method was employed by Walker and Kay* in their investigation of the conversion of ammonium cyanate into urea , and is capable of a more extended application . The chief conditions for the convenient application of the method are : first , that there should be a considerable difference in conductivity between the initial and final systems , and second , that the change in conductivity should be proportional to the progress of the reaction . It occurred to me that these conditions would be well fulfilled in the saponification of an ester by a caustic alkali . The conductivity of the alkali , say sodium hydroxide , is much greater than that of the sodium salt produced by the saponification , owing to the high velocity of hydroxidion as compared with the salt anion . Since , too , sodium hydroxide and sodium salts of monobasic acids are approximately equally ionised under the same conditions , the ionisation in dilute solution remains practically the same throughout the saponification , and thus the alteration in the conductivity is almost exactly proportional to the progress of the reaction . The following experiment on the rate of saponification of methyl acetate by caustic soda may be quoted as an example of the method carried out under ordinary laboratory conditions with the apparatus generally used for conductivity measurements in solution . The conductivity cell used was of the narrow Arrhenius type , and was immersed in a thermostat at 25 ' . In this cell were placed 4 c.c. of N/ 20 caustic soda , and 15 c.c. of water . To prevent access of carbon dioxide , the hole in the ebonite cover was plugged with a small rubber stopper . When the temperature of the thermostat had been reached , the solution was stirred by raising and lowering the electrodes , and the conductivity was read off . To the solution was then added 1 c.c. of N/ 5 solution of methyl acetate , the time being simultaneously noted , and the contents of the cell were well stirred by up-and-down motion of the electrodes . A reading of the conductivity was * ' Journ. Chem. Soc. , ' vol. 71 , p. 489 , 1897 . Prof. J. Walker . A Method for [ July 10 , at once taken after mixing , but this acted merely as a check , and was not used in the calculation . After a short interval readings were made of the conductivity of the solution ( which was now N/ lOO , both with regard to sodium hydroxide and to methyl acetate ) , at first every minute , and then every few minutes , when the reaction had become slower . The following table contains the results of the observations . In it a represents the bridge reading , and x the difference between the initial value of aj(\ \#151 ; a ) , which is proportional to the conductivity , and the value after t minutes . t. a/ ( l \#151 ; a ) . X. 1 X t 1 \#151 ; x 0 ( 1-564 ) 0 3 1 -304 0-260 0-117 4 1 -247 0-317 0-116 5 1 -198 0 -366 0-115 6 1 -153 0-411 0-116 7 1 -114 0-450 0-117 8 1 -083 0-481 0-116 10 1 -026 0-536 0-115 12 0-980 0-584 0-117 15 0 -927 0 -637 0-117 18 0-883 0 -681 0-118 21 0-852 0-712 0-118 25 0-818 0 -746 0-118 QO ( 0 -564 ) ( 1 -ooo ) Mean 0 *118 It will be noticed that the constant for the hi molecular reaction is here very satisfactory and in general it may be said that the maximum divergence from the mean value does not exceed 1 to 2 per cent. It is , however , advisable to neglect the first and last fourths of the reaction , since in them initial disturbances and the effect of a slight departure from exact equivalence of the reacting substances have a relatively large effect on the value of the constant . The initial reading of the conductivity cannot be taken directly , owing to the great speed of the reaction . In order to obtain it , the conductivity of the alkaline solution is read before the methyl acetate is added . In the above instance the conductivity read in this way is that of a solution N/ 95 with regard to sodium hydroxide , 4 c.c. of N/ 20 solution being contained in 19 c.c. When this is diluted to IST/ 100 by the addition of 1 c.c. of the methyl acetate solution , the conductivity will fall off in the ratio of 100 to 95 , since the quantity of methyl acetate in the solution after mixing is less than 0'1 per cent. , and can have no appreciable effect either on the speed or the number of the ions . From the conductivity of the solution before addition of the 1906 . ] Determining Velocities of Saponification . methyl acetate we therefore deduct one-twentieth of its value in order to obtain the initial conductivity after mixing . The final reading may of course be ascertained by waiting till the action has ceased , but it is both more expeditious and more accurate to measure the conductivity of a IN'/ 100 solution of sodium acetate prepared by neutralising the N/ 20 solution of caustic soda by means of acetic acid and diluting to the requisite extent . It is well to make this measurement of the end-point before beginning the actual saponification . Theoretically the end-point can be calculated from the initial reading and the known ratio of the conductivities of N/ 100 solutions of sodium hydroxide and sodium acetate , but it is advisable to perform the experiment as a check . 1 oc The calculation of the constant - . ---t 1\#151 ; x may be much simplified by the following device . For conductivity work a table is used which gives the ratio a/ ( l \#151 ; a ) for different values of the bridge-reading a. If therefore , we make the total range of the reaction equal to unity , we can use the same table to obtain the ratio x/ ( l\#151 ; x ) and have then merely to divide by the time t , a calculation which can be performed mentally if the intervals are suitably chosen . Now it is always possible to make the range between the initial and final values of a/ ( l\#151 ; a ) equal to unity by introducing the appropriate resistance in the resistance box . Thus in the above example it was found that the ratio between the initial and final conductivities was 2-773 : 1 . We have then if = 2*773 , and we wish to make i\#151 ; f = 1 . From these two equations we obtain i = 1*564 and / = 0*564 . We have therefore so to adjust the resistance that the initial value of aj(l\#151 ; a ) shall be 1*564 . This refers to the N/ 100 solution after mixing , whilst the conductivity actually measured is that of a N/ 95 solution . We must therefore increase the value 1*564 in the ratio of 100 to 95 , and thus obtain 1*646 as the value of a/ ( l\#151 ; a ) which the N/ 95 solution of caustic soda must exhibit if the difference between the initial and final values of \#151 ; is to be unity . In the table this value of u/ ( l\#151 ; a)corresponds to =0*622 . We therefore adjust the resistance in the box , either by trial or by calculation , until the minimum for the N/ 95 solution of caustic soda is exactly at this part of the bridge , and then proceed with the experiment . This adjustment , though tedious in description , only occupies a few minutes in practice , and saves much time in the subsequent calculations . Even if readings are taken every minute , the calculation of the constant - . \#151 ; \#151 ; \#151 ; from each observation can be performed t 1 \#151 ; x in the interval between two readings , generally without the necessity of putting pen to paper . 160 A Method for Determining Velocities of Saponification . 1 x To obtain the velocity constant from the mean value of - . -----it is only t -L \#151 ; X necessary to divide by the normality of the solution . In the above instance the velocity constant is thus 0T17 -4- O'01 = 11*7 . As a further example of the method , I append a series of observations made by Mr. D. C. Crichton , B.Sc. , on the velocity of saponification of ethyl acetate by caustic soda at 240-85 , the concentration of both substances being N/ 100 . t. al(l \#151 ; a ) . X. 1 X t 1 \#151 ; x 0 ( 1-560 ) 0 _ 5 1 -315 0-245 0 -0649 7 1 *247 0-313 0 -0651 9 1 -193 0-367 0 -0645 11 1 -146 0-414 0 -0642 13 1*101 0-459 0 -0652 15 1 -064 0-496 0 -0650 18 1 -020 0-540 0 -0652 20 0-994 0-566 0 -0652 25 0-945 0-615 0 -0642 27 0-923 0-637 0 -0650 33 0-880 0-680 0-0644 37 0-756 0-704 0-0644 00 ( 0 -560 ) ( 1 -000 ) Mean 0 *0647 The velocity constant of the saponification of ethyl acetate by caustic soda at this temperature is therefore 6'47 , a value in exact accordance with the curve which expresses the results of Warder* and of Reicherf obtained by the titration method . The conductivity method , even without special apparatus , is at least as accurate as the titration method carried out under specially favourable circumstances , and for rapid reactions is incomparably less trying in execution . * \#163 ; Amer . Chem. Journ. , ' vol. 3 , p. 203 , 1881 . t ' Liebig 's Annalen , ' vol. 232 , p. 103 , 1886 .

rspa_1906_0068

0950-1207

The tidal r\#xE9;gime of the river Mersey, as affected by the recent dredgings at the bar in Liverpool Bay.

161

166

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

James N. Shoolbred, B. A. (Lond.), M. Inst. C. E.|Lord Kelvin, F. R. S.

article

6.0.4

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10.1098/rspa.1906.0068

Geography

Meteorology

Geography

161 The Tidal Regime of the River Mersey , as Affected by the Recent Dredgings at the Bar in Liverpool Bay . By James N. Shoolbred , B.A. ( Lond. ) , M.Inst . C.E. ( Communicated by Lord Kelvin , F.R.S. Received May 30 , \#151 ; Read June 28 , 1906 . ) Liverpool , the premier port of the world after our metropolis , with the annual total of in-and-out tonnage , in 1904 , of 32 millions of tons , had suffered , in the approach thereto , up to about 15 years ago , from a sand-bar , situate at the outer or seaward entrance into Liverpool Bay , which afforded a depth of water over it , at low water of equinoctial springs , of only ten feet . When it is borne in mind that some of the large Atlantic liners have a draft of close upon 30 feet , it is easy to conceive the amount of inconvenience , chiefly by loss of time in enforced waiting outside the Bar , which this caused\#151 ; a period of waiting , which affected more or less , according to their individual tonnage , all vessels visiting the port . Attempts were made as far back as 1838 by the then Marine Surveyor of the Port of Liverpool , Lieutenant ( afterwards Admiral Sir ) H. T. M. Denham , to diminish the height of the Bar , by first harrowing the sand and then removing the loosened material by means of bucket-dredgers . After some years , however , it was found advisable to abandon these operations , since the effect thereof upon the Bar was so slight that a single storm from the Irish Channel often more than counteracted any deepening at the Bar , which had been effected by months of dredging . It was not , however , till shortly before 1890 , that the late Mr. G. F. Lyster , then Engineer to the Mersey Docks and Harbour Board , was able to resume the attempt to remove any material at the Bar , by calling to his aid the newly invented form of sand-pump dredger , which by means of exhaust suction displaced the material in a semi-liquid state with such rapidity as to cause very sensible progress to be made in the removal of the material . These preliminary experiments having proved sufficiently successful , in 1890 the problem of the removal of the Bar was vigorously attacked . At the end of ten years the problem was practically solved , so far as the cause of delay to incoming vessels entering the Port of Liverpool was concerned , since a minimum depth at the Bar of 26 feet of water at low water of equinoctial spring tides had been secured , or a gain of 16 feet of water over the conditions which prevailed in 1890 . Dredgings , however , are still continued ; not merely at the Bar itself , but VOL. LXXVIII.\#151 ; A. M ft* Plam of Liverpool Bay 1902 Showing Dredged Channel . SS . from The Bar to Liverpool Scale I inch = Statute Miles R \#171 ; ~\gt ; ti c LIVERPOOL R i v M I l\#187 ; _ Mersey ..-\#163 ; 0 ... ./ * \#163 ; 7'J* \amp ; V / \#151 ; -\#174 ; S ! \ \ f\#151 ; ^"\ / ;\#151 ; ^-IfoR/ viy B f\#163 ; \#163 ; lrsmp , \#163 ; y\#163 ; / : / 1-H.W . E.S.T. 1 W E.S.T. ."4# H.W : E.S.T. Cross Section at Taylor 's Bank Spit ( Bon Plan ) c* to y\#151 ; / * \A " i Irish Sea 'Bar iL^Ship ( Horiz ' : 450 ft. to I inch . Scales . -I m v \#151 ; _ . Mr. J. N. Shoolbred . Tidal Regina of the [ May SO , 1906 . ] River Mersey , as affected by Recent . 163 throughout the entrance channels right up to Liverpool , in the vicinity of the landing stage , so as to enable the largest Atlantic liners to make use , at any state of any tide throughout the year , of the entire length of this waterway , 16 miles , which at night is illuminated by gas-lit buoys . The total of the dredging operations by which the above results have been arrived at between 1890 and the present time may be thus summarised :\#151 ; Dredgings , at the Bar , 35 million tons of sand ; in the estuary channels 50 million tons ; in the river itself 15 millions ; making a total of 100 million tons . This has provided a channel at the Bar with a minimum width of 1500 feet and a depth throughout , at low water equinoctial spring tides , of 28 feet , from the Irish Sea right up to the Liverpool Landing Stage , thus forming a worthy approach to this most important port . ( See the accompanying plan and cross sections of dredged channel in Liverpool Bay . ) The British Association for the Advancement of Science , which has for the last thirty years , or more , paid considerable attention , by means of committees and in other ways , to the tides in the Mersey and in the Irish Sea , and inclusive of the Harmonic Analysis of the resulting records , naturally desired to ascertain whether , and to what extent , the extra facilities afforded at the deepened Bar to the ingress and egress of the tidal current had in any way caused any alteration in the tidal curves\#151 ; primarily at Liverpool , and also at other points throughout the tidal establishment of the river , that is , between the Bar and Warrington . With this object , a Committee of the Engineering Section of the British Association was appointed at the recent Southport meeting , consisting of Lord Kelvin , F.R.S. ( Chairman ) , and Professors Sir George Darwin , F.R.S. , Osborne Reynolds , F.R.S. , Hele-Shaw , F.R.S. , and W. Cawthorne Unwin , F.R.S. , together with the writer , as Secretary . That Committee presented their report at the succeeding meeting at Cambridge , in 1904 . They reported that by means of a large number of documents , tidal-curve records , etc. , which the Mersey Docks and Harbour Board had placed at their disposal , they had found , with the co-operation of Mr. Edward Roberts , of the Nautical Almanac Office , as to the Harmonic Analysis :\#151 ; ( a ) That in the principal factors in the Harmonic Analysis of the tidal-curves of 1902 at Liverpool itself there appeared to be no appreciable difference from the similar data which had been presented by Sir George Darwin , F.R.S. , to the Royal Society in 1885 , and in 1889 . ( b ) That a comparison of the tidal curves of the equinoctial springs and neaps of the vernal equinox , in 1893 and in 1903 , at Liverpool and at six other points on the river showed that no material change had occurred during that interval , either in the range of the tide or in the form of the 164 Mr. J. N. Shoolbred . Tidal Regime of the [ May 30 , curve ; but that in the extreme upper reaches of the narrow fluvial portion near to Warrington the tidal stream set in earlier , and remained somewhat later during the ebb , in 1903 than in 1893 . The object of the present communication is to submit the comparative diagrams of the tidal curves , in 1893 and in 1903 , at the seven localities above referred to , which cover the entire tidal establishment of the Mersey , and to do this , not merely at the vernal equinoctial spring tide , and at its corresponding equinoctial neap , as was done in the British Association Committee 's Report , but to extend the comparison so as to show by means of the continuous tidal curve , which occurred in 1893 , and also in that of 1903 , during the whole fortnight of the vernal equinox , there have been prepared likewise similar continuous tidal curves for the fortnight of the autumnal equinox in both of the above years . The result of this lengthened comparison of the tidal curves is that thereby may be seen the gradual progress , at each corresponding period , in the alteration in the times of high water and of low water , and also in the additional tidal water now introduced at certain periods into the upper reaches of the river . There is also brought out the relative value of the varying and progressive effects at the different points of the river . Diagrams ( not here reproduced ) indicate that , at the four points lowest down the river ( see accompanying plan ) , viz. , the Bar ( Helbre Island ) , Liverpool ( George'3 Pier ) , Eastham ( entrance to the Manchester Ship Canal ) , and Garston Docks , on the opposite Lancashire shore ( at all of which places the full range of all tides is felt ) , there is but little , if any , difference between the tidal curves of 1893 and of 1903 , that is , before the dredging operations were actively commenced , and the date when the present increased depth of channel was attained . A line drawn across the river from Garston to Eastham forms the . imaginary division between the Lower and the Upper Mersey navigations . The former , with its total navigable length from the Bar of 20 miles , obtains therefore the full advantage for the Port of Liverpool of the complete range of all tides . This is a matter of the utmost importance , since of the 32 millions of the tonnage of the shipping in and out of the Mersey , in 1904 , no less than 28 millions were confined to the Lower Mersey , while of the balance of 4 millions in the Upper Mersey , 3\#163 ; millions went up the Ship Canal to Manchester , and the remainder to Widnes and to Ellesmere Port . All the larger steam and sailing vessels entering the Mersey , with but a few exceptions which go to Manchester by the Ship Canal , make the Port of Liverpool their destination . Prom the connecting line between Eastham and Garston above referred to , 1906 . ] River Mersey , as affected by Recent Dredgings . as dividing the Lower and the Upper Mersey Navigations , the bed of the River Mersey rises rapidly , through what is known as the Upper Estuary , to Runcorn Bridge , joining the towns of Widnes and Euncorn ; throughout a distance of nearly 11 miles of the wide , sandy Upper Estuary there is an average rise of 18 inches per mile in the river bed . From Euncorn Bridge to Warrington , somewhat over nine miles , where the river partakes more of the character of an inland stream , the rise in the bed is not so steep , having an average gradient of but 12 inches per mile . The effect of this steep rise in the river bed upon the tides , and particularly upon the range thereof , is very marked . Throughout the entire length of the Lower Mersey Navigation of 20 miles , the full range of each tide is available . This may be taken as 31 feet on equinoctial springs , and as 10 feet on equinoctial neaps ; the high water of the former tide rises to 21 feet above the " Old Dock Sill " at Liverpool , and the latter reaches there to 10 feet above the same level . This " Old Dock Sill " datum-level has been in use , in this part of the Irish Sea , for the last 150 years at least , and the more recent , but more generally known , " Ordnance Datum " or " Mean Tide Level at Liverpool " is usually taken _ at 4*7 feet ( 4 ' 8 " ) above the " Old Dock Silk " At Widnes , however , the range on the same springs is reduced to 14 ' 6 " , and for the neaps to 9 feet ; while at Warrington , those springs have barely 9 feet of range and at the neaps in 1893 it was practically nil . But in 1903 these weak tides are much more visible at Warrington , though their influence is distinctly felt at Fiddler 's Ferry , five miles lower down the river . The effect of the up-hill gradient upon the rising tide is further shown in the additional height to which the high waters reach in the upper portions of the river . Thus at Widnes the equinoctial springs and neaps respectively reach a level of 1 foot at springs , and of 3 feet at neaps , higher than at Liverpool ; while at Warrington the corresponding levels are , on an average , higher by 3 feet at springs , and by 7 feet at neaps than at Liverpool , The result , therefore , of the examination of the continuous curves , each extending over a fortnight , does but confirm the conclusions of the Committee of the British Association , based upon the curves of the equinoctial springs and neaps only , that but little , if any , changes occur in the tidal conditions which prevail in the " Lower Mersey , " and which affect the Port of Liverpool itself , consequent upon the recent dredgings at the Bar ; this lower portion of the river being by far the most important as far as the interests of navigation are concerned . Eespecting the upper reaches of the river , near to Warrington ( where , however , the navigation is not of much importance ) , these fortnightly conThe Tidal Regime of the River Mersey , etc. tinuous tidal curves show that there now remains in the river , between the respective high waters , a considerable body of water , more than there used to be before the dredgings at the Bar took place\#151 ; an advantage , no doubt , to the local navigation . This increase in the amount of water appears more clearly upon these fortnightly continuous curves in the interval between the equinoctial springs and neaps than at the times of maximum and minimum range respectively of the tides . It is not possible , however , to arrive at any definite statement of the correctness , generally , of this effect without a careful examination of all of these fortnightly periods , throughout the entire year , since during each of these periods the strength of the tidal force would vary from that of its immediate predecessor , or successor . The following table may prove of interest in connection with the above remarks , and as confirming the statement as to the small amount of change which has taken place in the tides at Liverpool during the last 50 years:\#151 ; Comparison of Harmonic Analyses of Tidal Observations at Liverpool . 53 ' 24 ' Lat. K , 3 ' O ' Long. W. Mean of 1857\#151 ; 60.* Mean of 1866\#151 ; 70* 1902.f Principal Solar Series\#151 ; 0-066 0-038 0-003 62 83 97 SJH 3-240 3-101 3-188 b2t\#171 ; 11 12 11 -32 0-056 0-058 0-043 316 313 307-4 Principal Lunar Series\#151 ; M , iIJC - 0-020 0-039 0-032 l\#171 ; 258 336 345 -5 mJh 10 -100 9-881 10 -091 ' 2 l\#171 ; 326 327 326 -45 0-124 0-097 0-111 324 324 319 -0 M , iH 0-702 0-683 0-657 222 223 224 -2 mJh 0-211 0-184 0-180 348 350 353 -6 0-077 0-061 0-052 m8\K 271 285 248 -6 * Communicated to the Koval Society , in 1885 , by Sir Gh H. Darwin , F.R.S. ( cRoy . Soc. Proc. , ' vol. 39 , p. 135 ) . t Computed by Mr. Edward Roberts , F.R.A.S. ( Nautical Almanac Office ) . Of the constants k and H , the angles " k " are referred to the meridian of Greenwich , and denote the lag of the tide ; the " H 's " are in feet and decimals thereof , and indicate the semi-tidal range . The mean tidal level for 1902 = 4-952 feet above " Old Dock Sill . "

rspa_1906_0069

0950-1207

Ionic velocities in air at different temperatures.

167

191

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

P. Phillips, B. A., M. Sc.|Professor J. J. Thomson, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0069

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10.1098/rspa.1906.0069

Electricity

Thermodynamics

Electricity

]\gt ; Ionic Velocities in Air at Different Temperatures . By P. PmLLIPS , B.A. , M.Sc . , 1851 Exhibition Scholar of the University of Birmingham . ( Communicated by Professor J. J. Thomson , F.R.S. Received June 7 , \mdash ; Read June 21 , 1906 . ) The object of this paper is to find at different temperatures the velocity in an electric field of the ions produced by Rontgen rays in air at atmospheric pressure . The different values obtained will tell us whether the masses of the ions depend in any way upon the temperature . Langevin , 1902 , described a new method which he had devised to determine the velocities of ions in an electric field . The principle of the method is as follows:\mdash ; any instant that potential can be reversed . arthed oonnected tuadrants octrometer aaised tgiven ppose tonisation iniformAt acertain tfter tischarge hassed iates distant dapart . sent through a Rontgen bulb which ionises the air between bulb , the potential on is reversed . If we represent by a curve the quantity received by when is altered we shall get a curve of the form given in fig. 2 . By varying the time and measuriug the quantity received by Fro . 2 . * Langevin , ' Recherches sir les gaz ionises , ' Paris , 1902 . 168 Mr. P. Phillips . Ionic Velocities in [ June 7 , we can experimentally realise this curve and so obtain the points of discontinuous curvature , , and R. The time between and is and between and is , where and are the velocities under unit field of the positive and negative ionH respectively , and X is the field . Knowing , and , we calculate and If the ionisation be not uniform but be localised close to one of the plates , the form of the curve will be altered . Suppose the ionisation is very intense close to A and that before reversal is positive , then the form of the curve will be that given in fig. 3 , while , if is negative before the reversal , the form will be that given in fig. 4 . FIG. 3 . We see that in the first case the point of discontinuous curvature is very marked and in the second case is very clearly marked . Using localised ionisation in this way we can find the points with greater precision . In this investigation we have neglected the effect caused by diffusion and recombination of the ions and by the distortion of the field due to unequal distribution of the ions . Langevin , in the thesis already referred to , has shown that diffusion and recombination only round off the corners on the curve and do not displace them ; consequently the experimental curve will inform us whether these are serious . Langevin also shows that the distortion of the field is negligible if the total charge received by the plate A is less than a quarter of the charge induced on A when the potential on is raised from zero to the potential used iu the experiment . In my experiments this fraction never rose above one-twentieth . The general arrangement of the apparatus , by means of which this method was experimentally realised , is shown in fig. 5 , and is essentially the same as that described by M. Langevin . 1906 . ] Air at Different Temperatures . FIG. 5 . and are two weights which can be allo to fall simultaneously and break the contacts I and I ' . The breaking of the contact at I ' causes a single discharge to pass through the bulb X , while the breaking at I reverses the potential on the electrode B. I can be fixed at any point on a vertical scale , and thus the contact may be broken at any required time before or after it is broken in I ' . As in M. Langevin 's experiments , a standard pair of electrodes , , is used , and the ratio of the charge received by A to that received by is the quantity which is plotted against the time in order to obtain the experimental curves . For a fuller account of the apparatus , vide Langevin 's thesis . When the ionisation used is intense close to one of the plates , as in and 4 , a null method may be used . are so adjusted that when we travel the horizontal parts of the curve , receives an equal and opposite charge to A. A and are connected together and to the electrometer , and so , while we on the horizontal part of the curve , we shall get no deflection , but as soon as we get beyond , or , as the case may be , we shall get a deflection . This is a very convenient and quick method of obtaining the position of the points , and it is used in most of the experiments described in this paper . The electrometer has a phosphor-bronze suspension , gives 496 mm. deflection fcr 1 volt between the two pairs of quadrants , and has a capacity of about cm . It was found convenient to use diflerent forms of vessel at different Mr. P. Phillips . Ionic Velocities in temperatures , and so the description of the vessel in which A and are enclosed will be reserved for the account of the experiments at the various ; temperatures . The experiment has been carried out at the following temperatures absolute : , and , i.e. , at temperatures ranging from C. to C. Between C. and C. the velocities of bobh the positive and negative ions are very nearly directly proportional to the absolute temperaGure , but at C. the two velocities seem to be equal and much smaller than would be given by this linear law . Determination of the Velocities at the Temperature of Boiling Air.\mdash ; In order to reduce the size of the ionisation vessel as much as possible the plane parallel electrodes were replaced by concentric cylindrical ones . This slightly alters the ulation . Let the diameter of the outer cylinder be , of the inner Then at a point between and distant from the centre the electric intensity is equal to , where is the difference of potential between and . The velocity of the positive ions at this point will be therefore where is the time which a positive ion would take to travel from to i.e. , the time between the two discontinuities and Thus i.e. , Similarly , for the negative ion , T2 being the time between the two discontinuities and Q. In this experiment the inside diameter of the outer cylinder is cm . , and the outside diameter of the inner cylinder is cm . 3 is therefore equal to Therefore Several different forms of ionisation vessel were tried before one was Air Different Temperatures . found which worked satisfactorily when immersed in liquid air . In several forms the strain on the ebonite insulation which was caused by the unequal contraction of ebonite and brass was sufficient to break the dielectric , while in another form this unequal contraction made the vessel leak and so liquid air made its entrance . The form of vessel shown in longitudinal section in fig. 6 , however , worked quite satisfactorily . is a cylindrical brass vessel which contains the two brass electrodes A and B. FIG. 6 . is very little smaller than the vessel and is kept in position and insulated from it by means of ebonite rings at the top and bottom which are shown in section at It is connected with the point ( fig. 5 ) by means of the wire which is led out through ebonite plugs in the side tube S. Through the centre of bottom of the vessel is soldered the lower guard tube , while the upper guard tube is screwed to the centre of the aluminium lid Al . Mr. P. Phillips . Ionic Velocities in [ June 7 , The electrode A is supported between these two guard rings by means of ebonite plugs which are shown in section shaded , and it is connected to one of the mercury cups ( fig. 5 ) by means of a wire led out through the tube T. The ebonite plugs are turned as shown in order to increase the insulating surface and so improve the insulation . P6 is a platinum resistance which takes up very little space and which serves to measure the temperature of the air between the electrodes . The leads to this are led out through ebonite plugs in another side tube . The aluminium lid Al fits into a depression which is turned in the lower flange and is squeezed by screws between the two flanges , F. The ebonite plugs are very close fitting so that the vessel is very nearly air-tight and a drying tube , which is not shown , communicates with the interior of the vessel by means of another side tube . The whole vessel and side tubes can be contained in a beaker 8 cm . diameter so that it may easily be immersed in liquid air up to the position indicated by the dotted line . The Bontgen bulb is vertically above the vessel so that rays enter through the aluminium lid Al . The standard vessel is of much simpler design , being merely a brass vessel with an aluminium window through which rays enter between two plane electrodes , one of which is connected to one end of the 160-volt battery , while the other is connected to one of the mercury cups in fig. 5 . single reading is taken as follows:\mdash ; First I is placed at the required height on the scale and the contact is made . and the electrometer are all earthed . The electro-magnet circuit is closed and the rrhts W and are placed in position . A and are insulated . The contact I ' is made and then the electro-magnet circuit is broken , allowing the weights to fall and break the contacts I and I ' . The contact I is re-made and the quantities received by A and are measured successively on the electrometer . The ratio of these two quantities is plotted against the scale reading of I. A typical series at C. is given on p. 173 . Plotting these quantities against each other we obtain Curve No. 1 , from which we see that the points , and occur at the scale readings 30 cm . , cm . , and cm . , respectively . 1906 . ] Air Different Potential of cells volts . When the contact breaker I is placed at 30 cm . on the scale the distance between it and the electro-magnet is cm . The height of the falling weight itself is cm . , therefore the actual height of fall of the weight before breaking the contact cm . Height of fall to cm . cm . 27 . The time of fall to cm . sec. sec. Mr. P. Phillips . Ionic Velocities in [ June 7 , The time of fall to cm . sec. , , sec. sec. Therefore The time from to sec. and , , , , to cm . . per volt/ cm . , The results at ordinary temperatures show that the apparatus is working satisfactorily . The , is a typical set of readings taken when the apparatus is immersed in liquid air up to the position indicated by the dotted lines in fig. 6 . Potential of cells volts . Resistance of Pt thermometer steady at ohm . These numbers are plotted in Curve No. 2 , which only shows two points of discontinuous curvature , the one occurring at the scale-reading 30 cm . , the other at cm . This would lead us to the conclusion that the velocities of the positive and negative ions are equal to one another . Time to fall to 30 cm . sec. , 5 . ' sec. Thus Time between discontinuities sec. , i.e. , and cm . . per volt/ cm . To calibrate the platinum thermometer its resistance was found when Air at Different Temperatures . . of 1 it was immersed in freshly prepared liquid air water at C. , water at C. , and water at C. The calibration curve is given in Curve No. 3 , which shows that when the resistance is ohm the temperature is C. Mr. P. Phillips . lonic Velocities in [ June The disappearance of the one point of discontinuous curvature might be due to some defect in the apparatus ; such a defect , for instance , as would arise from the difference of coefficient of expansion of ebonite and brass . This might conceivably allow the central electrode to get a little out of the centre , and this would very soon round off any corners in the curve . After taking several precautions to prevent such an occurrence , however , the other point does not reappear , and if we examine the curve the sharpness of the other discontinuities seems to show that there is no such defect . Five series of readings were obtained with the vessel immersed in liquid air , and the curves obtained were exactly similar . The velocities found were :\mdash ; i.e. , at C. the velocities of the positive and negative ions are each equal to cm . . per volt/ cm . Deterrnination of the Vdocities at C.\mdash ; In this experiment the ionisation vessel consists of a double-walled metal jacket , inside which the electrodes are contained , and the space between the walls of which is filled with solid A diagram of the vessel is given in fig. 7 . In order to keep the space between the double walls filled with solid liquid is allowed to escape from a cylinder through a small hole . It enters the jacket through the tube , which is screwed into the cylinder , and the gas is led out through the tubes and allowed to escape outside the window . 06 . ] Air at Different Temperatures . Unfortunately a steady stream of cannot be maintained in way , for the small hole gets choked with the solid and so one cannot merely leave the stream flowing , but by keeping an eye on the temperature and blowing more through when it shows signs of falling , it is quite easily maintained between the limits and C. The vessel was surrounded with three layers of thick felt in order to protect it from being warmed up too rapidly by external radiation . The electrode A is of thick brass , and is insulated from the guard by meaus of three rods of , whose ends are soldered to and respectively . The guard ring is supported by three brass pillars , which are soldered to it and rest on the base of the vessel . The electrode is of aluminium and is screwed to the brass ring R. It is supported by three quartz rods , which are soldered into holes in and R. Three spacing blocks , cm . thick , vere placed between and while the qualtz rods were being soldered , and thus the electrodes were fixed accurately parallel . The vire connecting with the point in fig. 5 is led out through an ebonite plug in the side tube S. The wire connecting A to a mercury cup is threaded through a narrow brass tube . This is soldered into the quartz tube which in its turn is soldered into a wider brass tube . This brass tube VOL. LXXVIII.\mdash ; A. Mr. P. Phillips . Ionic Velocities in [ June 7 , slides tightly into the side tube , making a fairly air-tight joint . The wire is pulled taut , and is then soldered to the outer end of The leads to the platinum thermometer Pt are led in through an ebonite plug in the side tube C. The side tube serves a double purpose . A drying tube is attached to it , and through it a wire which is soldered to the guard is led out and soldered into good contact with the vebsel . The lid of the yessel Al is of thin aluminium and is made fairly air-tight by being squeezed between a brass ring and the top of the double-walled jacket . A lead shield Pb only allows the rays to impinge centrally on the electrodes . Since the rays impinge directly on the brass electrode , the secondary radiation makes the ionisation intense close to , so that in this case the null method is applied . The method of taking a reading is exactly the same as described for the temperature , C. , except that the two electrodes A and are connected ether all the time instead of being connected separately to the electrometer . A typical series of readings is given below : Potential of cells volts . Electrode is negative before reversal . These numbers are plotted in Curve No. 4 which shows that the point oi discontinuity is at cm . 1906 . ] Air at Different The resistance of the platinum thermometer never varied beyond the limits and ohms . Exactly similar series of readings were conducted to find the points and Q. The point is at cm . scale reading , and , Now the height of fall to cm . cm . , , , , Thus Time of fall to sec. , , sec. , , sec. Thus Time between and sec. , and , , PandB Now distance between electrodes cm . , and potential on electrodes volt . Thus . per volt/ cm . Inspecting the Pt thermometer calibration curve , we see that the temperature is between and C. The mean temperature is thus C. Owing to the large amolmt of which was required to keep the temperature constant , only three series of could be taken before the cylinder of liquid was exhausted . The results of these three series FIG. 8 . ling the horizontal parts of the curves until a deflection was obtained . A number of determinations were made at the ordinary temperature of the room and the es- of and were obtained:\mdash ; Probably the most accurate determinations so far are those of Langevin and Zeleny . . results 1906 . ] Air at Temperatures . We may , therefore , conclude that the apparatus is working quite satisfactorily . The series of experiments with the jacket heated to C. by means of methylated spirits the following results:\mdash ; Experim From these experiments we have : Mean Mr. P. Phillips . Ionic Velocities in [ June 7 , With the boiler filled with water , i.e. , with the vessel maintained at 10 C. , the following results were obtained:\mdash ; With the boiler filled with water , i.e. , with the vessel maintained at 10 C. , the following results were obtained:\mdash ; With the boiler filled with water , i.e. , with the vessel maintained at 10 C. , the following results were obtained:\mdash ; Thus we have at 10 C. :\mdash ; Mean 1 06 . ] Air Difleren Temperatures . With the boiler filled with amyl alcohol , , with the vessel at a temperature of 12 C. , the following results were obtained:\mdash ; iment.expts PThus we have at C. :\mdash ; 1.91 1.97 1.97 1.92 1.99 1.91 1.97 1.97 1.92 1.99 1.91 1.97 1.97 1.92 1.99 1.91 1.97 1.97 1.92 1.99 1.91 1.97 1.97 1.92 1.99 Mean 195 2.41 2.43 240 cm . . per The velocities of the ions at , 11 and 13 were also found by means of another ionisation vessel . It is shown in section in fig. 9 . The vessel itself , , is a brass casting of which the inside dimensions are about inches . A and are two brass electrodes and is a gual.d ring . A and are fixed in position by being to brass rods which are soldered into quartz tubes , while these in their turn are soldered into the cups , which are turned in the sides of the vessel . While the solder is being poured into the cups the two electrodes are fixed parallel and cm . apart by means of three spacing blocks . The two tubes and fit on to the outside of the cups , and are soldered in position . Through them the connections to and A are made by means 184 Mr. P. Phillips . Ionic Velocities in [ June 7 of the two brass rods , which screw into little blocks on the ends of : Al is the aluminium lid to the vessel and is made tight by being squeezed between bhe two flanges , F. are two brass diaphragms which only allow a flat pencil of rays about 3 mm. thick to enter the vessel , and which are so placed that this pencil just grazes the surface of B. There is a continuation of the vessel above the aluminium lid so that the whole may be immersed in an oil bath up to about the position indicated by the dotted lines . The oil bath can be maintained at any constant temperature between about and 15 by means of a thermostat . The mode of using this vessel was exactly the same as in the last experiments . A null method was used and the height of the movable contact breaker I varied , to find the point at which one begins to get a permanent deflection . With this apparatus the point was very sharply marked . 906 . ] Air at Different Ternperatures . 18Thus we have : Thus we have : Thus we have : Thus we have : 1 when the vessel was at the temperaTemperature . The following results were obtained with the oil bath maintained at C.:\mdash ; Mr. P. Phillips . Ionic Velocities in Thus we have at C. :\mdash ; With the oil bath maintained at C. the following results were obtained:\mdash ; Time . Thus we have : 1.85 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 Mean 185 230 cm . . per volt/ cm . at 11 C. 1906 . ] Air at emperattl r With the oil bath maintained at C. the following results were obtained : \mdash ; 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 2.52 2.44 2.49 Thus we have : Mean 2495 cm . . per volt cm . at C. Collecting all the results at the different temperatures we These numbers are plotted in Curve No. 5 . bure . AbsoluCe . We see that except for the case of the velocities at . the points lie very close to straight lines through the origin , i.e. , and are very nearly proportional to the absolute temperature . This is a strangely simple result when we consider what a complication of circumstances affects the velocities . Interpr.etation of the Results.\mdash ; As is well known , by making use of the kinet , ic theory of gases , we can obtain an expression for the drift velocity of an ion in an electric field in the form where X is the field , is the mass of the ion , is the mean free path of the ion , and is the mean molecular velocity of the ion . This formula depends upon the fundamental assumptions\mdash ; 1 . That.statically the previous history of the ion is wiped out at each collision . 2 . That the drift velocity is small compared with the mean molecular velocity . This condition is easily fulfilled . It is easy to see that the first assumption is correct if the ions consist of one molecule each , but it is probably not quite accurate when they consist of more than one . It is difficult , however , to make any other workable assumption and , if we make it , it is fairly simple to find in terms of ( the corresponding quantities for the gas molecules ) , and , the number of molecules which go to make up one ion . For let be the number of molecules per cubic centimetre , and N2 , , , , ions 1906 . ] Air at Different Let be the radius of a molecule , and of an ion distance between centres of a molecule and an ion at collision , Then , treating the mixture of ions and molecules as a mixture of two different gases , the mean free path , , of an ion is given by Now is negligible compared with ; thus Thus The factor in the brackets is too complex for one to see at aglance how it varies with . The following are the values of its inverse when , 2 , 3 , 4 , and 5:\mdash ; o These are plotted in Curve No. 6 . Now the value of for air at 76 cm . pressure and C. is to 770 , when we use the values for the size of the nlolecules given in Jeans ' * Jeans , ' Din . Theory of Gases , ' p. 234 . Mr. P. Phillips . Ionic Velocities in Din . Theory of Gases , ' p. 340 , the number of molecules per cubic centimetre given by tfJe electrical methods of J. J. Thomson and H. A. Wilson , and the 3 electrolytic values of . These , I think , are the most reliable values we can get . The velocity of the positive ion given by Curve 5 is about cm . per , i.e. , 399 cm . . per absolute unit of field , at C. This is times too small , therefore diffusion ossign tsize twice ohrice tositive ionsists o of molecules . molecule , while Dr. Richardson , from considerations based on the variation of the ionic velocities with pressure , came to the conclusion that a positive ion air at atmospheric pressure and at ordinary temperatures consists of about 3 molecules . By making the same calculation as the above from the experimental results at different temperatures , we get the variation with temperature of the number of molecules in the ion . The calculated values of are given in the following table : \mdash ; These numbers are plotted in Curve No. 7 . Of course , the first assumption made in deducing the nula will show us that we cannot accurately deduce the number of molecules in an ion in this way . Probably all the numbers to be multiplied by a factor which is not very far different from unity , but at least this curve will us how the size of the ion vttries with the teml ) erature . ComptPs Rendus , ' vol. 111 , p. 35 , 1905 . 'Phil . Mag July , 1905 . . at Different Temperatures . TemperaCure . AbsoluCe . The fact tlJat it varies continuously and not in jumps would seem to show that there is a continual exchange going on between ions and rred molecules ; at some collisions several molecules remain attached to the ion , while at others one or more of them is knocked off , and so a dynamical equilibrium is set up . As the temperature of the gas rises , the collisions are more violent , and statistically fewer molecules are attached to an ion ; this gradual change would go on until the collisions become so vioIent that at times corpuscles are shot off without even a single molecule attached to them . When this happens the velocity of the ion would very rapidly increase with the temperature , and so in flames we might expect those rapidly moving ions which are unloaded corpuscles for an appreciable fraction of their life . In conclusion , wish to express my indebtedness to Professor J. J. Thomson for suggesting this subject for investigation and for the kindly interest he has shown while the experiments have been in progress . I also wish to thank Dr. Richardson for some helpful suggestions .

rspa_1906_0070

0950-1207

The ionisation produced by hot platinum in different gases.

192

196

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

O. W. Richardson, M. A.|Professor J. J. Thomson, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0070

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0070

10.1098/rspa.1906.0070

Thermodynamics

Electricity

Thermodynamics

192 The Ionisation Produced by Hot Platinum Different Gases . By 0 . W. Richardson , M.A. , Fellow of Trinity College , Cambridge , Clerk-Maxwell Student . ( Communicated by Professor J. J. Thomson , F.R.S. Received June 19 , \#151 ; Read June 28 , 1906 . ) ( Abstract . ) The primary object of this investigation has been to try to discover the mechanism of the action by which the positive ions set free by hot bodies originate . It deals principally with measurements of the steady positive ionisation produced by hot platinum in various gases under different conditions . In 1901* the writer showed that the negative ionisation from hot metals could be satisfactorily explained by supposing that it was caused by the freely moving corpuscles inside the metal escaping from the surface when their kinetic energy exceeded a certain value . In the present paper reasons are assigned for believing that a view of this kind will not account for the origin of the positive ions , which seem to be liberated by an action in which the atoms of the gas play a direct part . In the cases of steady ionisation here investigated it seems probable that it is not so much the external gas as that adsorbed by the metal which is effective . It has been known for a long time that when a wire is heated for the first time it furnishes a very copious emission of positive ions . This effect has been examined previously in some detail by the writer , f who showed that it was very noticeable in a good vacuum and that the ionisation decayed asymptotically with time to a very small value . More recently the writer ! has succeeded in showing that the reduced value of the leak thus obtained could be increased by the admission of small quantities of air . Further investigation has shown that there is a portion of the positive ionisation which is a function of the pressure of the external gas . It is with this part of the ionisation that the present paper chiefly deals . Although the ionisation of this type is well marked and definite , its value even at atmospheric pressure is small compared with the initial value of the leak from a new wire . The experimental methods employed are similar to those previously made * ' Camb . Phil. Soc. Proc. , ' vol. 11 , p. 286 ; cf. also ' Phil. Trans. , ' A , vol. 201 , p. 473 . t ' Phil. Mag. ' [ 6 ] , vol. 6 , p. 80 . f ' Camb . Phil. Soc. Proc. , ' vol. 13 , p. 58 . Ionisation Produced by Hot Platinum Different Gases . 193 use of by the writer . Any important deviations from earlier methods are-described in the paper . The investigation is more complete in the case of oxygen than of the other gases investigated , because : ( 1 ) oxygen was found to have a considerably greater effect on the ionisation , especially at low pressures ; and ( 2 ) it is a simple elementary gas , which is easily prepared in a. state of considerable purity . Besides oxygen the paper contains an account of measurements of the ionisation of both signs from hot platinum in air , nitrogen , helium , and hydrogen . There are also measurements of the ionisation from a platinum surface in air when a calculable quantity of hydrogen is diffusing out from the interior of the platinum . The last-named experiments shed a considerable amount of light on the mechanism of the processes by which both the positive and negative ions are produced . It has been found convenient to subdivide the paper according to the . following scheme:\#151 ; I. S 1 . Introduction . II . S 2 . Experimental Arrangements . III . The Ionisation in Oxygen :\#151 ; S 3 . Current and Electromotive Force . S 4 . Hysteretic Eelations between Current and Electromotive Force . S 5 . Current and Pressure . S 6 . Current and Temperature . S 7 . Uncontrollable Variations . S 8 . Comparison of different Wires . S 9 . Special Properties of New Wires . S 10 . Theory of the Steady Positive Leak in Oxygen . IV . S 11 . The Ionisation in Nitrogen . V. S 12 . The Ionisation in Air . VI . S 13 . The Ionisation in Helium . VII . S 14 . The Ionisation in Hydrogen . VIII . S 15 . Experiments with a Platinum Tube . IX . S 16 . Theoretical Considerations . X. S 17 . Summary of Principal Eesults . The following is a brief account of the chief results of the investigation:\#151 ; The positive ionisation , i.e. , the number of positive ions produced by 1 sq . cm . of platinum surface per second , possesses a minimum value , which depends on temperature and pressure , in most gases . The positive ionisation in oxygen at a low pressure ( less than 1 mm. ) is much greater than in the other gases tried . In oxygen , at low pressures and temperatures below 1000 ' C. , the ionisation varies as the square root of the pressure ; at higher VOL. LXXVIII.\#151 ; A. O 194 Mr. O. W. Richardson . The Ionisation [ June 19 , temperatures and low pressures it varies nearly directly as the pressure ; whilst at higher pressures at all temperatures the variation with pressure is \#166 ; slower , so that at pressures approaching atmospheric the ionisation becomes practically independent of the pressure . The variation with pressure in air is similar to that in oxygen . In nitrogen and hydrogen the ionisation appeared to increase more rapidly with the pressure at high pressures than in oxygen . In very pure helium at low pressures there was a positive ionisation which was a function of the pressure . The experiments on ionisation by collisions indicate that the positive ions liberated by hot platinum in oxygen are of the same order of magnitude as those set free by the collisions . They are not great masses approximating to dust particles . The positive leak in oxygen always oscillated around a certain value under specified conditions . It was , therefore , never steady , so the minimum values were taken . This variability was much less marked , if it occurred at all , in the other gas\amp ; s. The minimum value of the positive ionisation was found to remain practically constant with a wire heated during three months at various times ( for 150 hours altogether ) in oxygen at 900'\#151 ; 1000 ' C. Moreover , four different wires of different dimensions after continued heating in oxygen gave nearly the same value for the ionisation at the same temperatures and pressures . The positive ionisation in air at constant temperature is smaller than that which would be obtained if the nitrogen were withdrawn , so as to leave only oxygen at a low pressure . The nitrogen , therefore , exerts an inhibiting effect on the oxygen . The minimum value of the positive ionisation at a definite pressure in all gases appears to be connected with the temperature by the relation first deduced by the author for the negative ionisation . This relation may be written i = A6ie~\lt ; i'2e , where i is the ionisation , 6 is the absolute temperature and A and Q are constants . The value of the constant Q , which is a measure of the energy associated with the liberation of an ion , is in most cases smaller for the positive than for the negative ionisation . These results refer to wires which have been heated in a vacuum , and subsequently in the gas considered , for a long time . New wires exhibit peculiar properties , especially in regard to their behaviour under different electromotive forces . Old wires also exhibit hysteretic effects with change of pressure . The view is developed that the positive ionisation is caused by the gas 1906 . ] Produced by Hot Platinum in Different Gases . adsorbed by the metal and the consequence examined of supposing the ionisation to be proportional to the amount of the adsorbed gas present . In the case of oxygen , by making the assumption that the rate of increase of the amount of the adsorbed gas is proportional jointly to the concentration of the external dissociated oxygen and to the area of " unoccupied " platinum surface , whilst the rate of breaking up is proportional to the amount present , a formula is obtained which agrees with the experimental results . This formula is that the ionisation i = Ap/ ( B-f^\gt ; ) , where \#151 ; ( / jP + \k ? )h \#151 ; -|/ j , P being the external pressure and k the dissociation constant of oxygen ; A , B and are constants depending on the temperature and are of the general form a6ie~h:e . Thus this view accounts for both the temperature and pressure variation . The positive ionisation from the outer surface of a hot platinum tube in air is increased when hydrogen is allowed to diffuse through from inside the apparatus . The increase in the ionisation is proportional at constant temperature to the quantity of hydrogen escaping from the surface in unit time . For different temperatures the effect produced by a given quantity of hydrogen is greater the higher the temperature . The negative ionisation from hot platinum in air is unaltered when hydrogen is allowed to diffuse out through the platinum . These results show that neither the negative nor the positive ionisations usually observed with hot platinum heated in air or oxygen are due to residual traces of absorbed hydrogen . Careful measurements were made to see if the negative ionisation in oxygen at low pressures varried with the pressure of the oxygen at constant temperature . Although the addition of oxygen increased the positive leak by a factor of 10 , the negative leak was constant within the experimental error , in agreement with the work of previous observers . The negative ionisation was found to have very nearly the same absolute value and the same temperature variation for two wires of different dimensions when heated in oxygen . A wire which has been heated in hydrogen furnishes a negative ionisation which is very big compared with that from a wire heated in oxygen at the same temperature . If the hydrogen is at a pressure of the order of 1 mm. the negative ionisation can be rapidly reduced to a much smaller value by applying a high negative potential to the wire . The wire subsequently recovers its ionising power if the potential is reduced again . Under these conditions the ionisation varies in an interesting way with the time . The reduction in the ionising power of the wire appears to be caused by the bombardment of the surface by positive ions produced by collisions . When a platinum wire , which has previously been allowed to absorb 196 Mr. A. Campbell . On t Electric Inductive [ June 12 , hydrogen , is heated for a long time in a good vacuum so as to expel the gas , its ionising power does not appear to be reduced . The ionisation apparently is not a definite function of the quantity of gas absorbed by the wire . The amount of hydrogen which a platinum wire will absorb at a low pressure is much greater than is usually suspected . The results indicate that the increase in the negative ionisation is not caused by the hydrogen directly but rather by some change it produces in the surface of the platinum . \ On the Electric Inductive Capacities of Dry Paper and of Solid Cellulose . By Albert Campbell , B.A. ( Communicated by Dr. R. T. Glazebrook , F.R.S. Received June 12 , \#151 ; Read June 21 , 1906 . ) ( From the National Physical Laboratory . ) Although dry paper is widely used as a supporting and insulating material in telephone cables , the published data with regard to its specific inductive capacity ( or permittivity ) appear to be very meagre . For this reason Mr. Gavey , C.B. , Engineer-in-Chief of the Post Office , asked us to investigate the matter , and sent for test a large number of samples of paper obtained from four different cable manufacturers . All the samples consisted of what is known as " chemical wood paper , " presumably free from lignified fibre . This type of paper , according to the Society of Arts Report on the Durability of Papers , is better in lasting quality than " mechanical wood paper " or paper made from straw , jute or esparto grass . Mr. Gavey , in addition , has kindly supplied the results of some tests on actual cables and further data for some of the samples of paper . This information is embodied in Part II of the present paper . Part I.\#151 ; Tests on Dry Paper . One of the main difficulties in the testing of paper lies in the fact that it absorbs moisture so readily ; and the presence of moisture has a large effect on the specific inductive capacity and an enormous effect on the insulation-resistance . The nature of these effects is well illustrated by the curve in fig. 6 ( Part II , p. 204 ) , which shows how the capacity increases and the resistance decreases as a well-dried cable is allowed to absorb moisture from the atmosphere .

rspa_1906_0071

0950-1207

On the electric inductive capacities of dry paper and of solid cellulose.

196

211

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Albert Campbell, B. A.|Dr. R. T. Glazebrook, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0071

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0071

10.1098/rspa.1906.0071

Electricity

Thermodynamics

Electricity

196 Mr. A. Campbell . On the Electric Inductive [ June 12 , hydrogen , is heated for a long time in a good vacuum so as to expel the gas , its ionising power does not appear to be reduced . The ionisation apparently is not a definite function of the quantity of gas absorbed by the wire . The amount of hydrogen which a platinum wire will absorb at a low pressure is much greater than is usually suspected . The results indicate that the increase in the negative ionisation is not caused by the hydrogen directly but rather by some change it produces in the surface of the platinum . On the Electric Inductive Capacities of Dry Paper and of Solid Cellulose . By Albert Campbell , B.A. ( Communicated by Dr. R. T. Glazebrook , F.R.S. Received June 12 , \#151 ; Read June 21 , 1906 . ) ( From the National Physical Laboratory . ) Although dry paper is widely used as a supporting and insulating material in telephone cables , the published data with regard to its specific inductive capacity ( or permittivity ) appear to be very meagre . For this reason Mr. Gavey , C.B. , Engineer-in-Chief of the Post Office , asked us to investigate the matter , and sent for test a large number of samples of paper obtained from four different cable manufacturers . All the samples consisted of what is known as " chemical wood paper , " presumably free from lignilied fibre . This type of paper , according to the Society of Arts Report on the Durability of Papers , is better in lasting quality than " mechanical wood paper " or paper made from straw , jute or esparto grass . Mr. Gavey , in addition , has kindly supplied the results of some tests on actual cables and further data for some of the samples of paper . This information is embodied in Part II of the present paper . Part I.\#151 ; Tests on Dry Paper . One of the main difficulties in the testing of paper lies in the fact that it absorbs moisture so readily ; and the presence of moisture has a large effect on the specific inductive capacity and an enormous effect on the insulation-resistance . The nature of these effects is well illustrated by the curve in fig. 6 ( Part II , p. 204 ) , which shows how the capacity increases and the resistance decreases as a well-dried cable is allowed to absorb moisture from the atmosphere . 1906 . ] Capacities of Dry Paper and Solid Cellulose . Methods of Testing . In all cases small squares of the samples ( each about 10 x 10 cm . ) were dried in an electrically-heated oven , the mean temperature of which was kept at about 110 ' C. The dry paper was then made to form a part of the dielectric of a small plate condenser and the capacity of this was measured . Two distinctly different arrangements were used in forming the small condenser , and two series ( A and B ) of results were obtained . In the first method ( A ) , the specimen to be tested was placed while still hot between indiarubber discs ( of area 50 sq . cm . ) covered with tinfoil also dry and warm . A weight of 15 kgm . was placed on the upper disc ( being insulated from it ) and the resulting condenser was tested as it cooled down . In method ( B)* a small air condenser was formed from two well-trued circular brass surface plates ( each of area 50 sq . cm . ) placed horizontally and separated from one another to a distance of about 0-6 mm. by three very small accurately gauged distance-pieces of ebonite . This small condenser was kept in a desiccator , and out of this the leads were carried in an air-tight manner through ebonite tubes ringed with sulphur for better insulation . The capacity of the air condenser was first measured and then the dry sheet of paper was slipped between the plates , and the altered capacity was tested . From these measurements the specific inductive capacity of the paper was deduced as follows:\#151 ; Let b = distance between the plates ; = bi + b2 , where bi and b2 refer to air and paper respectively ; s = area of paper between plates . Let Ki and K2 be the observed capacities . If K = capacity for area s with air only , then , neglecting edge action , K 47 rbx 900,000 mfds . and is thus known ; let K = ~ . Now Ki = x + % , and b Let Q = then 0 \#151 ; ^ H~b1+b2/ k ' Hence k = * K2 = K 2\#151 ; ay k7^ ; or k b\ + b2/ k h b/ Q-h Ka-Ka + K K\amp ; 2/ \amp ; 1-K2+KV ( 1 ) * This method was used by Mr. Packer , of the British Insulated Wire Company , in a series of paper tests made in 1901 . 198 Mr. A. Campbell . On the Electric Inductive [ June 12 , Measurement of Capacity.\#151 ; The measurements of capacity were made by Maxwell 's method , * the connections being shown in fig. 1 . Fig. 1 . Fig. 2 Fig. 3 . By a rotating contact-maker , the moving part of which is represented by m , the condenser p is charged and short-circuited with a frequency of n per second ; during the charge only it forms one arm of the Wheatstone 's bridge shown . A moving coil galvanometer of slow period is used , the resistance r is set so as to give nearly a balance , and then the speed of the contact maker is kept at such a value as to hold the light-spot at zero . The capacity was calculated by the usual formula , a deduction being made for the capacity of the commutator and leads ( found by a blank experiment ) . The voltage used was about 40 volts . Correction for Conduction.\#151 ; In nearly every instance readings were taken with at least two frequencies ( usually about 20 and 40 ~ per second ) . Sometimes the apparent capacity was found to vary with the frequency , being greater at the lower frequency ; this is due to conduction in the condenser , which behaves as a pure capacity shunted by a high resistance . When the conduction was not negligible , a correction for it was applied , the capacity and resistance being separated in the following way :\#151 ; Let K and B be the true capacity and resistance respectively : and let Ki and K2 be the apparent capacities for frequencies n\ and n % . The commutator inserts the condenser in one arm of the bridge during a certain fraction of each revolution ; let this fraction = cr . The value of a may be obtained by measurements at the rim of the commutator . * As used by Professor J. J. Thomson , Mr. Searle , Dr. Glazebrook , and others . 1906 . ] Capacities of Dry Paper and of Solid Cellulose . 199 We have -^- + K = Ki , and + K = K2 . n\ R n2R Hence K = Kx ^_(K2-Kx ) , ni \#151 ; n2 ( 2 ) and v_ni \#151 ; n2( ( T \ \#171 ; i\#171 ; . \k ( 3 ) In order to test these formulas , a condenser of capacity 1*011 mfd . ( with high insulation ) was shunted ( a ) by 100,000 ohms , ( b ) by 10,000 ohms , and the apparent capacity in each case was measured for two frequencies ( about 14 and 38 ~ per second ) . Case ( b)was chosen as an extreme one , the apparent capacities rising to about 2 3 and 4'7 mfds . respectively . The values of K obtained by equation ( 3 ) from tests ( a ) and ( were 1020 and 1-009 mfd . respectively . From ( a ) , taking E = 01 megohm , a was found by ( 4 ) to be 0-463 , whilst measurements of the commutator gave a = 0'446 . From the results of ( b ) , using o- = 0"463 , equation ( 4 ) gave E = O'OOIOO megohm , agreeing with its known value . These results show that even in extreme cases the equations ( 2 ) and ( 3 ) may be used . Test with Small Air Condenser.\#151 ; The capacities which had to be measured were all very small , being from 0-0002 to 0"001 mfd . , and the correction for the leads and commutator amounted to about 0-00001 mfd . Besides , no correction was applied for the edges of the plates , * which were without guard rims . For these reasons the method was checked by applying it to test a small air condenser , the capacity of which was of the same order as the paper condensers to be tested . This air condenser was built up of two pieces of plate glass ( each of about 100 sq . cm . area ) , silvered on the sides that faced one another , and separated by minute distance-pieces of ebonite or dry paper . The distance between the plates was from 0'03 to 0-05 cm . , and was measured by gauging the distance-pieces . The conduction by surface leakage over the distance-pieces was relatively considerable , and had to be corrected for as described above . The values found by experiment were compared with those calculated from the , measured dimensions , and the agreement was quite satisfactory , e.g.\#151 ; Calculated , mfd . Observed , mfd . 0-000243 0000244 0000153 0-000153 * It appears that no complete mathematical treatment of the simple plate condenser has yet been carried out . 200 Mr. A. Campbell . On the Electric Inductive [ June 12 , Measurement of Thickness.\#151 ; The thickness of each sheet was tested immediately after the capacity measurements . As the surface of the paper presents much irregularity , it is a very difficult matter to find the average thickness . After several other arrangements had been tried , it was decided that an ordinary screw gauge was as good as any , and it was used throughout . The contact ends of this gauge had each an area of about 02 sq . cm . , while the safety ratchet head applied a pressure of about 1 kgm . per square centimetre . As this pressure is about three times that applied to the indiarubber discs in method ( A ) , it is probable that the increased compression will tend to make some allowance for the tinfoil penetrating the irregularities of the paper surface . Besults of Tests.\#151 ; In Table I are given some of the results . A few of the samples were tested by method ( A ) , both with a single sheet and with a pile of three sheets ; the latter tests are included in the table.* Table I. Specific inductive capacity . Sample number . Approximate thickness . By tinfoi From 1 sheet . 1 clamps . From 3 sheets . By plate condenser . 14 mm. 0*08 2 *5 2 -6 15 0*12 1 -8 \#151 ; 1 -8 54 0*13 1 *9 1 9 49 0*18 2 1 2 *2 9 0*19 2 3 .\#151 ; 2*1 17 0*25 1 *9 \#151 ; 2 *0 18 0*25 2 *0 \#151 ; 1 '8 56 0*28 1 *8 \#151 ; 1 -7 58 0*28 2 0 \#151 ; 1 *9 2 0*5 2 *2 2*3 From the foregoing table it will be seen that the two methods show as good agreement as could be expected from the nature of the material , but there is considerable variation from sample to sample . By weighing six samples it was found that their specific capacities were nearly in the order corresponding to that of their densities , which varied from 0'55 to 0'78 . It was suggested that it would be of interest to compare the above values of specific inductive capacity with that for solid cellulose . As no data for the latter appeared available , a research ( which forms the third part of this * A sample of special black paper ( partly parchmentised ) , kindly supplied by Mr. Clayton Beadle , gave k = 2'3 . 1906 . ] Capacities of Dry Paper and of Solid Cellulose . paper ) was undertaken upon the electrical properties of solid cellulose Its specific inductive capacity was found to be about 6-8 . Now , when the cellulose fibres ( which we shall assume to form the whole solid part of the paper ) are assembled with a certain amount of air space between them , the specific inductive capacity ( kp ) of the resulting paper depends very largely upon the relative arrangement of the air and the cellulose . The following simple investigation will illustrate this point:\#151 ; Let d = density of cellulose ( about T50 ) , D = that of paper , 0 = that of air , q = ratio of cellulose volume to air volume . Then Di 2 d\#151 ; Dj Di 1-50-Di ' ( 4 ) and thus q can be found by experiment . Now , for a given value of q , it will be found that is least when the cellulose and air are in strata parallel to the condenser coatings , and greatest when these strata run at right angles to the coatings . These cases are represented sufficiently by figs. 2 and 3 . Let and k2 be the resulting specific inductive capacity in these cases respectively . It is easy to show that and h ( l+g)fr q + k ' k2 =1+fo . 1 + 2 ( 5 ) ( 6 ) By weighing and gauging a number of the samples the value of q was found for each ; from these values the minimum and maximum ki and k2 were calculated . From Table II it will be seen that the actually observed values of kp all lie below the mean of kx and k2 . This indicates ( electrically ) that the fibres of cellulose are arranged more in a direction parallel to the surfaces of the paper than at right angles to it , which is otherwise known to be the case . Table II . 9- Jc\lt ; 2 . 2 ( \amp ; 1 + 7c\lt ; ^ ) . Observed 7cp . 0*577 1 -45 3 -12 2-28 1 -93 0*629 1 -49 3 *23 2 -36 1 *89 0*843 1 -64 3-65 2-70 2*21 0*930 1 -70 3-79 2-75 2*25 1-078 1-79 4-02 2 *90 2-30 It is clear that the law of mixtures found by L. Silberstein* does not apply here . * ' Wied . Ann. , ' vol. 56 , p. 661 , 1895 . 202 Mr. A. Campbell . On the Electric Inductive [ June 12 , Table II is of interest in connection with practical telephone work , in which the lowest possible value of the mean specific inductive capacity is aimed at . From the values of Jcx and k2 we see that the mean resultant k depends very much on the relative positions of the paper fibres and the air spaces . The numbers in Table I give about 2*0 as a mean value for the specific inductive capacity of dry telephone paper , and this is in fair agreement with results already published by other observers . Signor E. Jona , by testing dry paper between metal plates , found approximately equal to 2'0 . Herr M. S. von Pirani* gives k = 2 0 to 2'6 , but he does not indicate clearly the conditions of his tests . Part II ( supplied by Mr. Gavey).\#151 ; Additional Data and Tests on Cables The undermentioned samples of oven-dried paper have been tested , with the results shown in Table III . Table III . Sample number . Weight of ash , per cent. Proportion by volume . Fibre , per cent. Air space , per cent. 9 1 *37 49 0 51 *0 15 1 *45 35 -0 65 0 17 1 *80 36 *0 64 -0 18 1 11 36 *5 63 *5 56 0-96 32 *5 67 *5 58 1-70 36 0 64 -0 The thickness of the paper 's was measured with a screw gauge which exerted a pressure of about 1*5 kgm . per square centimetre on the paper when the safety ratchet was used . It was found that the thickness of the paper measured with this pressure , and also with that of a light touch with the fingers on the screw gauge , differed by 10 per cent. , i.e. , the air space figures given above would have been 6 per cent , higher if the ratchet were not used . It was also found that the thickness of the paper when several sheets were measured together was 2 to 3 per cent , less than when measured in single sheets . The method finally adopted was to measure single sheets , using the ratchet referred to above , which it was thought would approximate as closely as was possible to the conditions observed by the National Physical Laboratory . The figures used for the density of fibre arid ash were 1*5 and 2'0 * 1 Berlin Dissertation , ' 1903 . 1906 . ] Capacities of Dry Paper and of Solid Cellulose . respectively . From the weights per cubic centimetre and the respective densities , the volume of fibre and air space in each paper was calculated . The samples of paper , although classed commercially as " Manilla " papers , on microscopic examination proved to be composed of mixtures of chemical wood pulp and hemp in different proportions . There was no trace of lignified fibres or mechanical wood . The minimum breaking stress specified by the Post Office for papers of this class is 4000 lbs. per square inch , but 7000 lbs. per square inch is about the average value obtained ( . , about 490 kgm . per square centimetre).* With the kind assistance , of Messrs. W. T. Henley 's Telegraph Works Company , Limited , an attempt has been made to determine the effect of temperature on the electrical properties of the combination of air and dry paper as found in telephone cables . The results are indicated graphically in the curves in figs. 4 and 5 , showing the variation of insulation-resistance and capacity respectively with temperature . 20,000 10,000 Temperature . Fig. 4.\#151 ; Variation of Insulation-Resistance with Temperature in Air Space Paper Core Cable ( P.O. ) . 0130 0-125 0-120 Temperature . Fig. 5.\#151 ; Variation of Capacity with Temperature in Air Space Screened Cable ( Post Office Type ) . * The construction of a paper-screened telephone cable is as follows :\#151 ; The conducting wires are wrapped loosely in longitudinal ( not spiral ) strips of thin paper ; two or more wires thus covered are placed together and thoroughly dried in an oven . While they are still dry and warm , a covering of lead is applied by a lead press , and in this way the moisture from the outside air is excluded . The paper merely acts as a mechanical separation between the conductors ( and the lead sheath ) . As the lowest possible electrical capacity is desirable , anything that tends to decrease the permittivity of this separating medium is of practical advantage . 204 Mr. A. Campbell . On Electric Inductive [ June 12 The proportion of air space and paper in the cable to which these tests refer was approximately 26 per cent , air , 74 per cent , paper . 0120 O-IIO Megohm-miles . Fig. 6.\#151 ; Variation of Capacity with Insulation-Resistance in Air Space Paper Screened Cable ( Post Office Type ) . The curve in fig. 6 was obtained with the kind assistance of the British Insulated and Helsby Cables , Limited , and shows the variation of capacity with the amount of uniformly distributed moisture in a cable as measured by the insulation-resistance . Each wire in this cable was insulated with paper and then covered with a copper tape wrapped on spirally . The cable was tested before being sheathed with lead , the copper tape making a sufficiently good earth . The method adopted was as follows:\#151 ; The cable was first dried and then allowed to stand exposed to the air for over a week . The moisture in the air penetrated through the interstices in the copper tape , making the paper damp , and tests were taken periodically to determine the capacity and insulation-resistance . The ends were kept well waxed and tests taken with and without a guard wire showed there was no leakage at the ends . The proportion of air and paper in this cable was about 31 per cent , air , 69 per cent , paper . The capacity in each case was measured by the comparison on a galvanometer of the charge deflection from the cable with that from a standard condenser . No correction has been applied for leakage , but the error was found to be about 1J per cent , on the capacity corresponding to 5000 megohm-miles , and 2| per cent , on the capacity corresponding to 2000 megohm-miles . This would reduce the alteration in the Temperature-Capacity Curve between the limits of temperature shown from 7A to 5 per cent. It is suggested that the reason of the alteration in the capacity with increasing temperature may in some part be due to the absorption of the moisture in the paper by the hot air , thus altering the distribution of the 1906 . ] Capacities of Dry Paper and of Solid Cellulose . 205 dielectrics in the cable . This view is somewhat borne out by the fact that another cable which was dried to an insulation-resistance of 140,000 megohm-miles , and therefore contained less moisture , has only 2 per cent , difference in the capacity between the same limits of temperature . Part III.\#151 ; Solid Cellulose . A series of tests were made on a number of samples of nearly pure cellulose kindly supplied to the laboratory by Mr. C. F. Cross . The material was prepared by the following process:\#151 ; Crude viscous 10-per-cent , solution of cellulose xanthogenic acid ( sodium salt ) , with alkaline by-products , was spread on a glass plate , dried at 60 ' C. , salted out with pure brine to remove soluble by-products , and the cellulose finally " fixed " and purified by treatment with acid and thorough washing . The samples were in the form of fairly uniform translucent sheets from 0'06 to 0*3 mm. in thickness . For most of the experiments the sheets were dried for several days in an oven at 80 ' to 110 ' C. As the air-dry material is of the nature of a colloidal solution , the thorough drying is a long process , and the reabsorption of moisture from the atmosphere is very much slower than in the case of fibrous cellulose like paper . In the first experiments clamps of indiarubber and tinfoil were used , but it was found that these did not make satisfactory contact with the very smooth surface of the cellulose ; they were therefore discarded and were replaced by mercury clamps* consisting of troughs with indiarubber edges pressed against opposite sides of the sheet and filled with mercury . The clamps and the mercury were usually dried in the oven and applied while still hot , a set of tests being taken as the whole apparatus cooled down to the temperature of the room . Capacity tests made on mica sheets of two different thicknesses gave concordant results and so proved that the mercury contacts were satisfactory . The drying made the cellulose very brittle , but immersion in water restored it to the flexible condition . Some of the capacity measurements were made by Maxwell 's method ( as already described ) , but in order to avoid polarisation and minimise the effect of conduction the method ! shown in fig. 7 was usually employed . S is a small standard condenser , K the condenser to be tested , Ri and Ii2 variable resistances , while M is a telephone-plate sounder ! ( giving 800 ~ per second ) , such as is sometimes used in place of an electric bell . The intermittent current from M gives , by means of the transformer T , an * See R. Appleyard , ' Proc. Phys. Soc. , ' p. 724 , vol. 19 , December , 1905 . t Used by Nernst and others . X An u Electric Trumpet " supplied by The General Electric Company . Mr. A. Campbell . On the Electric Inductive [ June 12 Fig. 7 . alternating current in the bridge SKR2Ri . The ratio Ri/ R2 is altered until there is silence in the telephone N ; then K/ S = Ri/ R2 . When the cellulose was thoroughly dry , the point of balance was quite definite , but when it was only air-dry , a point of minimum sound was all that could be obtained ( but see below ) . The results obtained from sheets of different thicknesses ( 0'06 to 0-3 mm. ) were in very fair agreement both for capacity and resistivity throughout a considerable range of temperature . The resistivities were measured by the method of direct deflection at 200 volts with 1 minute 's electrification . Table III gives mean results for a range of temperature from 70 ' down to 20 ' C. , and figs. 8 and 9 give the corresponding curves . ( The resistivities with 2 minutes ' electrification were 20 to 30 per cent , higher . ) 0 ' IO ' 2 0 ' 3 0 ' - TemperatureC . Fig. 8.\#151 ; Oven-dried Cellulose . * Specific Inductive Capacity . . 2,000 1.000 Pt Mega- Megohm 0 ' IO ' 20 ' 30 ' 40 ' 50 ' 60 ' 70 ' t Temperature C. Fig. 9.\#151 ; Oven-dried Cellulose . Apparent Resistivity by Direct Deflection Method . 1906 . ] Capacities of Dry Paper and of Solid Cellulose . 207 Table IY.\#151 ; Dry Cellulose . Temperature . Sp. ind . capacity . Resistivity . 'C . megohm-cm . 20 6*7 25 \#151 ; 1600 x 106 30 6*8 900 x 106 40 7*0 330 x 106 50 7*2 125 x 106 60 7*3 40 x 106 65 \#151 ; 20 x 10s 70 7*5 Part IV.\#151 ; Tests on Damp Cellulose . The influence of moisture upon the electrical properties of paper ( illustrated by the curve of fig. 6 ) is striking . Some years ago I observed that , when even a trace of moisture was present , a sudden lowering of the temperature always caused a considerable increase in insulation-resistance.* At that time I advanced the theory that the effect was largely a mechanical one , the lowering of temperature causing the moisture to be drawn into the hollow tubular interiors of the fibres . Since the solid cellulose is not of fibrous structure , it was of interest to try its behaviour when in the " air-dry " condition , i.e. , after exposure to the atmosphere for a considerable time . Of course , the amount of moisture present depends on the humidity of the air , the temperature , etc. , and therefore the conditions vary from day to day ; thus the results refer only to the actual conditions holding at the time of the particular experiment . In each case the cellulose was placed between the clamps , hot mercury was poured in , and observations were made during the cooling . Tests of apparent resistivity were made by observing the current due to a constant potential difference kept continuously applied . Fig. 10 gives an example of a curve thus obtained . As might be expected , strong polarisation effects made their appearance . When attempts were made to measure the capacity by Maxwell 's method the polarisation caused a large displacement of zero , and made it impossible to obtain any true result . With the telephone method of fig. 7 the relatively good conductance of the specimen made it impossible to obtain a balance . However , by shunting the standard condenser S ( as shown in fig. 11 ) by a variable resistance X , it was always possible to get a good balance . * See E. H. Rayner , ' Proc. Inst. Elec . Eng. , ' p. 625 , vol. 34 1905 . Mr. A. Campbell . On the Electric Inductive [ June 12 I Megof ' o 20 ' 30 ' 40 ' 50* b Temperature C. Fig. ]0.\#151 ; Air-dry Cellulose . Apparent Resistivity by Direct Deflection Method . X AAAAAAAAAAA A/ WW Humme-r Fig. 11 . As high frequency is desirable , the source of current was a microphone hummer* of special construction giving 2000 ~ per second . The arrangement of this is shown in fig. 12 . A is a rod of mild steel ( or tool steel ) supported horizontally at nodal points , and carrying at one end a very light microphone B shunted by a condenser C. T is a transformer whose secondary is connected to the coil of a polarised telephone magnet M. If A is set vibrating by a blow , the pulsating current in the microphone circuit gives an alternating current round M , and so maintains the vibration . * For earlier microphone hummers see the following K. Appleyard , ' Elec . Review , pp. 57 and 656 , vol. 26 , 1890 ; J. E. Taylor , ' Inst , of Elec . Engs . , ' p. 396 , vol. 31 , 1901 ; and F. Dolezalek , ' Zeitsclir . fur Instrumentenkunde , ' p. 240 , August , 1903 . 1 t A \ \ 1 \ \ x \ \ \ s \ . 1 1 1 1 1906 . ] Capacities of Dry Paper and of Solid Cellulose . 209 The testing current is taken from another secondary winding of T. A mild-steel rod 2'5 cm . in diameter and 23'7 cm . long gives 2000 ~ per second . By using a shorter rod a frequency of 3000 to 4000 can be attained . Fig. 12.\#151 ; Microphone Hummer for 2000 ~ per second . When the telephone is silent K/ S = Bi/ B2 = X divided by insulation resistance of K. In fig. 13 is shown the variation of capacity with temperature for a sample of air-dry cellulose , suddenly heated and allowed to cool slowly . / / / / / / j s I00 ' 10 ' 20 ' 30 ' 40 ' 50 ' 60 ' 70 ' Temperature C. ( 1 ) ( 2 '(3 ) i \ \ \ i \ 1 \ \ \ \ \ A X \J i\ V N : L . 1 MH pi I i I S 1___ I t~4 o ' IO ' 20 ' 30 ' 40* 50\#174 ; 60 ' 70 ' Temperature C. Fig. 13.\#151 ; Air-dry Cellulose . Sp. Inductive Capacity . Fig. 14.\#151 ; -(1 ) Cable , ( 2 ) Oven-dried Cellulose , ( 3 ) Air-dry Cellulose . From the values of the shunt X required to give a balance , the values of the insulation resistivity of K at the various temperatures can be obtained . Measurements made with the high frequency ( = 2000 ~ per second ) at room temperatures gave values of the resistivity about 10 times smaller than the apparent resistivity shown by the steady deflection method ( as in fig. 10 ) ; the variation with temperature was also much less with the high frequency alternating current . It may be mentioned that in the direct deflection test the immediate deflection fell off 10 to 15 per cent , after 1 minute 's electrification . In telephone work the frequencies are high , and therefore it is the lower values of the resistivity that would occur when leakage due to moisture happens . vol. lxxviii.\#151 ; A. p 210 Mr. A. Campbell . On the Electric Inductive [ June 12 , The matter , however , seems to want further investigation . It will be seen from fig. 13 that when air-dry cellulose is quickly heated the specific inductive capacity increases very considerably . If the raised temperature is maintained and the moisture allowed to escape , the capacity gradually falls to a value dependent on the temperature . Since the material is not porous in the same sense that paper is , the mechanical theory based on the tubular nature of the fibres is thus excluded . The observed facts seem to indicate that a part of the moisture is chemically combined with the cellulose , the whole forming an electrolytic solution ( possibly of water in cellulose hydrate ) . When the temperature is raised , partial dissociation appears to occur and , with continued steady temperature , dissociation equilibrium is attained . High specific inductive capacity and low resistivity would thus correspond to the presence of a relatively large amount of dissociated moisture present throughout the material . Dielectric Strength of Solid Cellulose.\#151 ; A number of sheets of cellulose , from 0*06 to 0*3 mm. thick , were tested for break-down voltage , both air-dry and oven-dried specimens being tried . The apparent dielectric strength ( i.e. , Vmax . divided by thickness in centimetres ) varied with the thickness of the sheet ; for air-dry cellulose it was of the order of 250,000 volts per centimetre , and for oven-dried material 500,000 volts per centimetre . Cellulose Acetate.\#151 ; As cellulose acetate is coming into common use as an insulating material for covering thin wires , its electrical properties are of practical interest . It was therefore thought desirable to make a few tests upon it with a view to comparing its properties with those of cellulose . The acetate is soluble in chloroform , and by pouring the solution on to a glass plate a smooth and tough film may be obtained . Two specimens were tested namely:\#151 ; ( a ) Normal tri-acetate ( kindly supplied by Mr. C. F. Cross ) . ( b ) A sample from a German source , said to contain both tri- and tetraacetate ; it was found to contain also a small amount of sulphur in combination , probably S04H residue . By more recent methods of acetylation these products are more economically obtained : the acetylizing mixtures contain sulphuric acid , and a proportion of S04H residues is fixed together with the acetyl . Sample ( a ) when air-dry gave a specific inductive capacity of about 4*7 ; when oven-dried the value was about 3*9 . The variation with temperature was scarcely perceptible , being of the order of one per cent , for 40 ' C. Sample ( b ) gave less consistent and somewhat higher values . The resistivities were also determined approximately , the result at 200 volts with one minute 's electrification being given in Table V. 1906 . ] Capacities of Dry Paper and of Solid Cellulose . Table Y. Material . Condition . Temperature . Resistivity . Cellulose acetate ( a ) Air-dr j 'C . 16 *5 . Mega-megohm-cm . 200 a \#187 ; Oven-dried 26 -0 over 9000 Cellulose acetate ( b ) Air-dry 26 -0 13 n Oven-dried 26 *0 121 General Remarks.\#151 ; On comparing the temperature-capacity curves for the cable and the dry cellulose sheet , it will be found that the rate of variation of capacity with temperature is about 50 per cent , greater in the cable than in the sheet ; this indicates probably that the paper of the cable was not dried to such an extreme extent as the cellulose sheet . The air-dry cellulose , on the other hand , has a very much larger k to start with and this increases very rapidly with temperature ( if the moisture be kept from escaping ) . With regard to the resistivities , the curves of figs. 4 , 9 , and 10 have been brought together in fig. 14 ( by altering the scales ) so as nearly to coincide at 40 ' C. It will be noticed that between 30 ' and 40 ' C. the cable shows the least , and the air-dry cellulose the greatest variation with temperature . This is probably due to the fact that in the cable the moisture can partially escape into the air spaces . It is curious to find , for the dried cellulose , that while the capacity does not alter much with temperature , the insulation alters enormously . This leads to the inference that in spite of the extreme drying ( to brittleness ) the alterations with temperature are still due to dissociation of combined moisture . The amount of this moisture may be very infinitesimal when we remember that the drying raises the resistivity 300 million times . With regard to the cellulose acetate , even in its air-dry condition it is a good insulator . Its specific inductive capacity also is lower than that of cellulose . It is evident , therefore , that it is far less susceptible to the effects of moisture than either paper or solid cellulose . In conclusion , I must express my hearty thanks to all who have aided me in the above investigation ; to Dr. Glazebrook for constant and valued advice and help ; to Mr. Gavey and his colleagues , Mr. H Hartnell and Mr. A. G. Lee , for all the data in Part II , some of which were obtained expressly for this paper ; to Mr. C. F. Cross for all the material used in the cellulose tests and for kind advice ; to Signor E. Jona for valuable information ; and to Dr. W. A. Caspari and Mr. W. Gemmell for help in connection with the chemical part of the subject .

rspa_1906_0072

0950-1207

Note on the production of secondary rays by \#x3B1; rays from polonium.

212

217

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

W. H. Logeman, M. A.| Professor J. J. Thomson, F. R. S.

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Electricity

Atomic Physics

Electricity

212 Note on the Production of Secondary Rays by a Rays from Polonium . By W. H. Logeman , M.A. , Fellow of the University of the Cape of Good Hope ; 1851 Research Scholar of the South African College , Cape Town ; Trinity College , Cambridge . ( Communicated by Professor J. J. Thomson , F.R.S. Received June 25 , \#151 ; Read June 28 , 1906 . ) In the 'Philosophical Magazine ' for May , 1896 , Professor Brag points out that since the a rays are absorbed by a solid according to the same law as by a gas , it seems reasonable to expect that the atoms of the solid are ionised in the same manner as are those of a gas . Hence we should expect that slowly-moving negative rays would be given off at the surfaces where the \#171 ; rays enter or leave a solid . Professor J. J. Thomson has shown* that when a solid is subjected to bombardment by a stream of canalstrahlen , it emits cathode rays . In the course of some experiments which were undertaken with the idea of determining the velocity of projection and the ratio of the charge to the mass of the slowly-moving negative or 8 rays emitted by polonium , the writer has obtained some results which appear to indicate clearly the existence of slowly moving negatively charged secondary rays which are produced when an aluminium or copper plate is bombarded by a stream of a particles . The apparatus used in these experiments is shown in the accompanying figure , p. 213 . A is a circular disc of copper , 4 cm . in diameter , coated on the side facing B with a thin deposit of polonium . This was obtained from Sthamer , of Hamburg . B is an aluminium disc of the same diameter as A , and supported parallel to A by the stiff brass wire F. C is an ebonite stopper fitting into the narrow end of the glass tube G. Through C passes a brass tube E , inside which is fitted a second ebonite stopper J , supporting the wire F to which the plate B is attached . The dotted lines in the figure show where the tube is silvered inside to render its surface conducting . The disc A is supported centrally in the tube by means of three small metal feet projecting from its circumference and is rigidly attached by the wire loop L to the brass plate M which fits loosely in the tube . Contact can be made with the disc A by means of the flexible wire spiral H and the platinum wire terminal 0 . The distance between the plates A and B can thus be adjusted by tilting the tube and allowing the whole system ALM to slide inside . * 'Camb . Phil. Soc. Proc. , ' November , 1905 . Production of Secondary Rays by a Rays from , Polonium . 213 Fig. 1 . D is a glass bulb filled with pieces of hard charcoal for immersing in liquid air , in order to absorb as much as possible of the last traces of gas in the tube . The joints at C and H were made air-tight with sealing wax . The whole apparatus was attached to a mercury pump and evacuated down to a pressure of about O'OOl mm. of mercury , and then sealed off at K. Most of the readings were taken while the bulb D was surrounded by liquid air . The plate B was connected to the insulated terminal of a quadrant electrometer through a mercury key with sulphur insulation in the manner shown in the figure , all the usual precautions being taken to shield the connections from external electrostatic fields . The tube E was connected to earth , so as to form a guard ring , and prevent any direct leak from the silver lining of the tube ( which was in metallic connection with the disc A ) to the insulated wire F. The method of taking observations was as follows :\#151 ; The polonium disc was first brought to the required potential by connecting it with a battery of small secondary cells . The earth connection at R was then broken by raising the wire P. Exactly one minute later the connection between B and the electrometer was broken by raising the bridge-piece Q , and B was earthed again by lowering the wire P. Half a minute was allowed for the spot of light to come to rest , and the reading was then taken . The tube was placed with the gap AB between the poles of an electromagnet , so that different strengths of magnetic field could be applied at right angles to the line joining the centres of the discs A and B. The sensitiveness of the electrometer was about 800 divisions per volt . 214 Mr. W. H. Logeman . Note on the Production of [ June 25 , The following two tables of results may be taken as typical:\#151 ; Table I. ( Distance between discs = 5 mm. ) Strength of magnetic field . Potential of polonium . Reading . C.Gt-.S , units . volts . Scale divisions . 0 0 - 58-0 0 + 2 + 86-0 0 + 4 +138 -0 0 + 6 +169 -0 0 + 8 +176 5 0 + 10 +181 -5 0 + 12 +182 -0 0 + 14 +185 -0 8 0 - 31-5 20 0 - 5-0 32 0 + 9-0 45 0 + 16-0 59 0 + 18-5 72 0 + 21-0 85 0 + 22-5 98 0 + 24-0 111 0 + 26-0 125 0 + 26-5 153 0 + 27-5 178 0 + 29-5 202 0 + 30-5 350 0 + 33-0 Table II . ( Distance between discs = 10 mm. ) Strength of magnetic field . Potential of polonium . Reading . C.G-.S . units . volts . Scale divisions . 0 -20 -298-0 0 -14 -286 -0 0 -12 -277 -0 0 -10 -268 -0 0 - 8 -252 -0 0 - 6 -232 -0 0 - 4 -196 -0 0 - 2 -143 -5 0 0 - 56-0 0 + 2 + 57-0 0 + 4 + 88-0 0 + 6 + 100 -o 0 + 8 +103 -5 0 + 10 +107 -5 0 + 12 +108 -5 0 + 14 +109 -0 0 + 20 +110 -o 700- + 20 + 31-5 1906 . ] Secondary Rays by a Rays from Polonium . 215 It is important to note that ordinary ionisation can have nothing to do with these results , as the pressure in the tube was far too low to allow of any appreciable amount of ionisation . This is shown to be the case by the fact that when the liquid air was removed and the carbon allowed to acquire the temperature of the surrounding air , the only observable change was a very slight diminution in the charge acquired by B. These results are shown graphically in the three curves on p. 216 . From these figures and curves it is seen :\#151 ; ( 1 ) That under ordinary conditions , iwhen not acted upon by an electric or magnetic field , the polonium gives off a larger amount of negative than of positive rays . ( 2 ) Under the influence of a gradually increasing electric field more and more of the slowly moving negative rays are stopped , and the charge carried by the a rays becomes more and more predominant . ( 3 ) A potential difference of about 10 volts between the plates is sufficient to stop the last of the 8 rays . The fact that the Curve No. I goes on rising slightly for values of the abscissm higher than 10 volts is easily accounted for on the supposition that a few of the oblique a rays which previously just missed the plate B get pulled in when the field is increased . ( 4 ) The slowly moving negative rays can also be prevented from reaching the plate B by curling them up in a magnetic field . The fact that the Curve No. II continues to rise for values of the magnetic field above 100 C.G.S. units is very difficult to account for in view of the results obtained by Ewers , * according to which a field of 100 units should curl up the 8 rays into circles of about 2 mm. diameter or spirals ( in the case of those shot off obliquely ) of still smaller diameter . ( 5 ) The point of special interest for our present purpose is this : The limiting value of the positive current across the gap from A to B when the 3 rays are stopped by a magnetic field is only about one-fifth of that obtained when an electric field is used to stop the 3 rays . This fact appears to the writer to admit of only one interpretation , viz. , when the potential difference between the plates is 10 volts or more ( A being the positive plate ) the positive current from A to B consists of the following two parts : First , a stream of a particles travelling from A to B. Second , a stream of negatively charged particles travelling from B to A. The magnetic field curls up this latter stream of negative rays , as well as the 8 rays emitted by the polonium . This theory fits in well with the last two observations given in Table II . Here we have the polonium plate at a potential of +20 volts and the current between the plates ( consisting of the two parts mentioned above ) is * ' Phys. Zeitschr . , ' March 1 , 1906 , pp. 148\#151 ; 152 . 216 Mr. W , H. Logeman . Note on\the Production of [ June 25 , Curve I.-\#151 ; 5 mm. between discs . No magnetic field . -o +IOO Potential of Polonium in volbs . Curve II.\#151 ; 5 mm. between discs . Polonium disc earthed . jo o IOO 200 300 Magnetic field strength in C.G.S.units . Curve III.\#151 ; 10 mm. between discs . No magnetic field . -20 -16 -12 -8 +12 +16 +20 Potential of Polonium in volts . 1906 . ] Secondary Rays by a Rays from Polonium . 217 represented by the number 110 . A magnetic field is then brought into play of such strength as to prevent the negative particles which leave B from reaching A , and to make them return to the plate B. The current is thus cut down to a value represented by 31*5 . Very similar results were obtained when the aluminium disc B was replaced by one made of copper . There is one other respect in which the above results are difficult to reconcile with those obtained by Ewers . According to his figures for the velocity and ratio of the charge to the mass of the S rays , a potential difference of 30 volts should be required to stop those shot off normally . As will be seen , this is far from the case with the sample of polonium used by me . I hope before long to be able to publish results giving the values of v and e/ m ior the 8 rays from my sample of polonium , and also for the secondary rays , the existence of which is proved above . In conclusion , I have to thank Professor Thomson for his kind interest , and his readiness to assist me with his advice throughout these experiments .

rspa_1906_0073

0950-1207

Researches on explosives. Part IV.

218

224

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sir A. Noble, Bart., K. C. B., D. Sc. (Oxon), D. C. L., F. R. S.

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10.1098/rspa.1906.0073

Thermodynamics

Tables

Thermodynamics

]\gt ; Researches on Explosis ) . Part IV . By Sir A. NOBLE , Bart. , K.C.B. , D.Sc . ( Oxon ) , D.C.L. , F.B.S. , etc. ( Received and read June 28 , 1906 . ) [ PLATE 6 . ] ( Abstract . ) In Part III of my " " Researches on Explosives I gave the results of a very extensive series of experiments , the completion of which necessarily occupied a very long time , and the particular explosives with which I experimented were those with which artillerists in this country were familiar , and with which a considerable number of experiments had been made . The , se explosives were , first , the cordite of the Service , known as Mark I second , the modified cordite , known as M.D. ; and third , the nitrocellulose , known as Rottweil R.R. The experiments made by myself extended , for all the above explosives , from densities of to or , and pressures of from tons per square inch ( 419 atmospheres ) to pressures of 60 tons per square inch ( 9145 atmospheres ) . The composition of the various explosives referred to are given , and experiments quoted to show that the transformation experienced on explosion at diHerent densities is practically identical . When explosives are fired in a gun , the chamber in which the charge is placed is , of course , full of air , and in my experiments the charges were similarly treated , but , to test the resulting difl'erences , charges were fired at the lowest densities in air , in nitrogen , and in vacuo , and the analyses of the products of explosion are given , and compared with the analyses of gases taken from the chamber of a gun after discharge . Although for the elucidation of the laws which govern the transformation of the explosives when fired I have taken the densities named , I must point out that the requirements of the artillerist are con fined to much narrower limits , the . density , of course , varying cousiderably with the particular explosive used . In modern guns , for example , the chamber density varies from about to nearly , a good deal of the variation being due to the nature of the explosive used . It is hardly necessary to point out to artillerists that the chamber density is not the density which is responsible for the pressure developed in the gum . The difference , which is frequently very considerable , is due to the time ffifk . A. Researches on Explosives . taken by the explosive to burn , and this depends upon the nature , form , and dimensions of the explosive , the expansion suffered by the nascent gases , and the heat lost , due to work done upon the projectile and by communication of heat to the gun , and , under these circumstances , the )ressuredevelo } ) would , with full charges , if compared with close-vessel pressures , represent densities approximately between and The tables which are given in my late commlmication* to the Royal Society gave for each particular density the actual result observed . In the present paper the observations have been corrected by drawing curves to represent as nearly as possible the whole of the results , the actual observations , which are also given , showing in each case the departure from the curve . If reference be made to the tables , it will ) observed how wide are the differences between the explosives , not only in the absolute volumes of the several gases , but in the variations with reference to the densities at which they were fired . Thus , for example , comparing and Italian Ballistites , while in the former the carbon monoxide colnmences at the density with a percentage volume of at a density of to 22 per cent. , the carbon dioxide commences with per cent. , rising rapidly to 31 per cent. In the latter explosive the CO commences at per cent. , and slowly to 15 per cent. , while the commences a little over 26 per cent. , rising also comparatively slowly to nearly 34 per cent. I may remark in passing that the Italian Ballistite is the only explosive with which I have where , at low densities , the volume of is greater than that of CO. But there are , in these two explosives , other remarkable differeIlces . Thus , in the Italian Ballistite , at a density of , the volume of lnethane , , is a mere trace , about per cent. , but it remains very much lower than is the case with any other explosive , being only per cent. at the density of . With the Norwegian , on the other hand , the , although the volume at commencement is only per cent. , is , at density , 11 ) cent. Again , as might be expected from the large quantity of found in the case of the Norwegian Ballistite , the volume of falls from over 20 per cent. to about 9 per cent. ; in the Italian the rises from about 8 per cent. to about 10 per cent. , slightly at higher densities . In both explosives the is practically constant at about 12 and 16 per cent. respectively , but there is a very great difl'erence as regards the 'Phil . Trans , pp. 221\mdash ; 223 . Not given iu this abstract . volume of 29 per cent. , falls at a density of 045 to about 24 per cent. No other explosive approaches the Italian Ballistite in respect to the large volume of aqueous vapour formed , especially at low densities . In the tables are given the volumes in cubic centimetres per gramme of the permanent and total gases , and curves have been drawn representing for the six explosives the observations of these volumes . In the case of five of the explosives there is , with increasing density , a very considerable decrease in volume , but with the Italian Ballistite , throughout the range of the experiments , there is hardly any change . Curves representing these volumes are concave to the axis of abscissae . In the tables are shown the units of heat , both for water fluid and water gaseous . Curves have also been drawn for the units of heat ( water gaseous ) ; the curves in this instance are all convex to the axis of abscissae , and it may be noted that , where the volumes of gas per gramme are large , the units of heat are low , and that , where the volumes of gas are rapidly decreasing , the curves representing the amount of heat developed show a rapid increase . The next point we have to consider is , the data being as shown in tables , what temperature are we to assign to that generated by the explosion ? With the view of studying the question , I resorted to two methods : ( 1 ) knowing with very considerable accuracy the units of heat ( water gaseous ) generated by the explosion , and having determined approximately the specific heat of the gases , the temperature of explosion should be given by the equation ( 2 ) Knowing also with considerable accuracy the pressure at any given density , and knowing the pressure when the volume of gas generated is reduced to the temperature of C. and a pressure of 760 mm. of the temperature is given by the equation With reference to Equation ( 1 ) , the specific heat of is a very important factor in this determination , and the recent researches of Messrs. Holborn and Austin upon the specific heat of gases at constant pressure at high temperatures having apparently shown that the specific heats given by Mallard and Le Chatelier for temperatures above C. are considerably too high , I have taken the ures given by these physicists\mdash ; which , I may observe , up to temperatures of 80 C. are confirmed by Langen . 1906 . ] on Explosires . The equation given by Holborn and Austin for the specific heat of at constant pressure is Specific heat being the temperature . The correctness of this equation for temperatures up to C. has been proved , and , assuming that the same equation holds up to 1300o C. , the specific heats for each 10 are riven in a table in the full paper . It will be observed from this table , that , between and 1400o C. there is a large increase in the value of the specific heat , yet the increments per are rapidly decreasing , vanishing at about 1400o C. , at which temperature* there would be partial dissociation at atmospheric pressure . The temperature would , however , probably require to be considerably at the pressures we are considering . The specitic heats given are , as I have said , those for constant sure , and to obtain those at constant volume it is necessary to divide by the constant , connecting the specific heats of gases and vapours at constant pressure and constant volume . I give the values I have used , ( 1 ) of the specific heats at constant pressure\mdash ; these are taken either from Holborn and Austin 's paper , or from Landolt Bornstein , ' Physikalisch-Chemische Tabellen , ' 1905 ; ( 2 ) of ths constant these are all taken from Landolt , pages 407-8 ; ( 3 ) of the specific heats at constant volume . The specific heats calculated from the above data , of the gases generated by the explosion of the six propellants , are given in the tables the results of the whole of the experiments for each propellant , and in the tables are also given the temperatures of explosion deduced from Equations ( 1 ) and ( 2 ) , and here yain it must be remembered that the temperatures with * Mendeleef , ' Principles of Chemistry , ' vol. 1 , ; also Deville , ' Comptes Rendus , vol. 66 , p. 729 ; and Berthelot , ' Comptes Rendus , ' vol. 68 , p. 1036 . Sir A. Noble . [ June which artillerists are chiefly concerned are those due to densities varying approximately between and Beginning with Equation ( 1 ) , the Italian Ballistite , which shows the highest temperature , commences at the density of with 494 C. , this temperature hardly varying at all till the density of is reached , when it slowly but regularly increases to about 5000o C. at . Cordite Mark I commencing at 4742o C. with a very fall is practically constant up to , after which it rises somewhat rapidly to a temperature of 492 C. at , and to 5065o C. at When , however , we come to the temperatures given by Equation ( 2 ) , we are met with some very remarkable differences , which are shown by the tables , but which are more readily appreciated if reference be made to reduced copies of Plates 7 , 8 , and 9 , in which the explosives are arranged in descending order of the temperatures developed . It will be observed that at the higher densities and pressures , there is generally a very tolerable accordance in the temperatn res obtained from the two formula , but as the density and pressure diminish , the divergence becomes in all cases considerable , but very greatly more with the explosives which develop very high temperatures , and which give rise to large of carbonic anhydride . The only construction I am able to put upon the tolerably close approximation of temperature given by the two formulae at densities and and the wide differences which exist in some of the explosives at low densities , is that , as I think it reasonable to expect , at high densities dissociation of the carbonic anhydride is prevented by the very high pressure , and that the great difference between , for instance , Italian Ballistite and Nitrocellulose B.R. at , say , the density of is due , firstly , to the difference of the temperature at which nascent gases enerated , and secondly , to the proportion of which is subject to dissociation . Formula ( 1 ) gives for Italian Ballistite at a temperatule of nearly 5000o C. ( and for this explosive the temperature given by units of heat divided by specific heat is nearly constant ) , while the percentage of is . The same formula gives for the nitrocellulose at the same density a temperature of formation of 3200o C. , while the percentage of is only I have pointed out that under atmospheric pressure the dissociation of commences at about 1300o C. , and the very much higher temperatures of formation of the gases of the Italian Ballistite , combined with its double percentage of , appear to me to be sufficient to explain the results obtained with this explosive . If reference be made to on Plate 6 , it will be seen that while at the 1906 . Researches on Explosives . density of there is , with Italian Ballistite , a difference of about 1800o C. between the two formulae , there is with the nitrocellulose a difference only of under 80 C. The theory I venture to submit is as follows:\mdash ; The nascent gases are generated at temperatures approximately as given by Equation ( 1 ) and by the upper curve of each explosive in figs. , VIII , and IX . Under the low densities and pressures at the very high temperatures with which we are concerned , the , and possibly some , are partially dissociated , giving rise to the fall in temperature exhibited by the results obtained from Equation ( 2 ) at low densities . At high densities , as already pointed out , the two equations give , in some cases , accordant results , in all cases tolerable agreement ; it therefore appears to me to be reasonable to suppose nhat the facts I have recorded are due to partial dissociation at low densities and pressures , which dissociation is preyented by the very pressures ruling at densities of , and As no free oxygen is ever found in the analyses , in down , any free oxygen due to dissociation must have re-combined , and the heat lost by dissociation regained . The re-combination must , however , be very gradual , as no discontinuity is observed in the cooling curves . It is then pointed out that a certain amount of confirmation is given to the view taken by the fact that if the explosives be arranged according the amount of heat generated , derived from Equation ( 1 ) , regard being also had to the amount of found , it will be found that the between the two formulae decrease approximately as the factors , to which I have referred , decrease , and a table is given showing these differences . At the density of the differences between the two formulae are as follows:\mdash ; Difference . Italian Ballistite 15 C. Cordite Mark I 200 M.D . 320 Norwegian Ballistite 167 250 Norwegian Ballistite 165 130 Nitrocellulose 180 It will be observed , both from the above figures and the curves , that with the Italian Ballistite alone at the density is the temperature derived from Equation ( 2 ) lower than that derived from Equation ( 1 ) . With all the other explosives the temperatures derived from Equation ( 2 ) are the higher . Researches on Explosives . The differences , however , are not great , being generally under 5 per cent. , that is , under 20 C. In the case of experiments carried on both at pressures and temperatures very greatly above the limits at which physicists ordinarily experiment , I can hardly hope that the methods I have employed , and the conclusions at which I have arrived , will escape criticism . The results of the experiments given in the tables and plates , may , however , be taken as very approximately correct , and the repeat experiments I have made show that there is great constancy in the transformation which takes place on explosion at any given density . I conclude by expressing my obligation to Dr. Sodeau and Mr. Hutchinson for their assistance in carrying out the various experiments , in the analyses and in the laborious but necessary calculations . \mdash ; In the case of the Norwegian Ballistites , the pressures at densities above have been corrected to accord with the values obtained from the volume of the gas generated , multiplied by the units of heat determined ,

rspa_1906_0074

0950-1207

On the \#x201C;Kew\#x201D; scale of temperature and its relation to the international hydrogen scale.

225

240

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

J. A. Harker, D. Sc.|R. T. Glazebrook, D. Sc., F. R. S.

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10.1098/rspa.1906.0074

Thermodynamics

Tables

Thermodynamics

225 On the " Kew " Scale of Temperature and Relation to the International Hydrogen Scale . By J. A. Harker , D.Sc . , Assistant at the National Physical Laboratory . ( Communicated by R. T. Glazebrook , D.Sc . , F.R.S. Received June 23 , \#151 ; Read June 28 , 1906 . ) ( From the National Physical Laboratory . ) In October , 1887 , the International Committee of Weights and Measures adopted as the standard thermometric scale to which all temperature measurements were to be referred that of the constant-volume hydrogen thermometer.* When , therefore , thermometric readings are expressed on any other scale the correction to be applied to these to bring them into accord with this standard becomes of importance . By far the majority of temperature measurements are made by means of mercury thermometers . The ideal mercury thermometer would be one which when subjected to any steady temperature would assume immediately a steady reading identical with that given by the hydrogen thermometer at the same temperature . This ideal is , as might be expected , not attained by any known mercury-in-glass thermometer , and the amount of the departure from the ideal at different temperatures depends on the particular kind of glass employed . So long ago as 1847 Regnault was aware of this fact , and showed that for several of the best thermometric glasses then in use the departure might attain as much as 10 ' C. above 300 ' C. For many years thermometers have been verified at Kew Observatory in large numbers annually , their indications being referred to the Kew Scale of temperature . It has recently become a matter of interest to determine to what degree of accuracy the Kew Scale may be considered as identical with that of the hydrogen thermometer , and this memoir gives an account of some experiments undertaken at the National Physical Laboratory with a view to elucidate this question . The only comparisons between Kew thermometers and the gas thermometer of which the author has been able to find a record are those by * The resolution was as follows :\#151 ; " That the International Committee of Weights and Measures adopt as the normal thermometric scale for the international service of weights and measures the centigrade scale of the hydrogen thermometer , having as fixed points the temperature of melting ice ( 0 ' ) and that of the vapour of distilled water in ebullition ( 100 ' ) , under the normal atmospheric pressure ; the hydrogen being taken under the nianometric initial pressure of 1 metre of mercury , i.e. , at 1000/ 760 = 1.3158 of the atmospheric pressure . " VOL. LXXVIII.\#151 ; A. Q 226 Dr. J. A. Harker . " Kew"Scale of Temperature [ June 23 , Balfour Stewarb * the observations of Wiebe , t the observations of Guillaume , made at the Bureau International des Poids et Mesures , and the work of ChreeJ Of these , the first and the last are confined to determinations of the difference between the two scales at the freezing point of mercury . Chree found that at this temperature the mean departure of 20 calibrated Kew standards was 0a45 F. , the mean temperature on the Kew scale being \#151 ; 38''35 F. , while Balfour Stewart 's value for the true temperature on the air scale was \#151 ; 37'"9 F. Wiebe 's determinations were confined to a single thermometer , which was only divided to | ' C. The composition of the glass of this instrument is given as:\#151 ; Silica 44-49 Lime L20 Lead oxide 33-90 Magnesia 0-67 Potash 12-26 Alumina and iron oxide. . 0-35 Soda 1-54 Manganese oxide 0-13 He compared the instrument directly against an air thermometer between 0 ' and 100 ' C. In a rSsumS on mercury thermometry by SchloesserS the results of Wiebe are given re-calculated as divergences from the hydrogen scale as follows :\#151 ; Difference . Temp. TEng . gl . - THyd . 10 ' ... ... ... ... ... . +0-008 ' 20 ... ... ... . . +0-001 30 ... ... ... ... . +0-017 50 -0-057 60 -0-073 70 -0-079 90 -0-046 These numbers are derived from a smoothed curve drawn through the observed values , and take no account of considerable irregularities , which manifested themselves at various points throughout the scale . The fact that the mercury thermometer reads lower than the hydrogen over nearly the whole range is pointed out by Wiebe as very unusual . * 'Phil . Trans. , ' 1863 , p. 425 . t 'Berliner Sitz . , ' 1885 , p. 1021 ; and later , ' Zeit . fUr Instr . , ' vol. 10 , p. 435 , 1890 . X ' Phil. Mag. , ' vol. 45 , p. 225 , 1898 . S ' Zeit . fur Instr . , ' vol. 21 , p. 296 , 1901 . 1906 . ] and its Relation to the International Hydrogen Scale . 227 The observations of Guillaume quoted by Benoit* relate to a single English glass standard and appear to have reference to the " movable zero " method . They gave\#151 ; Difference . Temp. Tfing . gi.\#151 ; THvd . 0'C ... ... ... ... ... . +0-000 10 ... ... ... ... ... +0-007 20 +0-005 30 -0-004 40 -0-012 50 -0-021 The usual type of Kew standard thermometer is an instrument having a range from below 32 ' to above 212 ' F. , and is usually divided only to 1 ' F. The stems are always of the solid cylindrical type , 5 to 7| mm. in diameter , and are sometimes with , sometimes without , milk-glass backing . The capillary is always of circular section , and the diameter of the bulb is never greater than that of the stem ; but large spherical bulbs were used on some of the oldest specimens . Measurement of a number of representative specimens made at various times over a period of 50 years showed the length of a division ( 1 ' F. ) varied from 1 to 3 mm. , and that the thickness of the division line subtended a length of stem corresponding to from 0o,04 to 0o,08 F. This type of thermometer was intended for work to an accuracy of 0'-l or 0'-05 F. For the purpose of this research it was thought desirable , after studying the behaviour of a number of these old thermometers , to construct new standards , having a more open scale and capable of being read to higher accuracy , and to treat these from the beginning in a definite and systematic manner . The usual type of Kew standard is graduated so as to correct any irregularities in the calibre of the stem , this being effected by making a preliminary calibration of the tube , and appropriately lengthening or shortening the divisions throughout the scale . This is generally successful to the extent that no calibration error exceeding 0'"05 C. persists . Hence the application of a calibration correction is rendered unnecessary . The readings of a Kew standard are always understood to apply to the thermometer in a vertical position when immersed in water up to the reading , and the instruments are always intended to be used as " fixed " rather than " movable zero " instruments . That is , the normal procedure to measure any temperature on the Kew scale would be to first determine the zero and afterwards the temperature in question , applying to the latter a * " D6termination du Rapport du Yard au Metre , " Bur . Int. Poids et Mes . , 1896 . 228 Dr. J. A. Harker . " Kew"Scale of Temperature [ June 23 , constant correction for any deviation of the zero point from its nominal correct value , 0 ' C. , or 32 ' F. , and ignoring all changes of zero produced in the thermometer by exposure to the higher or lower temperature in question . The increased sensitiveness desired in the new instruments was obtained by constructing them as is now usual for standard work so that the range between boiling and freezing points was spread over two distinct stems . Accordingly , in 1902 , 12 thermometers of the solid stem type were blown by Mr. Hicks from glass furnished by Messrs. Powell from their stock , the makers assuring us that it was identical in composition with that supplied for ordinary Kew standards . The thermometers were annealed very thoroughly according to the following scheme:\#151 ; On August 19 , 1902 , they were heated for eight hours to temperatures varying between 260 ' and 290 ' C. During this heating the ice-points rose permanently an average of 15 mm. on the scale , i.e. , almost exactly 2 ' C. On August 27 they were again heated for six hours to 250 ' C. , and slowly cooled . There was no further general change of zero point . On September 22 they were heated to 150 ' C. for 24 hours , and slowly cooled , and in November their fundamental and 50 ' points were determined . To permit of the relatively high temperature of this anneal the thermometers were provided with an auxiliary chamber at the top of the stem , in addition to the one always present in Kew standards ranging to the boiling point . This chamber was sufficiently large to contain the necessary mercury to permit of the exposure of the thermometers to a temperature of about 300 ' C. Of the 12 thermometers , six were used for this work , all having about the same dimensions and sensitiveness ; Nos. 776 , 778 , and 780 read from below 0 ' to above 50 ' , and had the portion between 50 ' and 100 ' shortened by substitution of a small bulb for the upper part of the stem between about 52 ' and 98 ' . In Nos. 777 , 779 , and 782 the shortening was between -f 2 ' and 48 ' , a few degrees of stem being also available above and below the boiling point.* The table on p. 229 shows their characteristic dimensions . They were all graduated into approximate degrees centigrade by Mr. Foster at Kew , in March , 1903 , with the exception of No. 782 , which was completed in January , 1905 , to replace No. 781 accidentally broken . * Thermometers Nos. 776 and 777 were only used in the later comparisons , the initial experiments being confined to the other four . 1906 . ] and its Relation to the International Hydrogen . 229 No. Range . Nature of stem . Length of one degree . Thickness of stem . Centre of bulb to 0 ' . 0\#151 ; 50 ' . 50\#151 ; 100 ' . 776 'c . 'c . \#151 ; 2 to 51 and 98 to 102 Milk glass mm. 8-05 mm. 5 -45\#151 ; 5 -50 mm. 55 mm. 402 mm. 53 777 \#151 ; 2 , , +1 " 49 " 107 7 -30 5 -55\#151 ; 5 -60 62 30 365 778 \#151 ; 2 " 53 " 97 " 102 u 7-60 5 -75\#151 ; 5 -80 60 380 73 779 -2 " +l " 48 " 105 7*40 5 -95\#151 ; 6 05 58 44 370 780 -2 " 52 " 97 " 102 Transparent 7-76 5 -95\#151 ; 6 -00 53 388 71 782 -1 " + l " 48 " 105 7-41 5 -90\#151 ; 5 -95 53 56 371 Each thermometer was then calibrated with threads of varying length . First a division into two parts was made with four different columns , approximately 50 ' C. ; then a further subdivision of the principal 50 ' on each stem by two different 10'-columns . This gave with very considerable accuracy the calibration correction for every 10'\#151 ; the points close to which comparisons were subsequently made . In addition two different 2'-columns were observed with their ends at every even two degrees throughout the scale . From the general mean of the 2'-calibrations perfectly independent values were found for the corrections at 10 ' , 20 ' , 30 ' , 40 ' , etc. In all cases where the length of the 2'-column was a close approximation to 2 ' , the results of the two independent calibrations agreed to within the limits of error of such work , and it was always possible to deduce the true calibration correction near the principal points\#151 ; 10 ' , 20 ' , 30 ' , etc.\#151 ; to within two or three thousandths of a degree . As in this type of thermometer , owing to the presence of the auxiliary chamber , increments of pressure on the bulb are not directly proportional to increments of temperature , a correction has to be determined to reduce the readings at any point to what it would have been had the point 50 ' C. been exactly half way between 0 ' and 100 ' . For this purpose observations of the 100 ' point of each of the thermometers were made in the Chappuis steam bath in both horizontal and vertical positions , and from these the pressure coefficient of each thermometer was calculated . From these observations the following corrections were found for the six thermometers for the point 50 ' C. , giving the amount to be added or subtracted from the reading to make the indications of the instrument comparable with the normal type having a continuous scale from 0 ' to 100 ' C. on p. 230 . The thermometers were compared with the standards of the laboratory and one or two other Tonnelot thermometers of French " verre dur , " the relation of whose indications to the hydrogen scale had been previously thoroughly 230 Dr. J. A. Harker . " Kew " Scale of Temperature [ June 23 , No. of thermometer . Pressure correction for point 50 ' C. Internal pressure coefficient , degrees per millimetre . 776 + 0-029 0 -0001676 777 -0 -029 0 -0001762 778 + 0 -026 0 -0001670 779 -0 -028 0 -0001706 780 + 0 -036 0 -0002259 782 -0 -036 0 0002310 studied . Great care was taken to use the Kew standards under the same conditions as they would ordinarily be subjected to at Kew . It is known that the indications of a Kew standard depend on the treatment to which it has been subjected previous to use , and that a thermometer which had often been used over the higher part of its range would not follow the same law as to depression of its zero as one used but seldom . In order to make strictly consistent the results obtained for the upper and lower parts of the range , got from the two different types of thermometers , in all cases the pairs Nos. 776 and 777 , 778 and 779 , and 780 and 782 were treated as single instruments , being always taken through precisely similar cycles of temperature change . Dr. Chree , the Superintendent of the Observatory Department , was good enough to draw up a detailed memorandum as to the methods employed at Kew for their standards used in verification work , and it has been the object throughout this investigation to imitate this practice as closely as possible . After finishing the calibrations , etc. , and determining the zeros , the thermometers were placed in the comparison bath , * which was electrically heated and stirred continuously , and were slowly taken up from the ordinary temperature to the boiling point , the latter being attained in about five hours . The current was shut off after the boiling had continued about half an hour , and the bath was then allowed to cool slowly , with the thermometers in position . This treatment was repeated on three successive days . An interval of one clear day was then allowed , and the comparisons were begun on the following day , an observation of the zero being previously made , and a boiling point determination at the close . * The bath consisted of two vertical cylindrical vessels , about 20 inches high , connected by horizontal cross tubes near the top and bottom . The whole vessel held about 20 litres of water . The stirring was continuous and very perfect throughout the whole of the larger tube , in which the thermometers were placed . The heating was electrical and could be arranged to give either a stationary temperature or any desired rate of slow rise or fall . It is hoped shortly to publish descriptions , with drawings , of this and other thermometric appliances used at the Laboratory in a special paper . 1906 . ] and its Relation to the International Hydrogen Scale . 231 This treatment of heating to the boiling point , and allowing a clear day subsequent to this before commencing the observations , was repeated on each separate occasion , when a complete comparison was made . The sets of observations were made intentionally at intervals of several weeks to test the behaviour over a considerable period . The following table gives a summary of the observations with thermometers Nos. 778 and 779 , the different columns giving the mean values obtained , usually from two , sometimes from four , groups of readings , each group consisting of four observations of very slowly rising temperatures :\#151 ; Summary of Comparisons\#151 ; Thermometers Nos. 778 and 779 . Date . Zero position before observation . Temp , on Kew scale . Temp , on Hydr . scale . Difference , Kew\#151 ; by dr . No. 778 . December 1 , 1905 -0-044 10 -051 10 -044 + 0-007 19 -853 19 -845 + 0-008 29 -840 29 -838 + 0-002 40-038 40-036 + 0 -002 50 -061 50 -070 -0-009 February 6 , 1906 -0 -020 20 -006 20 -000 + 0 -006 40-048 40-049 -o-ooi 49 -842 49 -849 -0 -007 April 30 , 1906 -0 -036 10 -296 10 -296 0-000 10 -377 10 -375 + 0-002 20 -232 20 -240 -0-008 30 -389 30 -398 -0 -009 40-067 40 -077 -0 -oio 50 -214 50 -231 -0-017 May 30 , 1906 -0-002 20 -052 20 -039 + 0-013 30 -201 30 -184 + 0-017 40 -257 40-248 + 0-009 50 -089 50 -084 + 0 -005 No. 779 . December 1,1905 1 + 0 -015 50 -052 50 -070 -0 -018 59 -945 59 -959 -0 -014 69 959 69 -979 -0 -020 79 -411 79 -448 -0-037 89 -060 89 -090 -0-030 February 6 , 1906 + 0-027 50 -468 50 -517 -0-049 60 -423 60 -445 -0 -022 80 -402 80 -420 -0 -018 April 30 , 1906 + 0 -003 50 -357 50 -365 -0 -008 60 -317 60 -342 -0 -015 69 -786 69 -811 -0 -025 79 -979 80 -009 -0 -030 89 -805 89 -837 -0-032 89 -933 89 -956 -0-023 May 30 , 1906 + 0 -031 50 -510 50 -509 + 0-001 59 -887 59 -889 -0 012 69 -800 69 -825 -0-025 79 -852 79 -882 -0 -030 89 -573 89 -609 -0-036 232 Dr. J. A. Harker . " Kew"Scale of Temperature [ June 23 , The concordance of the different observations at any temperature is seen from the accompanying curves , in which all the observations are plotted . Departures . Kew-Hyd . in degrees Centigrade . Op Op Oq Qq O Oq Qq Op Op Op Op Oq O Oq 0o Oq Qq 1906.1 and its Relation to the International Hydrogen Scale . 233 The following example , selected at random from the note-book of observations , shows the order of accuracy of the individual comparisons , etc.:\#151 ; Comparisons of February 6 , 1906 , Thermometers Nos. 778 and 780 with Tonnelot No. 15,504 and Baudin No. 15,959 . Zero readings after thermometers had been at room temperature , approximately 10 ' C. , for several days , then for an hour in bath at about 20 ' C. Zero corresponding to 20'\#151 ; Tonnelot No. 15,504 ... \#151 ; 0-007 Kew No. 778 ... ... ... . \#151 ; 0-020 Baudin No. 15,959 ... . + 0-109 Kew No. 780 ... ... ... . \#151 ; 0'060 No. 15,504 . Kew No. 780 . Kew No. 778 . 1 No. 15,959 . First set of observations ( J. A. H. , observer ) . 19 -852 20 -045 19 -900 20 -020 .870 .060 .910 .025 .900 .080 .950 .060 .920 .100 .955 .060 19 -885 20 -071 19 *929 20 -041 Second set of observations ( W. H. , observer ) . 20 -120 20-300 20 -160 20 -280 .140 .310 .170 .290 .155 .330 .190 .325 .165 .350 .195 .325 20 -145 20 -322 20 -179 20 -305 For the Kew thermometers the fundamental interval , as got from observations of the steam-point at the close of the day 's work , was found\#151 ; For No. 778 ... ... . . \#151 ; 100-012 Hence F. I. correction ... = \#151 ; 0-012 And for No. 780 ... \#151 ; 99*996 " " ... = -t-0'004 Reduction of Observations . Kew No. 778 . Kew No. 780 . Tonnelofc 15,504 . Baudin 15,959 . I Reading Cal . cor Press , cor F. I. cor Zero cor \#166 ; 19 -929 -0 -077 + 0-011 -0-003 + 0 -020 20 -071 -0 -274 + 0-014 + 0-001 + 0 -060 Reading Cal . cor Int. press Ext. " P. I. cor Zero cor 19 -885 + 0 -066 + 0-027 + 0-000 -0-016 -0-007 20 -041 -o -on + 0-031 + 0-000 + 0-000 -0-109 19 -880 19 -872 Hyd 19 -955 -0-085 19 952 -0 -085 19 -870 19 -867 Mean hydrogen temperature for first set = 19"869 . 234 Dr. J. A. Harker . " Kew " Scale of Temperature [ June 23 , Kew No. 778 . Kew No. 780 . Tonnelot 15,504 . Baudin 15,959 . Beading Cal . cor Press , cor F. I. cor Zero cor 20 -179 -0-075 + 0-011 -0-003 + 0-020 20 -322 -0-275 + 0 -014 + 0-000 + 0-060 Beading Cal . cor Int. press Ext. " P. I. cor Zero cor 20 -145 + 0-066 + 0-027 + 0-000 -0 -016 -0-007 20 -305 -0 Oil + 0-031 + 0-000 + 0 -ooo -0 -109 20 -132 20 121 Hyd 20 -215 -0-085 20 -216 -0-085 20 -130 20 -131 1 Mean hydrogen temperature for second set = 20131 . Kew No. 778 . Kew No. 780 . Mean of two sets ... ... . . 20*006 19*998 Mean hydrogen temperature Departure from hydrogen +0*006 \#151 ; 0*002 for mean of both sets = 20*000 . It will he observed that , owing to calibration and zero corrections of considerable magnitude , the readings of the two standards differed at this temperature about 0'*16 C. , but when the various corrections were applied in accordance with the usual procedure the concordance between the two thermometers was very satisfactory . Owing to the fact that four out of the six Kew thermometers have milk-glass back to the stems it is only possible to read them in one position , i.e. , divisions at the front , and therefore no elimination of any want of verticality in the bath is possible by the method of turning round the thermometer usually employed in the best work . For the same reason only one position is possible for the zero observations . In the zero bath great attention was paid to the strict alignment of the spring clips holding the thermometer in the ice , but in the comparisons , owing to the surging caused by the stirrer , slight motions of the thermometers were inevitable . A tilt of 1 ' from the vertical position would in the Kew thermometers cause a parallax error of about 1/ 20 mm. or 0'*007 C. The whole of the observations were plotted on a large scale , a reproduction of which is given in the figure , and from a consideration of the individual values , curves were drawn representing the mean departure of each thermometer from the hydrogen scale throughout its range . From these curves the following values were read off:\#151 ; 1906 . ] and its Relation to the International Hydrogen Scale . 235 Mean Departure from Hydrogen Scale . No. 776 . No. 778 . No. 780 . Mean . 1 ! 0 o-ooo o-ooo o-ooo o-ooo^ 10 -0-008 + 0-004 + 0-006 + 0-001 20 -0 -022 + 0-007 + 0-006 -0-003 30 -0 -020 + 0-006 + 0-001 -0 -004 40 -0 -028 -o-ooo -0-003 -0 -oio 50 -0 035 -0-008 -0 -009 -0 -017 No. 777 . No. 779 . No. 782 . -0 -oio 50 o-ooo -o-oio -o-ooo -0-003 60 -0-005 -0 -015 -0-005 -0-008 70 -o-oio -0 -022 -0 -oio -0-014 80 -0-015 -0-033 -0-018 -0-022 90 -0-020 -0 -032 -0 -020 -0-024 100 o-ooo o-ooo o-ooo o-ooo^ If the behaviour of the pairs of thermometers were absolutely consistent , the departure from the hydrogen scale of the low-range and high-range types at 50 ' C. should be identical . The discontinuity is , however , very small except in the case of Nos. 776 and 777 . The differences in the last column of the table above are many of them of the same order as the accidental errors of observation in the best work . Thus for example in his " Etudes sir le thermometre a gaz " during some elaborate comparisons of the primary standard thermometers Nos. 4428 , 4429 , 4430 and 4431 , on which the " verre dur " scale depends , Chappuis found that in one series at 60 ' C. , No. 4428 read 0o,008 higher than the mean of four , and No. 4429 0o,012 lower , while in a second series the positions were reversed , No. 4428 reading 0''008 lower than the mean , and 4429 the same amount higher . In addition to the work on the new special thermometers a systematic comparison was also made of a number of old Kew standards of the ordinary construction divided to whole degrees Fahrenheit . A selection was made of thermometers of widely differing types , which had necessarily been subjected to varying treatment . The zeros of some of them had been displaced appreciably from their original positions . After applying the usual zero-correction to all the observations , but no calibration-interval correction , the results in the table on p. 236 were obtained for the divergence of each from the hydrogen scale . Of these thermometers No. 560 , a high-range thermometer , had a considerable zero error , having been frequently used in the upper part of its scale , and No. 41 was of a somewhat unusual type , and much older than the others , with a transparent stem and spherical bulb . It was formerly the Old Kew Standards . Differences Kew\#151 ; Hyd . ( expressed in degrees Centigrade ) . No fundamental-interval correction applied.* No. 544 . No. 560 . No. 722 . No. 728 . No. 41 . No. 686 . Range -40 ' to 215 ' F. -10 ' to 555 ' F. -45 ' to 222 ' F. -20 ' to 122 ' F. 0 ' to 220 ' F. -20 ' to 225 ' F. Thickness of stem 7-5 7 7 6-5 ( Spherical bulb , transparent stem ) 7 5 Length of 1 ' in mm. ... 21 1 1-9 2 *7 2 2 1-9 Date of completion September , 1877 June , 1878 July , 1895 March , 1896 July , 1852 January , 1889 Maker T. W. Baker T. W. Baker J. Foster J. Foster \#151 ; J. Foster 0 ' c + 0-00 + 0-00 + 0-00 + o-oo -0-00 + 0-00 10 + 0-01 + 0-01 + 0-01 + 0-02 -o-oi + 0-02 20 + 0-02 + 0-02 + 0-02 + 0-03 -0 01 + 0-05 30 + 0-02 + 0-03 + 0-01 + 0-03 -0-02 + 0-07 40 + 0-03 + 0-03 + 0-02 + 0-03 -0-03 + 0 TO 50 + 0-04 + 0-04 + 0-04 + 0-03 -0-06 + 0T2 ( 50 + 0-04 + 0-03 + 0-05 + 0-02 -0-08 + 0T3 70 + 0-05 + 0-03 + 0-06 + 0-01 -0-09 + 0-14 80 + 0-06 + 0-05 + 0-06 + 0-01 -0-08 + 0-15 90 + 0-06 + 0-04 + 0-05 + 0-01 -0-05 + 0T5 * The usual Kew practice would be to apply to any thermometer , new or old , in which a fundamental interval error was observed , as , for example , No , 686 above , the requisite corrections throughout the scale . 236 Dr. J. A. Harker . " Kew " Scale of Temperature [ June23 1906 . ] and its Relation to the International Hydrogen Scale . 23 property of Mr. G. Griffith , of Harrow , and was obtained for the laboratory by the kindness of Mrs. Griffith in 1904 . It will be seen that its scale is almost absolutely identical with that of the thermometer examined by Wiebe . The above readings apply to the thermometers assuming their fundamental interval to be correct . As , however , the departure from the hydrogen scale is of the opposite sign in the first four instruments to that found in the new standards , it was thought desirable to make measurements of the fundamental intervals of some of them . Ho. 544 was found to need a fundamental interval correction of \#151 ; 0a07 , Ho. 560 of \#151 ; 0o,06 , Ho. 722 of \#151 ; 0o,03 and Ho. 686 of \#151 ; 0o,17 . Applying these to the results in the above table , we have as the true departure of the scale of these from the hydrogen scale:\#151 ; Old Kew Standards . True Departures from Hydrogen Scale . Temp. 'C . No. 544 . No. 560 . I No. 722 . No. 686 . 0 + 0-00 +o-oo + 0-00 + o-oo 10 + 0 '00 + 0-01 4-0-01 + 0-00 20 + o-oo + 0-01 + 0-01 + 0-03 30 + 0-00 + 0-01 + 0-00 + 0-02 40 + o-oo + 0-00 + 0-00 + 0-03 50 +o-oo + 0 -oi + 0-02 + 0 03 60 +o-oo -o-oi + 0-03 + 0-02 70 + o-oo -o-oi + 0-03 + 0-02 80 + o-oo -o-oo + 0-03 + 0-02 90 +o-oo -o-oi + 0-02 + 0*01 100 +o-oo o-oo + 0-00 + o-oo When it is remembered that the length of 1 ' C. on these thermometers only covers from 2 to 4 mm. and that the divisions are relatively thick , it will be seen that these divergences are wholly negligible , and that within the limits of error attainable all these thermometers used in the normal way by the " fixed zero " method give a close approximation to the hydrogen scale . Before commencing the first of the normal series of comparisons of the special standards it was deemed to be a matter of considerable interest to make a series of comparisons when the thermometer zeros were in the relatively high position they had attained after the instrument had been a long time at the ordinary temperature . The observations in this set were very complete and extended over two days . Zeros were taken before commencing work , after the comparisons at 50 ' on the first day , after a second comparison at the same temperature on the second day , and after the steam-points at the conclusion of the observations . From these were obtainable all the data required to calculate the observations , first by the ordinary method , 238 Dr. J. A. Harker . " Kew"Scale of Temperature [ June 23 , applying the fixed zero determined at the commencement , and second applying a depressed zero calculated by interpolation , from the observations after 10 ' , 50 ' and 100 ' . The fundamental interval correction determined from the steam-point values taken at the finish is , however , notably different in the two systems . Thus , for example , the fundamental interval of No. 778 on the fixed zero method is 100o,001 , and on the depressed 100o,085 . The table gives a summary of the differences , Kew\#151 ; Hyd . , obtained by calculating out the same set of values on the two systems . Summary of Observations calculated by both Methods . Temp. Ordinary method fixed zero after 10 ' . Mean departure ordinary method . Depressed zero method calculated from zeros observed after 10 ' , 50 ' and 100 ' . Mean departure depressed zero method . No. 778 . No. 780 . Kew \#151 ; Hyd . No. 778 . No. 780 . Kew\#151 ; Hyd . Sept. 11,1905 O 10 + 0-008 + 0-000 + 0-004 o-ooo -0-005 -0-002 33 20 + 0-009 -0-008 + 0-000 -0-003 -0-006 -0-004 33 30 + 0-009 -0 -009 + o -ooo -0-006 -o-ooo -0-003 33 40 -0-007 -0 -017 -0-005 -0-024 -0-002 -0-013 33 50 -0 011 -0 -036 -0-024 -0-030 -0-013 -0-021 No. 779 . No. 782 . No. 779 . No. 782 . \#187 ; 3 50 -0-018 + 0-004 -0-007 -0-037 -0-014 -0-025 Sept. 12,1905 50 -0 -019 + 0-004 -0-007 -o-ooi -0-008 -0-005 33 50 -0-011 + 0-008 -0-002 + 0-015 -0-006 -0-004 33 60 -0-020 + 0-002 -0-009 + 0-001 -0-008 -0-003 33 70 -0-017 + 0 -006 -0-005 -0 -002 -o-ooi -0-002 33 80 -0-039 -0-013 -0 -026 -0-029 -0-018 -0-024 33 90 -0-039 -0 -007 -0 -023 -0 -034 -0 -009 1 -0-022 In judging of the results obtained with this series it must be remembered that with thermometers in their virgin state the zero movements are relatively large , and that the time of exposure to any temperature higher than that to which they have been long subjected has a marked influence on the results obtained . A very long period of rest is necessary to completely eliminate the effects of the unavoidable warming of the bulbs in the severing of columns for calibration purposes , and it is not certain that the effect of this warming would be identical in all cases . In so far as can be judged from a single set of observations with the thermometers after lying by for a considerable period , there appears to be almost complete agreement between results of the two methods of using the thermometers , these being in the state when differences would be most likely to be manifested . The results given by 1906 . ] and its Relation to the International Hydrogen Scale . 239 the thermometers do not differ appreciably from what is obtained when in the more normal condition after exposure to varied temperature ranges . The main conclusions of the work are therefore:\#151 ; ( 1 ) The departure of the natural scale of the " Kew " mercury-in-glass thermometer from the international hydrogen scale is very small at all temperatures . ( 2 ) For measurement of temperature differences over ordinary ranges such as in calorimetry , the results obtained directly or indirectly from a Kew standard may be considered as hydrogen temperatures without application of any correction . ( 3 ) In some instances when defining the temperature at which certain standards have their definite value , such as , for example , the temperature 62 ' F. for the British standard yard , the temperature scale to which the measurement referred was not definitely specified . This research renders it probable that if the instrument were a good English glass thermometer approximating to a Kew standard , the error made in considering its indications as identical with the hydrogen scale would be within the limits of accuracy of length measurements . ( 4 ) For the ordinary ranges of meteorological and clinical thermometers reading to 0o , l F. , many thousands of which have been verified at Kew annually for many years past , the temperatures as given on the Kew certificate may be considered as hydrogen temperatures . ( 5 ) The table appended gives the mean departure from the hydrogen scale of the " Kew " scale of temperature as observed in this investigation , the figures being rounded to the most probable 0o-005 C. For comparison purposes the figures for French " Verre Dur"and for Jena " Glass 16 , / / " are added in parallel columns , it being understood that each glass is treated in the manner prescribed for it : the Kew glass being a " fixed zero " scale and the other two " movable zero . " Differences in Degrees Centigrade . Kew glass . TKew \#151 ; THyd . Verre dur . Tvd \#151 ; THyd . Jena glass . Ti6"'-THyd . 0 + 0-000 + 0-000 + 0-000 10 + 0-000 + 0-052 + 0 -056 20 + 0-000 + 0-085 + 0-093 30 -0-005 + 0 -102 + 0-113 40 -0 . 010 + 0-107 + 0 -120 50 -o-oio + 0-103 + 0-116 60 -o-oio + 0 -090 + 0-103 70 -0 015 + 0-072 + 0 083 80 -0 -020 + 0-050 + 0-058 90 -0 025 + 0 -026 + 0-030 100 -o-ooo + 0-000 + 0-000 240 Determinations of Wave-length from Eclipse Spectra . In conclusion , I must express my indebtedness to the Director of the Laboratory , Dr. Glazebrook , at whose instigation this work was carried out , to Dr. Chree , Superintendent of the Observatory Department , for much valuable information , and to Mr. W. Hugo , who was responsible for the whole of the observational work of the calibrations and also assisted in the comparisons . Determinations of Wave-length from Spectra obtained at the Total Solar Eclipses of1900 , 1901 and 1905 . By Professor F. W. Dyson , F.R.S. ( Member of the Expeditions from the Royal Observatory , Greenwich ) . ( Received April 25 , \#151 ; Read May 17 , 1906 . ) ( Abstract . ) This paper gives the wave-lengths deduced from measures of a number of photographs of the chromosphere and corona obtained in three eclipse expeditions from the Royal Observatory , Greenwich . The spectra extend from wave-length 3300 to 5875 . Nearly all the brighter lines of the chromosphere are identified with practical certainty , the observed wave-length differing in very few cases by 0T tenth-metre from the line with which it is identified . The identification was principally made by comparison with the spark spectra of Exner and Haschek , Sir Norman Lockyer 's results being used for " enhanced " lines . For comparison , the intensities of the corresponding lines in the spark , arc , and solar spectra are given , obtained from various published sources . The wave-lengths and intensities of a number of lines in the spectrum of the higher chromosphere obtained at Sfax in 1905 are also given . The wave-lengths and intensities of the lines observed in the spectra of the corona at the three eclipses are also given . The paper is purely descriptive and shows in detail the relation between the chromospheric spectrum and those of the spark and arc , but does not attempt to assign physical causes to the differences and resemblances .

rspa_1906_0075

0950-1207

Determinations of wave-length from spectra obtained at the total solar eclipses of 1900, 1901 and 1905.

240

240

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Professor F. W. Dyson, F. R. S.

abstract

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0075

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10.1098/rspa.1906.0075

Atomic Physics

Biography

Atomic Physics

240 Determinations of Wave-length from Eclipse Spectra . In conclusion , I must express my indebtedness to the Director of the Laboratory , Dr. Glazebrook , at whose instigation this work was carried out , to Dr. Chree , Superintendent of the Observatory Department , for much valuable information , and to Mr. W. Hugo , who was responsible for the whole of the observational work of the calibrations and also assisted in the comparisons . Determinations of Wave-length from Spectra obtained at the Total Solar Eclipses of1900 , 1901 and 1905 . By Professor F. W. Dyson , F.R.S. ( Member of the Expeditions from the Royal Observatory , Greenwich ) . ( Received April 25 , \#151 ; Read May 17 , 1906 . ) ( Abstract . ) This paper gives the wave-lengths deduced from measures of a number of photographs of the chromosphere and corona obtained in three eclipse expeditions from the Royal Observatory , Greenwich . The spectra extend from wave-length 3300 to 5875 . Nearly all the brighter lines of the chromosphere are identified with practical certainty , the observed wave-length differing in very few cases by 0T tenth-metre from the line with which it is identified . The identification was principally made by comparison with the spark spectra of Exner and Haschek , Sir Norman Lockyer 's results being used for " enhanced " lines . For comparison , the intensities of the corresponding lines in the spark , arc , and solar spectra are given , obtained from various published sources . The wave-lengths and intensities of a number of lines in the spectrum of the higher chromosphere obtained at Sfax in 1905 are also given . The wave-lengths and intensities of the lines observed in the spectra of the corona at the three eclipses are also given . The paper is purely descriptive and shows in detail the relation between the chromospheric spectrum and those of the spark and arc , but does not attempt to assign physical causes to the differences and resemblances .

rspa_1906_0076

0950-1207

An account of the pendulum observations connecting kew and greenwich observatories made in 1903.

241

247

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Major G. P. Lenox-Conyngham, R. E. |Dr. R. T. Glazebrook, F. R. S.

article

6.0.4

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10.1098/rspa.1906.0076

Tables

Astronomy

Tables

]\gt ; An Account of the Observations tecting K eenwich Otories made in 1903 . By Major G. P. TGHAbI , .E . ( Communicated by Dr. R. T. Glazebrook , F.R.S. Received June Read Jume 7 , 1906 . ) S1 . The observations , of which a brief account is here given , their origin in the decision of the overnment of India to resume the pendulum work which was brought to a close in . Professor F. Director of the Central Bureau of the International Geodetic Association , to whose advice the India Office is much indebteci , reColulnended the use of a half-seconds pendulum equipment as yned by Colonel von Sternec This equipment was ordered the Geodetic Institute at Potsdanl , and the constants for the necessary pressure temperature corrections were determined there by Professol L. Haasemanln , under Professor Helmert 's direction . A redetermination of these constants made at Kew , Helmert 's estion , and were obtained in close accordance with those found at The apparatus gives only deterlninations of it thus necessary to select a base station . As Kew ha dbeen the base station of the older Indian pendulum obseryations it was seleeted , Dr. Glazebrook , Director of the National , having given permission and promised all neccssal'y assistance . Meantime , a estio was made by the Astronomer Royal , and accepted by the Secretary of State for India , that the mity should be taken of crino the ] also at Greenwich , thus allowing of a fresh intercomp rison of at wich and New . The apparatus was llade by , of Vienna , aftor Colonel von Sterneck 's design . There are four unlS , ) ) , 139 , and 140 , having times of vibration which are vely nearly equal , and htly in of half a second . The are of ) rass , ilded , provided with vate edges on which to vibrate . Each carries a snnall mirror fastened to its head , just above the line of the ] stand is also of brass , in the form of a truncated cone . Tt rests on foot screws , whi * The full account will be pl.inted in the l ) of the reat T Survey of India . VOL. LXXVIII.\mdash ; A. pressure , but is protected from draughts by a cover . The most essential remaining part of the apparatus is a flash box , containing a contrivance whereby a shutter under the control of a break-circuit clock allows a flash of light to pass through a slit at every beat or alternate beat . This flash is reflected by the mirror on the half-seconds pendulum into a small telescope above the flash box . The times when the flash passes the horizontal wire in the telescope 's field correspond to the coincidences of the half-seconds pendulum and the clock . The coincidence interval , , is connected with the time of vibration , , of the half-seconds pendulum by the equation . the present case we have approximately secs . and sec. The amplitude of swing is observed by means of a scale on the front of the flash box , at a measured distance from the mirror on half-seconds pendulum . The most convenient initial semi-arc is from 12 ' to 15 ' . The clock belonging to the apparatus , , was constructed by Messrs. Strasser and Rohde , of Glashutte ; its pendulum , made by iefler , of Munich , is of invar . Use was also made of the sidel.eal standard clock at Greenwich , and at Kew of the clock ison 8 . Two break-circuit chronometers were also generously lent by Messrs. T. Mercer and Sons and Mr. . Kullberg at a time when it was feared that would not be ready for . The Mercer nometer was enlployed during two sets of vations at The equipment included thermometers by Messrs. retti and Zambra . A barometer and hygrometer were lent by the National Physical Laboratory . to of S2 . Reduction to a vacuum was made by the formula where is the external barometric pressure , the pressure of aqueous vapour , any excess of pressure inside the case\mdash ; all in millimetres of mercury\mdash ; t the temperature centigrade , and a constant . The values of 1905 . ] Observations connectinq Ken ) Greenwich . 243 for the four pendulums were very nearly equal ; the means obtained Potsdam and Kew were respectively and reduction to C. was made by the formula - , the mean found for at Potsdam and ICew being respectively and . The Potsdam values of and were employed iu the reductions , but the substitution of the values would in no way modihed the conclusions as to the relative values of at Greenwich and Kew . The reduction to an infinitely small arc\mdash ; in all cases a correction made by the formula , where denotes the time of vibration and the mean semi-arc . The results were also reduced to an ideal " " pillar\ldquo ; by a method used by Kater and developed recently by Professor . Schumann , of the Prussian Geodetic Institute . Two pendulums in very nearly equal times are simultaneously suspended from the stand , their planes of vibration the same . One is suddenly set with considerable amplitude , the other initially at rest . Obseryations of the at which the second takes up an oscillation from the first supply the means of , the small virtual increase in the of the pendulum , which ponds to the elastic flexure of the stand and pillar it . The correction thus obtained to the time of swing\mdash ; the stand being filmly clamped to ranite slab , cemented to a solid masonry pillar about 20 inches \mdash ; averaoed about second , the mean being nearly the same at Kew and Greenwich . In the application of the temperature correction mentioned above it is tacitly assumed that the temperature recorded by the hermometer is that simultaneously possessed by the pendulum . In reality , when the is at all rapid , the mean temperature of the penduluun la , behind that of thermometer , and a further correction may thus be necessary , which depends on the rate of change of temperature . This " " lag\ldquo ; correction WflS not defermined directly for the apparatus in question , but was assumed to be second for a rate of change of 1o C. per hour , ) eing the result ) ined for an almost identical apparatus to the Prussian Geodelic Institute . The mean values of the calculated corrections at Greenwich and in the final comparisons were respectively and second , temperature always ; the tions at , and enerally at Greenwich . The relative ness of ) correction at Greenwich was due to the temperature being easier to control , the room larger than that at Kew , and htted with electric light instead of gas . 244 Major G. P. Lenox-Conyngham . Pendulum bservatiovs cResults . S3 . The observations were made as follows , the tim.e of a coincidence being known very approximately in adyance . Ten consecutive coincidences were ; then , after an interval corresponding to 50 coincidences , ten more consecutive coincidences were observed . Ten values of a 60-coincidence interval were thus obtained and their mean taken . After 1 hours the observations were repeated , and a second mean obtained . Under normal conditions the mean of these two means should be but little influenced by arities in the rate the clock during the 24 hours . The observations were usually made from 9 . to 1 , and from 9 . to 1 . The rate of the clock or chrononleter llsed was derived from star observations at Greenwich . When at , use was made of the Greenwich 10 . and 1 P.lf . time nals , any necessary corrections to these being supplied by the Astronomer At Kew the pendulums in the plane of the prime vertical\mdash ; in the North Room the platinum thermometer room ) of the small ] house to the west of the main building . position was 100 feet 6 inches west of , 5 inches north of , and 6 feet 4 inches higher than that occupied by . G. . Putnam in 1900 , and by the Kater pendulums swung Mr. E. Constal ) in 1888 . Its coordinates are N. Lat. , and W. Long. ; its height above mean sea feet . At Greenwieh ) were in the plane of the meridian . The station was the same as that occupied by Colonel von Sterneck , Mr. Putnam , Mr. Hollis , and others . It is in the ecord Room , about 20 yards east of the prinle meridian . Its coordinates are N. Lat , E. Long. ; its height above mean sea leve1155 feet . S4 . The first observations were made by Major . G. Burrard , Mr. E. G. Constable , and Major G. P. Lellox-Conyngham at Kew from June 22 to June 25 , 1903 , using only the Morrison clock , the Strasser and Bohde clock not having arrived from Germany . On the arrival of the latter clock , it was employed observations , first at Greenwich , then at Kew , between June 29 and July 9 . The results , however , proved discordant on reduction and were rejected , the clock at the makers ' request being returned to them to be overhauled . Major Burrard mtime had to embark for India , the final observations were Jnade by Mr. Constable and Major LenoxConyngham . These consisted of observations at Kew from October 14 to October 16 and October 27 to October 31 , with intermediate observations at Greenwich from October 20 to October 24 . During each 24 hours two bservations were made with each pendulum , ploying the clock , Obserr . connecting Kew and a further two with either the Strasser and ohde clock or the Mercer cbronometer . Taking the mean of the corrected times of swing from the four penduhums the final result At Greenwiclr sec. The probable errors in these times were secoud at at ICew . The mean ence in the times of was seconds , and its probable second . Ihe results for the difference in the time of from the vere as follows:\mdash ; Pendulum 137 138 139 140 Excess at Greenwich ) ) ) ) The reement between the different pendulums is thus remarkably good . S5 . For at the value cm . has been accepted by Professor Helmert . * This depends on the preliminary result of the deter1nination of at 1otsdam , If and be the times of swing at two stations where and ( / 0 are ) values of , then or here ( is small , Hence , as . the yalue at Kew , and the in at Greenwich , we have at with a probable error of iprlrison orith S6 . Helmert 's formula is where is the latitude , } ) sea level , the thickness surface strata of low density , the earth 's mean radius , the assumed mcan density , the actual density of surface strata , the earth 's mean density , correction . * ' Bericht uber die relativen Messungen der lnit \ldquo ; ' Geodetic Conference of 1900 , ' p. 321 . evidence as to the surface strata near the two observalories has led him to the following conclusions:\mdash ; imestone absent , stimated depth faeozoic floor ifeet.ated cctions ttandard vfeet oondon Cfeet , feet ftrata aaeozoic floor Aondon Chere afeet overage specific gravity 2 latitude , are as follows:\mdash ; the , final values are\mdash ; Kew Greenwich The observed values are thus , in both cases , htly in excess of the calculated , and the difference veen them is greater than the calculated difference . S7 . The following table enumerntes ] ences between / at Kew and as found in the present and in direct comparisons:\mdash ; Behaviour of Substances at their Critical . 247 It is satisfactory to note that the results obtained with the modern forms of apparatus well with ome another and do not differ greatly from theoretical value . This the hope that henceforth the pendulum may prove as satisfactory in practice it has always been attractive in theory . On the of bstances Critical By W. TRAVEBS , D.Sc . , F.R. and ( Received June 13 , \mdash ; Read June 21 , 1906 . ) A work entitled " " Le Point Critique des Corps Purse \ldquo ; has recently been published by E. llathias , whose opinion on matters relating to the critical state must always carry . In this he discusses at length the various theories which have been put forward to explain certain ties observed in the behaviour of substances , which were supposed to be pure , their Cl.itical temperatures . These ulsrities are not accounted by the simpler theories of Andrews and Van der Waals . He calls attention to the experiments of certain ators , which appear to that the currently-accepted values of the critical constants of many nnlon substances may be vitiated , either to the time allowed for the establishment of equilibrium between the coexisting pbases near the critical point being insufficient , or the temperature at which the dividing surface vanishes 1lot being independent of the elative masses of the two phases the temperature at which this takes place . . to I. Traube , substances contain different inck of regates , which he calls \ldquo ; and molecules . It follows that if equilibrium demands that there shall be a certain concentration of these olecn les in the vapour and liquid phases respectively , then unless dissociation and association take place instantaneously , there must elapse a tinle , following any change of condition , before equilibrium can be established between the two phases . P. de Heen 's theory goes further , and , assuming existence of such complexes , suggests that it is possible that the concentration of them in the two phases is a function not only of the temperature , but also of the relative masses of the two phases , or , in other words , of the mean specific volume of the system umder investigation . In this case a system

rspa_1906_0077

0950-1207

On the behaviour of certain substances at their critical temperatures.

247

261

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Morris W. Travers, D. Sc., F. R. S.|Francis L. Usher

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6.0.4

http://dx.doi.org/10.1098/rspa.1906.0077

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10.1098/rspa.1906.0077

Thermodynamics

Fluid Dynamics

Thermodynamics

Behaviour of Substances at their Critical Temperatures . 247 It is satisfactory to note that the results obtained with the modern forms of apparatus agree well with one another and do not differ greatly from the theoretical value . This encourages the hope that henceforth the pendulum may prove as satisfactory in practice as it has always been attractive in theory . On the Behaviour of Certain Substances at their Critical Temperatures . By Morris W. Travers , D.Sc . , F.RS . , and Francis L. Usher . ( Received June 13 , \#151 ; Read June 21 , 1906 . ) A work entitled " Le Point Critique des Corps Purse " has recently been published by E. Mathias , whose opinion on matters relating to the critical state must always carry weight . In this he discusses at length the various theories which have been put forward to explain certain irregularities observed in the behaviour of substances , which were supposed to be pure , at their critical temperatures . These irregularities are not accounted for by the simpler theories of Andrews and Van der Waals . He calls attention to the experiments of certain investigators , which appear to suggest that the currently-accepted values of the critical constants of many common substances may be vitiated , either owing to the time allowed for the establishment of equilibrium between the coexisting phases near the critical point being insufficient , or the temperature at which the dividing surface vanishes not being independent of the relative masses of the two phases at the temperature at which this takes place . According to I. Traube , substances contain different kinds of aggregates , which he calls " gasogenic " and " liquidogenic " molecules . It follows that if equilibrium demands that there shall be a certain concentration of these molecules in the vapour and liquid phases respectively , then unless dissociation and association take place instantaneously , there must elapse a time , following any change of condition , before equilibrium can be established between the two phases . P. de Heen 's theory goes further , and , assuming the existence of such complexes , suggests that it is possible that the concentration of them in the two phases is a function not only of the temperature , but also of the relative masses of the two phases , or , in other words , of the mean specific volume of the system under investigation . In this case a system 248 Prof. Travers and Mr. Usher . Behaviour of [ June 13 , apparently consisting of a simple substance may be , to take the simplest case , bi variant , instead of being uni variant as is usually assumed . This last theory may , of course , represent a condition either of true or false equilibrium , and in support of the latter supposition certain indirect evidence is forthcoming . Brereton Baker has shown that association and dissociation are delayed and accelerated by the presence of minute traces of certain foreign substances . The dissociation of mercurous chloride , Hg2Cl2 , into 2HgCl takes place so slowly in the absence of water vapour that the vapour density of the dry substance is almost exactly twice that of the chloride , which has not been so thoroughly dried . It follows that two such samples of mercurous chloride would , at the same temperature , have different vapour pressures , and that if dissociation took place very slowly the intermediate mixtures which would be formed would constitute bivariant systems . The case in which the velocity of dissociation approaches zero corresponds to that involved in de Heen 's theory ; Traube 's view really involves no new principle . Whether , however , the views of either of them can be realised experimentally is the question which we have now to consider . The conclusions which have been drawn from the experimental work on which these theories are based have given rise to a distinction between the temperature at which the surface separating the two phases disappears , which is referred to as the temperature of Cagniard-Latour , and that at which the densities of the substance in those parts of the tube formerly occupied by the two phases become equal , which , as in the case of mixtures , is called the critical temperature . That the former is a function of the relative masses of the coexisting phases at the moment of the disappearance of the surface is the first consequence of de Heen 's theory , and that the results are markedly influenced by a time factor would follow ' from Traube 's theory . We find , however , that the results of our own experiments in no sense confirm this conclusion , and in fact support the views of S. Young and others , who are opposed to it . We have not investigated the second consequence of the theory , that the densities of the two phases do not become identical at the Cagniard-Latour temperature . However , it appears more than probable that if the first consequence falls to the ground the second will follow it : amongst a considerable amount of experimental evidence in opposition to it , perhaps nothing is more convincing in this respect than Ramsay 's simple demonstration of the equality of the densities of the two phases at the temperature of Cagniard-Latour.* It is worth while quoting some of the experimental results on which * 'Zeit . Phys. Chem. , ' vol. 14 , p. 486 . 1906 . ] Certain Substances at their Critical Temperatures . 249 de Heen 's and Traube 's views are based . The results of Batelli , Zambiasi , Galitzine , and others are given in Mathias ' book , but those of the first named will serve as an example . They are as follows:\#151 ; Substance . Date . Mean specific gravity of substance in tube . Mean value of Cagniard-Latour temperature . Alcohol ... % 1891 0 -3195 236 ' -59 0 3448 237 -26 0 -3888 235 -94 0 -3893 235 -67 1892 0 -3439 237 -02 0 -4000 236 -43 Ether 1891 0 -2409 193 -60 0 -2767 193 -44 0 -2889 193 -17 0 -3043 193 -01 1892 0 -2520 192 -63 * 0 -3192 192 -12 It cannot fail to be noticed that these results do not even show an agreement among themselves . It is common knowledge that it is very difficult to obtain pure dry alcohol , and that only prolonged washing with water will remove the last traces of alcohol from ether . Our first experiments with ether , which had only been washed a few times with water , led to results similar to those obtained by Batelli . There is , however , another interesting phenomenon which has been observed in connection with those which take place at the critical temperature . It appears that Altschul* was the first to observe that in the case of most liquids there appeared at the critical temperature ( Cagniard-Latour ) , at the level in the tube at which the surface vanished , an opalescent band . His description of the effect is somewhat obscure , and neither from him nor from Wesendonckf have we been able to derive a complete idea of what happens . As this particular phenomenon appeared to call for further investigation , and as , in spite of much evidence to the contrary , there appeared to exist a doubt as to whether the simple theories of Andrews and Van der Waals were sufficient to account for the changes which take place at the critical temperature , we decided to undertake the experiments which are described in the latter part of this paper . It suffices to state in advance that in making the observations we employed comparatively large masses of the liquids , enclosed in thin-walled glass tubes , and that particular precautions were taken * 'Zeit . Phys. Chem. , ' vol. 11 , No. 189 , p. 578 . t ' Zeit . Phys. Chem. , ' vol. 15 , p. 262 . 250 Prof. Travers and Mr. Usher . Behaviour [ June 13 , to obtain them pure , and to introduce them into the experimental tubes without contamination . Further , arrangements were made for maintaining a very steady temperature , which could be allowed to rise very slowly towards the critical point . The Phenomena which Accompany Disappearance of the Surface the Critical Temperature . It must be observed in the first instance that the following phenomena take place at a temperature , or are distributed in the same invariable order over a range of temperature , which is dependent only on the nature of the substance under investigation , and that they appear to be absolutely independent of the relative masses of the coexisting phases . That is to say , if we consider any part of the process , such as the disappearance of the dividing surface , we find that so long as the mass of liquid in the tube falls within certain limits , it takes place at a temperature which is constant within the limit of accuracy of the experiments , and in our own experiments to within 0o,05 . If we heat in a glass tube varying masses of a pure liquid , we observe , as we approach the temperature at which the surface of separation vanishes , one or other of the following changes taking place :\#151 ; ( a ) The liquid will have completely evaporated before the true critical temperature is reached , and in this case there is insufficient liquid in the tube . ( b ) The surface will sink towards the bottom of the tube and , at the critical temperature , will disappear at a short distance above it . ( c ) The surface will neither rise nor fall while the tube is heated through the last small temperature-interval and , at the critical temperature , will disappear about the middle of the tube . ( d ) The surface will rise and , at the critical temperature , will vanish near the top of the tube . ( e)The liquid will fill the tube before the true critical temperature is reached , and if the temperature is raised , the tube will probably burst ; in this case there is too much liquid in the tube . If the conditions described under headings ( ) , ( c ) , and ( d ) are produced in tubes of sufficiently large diameter ( in the case of our experiments about 1 cm . in diameter and 20 cm . long ) , the temperature being allowed to rise so slowly that the two phases are brought into equilibrium without ebullition of the liquid phase , the following phenomena will be observed:\#151 ; In case ( b ) , at a temperature slightly below that at which the surface vanishes , the space below the latter will become opalescent , appearing brown by transmitted light and whitish by reflected light . The effect is not 1906 . ] Certain Substances at their Critical Temperatures . 251 altogether dissimilar to that produced by the action of an oxidising agent on a solution of sulphuretted hydrogen . The nearer the surface is to the bottom of the tube the more intense is the opalescence . So long as the surface is still visible the effect is limited to the space below it ; and though it is fairly evenly distributed throughout that space , it is usually slightly more intense just below the surface . When the surface vanishes , the upper limit to the effect becomes less clearly defined , and if sufficient time is allowed , it becomes diffused throughout the whole tube ; the same result may be arrived at by stirring the contents of the tube by means of an iron stirrer operated by a magnet outside the tube . When the surface disappears there is observed , in the case of sulphur dioxide , evidence of optical discontinuity between the substance in the tube above and below the point at which this takes place ; it appears , however , to be merely transient in character , and if it does not vanish without the temperature being raised , it is certainly incapable of existence at a temperature 0o,05 above that of the disappearance of the surface . The opalescence appears to persist over a finite range of temperature ; it sets in , in the case of sulphur dioxide , at 0'T below that at which the surface vanishes , attains a maximum at about 0o,05 above it , and has completely disappeared at a temperature 0'T higher . In the case of ether the effects persist over about 2 ' . Under the conditions included under heading the position in the tube at which these phenomena make their appearance is exactly reversed . The opalescence appears above the surface , and its intensity increases as the latter disappears on approaching the top of the tube . If , while the tube is being heated through the last small temperature-interval below the temperature at which the surface vanishes , the latter remains stationary , the tube , at the same time , appears slightly and evenly opalescent throughout its whole length . This corresponds to condition ( c ) . As we have already stated , the same effect can be produced by stirring the contents of the tube at any moment when the opalescence is observed above or below the surface itself or the point at which it has vanished . Conditions ( b ) and ( cl)can be reproduced in the following manner . If , when the condition corresponds to ( c ) , and the temperature is within the range over which the opalescence is visible , the volume of the space containing the substance is increased or decreased so slowly that the temperature is not lowered or raised appreciably , opalescence will appear below or above the surface itself , or the point at which it vanished , and its intensity will be proportional to the space it occupies . In the case of some experiments which fall under headings ( b ) or ( cl ) it 252 Prof. Travers and Mr. Usher . Behaviour of [ June 13 , was observed that when the opalescence first made its appearance it was most intense immediately below or above the surface . This effect was only transitory in character , and it appeared as if the material giving rise to it were rapidly distributed , by convection or diffusion , throughout the phase in which it was formed . Discussion of these Results . In the first place , our experiments appear to indicate that liquid vapour ( one component ) systems in the neighbourhood of the critical point are univariant , as the simple theory demands . If complex molecules of different magnitude exist , equilibrium must be so rapidly established between them and the simple molecules as to negative de Heen 's theory , and to render Traube 's theory unnecessary . We now pass on to consider the phenomenon of opalescence . The observations of Altschul and Wesendonck* only extended to the formation of an opalescent band at the point at which the surface between the liquid and vapour vanished at the critical point , and their descriptions convey the impression that the phenomenon is much simpler than appears from our experiments . Bakker 's explanation of the effect , f which he attributes to the thickening of the surface layer as the temperature approaches the critical , is based on their work . It may be pointed out that in tubes of small bore the transient effect , which was described in the last paragraph of the previous section of this paper , may appear to have a prominent character as an opalescent band replacing the dividing surface . On considering the facts before us we were drawn to the conclusion that there might be a certain resemblance between the systems we were dealing with and those which constitute colloidal , or so-called " pseudo , " solutions . The existence of molecular complexes did not appear to be a tenable hypothesis , for reasons which have already been stated ; but the optical effects appeared to point to the presence of non-molecular aggregates . Before we proceed further , however , it will be well to consider certain views as to the constitution of colloidal solutions which have been put forward by DonnanJ and a suggestion of his with regard to the application of the same theory to the explanation of the appearance of opalescence at the critical temperature . In dealing with colloidal solutions lie combats the view that their * Loc . cit. t ' Zeit . Phys. Chem. , ' vol. 49 , p. 609 . J ' Zeit . Phys. Chem. , ' vol. 46 , p. 197 . 1906 . ] Certain Substances at tlieir Critical Temperatures . 253 properties are in any way connected with the existence of very large molecules , and considers the conditions under which " one phase of a system would be distributed throughout the other in a state of very fine division " as constituting a different phase . So far he is , of course , dealing with two component systems , though the nature of the aggregates is not altogether different from those which we shall refer to directly . At the British Association , in 1904 , Donnan put forward a suggestion " for discussion " as to the conditions which were necessary for the existence of such complexes in a liquid-vapour one-component system in the neighbourhood of the critical point . He suggests that at the critical temperature the interfacial tension becomes zero for ordinary values of the radius of curvature , but remains positive for very small values , for which it does not become zero till the critical temperature is passed . Hence we may assume that at temperatures slightly below the critical the interfacial tension is greater for very small radii of curvature than for ordinary curvatures . Over a range of temperature , including the critical temperature , limited above by the temperature at which the interfacial tension for small radii of curvature becomes zero , and below less sharply , we can imagine that small , non-molecular aggregates , or drops , can be differentiated from either the liquid or vapour phase , and have a stable existence . To such aggregates can we attribute the phenomenon of opalescence ; and the range of temperature over which it is observed , and the manner of its appearance and disappearance , are in agreement with the assumptions . The manner in which such aggregates or drops could be formed lies outside the discussion , but it is possible to arrive at an explanation of the fact that the opalescence is confined to the phase which is decreasing in volume , through movement of the dividing surface , or , at least , is more intense in that phase . Since it is an essential character of the aggregates that they are non-molecular , one cannot imagine them passing from the liquid to the vapour phase by the ordinary process of evaporation , forming for a moment a constituent of the surface layer . Further , the existence of the aggregates assumes that the interfacial tension at their surfaces is greater than that at the surface dividing the liquid and vapour in the tube , of which the radius of curvature is very large . Hence , an aggregate in contact with the surface will not coalesce with it , as would a small " drop " with a larger surface under ordinary conditions . The result would be that , supposing that a certain number of aggregates were formed in either phase , they would remain in that phase so long as they had a concrete existence , and the optical effect to which they would give rise would depend on their dimensions and the number of them in a given space . 254 Prof. Travers and Mr. Usher . Behaviour of [ June 13 , Experimental A Method of Maintaining Constant Temperatures.\#151 ; The apparatus employed was a modification of that described by Eamsay and Young * The experimental tube was enclosed within a vapour-jacket , which was surrounded by two outer tubes , on one of which a scale was ruled . The top of the jacket was connected with a large air reservoir and a manometer , by means of which the pressure could be measured . In the experiments with sulphur dioxide the temperatures were determined by reading the pressures and referring to Eamsay and Young 's table of vapour-pressures , but as this does not extend to pressures above 800 mm. , we determined the temperatures corresponding to the higher pressures by means of a Callendar platinum thermometer for which the constants have already been published.f To avoid possible confusion in the future we set down the following data:\#151 ; V apour-pressure Temperature from of aniline . platinum thermometer . 772-7 185 ' 793-4 186 814-8 187 835-9 188 857-6 189 879-8 190 902-0 191 925-0 192 949-0 193 972-9 194 It is interesting to note that though by using aniline we were able to maintain and to recover temperatures constant to nearly 1 / 50 ' C. , we were quite unable to obtain such good results by employing quinoline , which , boiling under a pressure of about 260 mm. , gives a temperature corresponding to that of aniline boiling under a pressure of 960 mm. This is probably due to the fact that the pressure of the vapour in the apparatus is the sum of the vapour-pressures of quinoline and of mercury , the latter being used to cover the rubber stopper which closes the opening at the bottom of the vapour-jacket , and that the saturation of the space inside the apparatus with mercury vapour is not complete . The consequent variations in the temperature will be a function not only of the total saturation pressure of the * ' Cliem . Soc. Journ. , ' 1885 , vol. 47 , p. 640 . f * Roy . Soc. Proc. , ' 1905 , vol. 74 , p. 528 . 1906 . ] Certain Substances at their Critical Temperatures . 255 'mercury vapour at the temperature of the experiment , but also of its relative partial pressure in the mixture . To guard against accident through the bursting of one of the experimental tubes , the apparatus was enclosed in a cubical box of about one metre on the edge , open at the back , and with an opening covered by a glass plate 2 cm . thick in front . On the two or three occasions on which the experimental tube burst , though the vapour-jacket and guard tubes were shattered , no other damage was done . Experiments with Ether . Preparation of Pure Ether and Method of Filling the Experimental Tubes.\#151 ; The ether was prepared from pure alcohol by the continuous process . About 1^ litres of the liquid was washed with caustic soda solution , and was then shaken 25 times with about its own volume of fresh water to remove alcohol . Rather less than | litre of liquid remained ; this was allowed to stand for a week in a bottle with excess of calcium chloride , and ( after shaking with dilute sodium amalgam to remove traces of ethyl peroxide ) was transferred to a flask containing a large quantity of fine potassium wire . After a week the liquid was distilled , and though only the middle fraction was collected , the whole mass appeared to evaporate at a temperature which was constant to within 0'*02 to 0a03 . The experimental tubes , which were of Jena hard glass , were 20 cm . long , 0'8 cm . internal diameter , and 1 mm. thick in the walls , and were made in the form shown in fig. 1 . They were first partially filled with ether by dipping the capillary a into the ether , and alternately warming and cooling . The tube was then cut off at b , the lower end was then cooled in liquid air while the open end was connected by a rubber tube with a Topler pump . The tube was then completely exhausted , and the exhaustion was continued while the solid melted . When the ether was evaporating freely into the pump the tube was sealed at c in a blow-pipe flame . Fig. 1 . ( Glass thickened at c. ) 256 Prof. Travers and Mr. Usher . Behaviour of [ June 13 , Details of Experiments with Ether.\#151 ; Three tubes were used in these experiments . The mean specific volume , that is to say , the volume of the tube divided by the mass of ether contained in it , is given below , the three tubes being referred to by the letters A , B , and C:\#151 ; c.c. per gramme . c.c. per gramme . c.c. per gramme . A ... ... . 410 . B ... ... . 3-96 . C ... ... . 3-56 . At the normal temperature , the fraction of the total volume which the liquid occupied was in the three tubes respectively:\#151 ; c.c. per gramme . c.c. per gramme . c.c. per gramme . A ... ... . 0-35 . B ... ... . 0-37 . C ... ... 0-41 . The following are the details of the experiments :\#151 ; Tube and date . Pressure of aniline vapour . Temperature , from platinum thermometer . Remarks . A mm. 962 -5 193'-57 Temperature falling from above Tc ; mist appeared and 21/ 3 963 -3 193 -60 then liquid , which filled one-fourth of tube ; whole tube opalescent . Tube cooled and re-heated . Temperature rising slowly . Meniscus falling . Whole 963 A 193 -60 tube very opalescent , liquid more so than vapour . As the meniscus fell , the region just above it remained more strongly opalescent than the remainder of the tube . Tube cooled and re-heated . Meniscus becoming nebulous , and replaced by opales964 -3 193 -64 cent band . Point of disappearance less than one-fourth from bottom of tube . Meniscus quite gone ; opalescence very marked , but A . 965-4 193 -70 diffused at point of disappearance . Ultimately opalescence diffused throughout tube . Opalescence persisted for at least two degrees above Tc . At this temperature the meniscus completely vanished , 22/ 3 B 963 -0 193 -59 as at 193 ' *64 on the day before . The behaviour of the ether in the two experiments was identical . Meniscus falling very slightly : liquid occupying about 22/ 3 963 -1 193 -59 two-fifths of tube . Meniscus still slowly falling . In this experiment the 963-2 193-60 effects observed were similar to , but less marked than in the case of A. Meniscus becoming nebulous , and finally disappearing C 963 '3 193 -60 slightly below two-fifths from bottom of tube . The whole tube was then opalescent , particularly at point of disappearance of meniscus . Liquid filling about five-sixths of tube ; vapour much 22/ 3 963 -6 193 -62 more opalescent than liquid . Meniscus rising and leaving opalescent band behind it . Meniscus very close to top of tube , becoming nebulous and disappearing , leaving the whole tube opalescent . 1906 . ] Certain Substances at their Critical Temperatures . Experiments with Sulphur Dioxide . Source of the Sulphur Dioxide and Method of Filling the Experimental Tubes.\#151 ; The substance was obtained in the first instance from a syphon of the commercial liquid . Part of the liquid was allowed to evaporate from the syphon , and then a quantity of it , amounting to about 70 c.c. , was introduced into the bulb a ( fig. 2 ) , which contained excess of phosphorous pentoxide , and which was cooled in a freezing mixture . The stem was then sealed at b , the bulb was removed from the mixture , and about a quarter of the liquid in it was allowed to evaporate , so as to remove all traces of air from the apparatus . To PU Fig. 2 . The experimental tube was attached by means of rubber pressure tubing at/ . When it was in position the whole of the apparatus on the left-hand side of the stop-cock c could be exhausted through the stop-cock which was closed while the apparatus was " washed out " with sulphur dioxide and finally filled . During the latter operation the experimental tube was cooled in a freezing mixture ; more sulphur dioxide was introduced than it was intended that the tube should eventually contain , the excess being allowed to evaporate into the pump , or to escape into the air through the stop-cock The tube was finally sealed at the constriction while the pressure in it was still below that of the atmosphere . It will be observed that we have no direct guarantee of the purity of the VOL. lxxviii.\#151 ; a. s 258 Prof. Travers and Mr. Usher . Behaviour of [ June 13 , sulphur dioxide . But the results of our experiments on the critical behaviour of successive fractions of the same quantity of liquid indicate that they are at least identical in their properties , and with almost equal certainty that they all consist of one and the same simple substance . Preliminary Experiments with Sulphur Dioxide.\#151 ; In the first set of experiments which we wish to record we employed two sealed tubes about 14 cm . long ( not counting the length of the capillary portion ) , and 1 cm . in diameter . The mean specific volumes of the substance in the two tubes , referred to as A and B , were as follows:\#151 ; c.c. per gramme . c.c. per gramme . A ... ... ... 1-75 B ... ... . . 1-67 The tubes were heated as in the case of the experiments with ether in the vapour of aniline , and as the temperatures were deduced by interpolation from the results of Bamsay and Young 's experiments , it is not necessary to set down the corresponding pressures . In the following experiments the two tubes were heated together in the same vapour-jacket:\#151 ; Temperature . Remarks on A. Remarks on R. o 18 156 -85 157 2 Liquid occupies 0*34 total volume " 0-07 As the temperature was raised the lie opalescent , the surface in the form was noticed that though the ten constant at any point , equilibriui minutes elapsing before the menii opalescence was attained . At this temperature the surface in disappearing ; after some minutes tl Liquid occupies 0*40 total volume 0*90 " juid in A and the vapour in B became er rising and in the latter falling . It [ iperature could be maintained very n was only slowly established , some scus came to rest and the maximum each tube became indistinct , finally le opalescence vanished . Second Series of Experiments with Sulphur Dioxide.\#151 ; In these experiments arrangements were made for changing the volume of the substance under investigation by means of a compression apparatus , for stirring it by means of a magnetic arrangement during the experiment , and for measuring the temperature of the interior of the tube as well as of the jacket by means of a thermo-electric junction . The apparatus is shown in section in fig. 3 . Into a steel cylinder b was screwed a steel tube a , about 150 cm . long , connected with another horizontal cylinder into which a piston could be forced by means of a screw , so as to decrease the internal volume of the apparatus , which contained mercury . The experimental tube , which was about 1 cm . in diameter and 50 cm . long , was cemented into the plug c , which was screwed into b , the Thermo-electric junctions at top and at lesrel of stirrer . At bottom of figure four wires should have been shown . 260 Prof. Travers and Mr. Usher . Behaviour of [ June 13 , junction being made good by means of a leather washer . The thermo-electric junctions were enclosed inside a capillary tube of very thin Jena hard glass , which was cemented into a screwed plug e , and was so arranged that one junction was at the top of the experimental tube close to the constriction , and another , which was enclosed within the same tube , terminated about 5 cm . lower down . The stirrer consisted of a piece of soft iron wire , bent so as to form two circles a little smaller than the inner diameter of the tube , joined by a straight piece about 2 cm . long , at right angles to them . The stirrer was operated by means of a powerful electro-magnet , the poles of which lay close to the outer guard tube of the vapour-jacket . The following is a summary of several independent sets of experiments . The measurements of the mean specific volumes of the substance in the .experimental tube are only approximate:\#151 ; Temperature at which surface vanished . Mean specific volume of substance . Remarks . o 2 -3 Probably too little liquid in tube . 157 -24 | 2 1 ( a ) When stirred , surface vanished at bottom of tube . No opalescence . ( l ) When not stirred , optical discontinuity at 12 mm. from bottom . No opalescence . ? 2 -05 Surface disappeared at bottom of tube . 157 -22 2 -0 Opalescence at surface , 15 mm. from bottom of tube . On stirring , opalescence was distributed throughout range through which stirrer moved , and optical discontinuity appeared at upper limit of stirring . ? 1 -9 As before . p 1 -8 Volume was reduced while the temperature was 157'*2 , opalescence became very marked , particularly above j surface , and diminishing in intensity towards top of tube . Temperature rose to 157'*26 ; on stirring , optical discontinuity moved to upper limit of stirring , and opalescence distributed itself over the same range . 157 -2 1 -9 Volume was increased while the temperature was 157'*2 , when opalescence appeared in liquid , spreading downwards from surface . Maintaining the temperature steady at 157'*2 , and the volume constant , the opalescence gradually diffused throughout the tube ; after 20 minutes it was impossible to see the window bar through the tube . 157 -26 1 -75 Tube cooled and volume reduced . On heating to near the critical point the surface now moved slowly upwards , and space above became opalescent . The range of temperature through which the opalescence was visible lay between 157'*15 and 157''4 , over the whole range of volumes investigated . In measuring temperatures by means of the thermo-electric junction , either of the junctions could be connected by means of a mercury switch with another junction surrounded with the vapour of bromo-benzene , boiling under normal pressure , the free wires being connected directly to the terminals of a 1906 . ] Certain Substances at their Critical Temperatures . 261 galvanometer . Observations of the pressures under which the aniline in the vapour-jacket surrounding the experimental tube was boiling , allowing ample time for equilibrium to be established , corresponding to certain readings of the barometer , served to calibrate the instrument . Before filling the experimental tube mercury was introduced into it to a convenient level , a bell-jar was fitted round it by means of a rubber stopper and the latter was filled with a freezing mixture . The capillary portion of the tube was then connected with the apparatus shown in fig. 2 , and the correct quantity of sulphur dioxide was introduced in the manner indicated . Third Series of Experiments with Sulphur Dioxide.\#151 ; In this series of experiments the same apparatus was used as in the last series , but the thermo-electric junction was omitted , and the temperatures were determined directly from the readings of the pressures . The following are the results :\#151 ; Temperature . Volume occupied by liquid in tube . Mean specific volume of substance in tube . Remarks . 157'-0 2*03 No opalescence ; surface moving downwards . 157 -12 0-12 \#151 ; Opalescence below surface . 157 -3 " in lower part of tube ; surface vanished , but slight discontinuity visible . Volume reduced ; tube cooled and re-heated . 157 -13 0-68 1 *69 Whole tube slightly and evenly opalescent ; surface almost stationary with rising temperature . ? \#151 ; \#151 ; Surface vanished . 157 -3 \#151 ; \#151 ; Opalescence increased and uniform . 157 -4 " almost vanished . Volume reduced ; tube cooled and re-heated . 156-1 0-76 1 *55 No opalescence . 157 -07 0-79 \#151 ; 33 157 -20 0-88 \#151 ; Opalescence above liquid , very strong at surface . 157 -3 Surface vanished , slight discontinuity remaining , with opalescence very strong above it . On stirring , opalescence became diffused throughout tube . Volume reduced ; tube cooled and re-heated . 157 -0 0-95 1 *46 No opalescence . 157 -15 Surface nearly at top of tube ; minute space above it opalescent .

rspa_1906_0078

0950-1207

Note on opalescence in fluids near the critical temperature.

262

263

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Sydney Young, D. Sc., F. R. S.

article

6.0.4

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10.1098/rspa.1906.0078

Thermodynamics

Tables

Thermodynamics

262 Note on Opalescence in Fluids near the Critical Temperature . By Sydney Young , D.Sc . , F.R.S. , Trinity College , Dublin . ( Received June 18 , \#151 ; Read June 21 , 1906 . ) The phenomenon of opalescence at and near the critical temperature has been observed by Travers and Usher* under exceptionally favourable conditions , owing to the great width ( 8 to 10 mm. internal diameter ) of the tubes they employed . The opalescence is , however , distinctly visible , and can be studied in much narrower tubes , such as those ( 0T5 mm. internal diameter ) used in my own investigations . The experiments of Travers and Usher were carried out , for the most part , in such a manner that the total vol ume of the substance investigated remained constant , while the temperature rose very slowly . In my experiments , on the other hand , the substance was kept at its critical temperature , ! and the volume was altered ( usually diminished ) by equal stages . The opalescence was always seen , but notes of its position and character were only made with a few substances\#151 ; isopentane and normal pentane , hexane , and octane . My observations\#151 ; mostly unpublished\#151 ; may be regarded as supplementing and , so far as a comparison is possible , confirming those of Travers and Usher , and the following generalisations may be deduced from them:\#151 ; 1 . When observations are made at the critical temperature ( Cagniard-Latour temperature ) at a series of diminishing volumes , no opalescence is visible so long as the volume exceeds a definite limit . When this limiting volume is passed , a slight opalescence appears at the bottom of the tube , that is to say , just over the mercury ; at still smaller volumes the opalescence or mist becomes denser and extends further up the tube . Near the critical volume the mist is very dense , especially near the middle ; it may extend all through the tube , or the tube may appear clear either at the top or both at top and bottom . When the volume is further reduced , the mist disappears below , but becomes dense above , and on further compression the clear part extends upwards and the remaining mist at the top becomes less dense and finally disappears at a definite volume . When observations at the critical temperature are made at a series of increasing volumes , there is a tendency for the mist to be lower down in the tube than when they are made during compression . This tendency may * Supra , p. 249 . t In the case of normal pentane the " Cagniard-Latour temperature " and the " critical temperature " were found to be identical or at least indistinguishable ( 'Trans . Chem. Soc. , ' vol. 71 , p. 446 , 1897 ) . Opalescence in Fluids near the Critical Temperature . 263 probably be explained by the fact that each expansion causes a temporary slight fall below the critical temperature and , consequently , a very slight condensation from the critical to the liquid state ( in three cases it was noted that the meniscus was actually seen for a moment ) . Some little time would be required for equilibrium to be re-established after such a disturbance of the density , and it may be that the time actually allowed\#151 ; one or two minutes at most\#151 ; was insufficient . On the other hand , during each compression , there is a very slight rise of temperature , but this does not cause any change of state or disturbance of density . 2 . When observations are made at a temperature slightly higher than the critical temperature , the mist is not only much less dense , but the range of volume over which it is visible is more restricted . 3 . The limits of volume between which mist is visible at the critical temperature seem to be nearly the same for the four paraffins examined ( about 1T7 or ITS to about 087 or 0*88 , taking the critical volume as unity in each case ) . One conclusion drawn by Travers and Usher from their experiments is that " the opalescence is confined to that phase which is decreasing in volume through movement of the dividing surface , or , at least , is most intense in that phase . " It happens , however , that in their experiments , whenever the liquid phase'was small at first , it diminished , and when large at first , it increased ; and it may be doubted whether the above relation would be found to hold good for a phase which was large but decreasing in volume , for example , under the following conditions : { a ) constant volume and slowly falling temperature ; ( 5 ) constant temperature and the total volume either large but decreasing , or small but increasing . It seems probable from my experiments that the position of maximum opalescence really depends on the mean specific volume of the substance , being near the bottom when the volume is large , near the top when small , and near the middle at intermediate volumes . This question , although it does not affect the main conclusions arrived at by Travers and Usher , seems to be of sufficient interest to repay further investigation .

rspa_1906_0079

0950-1207

The origin of osmotic effects.

264

271

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Henry E. Armstrong, F. R .S

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10.1098/rspa.1906.0079

Biochemistry

Fluid Dynamics

Biochemistry

The Origin of Osmotic Effects . By Henry E. Armstrong , F.R.S. ( Received and read June 14 , 1906 . ) [ International Catalogue of Scientific Literature . Author 's title-slip :\#151 ; C. D. Subject slips :\#151 ; C 0310 A theory of osmotic effects . C 1930 Association in solution . C 6250 Association of electrolytes with water . D 7065 Structure in relation to hydration . v 1 ) 7155 Theory of osmotic effects . D 7255 Explanation of peculiarities of electrolytes . Q 0224 Origin of osmotic effects . ] The result of the comparative study of enzymes and acids as hydrolysts may be held to be that an explanation based on an association hypothesis may be given of their action which is simple and rational and in accordance with the facts . The explanation which has been advocated from the point of view of the ionic dissociation hypothesis , if not inadmissible , is altogether improbable ; moreover , whilst this hypothesis is applicable to the explanation of but a very limited class of chemical interactions and is .in no way a necessary hypothesis , the assumption that association rather than dissociation is the condition precedent of change* appears to afford a sufficient explanation of chemical interchanges in general , of whatever kind . It is desirable , therefore , to consider somewhat closely what may be the behaviour of salts in solution , in order that their marked activity in comparison with that of nonelectrolytes may be accounted for . It is well known that salts in solution and indeed electrolytes generally produce effects , in lowering the freezing point or the vapour pressure , for example , which are abnormally large in comparison with those which are produced by non-electrolytes . It has therefore been assumed that electrolytes are more or less dissociated in solution into ions which play the part of individual molecules . It is neither desirable to dwell on the inherent improbability of the conception nor to enter into any discussion of the hypothesis , beyond saying that it is difficult to discover any argument of which it is the unavoidable consequence among the reasons put forward in support of its acceptance , as these are inconclusive when not based on uncertain premises ; my object is to consider an alternative explanation . In the case of osmotic phenomena generally , whatever may be the degree * 'Roy . Soc. Proc. , ' 1904 , vol. 73 , 537 ; 'Chem . Soc. Txans . , ' 1895 , 1171 . The Origin of Osmotic Effects . of fortuitous coincidence between calculated and observed values when they are treated as gaseous pressure effects , the effects cannot in reality be due to pressure in any ordinary sense . In liquids generally attractive forces must come into play between the molecules ; in solutions attractive forces must also come into play as between solute and solvent . It is necessary to account for two classes of facts , viz.:\#151 ; 1 . That non-electrolytes all have a similar influence when used in molecular proportions in solutions of equivalent strength . 2 . That electrolytes have an excessive influence as compared with nonelectrolytes . In virtue of 1 , it may be supposed that the primary or main osmotic effect is exercised by the solvent\#151 ; not by the solute . There is apparently no other way in which the constancy of molecular behaviour can be so easily , if at all , accounted for , as the one constituent common to all solutions in a particular liquid is the solvent itself . In all liquids the molecules must be regarded as in some degree associated . In the case of water it is generally admitted that not only are the molecules associated , but that a relatively large attractive force operates between the molecules\#151 ; the heat of formation of liquid water at 100 ' from the fundamental gaseous molecules being a high value ( 18 x 536.= 9648 calories ) . The effect of introducing neutral molecules\#151 ; non-electrolytes\#151 ; into liquid water must be to cause the dissociation of the molecular complexes to an extent corresponding to the proportion in which the neutral molecules are added . If a substance enter into solution entirely in the form of its fundamental molecules , it will produce its normal effect , provided that its own attractive effect upon the water molecules be inappreciable . Electrolytes , besides producing the dissociation effect , must be supposed also to exercise an attractive effect on water molecules . In ordinary water , the state of equilibrium involves the simple dissociative change pictured in the equation : ( H20)n = nB.20 , in which n may have several values , as probably there is a greater number of forms present than two . The introduction of any substance into solution involves the disturbance of the equilibrium in the direction ( H20)M \#151 ; \gt ; \#166 ; rtH20 . The osmotic " pressure " is the measure of the extent to which equilibrium is thus disturbed by the liberation of the fundamental molecules or monads These monads are to be regarded as the attracting element in the region of the solution and as conditioning a flow of similar molecules from the region of the pure solvent\#151 ; or from a more dilute solution\#151 ; until the two regions are in equilibrium . This explanation was definitely advanced by me in the 266 Prof. H. E. Armstrong . [ June 14 , ' Encyclopaedia Britannica , in the article " Chemistry " * published in 1902 . The conception has been arrived at from a somewhat different point of view and advocated recently as novel by Mr. Beilby in his Address to Section B of the British Association in South Africa.f Osmotic pressure has been treated as a negative pressure by HulettJ and again quite recently by Hudson . S It maybe supposed , in the case of non-electrolytes , that the osmotic attraction is exercised upon external water molecules by the water monads present in excess in the solution as the product of dissociation of the water complexes ; in the case of electrolytes , in addition to this attraction , that exercised by the dissolved substance comes also into play : on this hypothesis , electrolytes are substances which are attractive of water practically in proportion to the efficiency of their solutions as electrolytes . From the point of view here advocated , it is easy to see that , to compare the osmotic efficiency of substances , it is essential to measure their influence on one and the same proportion of solvent ; the use of weight-normal solutions , i.e. , of solutions made by dissolving the presumed molecular proportion ( or fractions thereof ) in a litre of the solvent , as practised by Morse and Frazer , || is thus entirely justified.1T The reason is also clear why only dilute solutions have afforded " normal " results in the hands of the advocates of the dissociation hypothesis and that they have overlooked the important fact discovered by Morse and Frazer , that the osmotic effect varies almost in direct proportion to the concentration , the results obtained with concentrated solutions being , in fact , scarcely less normal than those afforded by dilute solutions . The presumed distinction between dilute and concentrated solutions almost * * * S * Yol . 26 , p. 739 . t [ The ' Proceedings ' of the Koninklijke Akademie van Wetenscliappen Te Amsterdam , of May 26 , ' 1906 , issued June 21 , contains a communication , by J. J. van Laar , on " The Osmotic Pressure of Solutions of Non-electrolytes in connection with the Deviations from the Laws of Ideal Gases , " read on the 29th of April last . Taking Morse and Frazer 's observations into account , van Laar arrives at the conclusion that osmotic pressure does not follow the gas laws ; he is of opinion that it is " no longer possible to uphold the old conception of the osmotic pressure as arising in consequence of a pressure of the molecules of the dissolved substance comparable with the gas pressure . The molecules of the dissolved substance have nothing to do with the osmotic pressure except in so far as they reduce the water in the solutions to another state of concentration ( concentrated ) , which causes the pure water ( Concentration 1 ) to move towards the water in the solution ( Concentration 1 \#151 ; x ) in consequence of the impulse of diffusion.'1'1\#151 ; Note added Jidy 31 . ] + ' Zeits . Phys. Chem. , ' 1903 , vol. 42 , p. 361 . S ' Physical Review , ' 1906 , vol. 22 , p. 257 { re nature of osmotic pressure ; compare Batelli and Stephanini , ' Atti dei Lincei , ' 1905 ( v ) , vol. 14 , ii , pp. 3\#151 ; 14 ; also ' Pliysi-kalische Zeitschrift , ' 1906 , vol. 7 , p. 190 . || ' Amer . Chem. Journ. , ' 1905 , vol. 34 , p. 1 . IF Compare R. J. Caldwell , post , p. 272 . 1906 . ] The Origin of Osmotic Effects . disappears . This is well shown in the following table given by the authors named , in which N is the proportion of a gramme-molecular weight of sugar which is dissolved in 1000 grammes of water ; D the density of the solution at its freezing point ; A the observed depression of the freezing point . It will be seen that A is very nearly 1*85 NT ) for all concentrations . N. D. Ax = l -85 ND . A. o-io 1 -0129 O 0-187 o 0-187 0-20 1-0257 0-379 0 -373 0-30 1 -0380 0-576 0-574 0-40 1 -0497 0-777 0-776 0-50 1 -0611 0-981 0-970 0-60 1 -0717 1 -189 1 -187 0 70 1 -0825 1 -401 1 -398 0-80 1 -0918 1 -616 1 -612 0-90 1 -1016 1 -834 1 -837 1 -oo 1 -1110 2 -060 2 -082 1 '26806 1 -1340 2 -660 2 -660 It should be pointed out , however , that the fact that " normal " values are obtained in any case must not be taken without further evidence as proof that the molecules present in a solution are essentially of the presumed dimensions . As the presence of associated molecules Mm\#151 ; i.e. , polymorphs of the fundamental molecule or monad M\#151 ; would condition a smaller effect , whilst the attraction of molecules of the solvent by those of the solute would increase the effect , opposing tendencies may be at work unperceived ; especially is this true of electrolytes : the difficulty must always be met with in their case . It follows from this argument that the " normal " effect of a monad cannot be determined in any absolute manner by a purely physical method . Thus the value 1*85 used in calculating the molecular depression of the freezing point , which is based on the observation of the depression produced by alcohol and similar non-electrolytes , is presumably too high , inasmuch as alcohol , in all probability , exercises no inconsiderable attractive effect in solution . The numbers quoted by Morse and Frazer show in the clearest manner possible that such an effect is at work and that it comes more and more into evidence as the solution is made more and more concentrated . When the values in columns A and D in the above table are inspected , it is obvious that whilst the depression of the freezing point becomes greater at an increasing rate , the density increases at a corresponding diminishing rate\#151 ; the one 268 Prof. H. E. Armstrong . [ June 14 , compensating the other ; to judge from the depression of the freezing point , the attractive forces within the solution become more and more manifest as the concentration increases.* ! At the conclusion of their memoir , Morse and Frazer express the opinion that " some at least of the abnormalities ( in the depression of the freezing point ) will disappear when the problem is studied from the side of the volume relations of solution and pure solvent " : I venture to think that it is already clear that the apparent abnormalities may easily be explained . Much capital has been made of the additive nature of the properties of electrolytes and of the possibility of assigning specific mobilities to the ions as evidences of their dissociation . But it is forgotten that the properties of many organic compounds which no one dreams of representing as dissociated are additive . My object in referring to this contention here , however , is to lay emphasis on the conclusion which I stated in my paper on " Electrolytic Conduction " presented to the Society in 1886J that hydrogen and the metals generally may be regarded as the analogues of the CnH2n+1 hydrocarbon radicles and that their compounds with negative elements may be likened to unsaturated hydrocarbons of the form CwH2ra+i.CH : CH2 . Subsequent study has confirmed this view . 1 have little hesitation now in stating the opinion that in cases in which they function as simply as carbon * Compare R. J. Caldwell , post , p. 272 . t [ In a later paper , which has just been published ( ' Amer . Chem. Journ. , ' July , 1906 , vol. 36 , p. 39 ) , Morse and Frazer confirm the rule for cane-sugar , Aj = 1'85 ND = A. But it does not hold good , they say , for glucose , the freezing points of glucose solutions being normal in the sense that the magnitude of the depression is strictly proportional to the weight-normal concentration . On the other hand , they describe a new series of determinations of the osmotic pressures developed in solutions of cane-sugar , the results of which " are probably as precise as we can hope to obtain under present conditions . " They are certainly in remarkable agreement with those calculated on the assumption that " cane-sugar in aqueous solution exerts an osmotic pressure equal to that which it would exert if it were gasified at the same temperature and the volume of the gas were reduced to that of the solvent in the pure state . " They surmise , in order to account for the different results arrived at by the two methods , that at the comparatively high temperatures ( 20'\#151 ; 25 ' ) at which the osmotic pressures were determined , the whole of the water plays the part of solvent , while at lower temperatures a portion of it is appropriated by the solvent , giving rise , to an abnormal depression of the freezing point . Mr. Caldwell 's experiments , which were made at 25 ' , appear to confirm the conclusion arrived at by Lord Berkeley and Mr. Hartley that the osmotic pressures are in excess of the calculated values , although it is true that they worked at 0 ' . It is difficult to avoid the conclusion that the American observers ' values may be too low , perhaps on account of the lack of rigidity in the rubber stopper used in closing the cell . The " normal " behaviour of glucose may be the consequence of the formation of associated molecules compensating the dehydration effect.\#151 ; Note added July 31 . ] + ' Roy . Soc. Proc. , ' vol. 40 , p. 268 . The Origin of Osmotic Effects . 1906 . ] does in the paraffinoid compounds generally , metallic atoms are characterised as definitely as the paraffinoid or CnH2n+i radicles are by specific physical attributes ; in the one case as in the other the so-called constants are merely algebraic differences . Variations arise probably only when the metallic atoms become united among themselves by more than single affinities , as in the case of carbon compounds . But the CnH2\#171 ; +i radicle in the compound C"H2n+i.CH : CH2 is externally inoperative\#151 ; combination is effected solely through the agency of the CH : CH2 radicle . Applying this argument to metallic salts , the chlorides , for example , the metal may be regarded as inert in solution and the hydration of the salt may be supposed to take place solely through the combination of water with the halogen radicle . In the language of the ionic dissociation hypothesis , only the negative ion is hydrated . Probably , in all its interactions , the activity of a salt is primarily traceable to the negative ion.* From the electrolytic and osmotic points of view , mercuric chloride , HgCl2 , is one of the most remarkable of salts , its behaviour being almost that of a non-electrolyte . It may be contrasted with potassium and calcium chlorides , the former of which has been shown by E. H. Griffiths to depress the freezing point of water at excessively low dilutions to just twice the extent to which it is depressed by the non-electrolyte cane-sugar ; the calcium salt has a still greater effect , approaching to three times that produced by the non-electrolyte . Whilst mercuric chloride dissolves with difficulty in water and is very volatile , it is very readily decomposed into its elements by heat . Sodium and calcium chlorides are easily soluble salts , but neither do they volatilise nor do they decompose when heated , except at very high temperatures . Yet it is confidently argued that potassium and calcium chlorides undergo complete dissociation in solution into free ions , whilst mercuric chloride remains all but unchanged . It is difficult to consider such a contention seriously . In what manner then are the peculiarities of mercuric chloride * As to the meaning and use of the term ion and its derivatives , it may be pointed out that\#151 ; pending judgment\#151 ; no idea of dissociation need nor should be involved in the use of the term . All ions are radicles , but all radicles are not ions : the ion is a radicle which can be moved or separated from a compound by means of an electric current and which is also at once " attackable " under appropriate conditions . For example , the chlorine radicle is present as an ion in sodium chloride , but not in the chlorates nor in chloracetic acid . Used in this way , the term is a most valuable accession to scientific language ; it is not until it is coupled with the term dissociation that the radically different conception is introduced about which dispute rages . Faraday applied the term ion simply to " those bodies which can pass to the electrodes " : he in no way implied that they enjoyed separate existence in the electrolyte . We may well rest satisfied to use the word in the sense in which he used it . Prof. H. E. Armstrong . [ June 14 , and similar chlorides to be explained ? Conventionally , the three chlorides are represented by the formulae Hg\lt ; Cl Na\#151 ; 01 Ca\lt ; Cl But these symbols are equally misleading and inexpressive of their properties . Solid mercuric chloride is probably a weak polymorph , but even its monads must differ in constitution from those of the sodium and calcium haloids . As the mercury haloids all combine readily with other haloids , it cannot be supposed that the halogen is specially exhausted by combining with mercury : therefore , regarding the halogens as potential triads , it may be supposed that in mercuric chloride monads the atoms form a closed system , perhaps thus Sodium and calcium chlorides , on the other hand , may well be open systems . Na\#151 ; Cl= Ca\lt ; Cl= Cl= The closed system of the mercury salt is but slightly attractive of molecules of its own kind or of water ; the potential activity of the chlorine radicle becomes manifest , however , when the salt is brought into contact with other chlorides which combine with it , forming well-characterised mixed chlorides , e.g. , or it may be / Cl Hg\lt ; H+2KC1- C1 ClmClK = Hg\lt ; XC1\#151 ; C1K / Cl- Hg\lt ; | +2KC1= : Cl- Cl\#151 ; C1K = Hg\lt ; | | NC1\#151 ; C1K Chlorides such as those of potassium and calcium are undoubtedly polymerised in the solid state ; when dissolved , the polymorphs undergo simplification at the instance of the water molecules , becoming more or less hydrated . The extent to which depolymerisation and hydration take place depends both on the salt and the degree of dilution ; apparently it is only complete in very dilute solutions , judging from the fact that limiting values are only obtained in very dilute solutions . The formation of hydrates containing several molecules of water may be supposed to involve the association of the salt with water complexes , or it may be that more or less complex ring systems are formed of water 1906 . ] The Origin of Osmotic Effects . 271 monads corresponding to the ring systems which are so common among organic compounds . But from the point of view advocated in this note , the complexity of the hydrate would seem to be without influence on the osmotic effect exercised by the salt . To explain the " double effect " produced by potassium chloride monads , it may be supposed that the molecule as a whole has effect\#151 ; such as is exercised by molecules generally in freeing water monads\#151 ; and that , in addition , the chlorine radicle exercises its 'proper attractive effect . Other chlorides and salts generally may be expected to exercise an influence in proportion to the number of active " acidic centres . " To judge from the behaviour of the sugars and alcohols , it is not improbable that the hydroxyl group may also function as an acidic centre . But inasmuch as chlorides such as mercuric chloride have little or no attractive power for water , it is to be expected that the chlorine radicle or any other equivalent acidic centre will not in all cases exert the full unit effect , but that it will exercise an influence varying from unity to zero , according to the nature of the positive radicle with which it is associated ; in other words , the degree of so-called " ionisation " or attackability will vary with the nature of the molecule of which the acidic centre is a component .

rspa_1906_0080

0950-1207

Studies of the processes operative in solutions. part I.\#x2015;The sucroclastic action of acids as influenced by salts and non-electrolytes.

272

295

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Robert John Caldwell, B. Sc. (Lond.)|Professor H. E. Armstrong, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0080

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0080

10.1098/rspa.1906.0080

Biochemistry

Tables

Biochemistry

]\gt ; 'Studies of the Processes in . Part Tloe Action of Acids as influenced by Salts By JOHN CALDWELL , B.Sc. ( Lond. ) , , Leathersellers ' Company 's Research Fellow , Chemical Department , City and Guilds of London Institute , Central Technical College . Communicated by Professor H. E. Armstrong , F.R.S. Received and read .June 14 , 1906 . ) [ International Catalogue of Scientific Literatu ' title slip:\mdash ; C. D. Subject slips : \mdash ; 0310 of Sugar in 1ehtio to . 6240 of Acids in presence of Glucose , etc. 1820 Cane Sugar , hydrolysis of . 7090 Hydrolysis ) Acids as affected Salts . 7155 Hydrolysis of Suga ] in relation to . Conductivity of Acids in presence of Glucose , etc. 1424 Hydrolysis of Cane Sugar by Acids . ] The investigation of which the results now recorded is an extension of that undertaken in conjunction with . Frankland in which the sucroclastic action of acids was contrasted with that of enzymes ; it forms a necessary part of a larger inquiry which is being carried out at the Central Technical College in the hope determining the precise nature of enzyme action and of hydrolytic change generally . Evidence was advanced* that the processes must 1oe regarded as similar , notwithstanding the extraordinary difference in activity manifest on comparing the two classes of hydrolytic agents , except that and in so far as third substances produce somewhat different effects , the rate of modified in the case of enzymes only by substances which act selecCively , whilst in the case of flcids the added substance appeared to exercise an influence which might be regarded as a concentration effect . It is now obvious , however , that a fallacy underlay our conclusion in so far as the action of acids is concerned and that a like fallacy more or less affects , if it do not invalidate , the conclusions of previous workers in similar fields . It will be clear that to determine the influence of any added substance , this should be made the only riable at first : point of fact , a second variable\mdash ; the mount of water \mdash ; has been introduced . ' Boy . Soc. Proc 1904 , vol. 73 , p. 526 ; vol. 74 , p. 195 . , vol. 73 , p. 51 Studies of the ocesses OSolutio Solutions have been prepared , as a rule , by dissolving the various substances to produce a iven volume of solution : the result that water has been displaced in introducing the third substance . Morse and Frazer appear to have been the first to call attention to the consequences of this practice , in the comprehensive account of their observations on " " The Osmotic Pressure and Freezing Points of Solutions of Cane published in the July number , 1905 , of the 'American Chemical Journal . ' * They have shown , at least in the case of cane , that the normal standard volume for osmotic pressure is not that of a gramme-molecular proportion of substance dissolyed in water to a volume of 1 litre ; the true standard , instead of being such a volume- normal solution , is the ] -normal solution ( as they term it ) obtained by dissolving a -molecular proportion of the substance in 1 litre of water ; such a solution exercises an osmotic approximately equal to the pressure exerted by a } -molecular proportion of reduced to llitre . The need of intaining the proportions of water and acid as wcll as that of the hydrolyte constant hout the experiments , so amount of the odd bstcmce sbe , was contemplated at the outset of this inquiry ; indeed it was lmdertaken from this point of view at Professor Armstrong 's request , before my attention had directed to Morse and Frazer 's communication The experiments now described have shown that cane itself and several other carbohydrates have a relatively small although distinct effect ; alcohol , however , has a marked inhibiting effect\mdash ; probably because it enters into competition with the water and withdraws hydrogen chloride from it ; glycerol occupies an intermediate position between alcohol and the carbohydrates : in othel words , non-electrolytes , pp. 28\mdash ; 91 . In discussing the influence of concentration of the hydrolyte on the rate at which milk sugar is hydrolysed ( Armstrong and Caldwell , op . cit. , p. 531 ) , results were quoted to volume-normal solutions containing 9 , 18 and 27 grammes of lactose in 100 . Such solutions contain very different amounts of water , viz. :\mdash ; 9 grammes lactose . rammes water . , , The great increase observed in the rate of change is to be attributed mainly to displacement of water ; on reference to Table I it will be seen that the corresponding volume-nolmal solutions of cane sugar contain a larger proportion of water ; the greater influence of concentration on the rate at which milk undergoes hydrolysis in comparison with cane sugar , referred to in the paper under consideration ( p. 631 ) , is probably more apparent than real , but subject is oue which needs further experimental investigation . VOL. LXXVIIL\mdash ; A. Mr. R. J. Caldwell . have comparatively little influence in promoting hydrolysis . The weak electrolyte acetic acid also has but little influence . Metallic salts accelerale the rate of , the influence of those derived from monad metals already considerable and of salts derived from dyads at least twice as great ; it will be contended that their activity is due to their dehydratin intiuence . The literature relating to action of acids on cane sugar is extraordinarily voluminous , at least 140 papers having been published which bear on the subject . As the writer is in for the Briti , sh Association a report the work which has been done , it will be unnecessary to consider st length the uments which have been advanced . Ostwald , besides out a selies of observations on ) action of a variety of acids on cane sugar , which led him to conclude that the activity of the several acids was of the same order as that established by other methods , especially by the determination of their electrical conductivity , also made a few experiments on the influence of the concentration of ) on the rate of hydrolysis . The results he obtained led him to infer , in the case of chlorhydric acid , that the amount of hydrolysed in unit time increased rapidly , out of all proportion to the increase in the concent1ation of the sugar . On concentration of the acid , maintaining that of the constant , he noticed a similal lack of proportionality between the rate of inversion and the amount of acid present , the acid being less active in dilute than in strong solution : according to his method of the case , ] ereas the molecular conductivity of the acid diminishes its concentration is increased , its molecular sucroclastic activity increases as it is increased ] concentration . Ostwald was inclined to attribute the lack of parallelism to secondary effects , especially to the influence of the sugal , which became greater the bhe proportion of sugar present relatively to acid . Water was left out of account . In his memoir on the velocity of the inversion of cane by acidq , published in 1889 , Arrhenius introduced the conception of an active moss and attributed the inyertive power of acids to the free hydrogen ions ; this conclusion has been somewhat fully considered in the paper by . Armstrong and Caldwell , in which also reference was made to his later views published in 1899 . It is noteworthy that in his ' Allgemeine Chemie published in 1889 , Ostwald expressed the opinion that an acid inverts sugar because of the predisposing affinity of the acid for the alcoholic hydroxyls of the dextrose and levulose produced fronn the cane sugar . He appears , however , to have been at once converted by Arrhenius . In 1897 it was contended by Cohen that the great increase in velocity in lave comparatively little influence in promoting hydrolysis . The weak electrolyte acetic acid also has but little influence . Metallic salts accelerale the rate of , the influence of those derived from monad metals lilready considerable and of salts derived from dyads at least twice as great ; it will be contended that their activity is due to their dehydratin inliuence . The literatnre relating to action of acids on cane sugar is extraordinarily voluminous , at least 140 papers having been published which bear on the subject . As the writer is in for the Briti , Association a report work which has been done , it will be unnecessary to consider st length the uments which have been advanced . Ostwald , besides out a selies of observations on ) action of a variety of acids on cane , which led him to conclude that the activity of the several acids was of the same order as ) established by other methods , especially by the detcrminabion of their electx.ical conductivity , also made a few e , xperiments on the influenc of the concentration of ) on the rate of hydrolysis . The results he obtained led him to infet in the case of chlorhydric acid , that the amount of hydrolysed in unit time increased rapidly , out of all proportion to the increase in the concent1ation of the sugar . On ) concentration of the acid , maintaining that of the constant , he noticed a similal lack of proportionality between the rate of inversion and the amount of acid present , the acid being less active in dilute than in strong solution : according to his method of the case , ] ereas the molecnlar conductivity of the acid diminishes its concentration is increased , its molecular sucroclastic activity increases as it is increased ] centration . Ostwald was inclined to attribute the lack of parallelism to secondary effects , especially to the influence of the sugal , which became ' the bhe proportion of sugar present relatively to acid . Water was left out of account . In his memoir on the velocity of the inversion of cane by acidq , published in 1889 , Arrhenius introduced the conception of an active moss and aftributed the invertive power of acids to the free ions ; this conclusion has been somewhat fully considered in the paper by . Armstrong and Caldwell , in which also reference was made to his later views published in 1899 . It is noteworthy that in his ' Allgemeine Chemie published in 1889 , Ostwald expressed the opinion that an acid inverts sugar because of the predisposing affinity of the acid for the alcoholic hydroxyls of the dextrose and levulose produced the cane sugar . He appears , however , to have been at once converted by Arrhenius . In 1897 it was contended by Cohen that the great increase in velocity in 1906 . ] Studies the ocesses Operative more concentrated solutions be explained by assnming th , as in the case of gases , the space occupied by the molecules would be of consequence ; he supposed the rate of in version to be inversely proportional to the space at the disposal of the molecules . In all cases , the method of treatment adopted by previous workers has been influenced , in the first place , by the prevailing practice of with volume-normal solutions in laboratory work ; and subsequently by the conception introduced by Va n't Hoff that the state of the molecules of a substance in solution may be arded as analogous to that of . the molecules in a gas ; the fact that as the Yried the proportion of watjr present is also baried . No attempt has been made to evaluate the chemical iIlfluence of the omitted water . The extent to which the two methods of treatment different results will be at once apparent on reference to the upper half of the representing the results which I have obtained in a series of experiments\mdash ; carried out in the llanner described towards the close of this paper\mdash ; which are summarised in Tables I , TI and III . When sugar and are dissolved yether in water to a constant volume , solutions are obtained which undergo inversion at a rapidly rate the more concentrated they are , the rate being an tely linear function of the concentration ( Equation 1 , p. 288 ) . When -normal solutions are used , no such rapid acceleration is obseryed , the rate but reater in concentrated solutions as compared with dilute solutions . In the former case , the weight of watel ' present diminishes rapidly as that of the i , s increased , practically following a linear law ( Equation 2 ) : the proportion of water , therefore , is varied both with reference to the and to the acid . In the latter case , apart from changes in the bulk of the solution , only the sugar is varied , water and acid remaining constant . No useful conclusion as to the natul.e of the processes operative in concentrated solutions can be drawn from the experiments carried out with volume-normal solutions until the results are reduced to weight-normal The results of a series of determinations of the electrical conductivity ( molecular ) of chloride in presence of amounts of glucose are recorded in Tables and ; the results when 1 gramme-nloleculal ortion of hydrogen chloride was present are also represented in the lower half of the Diagram . It will be seen that the difference is but small , due to the use , on the one hand of volume-normal solutions , on the other of normal solutions ; but this arises from the fact that the molecular con- ductivity of hydrogen chloride changes only to a slight extent on dilution . It should perhaps be pointed out that lucose was used in these OF DIAGRAM . The value obtained ( 490 , Table III ) by exte1polating the volume-normal curve on the assumption that the rate is a linear function of the concentration is , doubtless , somewb low : hence the irregular character of the curve . If the more probable value deduced from weight-normal solutions be taken as the origin ( 498 ) , the curve becomes less irregular , as in curve of the Processes ) . 277 in place of cane sugar ( cf. p. 280 ) , as being its practical equivalent , in order to avoid the complications introduced by the attending inversion . The fact that the effect of the amount of the is to increase the invertive power of the acid whilst it diminishes its conductivity is a strong argument against the application of the hypothesis to hydrolysis , especially when taken in conjunction with the argument previously published in contrasting the hydrolytic activity of acids with that of enzymes . The results of experiments which I have made to ascertain the influence of added substances on the rate of hydrolysis of cane by an aqueous solution of chlorhydric acid are summarised in Table . The substances used were as follows:\mdash ; Lactose , Glucose , Glycerol , Alcohol , Potassium chloride , Amlnonium chloride , Barium chloride , Calcium chloride , Sodium chloride , Acetic acid . It will be seen that all these substances , excepting alcohol , have a more or less marked effect when used in volume-normal solutions , under conditions , that is to say , which involve more or less water displaced by the added substance ; when solutions are used , ylucose and lactose appear to have practically no effect , whilst lycerol and alcohol retard the change , all the remaining substances it . In view of the reneral character of the effect produced by salts , bearing in mind also that easily soluble , roscopic salts , such as calcium a far greater influence than sodium chloride , for example , it appears justifiable to regard the acceleration as a concentration ct due to the withdrawal by the dissolved substan ce of a certain proportion of the water molecules , which thus become removed from the sphere of action of the acid . To evaluate this effect I have determined the number of gramme-molecules of water which must be used in addition to the 1000 grammes originally taken , in order that the rate of change may be that characteristic of the solution prior to the addition of the " " neutral\ldquo ; substance . These values are iven in the last column of Table and are printed in thick type . The explanations iven by previous observers of the produced by added substances on the hydrolytic activity of acids have been of a varied character , but with scarcely an exception unsatisfactory and wholly biased by ionic conceptions . Arrhenius*uniformly resorts to his idea of an " " active part which is either reduced or increased in amount to suit the conditions of the problem . Lowenthal and Lenssen , who were the first to notice the accelerating effect of salts , attributed their action to the fixation of water and the consequent concentration of acid : hitherto , no one has accepted this explanation . ' Zeits . Phys. Chem 1889 . vol. 4 , p. 226 ; 1899 , vol. 28 , p. 31 ' Journ. Prakt . Chem 1862 ( i ) , vol. , pp. 321 and 401 . Mr. R. J. Caldwell . from apoint onzyme action Iirst.ement mprevious pvery s place , it may be assumed that acve is formed by combination of part of the sugar with part of the acid\mdash ; and as the water molecules in the solution are attracting both sugar and acid molecules , that there is , so to speak , competition between the water and the sugar for the acid ; there will be , therefore , at any iven temperature , an equilibrium between water , sugar and acid , depending on the relative proportions of these three constituents ; a in any one of them will necessarily also change the position of the equilibrium and therefore also the tion of the combination of acid and present lnflujnce of Conctration on theHdolysis of .\mdash ; If the change be of this kind , in order to explain the radual increase in the rate at which the cane sugar is hydrolysed as the solution is concentrated , it is necessary to consider the influence which an increase in the number of molecules of sugar present exercise . From the point of view of the increased opportunity afforded to the acid , the rate of should be propoltional to the of sugar present ; but if it be supposed the sugar or indeed any substance present in the water is to some extent associated with the solvent , increase in the amount of dissolved substance must involve a corresponding incl.ease in the concentration of the substances the and therefore increase the rate of hydrolysis . Actually , this is what occurs . The obscrwed increase in the rate cannot , however , be arded as the absolute measure of the extent of the influence of the sugar , as some portion of the latter may be present an associated and , therefore , probably less active , if not inert , form . In view of the presumed connection between osmotic pressure and rate of change , it may be pointed out here the osmotic pressures . Soc. Proc 1904 , vol. 73 , ) it is probable that the molecules not all equally hydrated in solutior , the molecules themselves be ated in a more concentrated solution : it may be that the less ydrated o anhydrous the more opeIJ to attack by the acid . this assumption nccou1lt for the effect of ssures on the inversion velocity , which effect has hitherto iled to receive a explanation . Rontgen ( ' Wied . Ann 1892 , vol. 45 , p. 98 ) , Stern Phys. and Rothmuud Zeits . Phys. Chem have independently recorded the fact that a high pressure decreases the inversion velocity to the extent of 1 per cent. per 100 atmospheres , although both the tion and the " " ionic mobility \ldquo ; are incleased . It lllay well be that the degree of hyd1ation of tlJe sugal is increased by pressure and that under a high pressure the sugar , being more highly hydrated , woudd be less open to attack and the inversion slowel in consequence . 1906 . ] of the ocesses Operatire in Solutions . 279 determined by lIorse and in -normal solutions of cane do not differ appreciably from the calculated values , the results Lord Berkeley Mr. Hartleyj have brought before the Society recently , calculated on a similar basis , appear to be somewhat above the calculated values , especially in the case of the more concentrated solutions . My observations appear to afford considerable support to the results arrived at by the obseryers . On the other hand , taken in tion with my results , the at which they have may be held to elevate the assumption that the molecules are hydrated almost to the level of certainty . Influ ( of single molecular proportion of alcohol per litre , in a volume-normal solution , is without influence ; smuch , however , as it displaces almost its own volume of water in the solution , it must be held to have a considerable retardilJg effect . That this is the case is seen on reference to the result obtained in weight-normal solution , the yalue being reduced from to Using larger proportions of alcohol , previous have noticed a effect eveu in volume-normal solutions ; the explanations which have been offered of its influence are in no way satisfactory . In certain cases alcohol has been shown to ] ] efiect , as in the formation of urea from amlnonium cyanate . Alcohol may be pictured as acting in at least Iechnnically , by its interposition between the acting substances ; ( 2 ) as a such as ) esugal'S exercise by combining ith water ; as entering into association with the ctive aoent , chloride , an " " alcoholate Of these ( 1 ) and ) ) would be untavourable , whilst ( 2 ) would the . There is every reason to } ) that all three influences are and that the c of alcohol is more than by the extent to which it interfer echanically and ( probably ) more especially by the formation of Influence of Glyccrol.\mdash ; Although ) arol ) , in volume-normal solution , glycerol has a sli , bt influence , the effect is more than cconnted for by the amount of water which it displaces . Considered the standpoint , i.e. , in weight-normal soJutions , it has distinct which is less , however , than that of alcohol . The arguments ' Amer . Chem. Journ 1905 , vol. 34 , p. 1 . ' Roy . Soc. Proc 1906 , A. vol. 77 , ) Compare Kblukow R Zaccoui , . Russ . iSoc 1891 , vol. ) ; Wakeman , ' Zeits . Phys. 189.3 , vol. 11 , p. 49 ; Cohen , ) , 1 : henius , ibid. , 1899 , vol. 28 , p. 317 . Walker and Kay , ' Chem. Soc. , p. 489 . Mr. R. J. used in respect of alcohol are also applicable to glycerol ; it may fain be supposed that the retardation is mainly due to a withdrawal of some part of the chloride in loose combination with the alcohol . The readiness with which lycerol is attacked acids is in harmony with this explanation . of Glucosc.\mdash ; A series of experiments , the results of which are not quoted , showed that in volume-nornlal solution the effect of a single grammellole , cular proportion of the allied substances glucose , galactose and mannitol is practically identical . Moreover , glucose can be substituted for cane sugar almost weight for in volume-normal solutions without sensible change in the rate at which the cane is hydrolysed , whatever the proportions present . But inasmuch as glucose displaces slightly more water than cane sugar the results obtained with weight-normal solutions are slightly lower in presence of glucose . Thus , the constant is lowered from 521 , the yiven by a gramme-molecular proportion of cane , to 518 by substituting for half the cane a gramme-molecule of ] ncose . that the glucose must echanically , the glucose must be supposed to be at least as hydrftted as the pproximately equal weight of cane sugar . There is ) to it will differ much from the cane sugar in its affinity for the It is very noteworthy that in all }xses the constant has practically the same value throughout the course of an experi1nent ( vide Tables X and XI ) . Hence it follows that whatever take place in the solution the influence exercised the products of change must be almost exactly equal to that exercised by the sugar inally 1 which undergoes hydrolysis in accordance with the equation:\mdash ; Glucose . uctose . It is that the argument already used with reference to glucose will apply equally well to fructose ; and as the two molecules of hexose are even superior in power to a tJle molecule of cane sugar , it would seem to follow that most , if not all , of the oxygen atoms exercise an influence on water molecules . in mind the complex nature of the influences at work , it is altogether remarkable that the simple monomolecular law should be found to hold throughout ; *this result may to show how very necessary it is to exercise caution in judging from apparently simple results as to the true nature of the phenomella . It ulay be expected that more concentrated solutions will results showing in velocity as the hydrolysis proceeds , owing to the fact that the proportion of water which Vide Mellor and Bradshaw , ' Zeits . Phys. Chem 1904 , vol. 48 , p. 363 . 1906 . ] Studies of Processes Opercl:tive . 281 enters into combination will be a sufficiently impol.tant fraction of the total water present to illfluence the rate . Experiments to test this conclusion are in progress . of liactos volume-normal solution the addition of half a molecular proportion of lacboseto the same amount of cane sugar , although it gives rise to the displacement of slightly more water , has actually less effect than the cane ; in other words , lactose is less effective as a dehydrating than cane . This conclusion is in harmony with the recognised character of the substance , especially its moderate solubility , which may be regarded as an indication of a tendency to relatively inert , associated molecules . In -normal solutions it is apparently without effect ; in other words , it exercises a dehydrating influence which is only sufficient to balance the small reduction in activity brought about by its mechanical interference . of Acctic Acid.\mdash ; As this acid has no hydrolytic effect on cane ( far in ) arison with the effect of chlorh.ydric acid , it is possible to determine its influence as a " " neutral\ldquo ; substance . It will be seen that it exercises a effect to the of a single molecule of water by each molecule of acetic acid . This is entirely in accordance with its known behaviour as veak dehydrant . of Satts.\mdash ; Salts have uniformly a effect ; the addition of a molecular proportion of calcium chloride to a volume-nol.mal solution more than doubles the rate of To determine the " " degree of hydration\ldquo ; of the salt , the to hich it was necessary to dilute the weight-nol.nlal solutions in order to reduce the yalue of the constant to 510\mdash ; the value\mdash ; was determined in each case . The values arrived at are as These values are necessarily solnewhat low , no allowance can made . the interference of the salt . They are clearly rational values , however ; moreover , they are in accordance with estimates arrived at in other ways . The results obtained by H. C. Jones his oues , con* No exception to the use of lactose in this connection can be taken on the ground it would be attacked ) ' the acid and thus give rise to lnplications . Under conditions of the experiments , no appreciable hydrolysis of lactose occurs during 24 hours . Vide ' Boy . Soc. ' 1904 , vol. , p. 530 . ) 'Amer . Chem. . 1904 , vol. 32 , p. 310 : , vo ] . 33 , ] ) . ) ; 1906 , vol. 35 , p. 445 . Mr. R. J. Caldwel ] . [ June of the values now arrived ac in the case or calcium chloride and ] probably also of barium chloride , are not in harmony with them in respect of other substances . literature on the subject is so voluminous that it cannot be ssed in an adequate manner on the present occasion ; but it may be pointed out that the method described in this communication is one which involves only the consideration of the effect produced on the cane , whereby a measure is se , cured ( in the case of salts ) of the concentration effect from which the average degree of hydration of the salt is inferred without reference to the condition of this salt in solution . The method of calculation adopted by H. C. Jones , however , is one which does not in itself permit of any line drawn between produced on the one hand by hydration and on the other by polymerisatio1l . From this point of view , it may noticed on comparing the of hydration of osium and sodium chlorides and of barium and calcium chloYides that the more soluble salt of each . is ydrated . It is probable that in most cases the less soluble salt is present iu solution to the greater extent in a polynlerised form . It is scarcely necessary to add that the in Table apply only to the particular of conccntration which was studied . It may be expected that in more dilute solutions the " " of hydration\ldquo ; would be greater , whilst in more concentrated solutions it be less . limits of variation in the of sodium chloride are relatively small , as showu in Table VIII , in which is iven the average of molecular hydration in solutions ) to 5 -molecular proportions of salt . ionductivit / tes . The equations given in Table IX represent results obtained in a series of experiments which were made with the object of ascertain ing the influence of various carbohydrates on the electrolytic conductivity of solutions of hydrogen chloride and of sulphuric acid , with a view of ascertainin what way the condition of the acid be influenced . The effect is in all cases of the same order , equal weights practically the same effect in the conductivity . Down to the } ) roportional influence of the dissolved substance is independent of ) concentration of the aoid ; at high dilntions as shown in Tables XT1 to , the added stance produces a greater proportionate effect thau in the more concentrated solutions . In all probability the effect of the added snbstance is mainly mechauical 1906 . ] Studies of the Processes in the more dilute solutions , however , the non-electrolyte apparently has a distinct dehydrating effect on the acid . Experiments are carried out to determine the influence of chlorides on the conductiviby of hydrogen chloride , in ' order to ascertain whether their influence may not also be regarded in the light of the view put forward in this communication . This is the more desirable , inasmuch as it is clear that the influence of salts on the hydrolysis of cane by acids is incompatible with the view which is commonly held that a neutral salt dimiuishes the extent to which the acid undel ' oes electrolytic dissociation in solution . \mdash ; An approximately twice normal solnCion of pure hydrogen chloride was used , which was standardised by tit , ration balyta against a solution prepared by Moody 's absolute method ; the conductivity of the acid was determined from time to time in order to ascertain whether any alteration had taken place . A measurements were made with sulphuric acid which had been standardised by lIarshall 's method . The purest obtainable cvalised crystals cane were used ; this matel.ial did not reduce 's solution . The milk sugar was crystallised from per cent. the of a solution containing -molecule of the dissolved in one litre of water was reciprocal ohms . 's purified glucose , mannitol were used ; these 11 ere all by the conductivity method . In determiuing the of these ates , a difliculty arises from the fact that , in presence of the platinum black of the electrodes , they are slowly products which are better electrolytes . It was , thel'efore , necessary to determine the conductivity at different intervals of time and to exterpolate , to determine the conductiyity at the moment of putting the solution into the meastlrino cell . The conductivity of solutions of one gramme molecular proportion of each in a litre of solution determined in this manner was , in the of glucose , eciprocal ohms , in that of mannitol and in that of galactose reciprocal ohms . On account of the high conductivity , it was susl ) ected that galactose contained some alL-aline impurity , especially as it was found to produce an diminution in the conductivity of hydrochloric acid . To purify it , 80 ammes were dissolved in 60 . of wa.ter by the ; 'Chem . Soc. Trans 1898 , vol. 73 , p. 'Soc . Chem. Ind 1899 , vol. 18 , p. 4 . Mr. R. J. Caldwell . 200 . of methyl alcohol were theu added tu the cooled solution , and carbon dioxide was bubbled into the liquid , which was subsequently filtered and allowed to stallise ; the latter occupied a considerable time . The galactose was washed with methyl . alcohol and dried during two weeks vacuo over potash . In this manner the conductivity of the gramme-molecular solution was reduced to reciprocal ohms . The salts used were ecrystallised until neutral , excepting the calcium chloride , which contained a little free alkali ; this salt was always carefully neutralised with the predetermined amount of centinormal chlorhydric acid before starting the inversion . temperature for the inversion of cane sugar is so that it is important that the temperature should be very carefully yulated . The inversion experiments were carried out in a polarimeter tube which was maintained at by a stream of water from a thermostat . The al.rangements are depicted in fig. 1 . Water taken from a low-pressure main at a temperature varying between and was passed through a condenser A in which it was warmed by the waste water returning from the polarimeter tube . Ihence it passed to the bottom of the funnel-shaped vessel , made of sheet copper , which contained a rough toluene thermo- 1906 . ] tudies of the Pr.ocesses Operative in Solutions . ulator in connection with a bunsen flame beneath the vessel ; the stream of water was heated to an approximately constallt temperature of in this vessel . It then passed into the bottom of the cylindrical vessel , also made of sheet copper and flanged at the bottom this vessel is almost filled by a sensitive toluene thermo-regulator with fluted sides ; a small flame beneath the vessel in connection with the regulator served to heat the stream of water to a constant temperature of . The water thus heated passed through the small chamber containing a sensitive thernlometer and thence directly into the jacket of the polarimeter tnbe . The temperature of the waste water was also read in E. When the polarimeter tube was removed , the stream of water could be diverted through the tube F. In order to reduce the loss of heat to a minimum , the vessels and and also the polarimeter tube were packed roumd with felt . The whole apparatus was placed in a room kept at a constant temperature of ( at the level of the polarimeter ) by means of a stove controlled by a large thermo-regulator shaped like a gridiron and with saturated solution of calcium The temperature of the liqmd in the polalimeter tube was found to oscillate C. on each side of the mean temperature , C. , in regular periods of about minutes . In experiments which extend ovel an hour , this small variation is of no importance . The drop in temperature of the stream whilst passing the jacket was ible . The conductivities were determined in a large thermostat maintained at C. by means of the spiral toluene thermo-regulator described by It was found to be of to use a gas-pressure ulator with the former thermostat ; a very simple and satisfactory device for this purpose is shown in fig. 2 . The gas is introduced from the main by tube and passes over the surface of the mercury in the cup , which is firnJly fixed to the inner bell-jar by a glass rod ; this rod is continued upwards and slides in the fixed tnbe , which serves as uide for the floating bell-jar . The pressure of the gas escaping through is that given by the difference in level between the water inside and outside the floating jar and is arranged to be less than the minimum pressure of the in the mains . When this regulator is at work the inner bell-jar is in a state of continuous vibl.cttion . : the gas is therefore passed into a Winchester quart hot , the which serves as a buffer ; it escapes as a stream of gas at the steady constant pressure indicated by the gauge glass Mcthod of the Inversion )\mdash ; The exact quantity of required together with any additional substance was out each experiment . The solids were then carefully transferred to a 50-c.c . Chenl . Soc. ) , , p. 1030 . 286 Mr. R. J. standard flask with water of low lctil polarimeter tube at C. and allowed a temperature of the thermostat before were then in all , in each expe : after the first and the final reading af rotation had reached its minimum . La mean of five readings taken at minute side of the mean time . The 65 hydroly over olarimeter readi . er ] each experiment is certainly very small to Tables X and , which are entirely in each separate experiment ; on this acco to reproduce more than four complete sets of the actual course of the riments . not in close accordance , the discrepallC ifferences in the preparation of the letermination of the velocity . 1906 . ] Studies of the Processes Solutions . 287 . \mdash ; The measurements of conductivity recorded in Tables , XIII , and were Dlade in a -tube resistance cell of the ordinary type , ? the usch wheel bridge , inductorium and telephone . Il was found to be of to insert a liquid rheostat the telephone circuit , which had no ence on the reading but enabled the noise in the receiver to be altered at will , thus eat accuracy . In all cases the calculation was of the type : Lessresistance , ofRes istanceLess { tance otance oSpecific cuctivityConductivity.ately.gwate . The values iven in the tables are multiplied by 1000 . The meRsurements with acids were made in a cell of the ' Arrhenius ' type . Table I.\mdash ; Inversion Velocities , using 1 gramme-molecule of Chloride . 288 Mr. . J. Caldwell . [ June Table II.\mdash ; Inversion Velocities and crhts of Water per Litre of Solution , using 1 -molecule of chloride and varying the amount of cane sugar in 1 litre . Equation 1\mdash ; ammes , Equation 2\mdash ; Water per litre rammes ; where is the inversion velocity for a solution of -molecule of cane sugar per litre . Table III.\mdash ; Relative Rates of Inversion by Hydrogen Chloride of various Concentrations of Cane ugar in Volume-normal and Weight-normal Solutions . Table of Chlorhydric Acid in presence of Glucose ( volume-normal ) . 1906 . ] of the Processes in Solutions . Molecular Conductivities of Chlorhydric Acid . , where is the conductivity in presence of gramme-molecules of the glucose per litre . Table Conductivity of Chlorhydric Acid in presence of Glucose ( weightnormal ) . ucose i Molecular Conductivities ( weight-normal ) . , where is the conductivity in presence of -molecules of lucose per kilogramme of water . VOL. LXXVIII . I ativo.nducti.vity . ativo.nducti.vity . ativo.nducti.vity . Table \mdash ; Inversion Velocities , using ' gramme-molecule of Cane 1 gl'amme-molecule of Chloride and 1 gramme-molecule of added Material ( unless otherwise stated ) . Added substance . itre 1906 . ] Studies of the Processes in Table VIII . Inversion Velocities , using amme-molecule of Cane 1 gramme-molecule of Cbloride and crramnles of Water , together with a variable number of gramnle-molecules of additional Water and of Sodium Chloride . Total volume of tion . Table \mdash ; Equations representing the Influence of ' on the Conductivity of Chlorhydric and Acids of Concentration varying between 1 gl.amnle-molecule ecule per ( volume-normal ) . Acid . Glucose . Galactose . Manmtol . Milk Sulphuric Acid . Glucose . represents the conductivity of a solution of acid ) molecules of added in a litre of solution . 1906 . ] Studies of the Processes in Table XII . Conductivity of Chlorhydric Acid in presence of Galactose ( volume-normal ) . Molecular Conductivities of Chlorhydric Acid . , where is the conductivity in presence of gramme-molecules of the $alactose per litre . Table XIII . Conductivity of Chlorhydric Acid in presence of Mannitol ( volume-normal ) . * Impure material , ) . , where is the conductivity in eIlce of ules of the per litre . Conductivity of Chlorhydric ence ( Lactose ( volume-normal ) . Molecular of id. , where is the conductivity -molecules of lactose litre . 1906 . ] of the Processes 5 Table Conductivity of Sulphuric Acid in presence of ucose ( . in Dilution of acid in litre per gl.amme-lnolecule . granlmeslitre . per S. l50 ; / 2 93 . ; / 2 93 . ; / 2 1SO ; / 2 93 . l50 ; / 2 1SO l50 ; 93 . ; 1SO ; 93 . ; 93 . ; / 2 93 . l50 ; 93 . ; 93 . l50 ; 93 . ; 93 . ; / 2 93 . ; / 2 93 . ; / 2 1SO ; 1SO ; / 2 93 . ; 93 . ; / 2 1SO ; 93 . l50 ; / 2 93 . ; / 2 93 . l50 ; / 2 93 . ; / 2 93 . ; 93 . ; / 2 1SO l50 ; 93 . l50 ; / 2 93 . ; 1SO l50 ; / 2 93 . ; / 2 93 . ; 93 . ; / 2 93 . l50 ; / 2 93 . ; / 2 93 . ; / 2 93 . ; / 2 93 . ; 93 . ; / 2 93 . ; 1SO ; / 2 1SO ; / 2 93 . ; 93 . ; / 2 93 . l50 ; / 2 93 . ; / 2 93 . ; 93 . ; / 2 93 . ; / 2 93 . ; 93 . ; / 2 93 . l50 ; 93 . l50 ; 93 . ; / 2 93 . ; 93 . ; / 2 93 . l50 ; 93 . ; / 2 1SO l50 ; 93 . ; / 2 93 . l50 ; / 2 93 . ; 93 . ; / 2 93 . ; 93 . ; / 2 93 . ; / 2 93 . l50 ; / 2 93 . ; 93 . l50 ; / 2 1SO ; 93 . ; / 2 93 . ; / 2 93 . l50 ; / 2 93 . ; / 2 93 . l50 ; / 2 93 . l50 ; / 2 1SO olecular Cluctivities ohuric Acid . Dilution of ' , the conductiv ity in ence of the rlncose p. litre .

rspa_1906_0081

0950-1207

A numerical examination of the optical properties of thin metallic plates.

296

341

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Richard C. Maclaurin, M. A., LL. D.|Professor J. Larmor, Sec. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0081

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0081

10.1098/rspa.1906.0081

Tables

Optics

Tables

]\gt ; ANumerical Examination of the Optical Properties of Thin Plates . By RICIIARD C. , LL. D. , formerly Fellow of St. John 's College , Cambridge ; ]'rofessor of Mathematics , Wellington , New Zealand . Communicated by Professor J. Larmor , Sec. R.S. Received August 30 , 1906 . ) The optical properties of thin metallic plates have been investigated by nulnber of physicists . * One of the earliest workers in this field was He predicted from theory and verified by experiment that if light incident on a gold leaf were plane polarised the ansmitted beam would be elliptically polarised . With the improvement in experimental methods since MacCullagh 's day , and the gradual removal of obscurities from the theory of metallic reflection and transmission , we now expect much more than a mere general agreement between theory and experiment . We look for an almost exact erical coincidence . The condition of the reflected or transmitted beam is precisely described by means of two quantities\mdash ; the ellipticity and the difference of phase between the components of the light ) olarised perpendicular and parallel to the planc of incidence . The object of the present paper is to obtain convenient formulae for these quantities and to compare them with the results of experiments , the most careful and the most recent that available . We shall admit into our theory no principle that has not foumd yeneral acceptance , S and shall thus be enabled to decide whether such principles are sufficient to the facts . If they fail in this , it will behove us to look for new , by a scrutiny of our so-called " " facts to indicate in what way experimental errors have brought about an apparent conflict between fact and theory . Suppose that a ray of light is incident at angle on a metal plate . If the plane of be taken as that of incidence , then an incident wave of * See references in Mascart , 'Traite ' vol. 2 , p. 550 , and Winkelmann , ' Handbuch der Physik , ' vol. 6 ( 2 ) , p. 1311 . Neither of these , however , mentions the vork of Conl.oy , ' Roy . Soc. Proc vol. 3 ] , 1881 , p. 486 . . Irish Acad. Proc. , vol. 1 , p. 27 , and ' Collected Works , ' p. 82 . , e.g. , ' Roy . Soc. Proc , vol. 77 , S Of recent investigations the most elabolate is of M. Meslin , ' Ann. de Chimie et cle Phys 1890 , pp. 56\mdash ; 177 . After giving the results of experiments , M. Meslin obtains , Jmpirically , a formula for of produced by qsion through a late . He then makes an ingenious attempt to deduce formula from theory . His gulnsnt , however , contains too many ) ecial hypotheses and assumptions to be final . Optical Properties of unit amplitude will be represented by a vector of the form where is the frequency , the time , V the velocity of in air . This incident wave will give rise to a reflected wave represented by and a refracted wave . The dynamical equation requires that , where is a complex of ) . Here is the " " refractiye index\ldquo ; of the metal , 2 ' . the ratio of the velocity of light in air to that in the metal , and is the coefficient of absorption . The refracted wave , which we shall refer to brietly the wave , will , after traversing the plate , become . When it reaches the bounding surface it will be reflected and refracted . In this waves will surge to and fro acl . OSS the plate , while an infinite series of waves will return into the first medium ( air ) and constitute the reflected beam , and another series will pass into the third medium ( air ) and constitute the transmitted beam . We shall denote by and the quantities to and when we are considering a ) from metal to instead of from air to metal . With this notation the reflected beam is represented by ' and the nitted 1 by . The values of the quantities and and are jive by the theory of reflection and refraction , and in this way we can easily ) that and esults can also be ined by means of Stokes ' principle of eversion , or ) noting that when the -ness of the metal is indefinitely diminished and becomes unity , then all the transmitted and none Making use of these relations , the reHected beam becones The first refracted wave was , where Hence , if be the thickness of the plate , we have where is the wave-length of the incident we have , tall , where , and tau We thus get , where and These relations suffice to determine in terms of the optical constants of the metal and the thickness of the plate . quantity is a complex . Its value is given by theo1y of reflection and proves to be dependent on the position of the plane of tion of the incident . If we egaxd the transition one the other to be abrupt , then , when the incident light is polarised perpendicular]y to the plane of incidence , is given by Fresnel 's folHlula . For ised parallel to the ) } incidence , have the corresponding We ] lave and putting where while Similarly \ldquo ; , ' ' If the incident wave ) elCprebented ) , then the eflected beam is represented by plitude and the change of phase produced by reflection . We . Soc. Proc 212 . of the Optical Properties of ) Jletallic ) We thus get where This determirle , the intensity of the reflected bealn . Vhen the of the plate is indefinitely small and . Hence , so that there is no reflected beam . As the thickness increases , approaches the linlit zero , so that approaches the limit \mdash ; as is to be ) ected . It llay be to observe , vever , that the intensity of the reflected light may be greater for a thin plate than for a thick one . wheu , , where Consider the case of direct incidence . We then , where cqufttio1l to deterlninc becomes For the silver and gold , to be con sidered latel , ( 1 is , so when is not very small , the quantity will be very small , we } very approximately . This . In of silver this makes . This is , so that our approximation is sufficiently accurate practical that can thus easily find the that gives the netals discnssed later this ) in the case of silver , and in the case of . If the tness is rather greater than this , we reater than , but as the thikess increases , once more approaches to equality with will then ] ) thickness that makes maximum , and it is not to deterlnine this thickness . We have ( is to ) we get , by to zero , i.e. As is small , this can easily bc by approximations . The first gives i.e. , For silver , this makes , which is so small that the hrst roximation is sufficie ] accurate . The thickness that gives the greatest intensity of reflected light is determined by in the case of silver , and in the caso of gold . In both cases , however , the of is greater than The table shows the intensity of the reflected depends on the thickness of the plate in the cnse of and silver . The intensity , of course , depends on the values of the ) tical consGants and , and in turn vary with the colour the incident . From ) 's experiments* with well cleaned silver in light , he calculated that , and , and from sinilar iments by Conroy , with in red we find that , and ' Wied . Ann vol. 39 , p. 481 . . Soc. Proc 1881 , p. 486 . These constants are deduced from tions of the Principal Incideuce and the Azimuth . It has often been bserve that these angles vary with different conditionls of the reflecting Slll.face . That this is to be expected is apparent if we regard the transition one nledium to the other as gradual and not abrupt . The Principal cidence and Azimuth depend on the nature of the layer of transition , when the matter examined efully it is found that the of the transition layer lead to considerable ) in the values of the optical constants . See ' Roy . . Proc 190 ) . , and post , p. 3 : , vote present we shall take the value derived from the experiments of lJrude and Conroy the hypothesis of an abrupt transition as sufficiently accurate hrHt approximation to the truth . 302 Prof R. C. Maclaurin . We have when is satisfied , very approximntely , by . For silver this corresponds to , and for To make a maximum we must have As a first approximation , i.e. , , so that . For both silver and gold this will be found to make nearly unity , so that is very ] , and the first approximation is sufficiently close . The maximum value of occurs when we have seen that when is less than , so that is reater than ; but in the case of the silver and gold , ah.eady discussed , it is not very much reater , so that the maximum is reached soon after is equal to silver the maximum occurs when and for when The following table gives the value of , ( ' xpressed as fraction of the halfll.ave-length . These results ftre represented boraphically in below , Curve 1 correto the silver and Curve 2 to the gold . Perhaps the most striking thing about these results is the large percentage of the change of phase due to a thick plate which is produced by a very thin plate . In the one case 64 per cent. and in the other 70 per cent. of the total change is produced by an thin plate . It must be borne in mind , however , that the intensity of the reflected light for such thicknesses is vanishingly small , so that it would not be practicable to measure the 1906 . ] of the Propcrtie Thin 300- that and that , we , to determine maximum of , the equation sill This is easily solved by approximations , and yields in the case of silver , and in the case of boold . The value of , expressed as a fraction of the half lelJgth , is ooiven in the table , and the results are represented graphically in below . As befc ) , Curve 1 corresponds to the silver and Curve 2 to the gold . We shall now considel to extent the results already obtained as ) the intensity and change of phase of the reflected are modilied } the metal is deposited on eolass . The second reflection and efraction in investigation of p. 297 now takes place at from to instead of at one from metal to air . The quantities and will therefore be altered , the values given , as before , by 's formulae . This method of attacking the problem is adopted later ( p. 313 ) , when we are with the more general case of incidence . As , howevel we have already calculated the amplitude and phase of the iected and transmitted beam for a 1netal plate surrounded by air , it is convenient to utilise these results in the present problem . enable to do this suppose the metal and glass sepnrated by an layer of An incident wave of unit amplitude gives rise to a reflected wave VOL. LXXVIIL\mdash ; A. -X 306 Prof. R. C. Maclaurin . [ Aug. } where and are and already calculated for the reflected wave . It also produces a transmitted wave and havin. . also been calculated ) . This wave reflected glass , glVlI ) a wave , in its tuln is transmitted the metal plate and emerges into the air as a wave say . The complete reflected wave is thus the resultant of the two compo ents and . If , as before , we denote it by , we have and tall If tIre incidence be direct , then is given by Fresnel 's formula where is the efractive index of the glass . Thus and For small thicknesses is very small , while is considerable . Under these circumstances is nearly equal to A and to . As the thickness increases , rapidly nishes , so that and approximate more and more closely to and . Thus , except very thin plates , the will be the same as if the metal were SUl.rounded by instead of deposited on glass . With very thin plates , however , the two cases will be quite different . we get the following values of 1906 . ] of the Optical Properties of Plates . These results are replesented graphically in above . Curve sponds to the silver and to the gold . A comparison of Curves 1 and 4 or Curves 2 and 5 will show the influencc of on the intensity of the reflected light . The difference of phase is given in the table . snlallIndef . Silver Fig. 2 above ives a graphical representation of these results , Curve 4 or the silver and Curve 5 for the gold . As is to be expected , the ence etween metal alone and metal on ylass is very marked for small thicknesses . all cases the change of phase is less for metal on than for metal , lone , but the difference between the two cases diminishes rapidly as the hickness increases . After a thickness has been reached there scarcely any appreciable difference between the results , and for the sake clearness the curves for on glass have not been drawn beyond this oint . If we compare these results with Wiener 's observations*of the change of has produced by reflection from thin films of silver deposited chemically lass , we see that there is a close reement . The of phase akes place rapidly , not so rapidly as Wiener 's first , but lore rapidly than with his second mirror ( B ) . With the silver , , bove , about 65 per cent. of the total chan , . of phase is reached when , i.e. , whelr mm. . With Wiener 's mirror almost the whole change took place within a thickness , but yith the second mirror the corresponding thickness was 12 So far we have been ) mainly with a discussion of the intensit . phase of the reflected and light in the of direct ncidence . We shall now return to the more general problem stated at the nset , that of the ellipticity and the differeuce of phase between he parallel and perpendicularly polarised light for any angle of incidence . the reflected light we have seen ( p. 298 ) that . ' Wied . Ann vol. 31 , p. We have said nothing of the ence of the glass on the transmitted beanl . It is hown later ( p. 337 ) that for direct incidence the ellipticity is not affected by the glass . Prof R. C. Maclaurin . Hence Thus if be the ellipticity and the azimuth of the reSlected light we have . As the thickness of the plate increases , diminishes and approaches the . We shall calculate for different thicknesses of the gold and silver already discussed . If be the of phase , we have , where is given by the formula Having obtained for a series of angles , we can represent the resnlts graphically and so determine the angle of incidence that makes equal to a quarter of the wave-length . This is the Principal Incidence and the corresponding value of is the Principal Azirmth . We proceed to tabulate the values of the constants occurring in these formulae for the silver whose optical constants are and Tf , we have . and . The other quantities are to be calculated from the formulae ; ; ; ; ; The formulae for , and have been already given on p. 298 . From these we get the following table . The values of and in this and later taUes refer to the case . As these quantities are directly 1906 . ] of the ptical Pof Plates . In this case the reflected wave , instead of , is now , where is the same as before , the correspdio quantity , when a ray of light goes from glass to metal instead of to metal . The quantity is the same as before , and in we must replace by and by , where and is the coefficient of refraction of the ylass . Putting taking we the set of values:\mdash ; We have Thus the ellipticity is iven by the formula and the difference of phase is where From these formulae and the constants above we derive table for These results are represented in above and . The dotted curves in exhibit as a function the thickness of film for difi.erenb angles of incidence . The continuous curves of that 1906 . ] of the Optical Properties of ThiMtxllic Plates . the polarising angle of the bolass , and we thus see we can pass from vitreous reflection to metallic reflection ffil intermediate tes by the aid of layers of silver radually i in thickness . One of the most facts about these results is the very rapid change in the Principal Incidence produced by slight thickening of the film wheu the film is very.thin . A of only ndth of the wave-len increases the Principal Incidence from This iudicates how considerable would be the influence of a surface layer of any kind on position of the Principal Incidence and serves to explain the observation all careful experimenters that the Principal Incidence alters with different conditions the reflecting surface . * It is also in good reelnent with experiment by on the )ject . A . fihn was deposited on glass by electrolysis . The film was so thin that its existence could not ] been suspected without previous . It was quuite ossible to estimate the thickness exactly , but it certainly not than fivethousandths of a wave-length . with this thin film the ) erties of he reflected from were considerably modified and the Incidence had increased from to onroy made various experiwith silver films on }lass . The films varied in thickness cm . to cm . Taking . for yellow , this makes vary from to } ) . This lies between Curves 5 and 7 of the above . Our raph makes the P Incidence increase in this range from to , an increase of 1o ConroY found an increase of . Although the Principal Incidence rapidly at first , it soon tends to a constant value and there is little change when the thickness exceeds mm. QuillckeS made a large number of observations with silver films and red light . He that values of the Incidence increased with the thikess , tended to a constant value and changed very little when the thickness of the film exceeded mm. To exhibit more clearly the influence of the glass on the Principal Incidence the results for silver alone and silver on glass are set out together and their differences stated . . ' Boy . Soc. Proc 1 , p. 211 . Contptes Rendus , ' vol. 76 , p. 866 . Soc. Proc 1881 , p. 486 . S 'Pogg . Ann vol. 129 , p. 177 . 316 Prof R. C. Maclaurin . Numerical mination It appears from this that , except for excessively thin fihns , the Principal Incidence is greater for silver on glass than for the same thickness of silver alone . The difference , ever , is nowhere very considerable , and it diminishes to zero as the thickness of the l1letal increases . The ellipticity is boiven by the fornlula on p. ; it is most conveniently expressed as the gent of the , whose value is set out in the A comparison of figs. 7 and 10 will indicate clearly tlJe change in the azimuth produced by the silver on . It will be seen ] Curves 4 , 5 , 6 , and 7 in the two ores are very similar , so that after a thick1906 . ] of the Optical ]erties of fetallic Plates . ness has been reached it does not make a great difference ether Che silver is alone or on glass . As is to be expected , however , with very thin films the diffel.ence between the two cases is marked . On comparing rves 1 , 2 , and 3 in the two figures see that they are completely different . For silver alone the azimuth incr with the thickness , whereas for silver films on glass it rapidly at first . The Principal Incidence been obtained above it is easy to determine the Principal Azimuth from the . The position of the Principal Incidence { Azimuth is 1narked in fig. 10 by a cross ( ) . The tabl the Principal Azimuth for different icknesses and compares it with the case of silver alone:\mdash ; The Principal Azimuth is thus always gl'eater for silver glass than silver alone . The difference is very considerable , but diminushes rapidly to zero as the thickness increases . When the thickness changes from to the Principal Azimuth increases . Conroy* found a much large increase , viz. , , in the same range . It appears , however , that the variation of the Principal muth with the thickness . considerable in the yhbourhood of . When the thickness increases from to there is a change of in the Principal Azimuth . Thus a error in the estimate of the thickness of the thinnest of Conroy 's films would for the apparent discrepancy between theory and experiment Havin discussed the of the light reflected from silver films , we proceed . to estimate the extent to which these results are modified whenl lnlS of some other metal are employed . So far our results have been obtained on the supposition that the transition from air to the metal is abrupt and not gradual . This , of course , is only an to the truth ; but in the case of silver the approximation has proved to be sufficiently close for the experimental results . When the influence of the layer of * Conroy , loc. , p. 31 thickness was calculated from the weight of a measured was necessarily some uncertainty as to the density of the silver in so finely divided a state . 318 Prof R. C. Taclaurin . transition is considered it is found* that the difference of phase is altered by a quantity which is a maximum the Principal Incidence , where it is iven the formula . ' enables us to determine for what metals the correction due to the layer of transition is most considerable ; e.g. , it would lead us to expect ) influence of the layer would be greater with gold than with silver . As , however , the analysis is necessarily much more complex when there is a snrface layer to be taken into account , we shall hold fast to the hypothesis of a sudden transition from one medium to the other as a sufficiently close approximation to the truth , unless we are driven from by too great a discrepancy between theory and observation . The metal that lends itself most readily to accurate experiments with thin lates is with red , Conroy found a Principal Incidence of and a Principal Azimuth of as the mean of several determinations . On the supposition of a sudden transition from air to gold the optical constants can be derived from these angles ) means of the formulae ' with the ] for and already ooiven ( 1 ) 308 ) . In this way we obtain and . With these constants and the formulae on we the following table:\mdash ; With the aid of these quantities we derive the following series of values from the formulae * See ' Roy . Soc. Proc 1906 , p. 224 . . cit. , p. 213 . 320 Prof R. C. Maclaurin . Nn than for silver . For siiver we that when when oInci JIncidence wthick poldis sfrom , howeveritsfinal value . * Conroy experimented with gold leaves varying in thickness cm . to cm . For red , taking cm . , this makes vary from to 0149 This range lies between the Curves 5 and 7 of fig. 11 , and we see that the variation of the Principal Incidence is small . The increase is only ) a degree , whereas Conroy found an increase of . The agreement is quite as close as could be expected considering the discrepancies between the different experimental results , uncertainty as to the optical constants and the specific gravity of the metal in the state of gold leaf , and fact that we have neglected influence of the glass on which the leaves were Conroy 's conclusion that the Principal Incidence always increases with the thickness of the llletal is supported by our theory with the optical constants that we have adopted for silver and boold . However , Meslin 's experiments with gold a much wider range of thickness show that the law is not universal , and we shall see later that this is supported by theory when the transition layer is taken into consideration . The azimuth is given in the table:\mdash ; These results are exhibited in below . On . this with above it will bc seen that there is not much ] difference between the behavioul ' of the two metals . The Principal Azimuths for the various thicknesses are found from the figure to be , and respectively . The crosses in the esent the positions of the Incidence and Azimuth . From the -k It must be remembered that is not the same in the two cases , the incident being yellow for silver and red for gold . This , of , affects the estimate of the thickness , and a slight change in this would easily account for the apparent difference between theory and experiment . . p. 316 . For such thicknesses the effect of the glass is small . 1906 . ] of the Optical Properties of Thin S25 The following table ives the values of the azimuth These results are represented in fig. 13 above , and on comparison ) fig. 7 we see that there is very little difference between the two metals regards the law of variation of the azimuth . of Layer . So far we have proceeded on the hypothesis that the transition medium to another is abrupt and not actual . This layer transition has led us to results that quite as well as could be expected with experiment . Unfortunately , however , the experiments that we ] ) been able to quote are all too few in number . * They deal almost exclusiyely with observations of the Principal Incidence and Azinluth , and eve1l these the vations extend over a rather of thickness the metallic film . We shall now turn , however , to a much more exteusive of experiments giving us the difference of phase for reflection and transmission over a wide of thicknesses . These experiments were made with l of and we have already ( p. :318 ) been led to expect that for this the influence of the transitio1l layer on the diffel.ence of phase would be appreciable than with silver . When we examine Meslin 's results for reflection from a thick plate of gold we find that the theory of an ab.ttl.ansiti ] ] not give us results that even approximately ( except in a very way ) with the facts of experience . It is known that on snch a theory the difference of phase is given by the formula and the Principal Incidence by the , or its equivalent , . * It would be a great advantage if we could obtain accurate measurements of difference of phase and azimuth both reflection and transmission . leslin iveh us the difference of phase , but not the imuth . See note p. 296 . See ' Roy . Soc. Proc 1906 , pp. 213 and 215 . 326 Prof R. C. Maclaurin . mination [ Aug. 30 Meslin found the Principal Incidence to be , and as must lie between and , we see that must lie between and When the incidence was , Meslin found , and from the formula for we see that cannot be greater than . This lies considerably outside the limits for fixed by the Principal Incidence and we should be to a similar inconsistency if we considered the value of at any other incidence than that of . The crosses in below represent Meslin 's values of for different incidences and it will be seen hat they are very fairly consistent . * The continuous urve of the represents the theoretical results obtained later when the layer of transition is considered . We proceed to develop some formulae applicable to the problem when the transition layer is taken into account . In that case in addition to the optical constants , and , two new constants and are required whose values depend on the law of variation of within the layer . The quantities hitherto * At least ) to . There is evidently a lnisprint in the values of given for and . They are set down and 0.648 respectively . An inspection of the figure shows that these are quite inconsistent with the other results and with the graph given by Meslin . Probably the numbers should be and , 5 being replaced by 8 , and the two values interchanged . Owing to the uncertainty of these results they have been neglected altogether in the subsequent determination of the optical constants of the gold . 1906 . ] of the Properties of Thin represented by 21 and are replaced by and , which given by the following , say , nately where where ; is the difference of phase that an abrupt transition would produce , and is given by the formula for on p. 325 , while is the correction due to the transition layer . Since and must be calculated in order to determine , it will be convenient to express and in terms of these quantities . From the bove formulae we have , whence and Similarly See ' Roy . Soc. Proc 1906 , 222 . Ibid. , p. 222\mdash ; 3 . has been aced by and by to avoid confusion with quantity called in the earlier part of paper . The quantity is printed with wrong sign in the paper referred to , and and of p. 224 should ench 1 by 328 Prof R. C. Maclaurin . [ Aug. 30 , whence and where It thus appears that there will be no great difficulty in calculating all the quantities involved in our formulae , once the four optical constants and are obtained . However , to obtain these four quantities accuratdy from a series of observations of the difference of phase at different angles of incidence is a problem involving some labour . Theoretically , we coul obtain the four constants from any four observations of ; but the equations are much too complicated to be solved a set of four simultaneous equations . ractically we must proceed by a series of approximations and in this consistent results are soon obtained , unless very great accuracy is aimed at . From the formulae it appears that ( the correction to the change of phase due to the layer ) vanishes at normal incidence and is small when the angle of incidence is small . We can , therefore , obtain a first approximation to and from two observations of the difierence of phas when the angle of incidence is not . As a first approximation in such circumstances we can neglect altogether , or to it any small value that seems reasonable . Knowing and ( approximately ) we can calculate , and from the formulae above . obtained by calculation , and from observation for auy othel angle of incidence , thus for that incidence . Also we have so that In this equation everything is known ( approximately ) except and , so that by using our of at two of incidence , other than those employed for obtaining the approximate values of and , we easily obtain the unknown quantities and thus obtained approximate values of the four optical constants , we can calculate in terms of them , and proceed , if necessary , to higher approximations . If the expeximental results give us the difference of phase for more than four of incidence , we can use the ordinary rules for finding the most probable values of the optical constants , and estimate the probable errors . In carrying the process sketched above with reference to set of 1906 . ] of the Optical operties of Thin Metallic Plates . observations actually ayailable at present , we find that the approximations need not be carried very far , for we soon obtain results that fit in with experiment well within the limits of experimental errors . We take Meslin 's results with red light reflected from gold ; and the second approximation in the above process yields the following values of the optical constants:\mdash ; . From these we derive the following table , giving the values of , and the difl'erence between theory and observalion : These results are represented in above , in which the continuous ctlrve corl'esponds to the theory and the crosses to the experiment . From the figure 01 the table we see that the agreement between theory nent is a close one , that , in view of the uncertainty as to some of the experimental results , not much could be , ained by to approximation . We shall therefore take the constants ooiyen above the basis of our calculations . From the iven we then del . iv the . table :\mdash ; We are now in a position to discuss all the problems with in the earlier part of this paper without ecting the layer of ansitio from one medium to another . effect of this layer is to rep lace by quantities remain before , nrnst Prof R. C. Maclaurin . [ Aug. remembered that on pp. 297 et . refers to a tbickness of homogeneous 1net . We shall sst out our results in terms of , but , of course , this is not the actual thickness of the plate . To goet that thickness we must increase by twice the thickness of the layer , and it is owing to the uncertainty as to the value of this latter quantity that we cannot state the results precisely in terms of the thickness of the metallic plate . If be the tbickness of the layer we should expect* to lie betweell and , and with the constants iven above this makes lie between and If be incident nornlally on a gold leaf whose optical constants are those just determined , then the intensity change of phase for the reflected transmitted are as follows:\mdash ; These results are esented graphically in Curve 3 of , 2 , 3 and 4 , above . If the gold , instead of being surrounded by air , is deposited on glass , these results must be modified as in the cnse of silver on p. 305 . The intensity and change of phase the reflected are then boiven by the table : See 'Roy . Soc. Proc 1906 , p. 229 . With the of variation of given on p. 230 , we have , for the gold alone , . This makes , which is about half way between the limits found in the text . is almost identical with the value obtained for the layer of transition in the case of reflection front diamond . See 'Roy . Soc. Prnc , vol. 76 , 1905 , p. 63 . That so thin a layer should produce an appreciable change in the Principal )lcidence and Azimuth is not altogether surI)rising after what been seen on p. . The gold under discussion here is a good example of the that may be made in deriving the optical constants of a metal from ervations of the Principal Incidence and Azimuth and neglect of the transition layer . The Principal Incidence is and the Principal Azimuth , obtained from the formula , is ecting the layer of transition these would give instead of and instead of . If , then we should get , instead of and instead of 1906 . ] of the Properties of Thin These results are exhibited in Curve 6 of figs. 1 and 2 above . the first of these figures we see , by Curves 1 and 4 , or 2 and 5 , for silver or gold and an abrupt transition the intensity of the reflected light is always reater for the metal deposited on glass than for the meta ] plate alone . The difference between the two cases is , however , snlall , and tends to zero as the thickness increases . On Curves 3 an . we see in this respect the layer of transition modifies the results considerably . After a thickness has been reached , the intensity of the light from gold on glass is less than that reflected from gold alone . To determine the ellipticity difference of phase when the is at any angle we have to modify the on by replacing by . For the reflected light we have ' where and where Thus , where A and are the modulus and respectively of the complex quantity . sin The difference of phase is and the ellipticity is From these formulae we get the following table for 336 Prof R. C. aclaurin . Examination instead of being surrounded by air . nlethod described on p. 306 above . can be done most simply by the A beam of unit amplitude incident on the metal gives rise to a reflected and a transmitted beam S . where , as we have seen , The beam is then incident on a glass plate and yives rise to a reflected beam and a transmitted beam . Here , where is obtained from Fresnel 's formulae for reflection and where is the coefficient of reflection and is tbickness of the glass . The wave leflected from the glass is transrnitted the metal plate and gives rise to a wave in the air . Thus the 1906 . ] of the Optical of Metallic Plates . wave is and the reflected wave is the resultant of and These results are quite general and would suffice to solve the problem iu the most complicated case when both plates ( metal and , lass ) were thin , i.e. , not large compal.ed with a wave-length . In problem at present in hand the glass plate is thick , and under these circumstances there is a considerable simplification . We then have and , so that the mitted beam is and the reflected one is the resultant of ) and The ransmitted wave is most readily disl ) of . The effect of the glass is to replace by . The factor is the same whether the light ) polarised parallel or perpendicularly to the plane of incidence . Hence the oolass has no influence on the of phase nor on the ellipticity of the transmitted beam . We should expect , then , that the results on p. 334 above should agree , within the limits of experimental , with Meslin 's values . A comparison shows that there is a very fair reement as far the law of variation of is concerned . to the uncertainty as to the thickness of the layer of transition and the difficulty of obtainino accurate measurements of the thickness of the metallic deposit , we cannot compare the numerical results of theory and experiment with much hope of exact equivalence . As we shall see later , the experiments on reflection , when compared with theory , us a fair basis of comparison as far as thickness is concerned . On determining in this way the thicknesses to be compared , it appears that the theoretical results , lGhough o much the same h of dependence on as Meslin 's values , are higher than these values . However , as was obseryed on p. 335 above , a change in the optical constants makes an appreciable difference in the difference of phase of the transmitted \mdash ; and in view of this fact tlJe agreement between theory and experiment as close as could be expected . Unfortunately , Meslin made no record of the ellipticity , so that we have no means of comparison in this The reflected light is the resultant of and this by , we have , and The difference of phase is iven by and the ellipticity by VOL. LXXVIIL\mdash ; A.

rspa_1906_0082

0950-1207

Experimental evidence of ionic migration in the natural diffusion of acids and of salts.\#x2014; Phenomena in the diffusion of electrolytes.

342

379

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Reginald Graham Durrant, M. A., F. C. S.|W. A. Shenstone, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0082

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0082

10.1098/rspa.1906.0082

Biochemistry

Chemistry 2

Biochemistry

342 Experimental Evidence of Ionic Migration in the Natural Diffusion . of Acids and of Salts.\#151 ; Phenomena in the Diffusion of Electrolytes . By Reginald Giiaham Durrant , M.A. , F.C.S. ( Communicated by W. A. Shenstone , F.R.S. Received May 2 , \#151 ; Read June 21 , 1906 . ) 1 . The origin of the following experiments was due to observations made in jelly tubes with red phenolphthalein , prepared according to the directions given in Dr. Liipke 's " Elements of Electro-Chemistry , " * being a modification of Sir Oliver Lodge 's original method . After tracing , for some time , the bleaching progress from opposite ends of the tube , under the electro-motive influence of eight storage cells , the current was stopped and the subsequent bleaching progress was observed from either end . The ends of the tube dipped respectively into hydrochloric acid and cupric chloride solution , and assuming the original bleaching to be due to hydrogen and to chlorine ions , it appeared probable that the subsequent bleaching was due to the same cause . The mean relative rates of the ions under electro-motive stress of the battery were\#151 ; H : 01 s : 5*7 i 1 , and the mean relative rates when the current was stopped\#151 ; H : 0 U :5T : 1 . The actual rates , in the second case , were naturally much slower and closely followed Stefan 's law for diffusion , viz. , distance covered varies as v time . 2 . It occurred to the author that it should be possible to trace an advance motion of hydrogen ions in ordinary diffusion of acids into jellies , if the jellies were suitably prepared as indicators , and thus to illustrate , and perhaps to extend , the theory originally propounded by W. Nernstf and M. Planck . J 3 . Experiments on the Diffusion of Acids into Jellies . As several hundred observations were recorded with various acids into variously prepared jellies , these observations are given as an appendix . * English translation , p. 53 . t 'Zeits . fur physikal . Cbemie , ' 1888 , vol. 2 , p. 613 . $ ' Wied . Ann. , ' 1890 , vol. 40 , p. 561 . On Ionic Migration in Natural Diffusion . The nature of the experiments and their more important results were as follows ( 1904):\#151 ; ( a ) By allowing acids to diffuse into jellies , suitably prepared and tinted with litmus , certain zones appear and become wider as time goes on . ( b ) The foremost zone is in advance of the " diffusion front , " and is well seen in a blue jelly having the following composition , calculated as grammes per cubic centimetre:\#151 ; Gelatine , 0*058 ; KHCO3 , 0*00128 ; KOH , 0*0002 ; Litmus , 0*0008 ; or " 0*06 ; " 0*0006 ; " 0*0002 ; " 0*00084 . The gelatine was Coignet 's " Gold Medal , " and the " litmus " was simply the ordinary blue extract , twice filtered , and its weight found by evaporating a sample at 100 ' C. in a platinum dish . This zone ( ad in the tables ) is purple . It starts from the diffusion front and fades away into blue higher up the tube . Its growth can be traced approximately ( under good conditions ) until it is 30 mm. long . ( c ) The next zone ( ac in the tables ) is separated from the last by the diffusion front only . It is observable in the same jellies , and also in jellies containing more potash . This zone is pale yellowish red , and at first is sharply marked at each boundary . It widens less rapidly than does the purple zone . Its back boundary , after about a week , becomes less clearly defined . ( d ) After about 400 hours a third zone appeared in five cases , well behind the yellowish red and separated from it by red litmus , Like the purple zone , this was clearly defined at its back boundary and merged into red at its front . o e f c a d Fig. 1 . This zone becomes absolutely colourless . Its growth was noted from 426 to 760 hours in the cases of N/ 6*51 HC1 , and N/ 6*51 HBr ( p. 370 ) . Also from 623 to 961 hours in the cases of N/ 5 HC1 , N/ 5 H2S04 and N/ 2 H3SO4 ( p. 378 ) . The cause of this zone was not understood at the time , but the more recent results with silver nitrate , and also with calcium chloride ( to be given later ) , show that it was probably due to the action of accumulating anions ( Cl , Br , and SO4 ) which had their origin at the concentration difference surface ; in these cases , therefore , the origin was the bottom of the jelly tube dipping into the acid . 2 a 2 Mr. R. G. Durrant . [ May 2 , As a general result of the other observations it may here be noted\#151 ; ( i ) The foremost purple zone ( ad ) was obtained with hydrochloric , hydro-bromic , sulphuric , nitric , and formic acids . ( ii ) The contiguous yellow-red zone ( ac ) was obtained with HC1 , HBr , H2S04 , and HNO3 , but not with formic acid ; neither could it be obtained with oxalic nor with acetic acid , though these three acids were subject to exactly the same circumstances as were the first four . The anions of HC1 , HBr , H2SO4 , and HNO3 are , on reacting , all of them bleaching agents , while the other three anions , CH02 , C204 , and C2H3O2 , are not . The author therefore believes that this yellow-red zone is due to these " bleaching " anions which are left behind when hydrions separate from the advancing diffusion front . The hydrions themselves , on reacting , produce the purple zone . ( The yellow-red zone never becomes bleached completely , because the action is constantly occurring in fresh litmus . ) 4 . Experiments on the Diffusion of Acids into Eerric Solutions WITHOUT THE USE OF JELLIES . The earlier experiments with ferric solutions were made in the following simple apparatus:\#151 ; A tube ( ah in figure ) was fitted to a tap by means of an indiarubber joint . The ferric solution was drawn up short of this joint , and the lower ( contracted ) end was dipped into the acid as shown , the whole being surrounded by cold water and left for about 20 hours in a room where there was but little change of temperature . The tube was about 30 cm . long , and contained just over 5 c.c. After 20 or 24 hours the tube ab was taken out and its contents run out , usually in six portions , into shallow porcelain cups , and there tested with potassium ferricyanide . At the same time blind experiments were made with other portions of the original ferric solution which had not been subjected to diffusion from the acid , and also with other portions which had been mixed with the same acid during the period of diffusion . The upper portions of the ferric solution indicated distinct reduction by giving a blue tint . The following experiments were made :\#151 ; Four experiments with normal sulphuric acid into a dilute ferric chloride solution . Three experiments with stronger sulphuric into the same solution . Two experiments with this stronger sulphuric into iron alum solution . All these showed considerable reduction . 1906 . ] On Ionic Migration Natural Diffusion . It was found , however , that a slow reduction does take place in all cases where sulphuric acid is used or where iron alum is used with other acids , though the difference in tint showed that greater reduction occurred after diffusion . Preliminary experiments showed that no reduction occurs when ferric chloride solution is left mixed with hydrochloric acid ; whereas in three experiments with 6N hydrochloric acid diffusing into ferric chloride ( 7'8 grammes per litre ) , distinct evidence of reduction occurred , as also in an experiment with 4N HC1 into the same ferric chloride , and , later still , normal hydrochloric acid into a solution of ferric chloride , containing 1*4 grammes of iron per litre , gave two unmistakable cases where reduction had reached the top of the tube . Only two experiments gave negative results , and in these the ferric chloride was taken from a bottle in the laboratory which had , for a long time , been in contact with air . Mr. R. G. Durrant . [ May 2 , In order to make sure of observing this reduction , the ferric chloride ( hydrated solid ) should be dissolved in distilled water which has been previously well boiled . The potassium ferricyanide also should be free from dissolved air ; in the later experiments ( with hydrochloric acid and with nitric acid ) the ferricyanide was delivered from a fine nozzle , and one drop only ( = 0-015 c.c. ) was used in each experiment . In order to experiment with oxidising acids , another form of tube ( fig. 3 ) was employed consisting of a syphon whose longer limb , dipped into the oxidising acid , while the shorter limb , ( with a ground glass tap at c ) , was connected with a burette . A glass plug e fitting an indiarubber tube made it easy to regulate the exact level of the ferric chloride solution as indicated in diagram by ff . This syphon ( over 40 cm . long ) held 9 c.c. from to 2 c.c. to c , and 1*8 c.c. c to d. It was filled completely with the ferric chloride , and the burette completely with wrnter , ab was then placed in a tube containing chromic or nitric acid , c was opened , and the burette tap very carefully turned so as to draw the acid up to about 30 mm. in ab . After 20 hours or so the acid in its tube was removed ; e was opened , which left the portion ac undisturbed . The branch ab was repeatedly rinsed with distilled water and the contents of the portion ac were tested . Distinct reduction was found in every experiment , two with chromic acid and three with nitric acid ; in the two last experiments the nitric acid was 2*7N and the ferric chloride 2'24 grammes of iron per litre . In all these experiments with acids diffusing into ferric chloride solution there is , therefore , evidence that hydrogen ions advance and cause some reduction of iron from the ferric to the ferrous state . '(There appeared also to be some evidence of an independent reduction on a smaller scale occurring at the free surface of the ferric chloride solution . Further experiments on this subject are contemplated . ) 5 . Three independent investigations , have been attempted which bear on the results cited already . They were :\#151 ; ( i ) A set of experiments on the nature of the hydrogen occluded by palladium . These will be extended ; the results up to the present seem to show that this hydrogen on leaving the palladium in purple litmus or red phenolphthalein is accompanied by hydrions sufficient to show acidity , amounting , however , to not more than 3 x 10-7 gramme of " acid hydrogen available from the palladium helix employed . ( ii ) An investigation to ascertain the best conditions for manipulating the erricyanide reaction and to determine the maximum delicacy of the test . 1906 . ] On Ionic Migration in Natural Diffusion . ( iii ) An investigation of the sensitiveness of the litmus reaction\#151 ; as compared with the ferricyanide reaction\#151 ; since on these two reactions the evidence of hydrions advancing in front of diffusion hitherto depends . ( ii ) The Ferricyanide Reaction . The preliminary results of this investigation went to show\#151 ; ( a ) The blue or bluish green tint actually observed is due to the reaction K3Fe , , , ( CN)6 + Fe"Cl2 = 2KCl + KFe , ,Fe'/ , ( CN)6 . . " Soluble blue . " ( b ) The reaction when observed on a surface of porcelain exposed to the air is more delicate in presence of large excess of ferric solution than it is when little or no ferric solution is present . This result is probably due to the excess of ferric iron obstructing the oxidation of ferrous iron by the air . ( c ) The rapidity of the reaction is greatly increased by admixture of hydrochloric acid , a result analogous to that of acceleration in hydrolysis . The method of experimenting , in the final work , was as follows :\#151 ; Eather more than a litre of normal hydrochloric acid was kept simmering for an hour and a-half , while pure hydrogen gas was bubbling through . This was allowed to cool in the hydrogen atmosphere . Then 24T grammes of iron alum were dissolved in the acid , so that the solution became at once normal hydrochloric and N/ 10 ferric , counted as 0'0028 gramme of ferric iron per cubic centimetre . Two flasks had been prepared and fitted with short capillaries . Into the first , A ( fig. 4 ) , a portion of this solution was introduced till it was full to the 435 cubic centimetre mark , while another portion was introduced into the similarly fitted flask B ( to a mark = 426 cubic centimetre ) . Hydrogen gas was bubbled through each to drive off air from above the mark . Into the flask A 0*0612 gramme of ferrous sulphate crystal was quickly dropped and was rapidly mixed and dissolved by passing more hydrogen through . Both flasks were kept closed and , when used , the liquid was slowly forced out of the tube either by hydrogen or nitrogen gas . The flask A contained finally\#151 ; N.HC1 ( app . ) 1ST / 10 ferric iron \gt ; N/ 1000 ferrous iron J The flask B contained N.HC1 and N/ 10 ferric iron . Fig. 4 . Mr. R. G. Durrant . [ May 2 , Experiments with the two solutions dropped into phials with N/ 10 potassium ferricyanide at once showed very marked colour differences . But as the test is usually made on porcelain , the volume of each drop as it fell from the capillary under nitrogen pressure was ascertained . This was 0*095 c.c. ( practically OT c.c. ) , and therefore each drop contained 0*0000028 gramme of ferrous iron from the flask A. A tube with a fine nozzle was made to allow very small drops of the ferricyanide ( N/ 10 ) solution to fall ; each drop corresponded to 0*015 c.c. Thus the volumetric ratios used in all the experiments* were easily calculated with fairly good approximation . In all the ratios of ferricyanide to ferrous iron ( within very wide limits ) the tints , as compared with the non-ferrous solution , were quite distinct , but the ratio which gave the most marked difference was when the ferricyanide added was ten times that required for the reaction K3Fe ' ' , ( CN)6 + Fe , 'Cl2 - 2KCl + KFe''Fe , , , ( CN)6 . By mixing one drop from flask A with nine drops from flask B , and then adding the ferricyanide to portions of the mixture and comparing with the non-ferrous solution alone , a distinct green appeared in the former case . But when the ferricyanide was diluted to become N/ 100 , and added to the now lST/ 10,000 ferrous solution in the same volumetric ratio as was found best before , a very distinct green-blue colour resulted . Thus , 0*00000028 gramme of ferrous iron , in presence of 1000 times its weight of ferric iron , and 10,000 times its equivalent weight of hydrochloric acid , appeared to show the " soluble blue " very clearly when 10 times its equivalent reacting weight of potassium ferricyanide was added . ( iii ) Sensitiveness of the JReaction . Approximately pure red litmus had been prepared early in 1905 . Blue litmus solution , obtained by the action of water on the solid extract , was first mixed with considerable quantities of hydrochloric acid , and then was repeatedly dialysed through parchment paper into large quantities of distilled water , until long after all recognisable traces of chloride had disappeared . There was practically no passage of litmus through the parchment paper , but there was evidence of osmotic pressure at the parchment surface . The parchment was stained blue , possibly on account of a polarity change occurring within the material of the parchment . The purest sample ( " No. 4 dialysed litmus " ) had been largely used already in other experiments . It appeared to contain 59 times as much red litmus as mineral matter ; this mineral matter consisted of colloidal ferric hydroxide and possibly aluminium hydroxide . 1906 . ] On Ionic Migration in Natural Diffusion . 349 The sample " No. 3 dialysed litmus , " which was used in the present case , contained\#151 ; red litmus : mineral matter : : 17 :1 . Ten cubic centimetres of this solution contained 0*0055 gramme of solid residue , of which 0*0003 gramme was left after ignition , consisting chiefly of FegOs . A carefully prepared N/ 10,000 solution of potash ( KOH ) was titrated against this litmus solution . Five volumes of the potash against one volume of the litmus just gave the full blue coloration . The litmus solution was now made one-fifth strength , and then it was found that equal volumes of potash and of litmus produced the distinct blue . It was easy , also , to perform the experiment on porcelain , as in the case of the ferricyanide reaction , and so to obtain strict comparison . It appears that the litmus and the ferricyanide reactions are of the same order of sensitiveness , both giving obvious colour changes in N/ 10,000 solutions , even when less than a tenth of a cubic centimetre of the solution is placed on a white porcelain surface . 6 . A Note on Certain Properties of Litmus . Experiments with the ''No . 4 dialysed litmus " showed\#151 ; ( i ) That it is an electrolyte ( with an anion which , on reacting at the positive platinum electrode , became nearly colourless , as finally did the whole solution ) . ( ii ) That this sample of red litmus will keep in a stoppered bottle for 16 months without apparent change and without any appreciable deposit . ( iii ) That its rate of diffusion into water or jelly is exceedingly slow . ( iv ) ( already cited ) That it dialyses very slowly indeed . The experiment already cited with N/ 10,000 KOH and " No. 3 dialysed litmus " would suggest that the equivalent weight of red litmus acid is in the neighbourhood of 1000 , but this would involve the assumption that equivalent reacting weights of litmus and of potash are those present , when the blue colour is reached , in these very dilute solutions , and this assumption is not necessarily correct . However , the facts that litmus ( i ) is an electrolyte and ( ii ) appears to form a true solution are arguments against its being of a colloidal nature , and therefore ( iii ) the exceedingly slow diffusive rate is probably due , partly to its being a very " weak " acid , and partly to its possessing a very high molecular weight . ( " Soluble blue , " on the other hand , is colloidal . A solution , however dilute , will , on standing for a few days , deposit all colour . ) Mr. R. G. Durrant . [ May 7 . Experiments on the Diffusion of Concentrated Salt Solutions . ( i ) The Diffusion of Sodium Chloride Solution . It was found that a concentrated solution of pure sodium chloride , after boiling , became slightly alkaline . To 10 c.c. of this solution five drops of a purple litmus solution were added1 and the mixture was placed at the bottom of a burette , the colour now being a light purple-blue . To 20 c.c. of distilled water ( previously well boiled ) 10 drops of the same litmus solution were added , and by means of a platinum wire sufficient potash was also added to make the tint identical with that of the salt solution . The water litmus solution was carefully placed over the salt litmus solution in the burette , which was then corked . After 23 hours a blue band was noticed just above the contact line , while the top portion of the water litmus became pinker . In a similar burette a similar experiment was made , in which distilled water was placed above a salt solution which had been previously mixed with a few drops of phenolphthalein . The phenolphthalein was not reddened by the salt solution , but immediately the distilled water came in contact a pink layer appeared which developed into a band . These experiments , which in themselves admit of more than one explanation , led to experiments with concentrated calcium chloride and with concentrated silver nitrate solution , the results of which appear to be of sufficient importance to justify a publication of results at this stage . ( ii ) The Diffusion of Concentrated Calcium Chloride Solution . Almost saturated calcium chloride solution occupied 14 mm. in a test-tube placed in a rather larger graduated cylinder surrounded also by water . Above it was placed a solution of purple litmus ( the same as was used after dilution in most of the experiments to be described with silver nitrate ) . After one day five or six long spiky crystals ( CaCl2.6H20 ? ) formed at the bottom of the tube and were visible for three days ( the corked bottle containing the stock solution of calcium chloride , placed close by , gave no crystals ) . Litmus gradually coagulated as a blue semi-solid deposit and covered these crystals , but left the supernatant solution colourless . The diagram represents the state of affairs after seven days . The band boundaries were very sharp indeed , and were accentuated ( as was shown eventually ) by a deposit on the glass . If the top boundaries of these bands\#151 ; viz. , 41 mm. and 21 mm. , are multiplied by 1*7 , they become\#151 ; 1906 . ] On Ionic Migration in Natural Diffusion . Top of bleached band ... ... 69*7 mm. " blue band ... ... ... ... . 34*7 " Bredig 's values* for ionic mobilities , calculated for infinite dilution , are\#151 ; Chlorine ... ... ... ... ... ... . 75T mm. Calcium ... ... ... ... ... ... . . 33 " The band boundaries were once more measured after nine days , and came \#166 ; out\#151 ; Top of bleached band ... ... 48*5 mm. " blue band ... ... ... ... . 23*5 " Multiply by 1*5\#151 ; Top of bleached band ... ... 72*75 mm. " blue band ... ... ... ... . 33*25 " On analysis , calcium chloride was found to have advanced beyond the bleached band . These results would imply that some accumulation of chlorine and of calcium ions had reacted ( as shown ) on the litmus . On removing the solution carefully , no crystals were to be found beneath the deposit of blue litmus . It would therefore seem that a temporary increase in concentration had occurred at the bottom of the tube , and , if so , this might be accounted for by supposing that the foremost layers of calcium chloride , on diffusing upwards , had , by mechanical reaction , forced back other molecules\#151 ; the phenomenon being somewhat analogous to the evaporation of liquid carbon dioxide , whereby a freer and a less free state ( the solid ) are coincidently produced . ( iii ) The Diffusion of Silver Nitrate Solution . Crystals of silver nitrate were dissolved in a small quantity of distilled water , and two drops of a purple litmus solution were also added . This mixture was placed at the bottom of a 50 c.c. measuring tube , and altogether occupied 6*9 c.c. ( fig. 6 ) . The tint was light pink , and the concentration was subsequently ascertained to have been 0*6689 gramme of AgNOs per cubic centimetre ( nearly a 4N solution ) ( = 3*93N ) . Some of the same purple litmus was mixed with well boiled distilled water . This was allowed to drop very slowly ( sliding down the tube ) on to the silver nitrate surface . A sharp blue line instantly appeared , which soon became convex upward . The total height reached up to the 30 c.c. mark . The concentration of the litmus was calculated approximately by subse* Given on p. 95 of Lehfeldt 's ' Electrochemistry , ' ( 1904 , Longmans ) . Mr. R. G. Durrant . [ May 2 , Original * purple liDmus Dark rblue zone Colourless concenbr\amp ; bed yC\amp ; Cl^solubion . ^--Librnus deposit r JCrysbcblsformed Fig. 5 . librhus ' 77im , . \#166 ; 6'9 X Blue . surface ^ Pink 'nfNa^liSll^ litmus J mm 40*3 m Z2r0 14*0 8-6 m m \#166 ; m-u m . . ... . .'.* sSi Purple Top of red Red Blue Pale blue Colourless k 5ilver bop \gt ; Pink 46*\lt ; j Fial len silver Fig. 7 . quent analysis from the contents of the bottle used . Expressed in grammes per cubic centimetre , it was roughly\#151 ; Alkali = 0*000007 , calculated as OH . Chloride = 0*000008 , " Cl. Mineral matter ( Fe20aAl203 , etc. ) = 0*00006 . " Organic " matter , including litmus = 0*00009 . The tube was corked and surrounded by water in a cylinder . Careful observations were made at intervals from the start of 3 , 28 , 47 , 77,100 , 123 , and 143 hours . All the readings were taken from the division marks ( in 0*25 c.c. intervals ) of the containing tube ; these readings were subsequently 1906 . ] On Ionic Migration in Natural Diffusion . 353 translated into millimetre readings , starting from the original 6*9 c.c. mark . The number 6*9 was subtracted from each reading , and the difference number was then multiplied by 100/ 15 , since 100 mm. happened to be the distance between 15-c.c . divisions . One advantage of this enforced correction was to eliminate the influence of personal equation ; moreover , each set of readings was made on a separate sheet of paper with no reference to , or recollection of , previous values . . The first observation was in itself of a somewhat startling nature , for after the first three hours three very sharply marked bands appeared\#151 ; bright red , blue , and colourless\#151 ; while immediately below the colourless band a deposit of silver was clinging to the glass , and more silver had dropped through the pink nitrate solution to the bottom of the tube . The blue band , though sharply defined at each boundary ( especially the lower boundary ) , was quite pale blue at its extremities , but near its centre a sharply marked deep blue band appeared . This deep blue zone persisted in the subsequent observations as the most striking feature in the general appearance . On translating the readings into millimetres , as explained , it was found that the top of the red , the bottom of the deep blue , and the bottom of the colourless band were distant from the starting point ( 0 mm. ) 40*3 mm. , 22 mm. , and 8*6 mm. , while the top of the silver deposit was about 2 mm. behind . The ionic velocities of hydrogen , hydroxyl , NO3 , and of silver at 1000 L dilution are from Kohlrausch 's values\#151 ; H. OH . No . Ag . 285*8 154*3 58*3 49*9 The above millimetre readings if multiplied by seven become\#151 ; 282*1 154 60*2 and although no reading was actually recorded of the position of the top of the silver deposit , a diagram was made at the time which would place it at about 2 mm. behind the 8*6 mark . This would give an approximate value of 6*6 x 7 = 46*2 . Subsequent observations made it clear that at first the silver deposit , after accumulating to a certain extent , dropped from the lower regions of its deposition on the glass , but that after the point 14 mm. had been reached , the silver ( now less quickly forming ) continued to adhere . Possibly by a coincidence this point , 14 mm. , was ( in the first reading ) the point marking the top of the bleached band . From the readings observed after the first three hours it appeared , Mr. R. G. Durrant . [ May 2 , therefore , that four distinct bands were formed , and were due to reactions caused by ions of hydrogen , OH , NO3 , and silver , and that the top limits of the two positive tracks ( H and Ag ) and the bottom limits of the two negative tracks ( OH and JST03 ) were then in positions , when measured from the concentration-difference-surface , which were directly proportional to the relative velocity of these ions . . The results of the subsequent observations gave continuous curves for the four bands . The chief points of interest are\#151 ; 1 . The rate of movement in the first three hours for all the bands was much greater than in former experiments . 2 . A considerable concentration difference was maintained , since in the final examination of concentrations it was found that the last 7 c.c. had only fallen in strength from 0'6689 to 04352 gramme of silver nitrate per cubic centimetre . 3 . The individual movement of the ions ( as indicated by the bands ) was probably due to high osmotic pressure in the silver nitrate , but a secondary influence may have been the attraction of congeries of H ions for OH and of NO3 for Ag . 4 . In the first observation ( after three hours ) the sharply marked bands were quite close to each other , and here this secondary influence must have been an important factor . It would appear that a set of sharply defined ( though moving ) fields of potential difference gave rise to the observation .of those division lines which marked , almost exactly , the relative velocities .of H , OH , N03 , and Ag.* 5 . In the later observations the red and blue bands were less sharply marked and were much further apart ; both also were considerably removed from the source of energy . The following calculations show that the tops of these two bands and also of the two others were , after 123 hours , at distances from the diffusion start approximately in the ratio of the square roots of the four ionic mobilities . Calling the square root of the mobility of the silver ion = 100 , the values ( for 1000 L dilution ) become\#151 ; * Subsequent experiments with silver nitrate showed evidence of discharges occurring at certain periods . In this case it is probable that discharges occurred at about the three-hour period . 1906 . ] On Ionic Migration in Natural Diffusion . 355 Ag . NO* . OH . H. 1 Mobility 100 mm. \ Ag=61-3 r S ( top ) " =100 108 *1 mm. bleached ] band \gt ; 72*7 ( top ) J " =118 6 175 -9 mm. blue 1 band \gt ; 94 ( top ) J " =153-5 239 *4 mm. red 1 band \gt ; 136 ( top ) J " =221 -8 [ Actual readings after r 123 hours I Whence ( x 100/ 61*3 ) In other words , each " front " was approximating to Stefan 's law for diffusion , each with its own constant . 6 . Gfreat care was taken in the final syphoning ( performed with a special apparatus ) and in estimating the silver present in the four portions selected . Standard solutions of sodium chloride N/ 100 and N/ 10 were employed with chromate indicator . The last portion , 7*25 c.c. of still concentrated AgNO3 , was diluted 100-fold before estimation . The results show that a very high fall in concentration occurred in the three portions taken from above the original silver nitrate solution . For whereas the mean concentration of this lowest portion was finally 0'4352 gramme AgNC\gt ; 3 per cubic centimetre = a , that in the next portion ( 10*25 c.c. ) was 0T934 per cubic centimetre = b , that in the next portion ( 4*8 c.c. ) was 0*00618 per cubic centimetre = c , that in the top portion { 7*5 c.c. ) was 0*00024 per cubic centimetre = d ; or b was 1/ 2*25 of a , c was 1/ 31*45 of b , d was 1/ 25*66 of c. These data are insufficient for a curve , but they indicate a geometrically progressive fall , so that the last few cubic centimetres at the top probably approximated to infinite dilution as regards AgNO^ It is interesting to notice that silver nitrate was found in advance of the three lower bands . ( The late-forming bleached band , obtained in the diffusion of HC1 , HBr , and H2SO4 , similarly occurred well within the region which had previously become acid . ) Six further experiments on diffusion of silver nitrate into litmus have been made since this paper was originally communicated , and one parallel .experiment was started on March 23\#151 ; in which " No. 3 " dialysed litmus was used\#151 ; with the same silver nitrate solution . In this parallel experiment the only apparent result after three hours was a slightly darker red band 2 mm. above the diffusion start , whereas with the common litmus , after three hours , the dark blue ( bottom ) was at 22 mm. and top of red was 40*6 mm. Here after 19 hours the top of this band had risen to 5 mm. ; the band Mr. H. G. Durrant . [ May 2 , appeared now to be a more concentrated red than the red dialysed litmus above it . Referring to the curves for the original experiment , it appears that the top of the red should , at 19 hours , have been at 68 mm. It would seem , therefore , that the effects , at any rate in this parallel experiment , were much less marked , and were about 13 times as slow as in the case where litmus containing small amounts of salts was employed . No silver deposit occurred . The note made at the time was as follows :\#151 ; " It therefore appears that diffusion will not appreciably occur when water practically free from ionisable matter is used , unless some action other than diffusion previously brings about the introduction of ionisable matter into the water . " . I must at this point express my very great indebtedness to Professor Larmor , who , at an exceptionally busy time , not only made many valuable suggestions from the theoretical standpoint , but also examined the work of Planck and of H. Weber , which bears on the subject . In reference to the results of the parallel experiment just cited I quote from his memorandum the following:\#151 ; On the Theory of Ionic Migration in the Process of Natural Diffusion . The following theoretical considerations must enter into the interpretation of results of experiments such as those described , of which a complete analysis would appear to be very complex:\#151 ; ( i ) Consider cases of diffusion starting from an initial state which involves no space measurements , e.g. , diffusion between long columns of salt solutions , ionised or not , which are separated initially at an abrupt plane surface . The theory of physical dimensions requires that , as time goes on , corresponding lengths will vary proportionately to the square roots of the times which have elapsed since the beginning . ( ii ) In all cases of natural diffusion it is a necessary condition that in each part of the volume positive and negative ions must be present in amounts electrically compensating , the very slight volume charge producing the potential gradient , which is involved on Nernst 's theory in all cases of diffusion of electrolytes , being in this connection negligible . This principle requires , as is known , that when only one electrolyte is present in solution in an absolutely non-ionisable solvent , its two ions must diffuse in company , whether we consider them to be dissociated or free ; but when more than two ions are present they diffuse in virtual independence subject only to electric compensation everywhere in the aggregate . ( iii ) If the liquid into which the ions diffuse is itself of sufficient conducting 1906 . ] On Ionic Migration in Natural Diffusion . 357 power , we can consider each such wandering ion to be electrically compensated by an opposite charge accumulating round it as the result of electrolysis of this liquid , and all electric gradients as thus neutralised ; it is only in such a case that each kind of ion present would diffuse at a rate determined by its own intrinsic mobility alone . In a very dilute portion of the solution , or with slight diffusion-gradient , proportionately small conductivity of the solvent ( such as the litmus solution infra ) might suffice to realise this state of affairs . ( iv ) When the conductivity of the upper liquid is slight , its ions diffuse down into the lower liquid , just as those of the latter diffuse up . Thus with impure litmus over AgNOs the H and OH ions travel rapidly down to meet the Ag and NO3 which travel more slowly up ; while with pure litmus there are only Ag and NO3 and the colour effects travel much more slowly , in each case subject to the condition in ( ii ) . In the following experiments a fresh stock of silver nitrate crystals ( triple crystallisation ) was used . If a little concentrated solution of this was placed in red dialysed litmus or in purple-red ordinary litmus the solution became blue ; but if a little purple litmus or just blue litmus was placed in the same concentrated silver nitrate solution it became red . These results , probably depending on the ionisation of the litmus , made it difficult to say if the silver nitrate solution was really acidic , neutral or alkaline , but the results of all the diffusions ( except the last , where nitric acid was mixed with AgNOs ) made it appear that the solution was not acidic , because the rates of band movement in their earlier stages were almost exactly half those of the March 23 experiment and H mobility : OH mobility : : 1 : 0*54 . In the first of these diffusions ( April 30 ) 9'9 c.c. of 4*76 normal AgNOs diffused into a more concentrated solution of the same litmus as that used in the original experiment ( March 23 ) . The diffusion was watched for 47 hours only and the curves made out as before . At the end of three hours the following readings were made:\#151 ; . mm. Centre of faint red ( from start ) ... ... . 18 Top of blue band ... ... ... ... ... ... ... . . 11'3 Top of colourless band ... ... ... ... ... ... 4 No silver yet visible . Since the tops of the blue and the colourless bands were almost as the ionic mobilities of OH and NO3 , and as their rates were about half those VOL. LXXVIII.\#151 ; A. 2 B 358 Mr. R G. Durrant . [ May 2 , of the March 23 experiment , it was possible to calculate from the curves that the top of the red ( though faint ) should be at 19*7 mm. Taking this value , the results come out thus\#151 ; mm. Ionic mobilities . Top of red band . . 19*7x14 = 275*8 285*8 = H Top of blue band . . 11*3x14 = 158*2 154*3 = OH Top of colourless band . . 4 x 14= 56 58*3 = N03 In the March 23 experiment all the readings after three hours were multiplied by 7 to give the Kohlrausch values . The important difference to be noted is that here there was no sharp red band and that the above values were calculated for the tops of the bands , whereas , in the March 23 experiment , the top of red , bottom of deep blue , bottom of colourless , and top of silver deposit were proportional to the Kohlrausch values . In the present case there was no evidence of sharp discharge occurring at this time , nor in the subsequent observations . The faint red was probably due to hydrions coming down from the litmus above toward the upward moving hydroxyl . The further features were very similar to those which will be given in more interesting cases . Nine sets of readings were taken and the curves were very regular . The red , having reached a maximum intensity soon after three hours , became fainter and fainter . After 47 hours the top of blue and top of colourless band were at 57*3 mm. and 34*4 mm. respectively , the ratio being 1 : 0*600 , while mobility OH : 4/ mobility NO3 : : 1 : 0*613 , a result which is in accordance with that in the later stages of the March 23 experiment . An experiment with the same silver nitrate was started on May 2 into dilute " No. 3 " dialysed litmus made blue by passing it through well washed moist silver oxide , AgaO ; this blue colour , however , soon became grey and finally left a thin film all over the tube above the silver nitrate . After 18*3 hours there was a fairly well marked yellow-brown band , the top of which was at 41 mm. and the bottom at 35 mm. On referring to the curves of the last experiment ( April 30 ) , at 18*3 hours the top of red was at 42 mm. and the top of blue at 34 mm. , the centre in both cases was at 38 mm. The conclusion drawn was that the top and bottom of this yellow-brown band corresponded to the top of red and top of blue in the previous experiment ( the colour below was strongly brown ) . The litmus in this experiment was much more dilute than in the previous experiment . Without disturbing the tube , the upper liquid and some of the silver 1906 . ] On Ionic Migration in Natural Diffusion . 359 nitrate was syphoned off slowly , and fresh 4*76N AgN03 added to reach the 10 c.c. mark . Then ( May 3 ) very dilute litmus from the March 23 original bottle ( 1/ 50 strength ) was added to reach the 40 c.c. mark on the tube , the whole being surrounded by water in a tall cylinder as before . The concentration of this litmus ( by analysis of 40 c.c. from the bottle ) was:\#151 ; 0*0058 OH ( alkali ) 0*0072 chloride ( Cl ) 0*048 mineral ( Fe203 , etc. ) f Per litre* 0*085 organic matter , including litmusJ , The results of this experiment are represented in the accompanying chart and the only comments will be in reference to some of the letters given at the bottom :\#151 ; Fig. 8 . b Single observation of strong blue by gas light . / Streamers begin to show from the strong blue . These streamers were observed in all the silver nitrate diffusions ( except the last one to be given ) , but they began to appear at different periods . They consist of negatively Mr. K. G. Durrant . [ May 2 , charged oxides of silver , Ag20 and Ag202 , and may also contain an insoluble silver salt of litmus at first . g 50 hours ( a critical period ) . The marks A represent very sharply marked surfaces , colourless between the two top surfaces , then sharp red then , in the brown cloud , a very dark sharp boundary corresponding evidently to the bottom of the strong blue ( blue colour now obscured by reaction with AglSTOs ) . Top of red _ 78*6 mm. _ Bottom of blue 42*6 mm. Mobility of H 285*8 mm. Mobility of OH 154*3 mm. 1*852 ( Kohlrausch ) . h ( 67 hours ) . Abnormal rise in the top of the blue-grey-brown cloud , thinner and extended rise of the granular silver deposit to meet the streamers which had descended . Five sharply marked rifts in the film , due to the May 2 experiment already cited . These rifts were at\#151 ; 102*6 mm. , 95*3 mm. , 88 mm. , 60 mm. , 30 mm. above 0 mm. Differences 7*3 mm. 7*3 mm. 28 mm. 30 mm. 30 mm. Note , 7*3 x 14 = 102*2 mm. , top of red = top rift = 102*6 mm. The first appearance of these now permanent rifts suggests that a discharge had occurred , before 67 hours , of sufficient intensity to set up vibrations ( between the starting point and top of red ) which broke the film . ( The rifts were also measured by a colleague , Mr. J. A. Ensor , M.A. ) + \#151 ; It would seem that a simultaneous discharge occurred between H and OH \#151 ; + and between NO3 and Ag , or , more strictly , between their products of reaction . j ( 97 hours ) . Top of blue had fallen abnormally , cloudy portion now much clearer . k ( 121 hours ) . Top of blue had again risen abnormally , all floating cloudiness had gone . j and k. Change in tint of fallen particles below , and depression in the line of reddish floating particles . Note also , on comparing position of maximum red in this experiment at 121 hours with that of March 23 at 123 hours , the values were\#151 ; March 23 experiment 121 mm. , this experiment 118 mm. As a general inference it would seem that in this medium of very dilute ordinary litmus solution the products of accunlulated ions only discharge after a considerable lapse of time and that the discharge ( judging from the abnormal movements following and from the rifts formed ) is more acute than 1906 . ] On Ionic Migration in Natural Diffusion . 361 it was after three hours in the first experiment ( March 23 ) , where the litmus was more concentrated . The concentration curve for AgN03 , obtained from analysis of eight portions , after 142 hours was very regular , showing a geometrical fall in concentration . The next diffusion was made with the 4*7 6N AgN03 into litmus l/ 40th instead of l/ 50th of the bottle concentration . The results of this experiment ( May 20 ) confirmed the inference just made . No very sharp surfaces appeared and the line showing the top of the blue moved abnormally at the same periods , but in a less marked degree . After three hours\#151 ; Top of red _ 20 mm. _ 1 Top of blue 11*3 mm. 1 H mobility _ 285'8 mm. _ 1 .QKO When OH mobility " 154-3 mm. " r852 ' The most remarkable point of interest was the formation , after 24 hours , of a black bramble-like aggregation of crystals , exactly resembling those formed at the anode wire when silver nitrate solution is electrolysed in a porcelain dish ( AgaOg ) . The nucleus of these crystals was due to a minute drop of silver nitrate which touched the perfectly dry surface of the tube on removing the capillary pipette ; the litmus was slowly allowed to trickle down , and , when the small drop was reached , a brown stream of AgaO detached itself from the glass and soon formed minute descending vortex rings ; these stopped at a certain point and moved up as diffusion proceeded\#151 ; till the above mentioned crystals formed and absorbed the brown deposit\#151 ; and then continued to grow , ascending with the strong blue for the next 68 hours . At 101 hours from the start they were found broken into 16 fragments . These fragments continued to ascend as long as the observations lasted ( up to 143 hours ) , but the fragments gradually moved apart , some rising well above the deep blue , and others , though still rising , actually taking up positions lower down in the blue . This result was important because it proved the similar charge ( no doubt negative ) on the fragments causing mutual repulsion , while the actual rise of the cluster and finally of the fragments against gravity for 119 hours would point to a charge repelled upward by the negative N03 following , and at the same time attracted upward by , the positive H still higher up . It was possible in this case to trace the blue throughout the experiment , since these crystals took the place of the cloud in the former ( May 3 ) experiment . Streamers appeared also at 100 hours and were observed at 117 and at 143 hours . 362 Mr. R. G. Durrant . [ May 2 , ( Note.\#151 ; The specific gravity of Ag202 is greater than that of very concentrated silver nitrate solution . ) Since the diffusion in all these cases where the triple crystallised silver nitrate was employed gave the earlier bands approximately with half the velocity of that observed on March 23 , an experiment was started on May 23 in a smaller tube ( 25 c.c. graduations ) , when a little nitric acid was mixed with the AgNC\gt ; 3 solution , 4*5N AgN03 + 0-019N HNO3 being the concentration at the diffusion start . The chart of these observations is given ( fig. 10 ) . The litmus was the same as that used in the last experiment . Here the nitric acid molecules were only 1/ 240 of the silver nitrate molecules . At first ( after five minutes ) the red band , apparently shaped as in diagram ( fig , 9 ) , drew down blue from the purple litmus ; this blue was soon removed by reaction with the red . Red only was apparent after one hour . After five hours an orange-red colour was seen below the top of the red . After hours the red had reached the top of the liquid in the tube . The approximately straight line from these observations shows that the top had only just been reached at 21\#163 ; hours . This distance ( 159*5 mm. ) evidently traversed by the hydrions in this time was far greater than had been the case in any previous experiments , except those of the ferric ch loride red uctions . Still more rapid colour ^transferences , however , had been obtained by silver nitrate diffusing into litmus containing considerable quantities of potassium nitrate , and there , as in this case , subsequent chemical action had been abnormally great . ( The experiments with potassium-nitrate-litmus are not otherwise cited in this paper . ) The chart ( p. 363 ) will explain most of the phenomena observed during 94 hours . The hydrions , as shown in chart , would appear to descend from the free surface more rapidly than they went up and to influence the three other ions thus:\#151 ; ( i ) The hydroxyl , which showed by blue tint at the very top , on meeting with the continued stream of hydrions ( from the original HNO3 ) reacted to form water , so that the blue colour was gradually reduced to purple . ( ii ) The NO3 , which showed ( by bleaching ) strongly at 30 hours and still sharply at 47^ hours , reacted with the hydrions to form HNO3 , i.e. , the ions ( H and NO3 ) again were brought into close proximity . jnm 5^1 AgNOJ HNOj KJ After 5 minutes ( Ma-y 25 -'06 ) Fig. 9 . Purple Blue Red 1906 . ] On Ionic Migration in Natural Diffusion . 363 Fig. 10.\#151 ; The critical period in this case was 30 hours . Since blue ( first appearance ) was at 155*5 mm. to 159*5 mm.\#151 ; mm. Sharp top of yellow-red was at 59*1 . " " silver deposit was at 48*8 . The Kohlrausch values at 1000 L dilution give mobility of OH = 154*3 \gt ; \#187 ; \#187 ; \#187 ; \#187 ; N03 = 58*3 " " " " Ag(ion ) = 49*9 And since these three experimental values agreed closely with the Kohlrausch numbers , OH being now at the free surface , the position of the advance reflected hydrions would be , by calculation , within the silver region , near the mark 32 mm. ( iii ) The positively charged silver particles , urged upward by the main diffusion and by following negative NO3 , were repelled downward by the returning stream of hydrions and the effect of horizontal strise , resembling cirrus clouds , seen for the first time in these experiments , must have been due to these opposing forces from above and below . General Remarks on Silver Nitrate Diffusion . Concentrated silver nitrate solution gives results such as have been indicated above . The phenomena differ largely according to whether the solution is slightly acid or slightly alkaline , also according to the concentration of the litmus solution and according to the concentration of electrolytes in that solution . 364 Mr. R. G. Durrant . [ May 2 , The chemical changes which occur when " acid acting " silver nitrate is allowed to diffuse appear to be as follows :\#151 ; + ( a ) Advance hydrions produce litmus acid ( red ) . ( h ) Hydroxyl ions manifest their effects , provided the hydrions are not in considerable excess . Subsequent analyses show that silver nitrate advances with hydroxyl , and the blue colour gradually degrades through grey-blue to grey , on account of AgaO and , later , Ag202 being formed . This deposit appeared to be negatively charged . When nitric acid was mixed with silver nitrate ink the molecular ratio AgNC\gt ; 3 : HNO3 : : 240 :1 , these hydroxyl reactions were not apparent . * ( c ) NO3 ions , which follow OH , gradually bleach the blue litmus in front ( when hydrions are in excess the red litmus is bleached ) ; the oxidising action of these NO3 ions may also account for the change of brown Ag20 into darker Ag202 evident in the lower portions of the deposit . + ( 1 d ) Ag ions readily tend to assume the metallic form , as they are known to be endothermic . It is probable ( though not yet proved ) that a silver-litmus salt is formed as long as litmus is in the neighbourhood of the deposit . The first deposit at the bottom of the tube is cherry-red , then chocolate , then brown , and finally dark grey . When " alkali acting " silver nitrate diffuses , the modifications in phenomena are as follows :\#151 ; ( a ) No advance red appears at first , that which appears later is induced \#151 ; _ + by OH drawing H toward it from the purple litmus above . ( b ) The- early stage of band movement here is almost exactly half as rapid as it is with " acid acting " silver nitrate . ( c ) The hydroxyl effects are much more marked\#151 ; the deep blue degrades more rapidly to brown and finally to black ( Ag202 ) unless , as was the case in one instance , the silver peroxide crystallises . The main deposit at the bottom is finally much darker . Otherwise NO3 bleaches as before and silver forms , partly settling as a granular deposit on the glass . It is highly probable that this silver deposit is positively charged at first though the charge may be rapidly conducted away . There is , therefore , strong evidence that H , , OH , NO3 and Ag ions accumulate in this order , while at certain critical periods ( depending on the circumstances of concentration and admixture ) these ions produce sharp 1906 . ] On Ionic Migration in Natural Diffusion . bands whose boundaries , when measured from the diffusion-start , are at distances almost exactly proportional to the known mobilities of the ions . The author believes that the sharp bands are produced by a balance of forces\#151 ; viz. , those due to osmotic pressure and accumulating charges . The phenomenon is somewhat analogous to the " flickefing " which occurs when the actual velocity of a mixture of air and coal gas ( due to pressure ) is nearly equal to the explosion velocity , as has been demonstrated by Prof. Smithells . In this case there is a " flickering " of ions over definite spaces , and therefore local chemical action evidenced by sharply marked effects . In conclusion I would say that the experiment of May 23 and that of May 3 seem to have some bearing on the effects observed in atmospheric electrical discharge , the effects being slowed down here to a very great extent . I believe also that the general result , viz. , the demonstration that ionic separation does appreciably take place in natural diffusion , will have some interest for the physiologist , because these conditions are fulfilled in the processes of diffusion in the body . Red \#166 ; \lt ; Appendix . Observations on the Diffusion of Acids into Jellies Containing Litmus . Acid \amp ; Te ^Colourless -b Fig. 11 . The general method employed is shown by the diagram ( fig. 11 ) . The bands or zones ad and ac are those referred to in 3 ( b ) and 3 ( c ) on p. 343 . The zone of ( 3 ( d ) on p. 343 ) only forms after a long time and is considered on pp. 370 and 378 . Tubes of various cross sections were used , from 0T5 sq . cm . to 1*15 sq . cm . The cross section does not influence the rate of diffusion . Mr. R. G. Durrant . [ May 2 , Tube A.\#151 ; Jelly Purple with Litmus and KHCO3 . Tubes A , A ' , and A " placed simultaneously in Normal HC1 . Time . ab . be . ac . ad . ab\ */ t. be/ Vt. be/ ac . hours . 25 mm. 40 mm. 36 *3 mm. 3 7 mm. 10 app . 8-00 7'26 %'8 46 53 48 5 4-5 13 " 7 -80 7-19 10 '8 63 61 54*8 6 2 13 " 7*69 6'95 8'8 93 74 67-0 7 *0 13 " 7-67 6'95 9'6 121 85 76 5 8 -5 15 " 7 -73 6'95 9'0 ( Mean temp. 44 ' F. = 6*6 ' C. ) Average ... 7'78 7'06 9 '6 Tube A'.\#151 ; Jelly Blue with Na2C03 and Litmus . Time . ab . ac . ab/ */ t. hours . 46 54 63 63 6 93 75 6 121 85 320 149 \#151 ; 8'3 Tube A".\#151 ; Yellow with Na2C03 and Methyl Orange . Time . ab . ac . ab\ V t. hours . 25 37 i 46 54 63 60 \amp ; a 93 73 121 83 s ? 320 142 CD \gt ; 7'9 Tube C.\#151 ; Same Jelly as in A , placed in N/ 3*7 HC1 . Time . ab . bo . ac . ad . ab\ Vt. be/ \'t . bejac . h0UT8 . 24 mm. 26 0 mm. 22 '5 mm. 3'5 mm. 10 app . 5*31 4'59 6'43 70 45 0 38 '5 6'5 12 " 5 '49 4'62 5'92 137 63 0 54 0 9 '0 14 " 5 '38 4'60 6'00 191 74'0 64'0 10 0 17 " 5 '36 4'63 6'40 213 '5 78'0 67*5 10 '5 18 " 5'34 4-59 6'43 235 83 0 72 0 11 '0 20 " 5 '42 4'69 6'54 262 86'5 75 '0 11 '5 21 " 5 '34 4'63 6'52 ( Mean temp , first 5 days 40 ' F. = 4-6 ' 0 . ) Average ... 5 '38 4'62 6'32 In Tube A diffusion constant for ab corrected for temp , at 2 per cent , rise per degree Centigrade gives 9*04 for mean temp , of 15 ' C. Tube C similarly gives 6#48 for mean temp , of 15 ' 0 . Note.\#151 ; i. The diffusion constant* is here expressed as ab/ Vt , and in later experiments the value be/ Vt was not calculated . ii : Experiments with sodium carbonate and with methyl orange jellies were not continued . # This expression gives a constant which only holds for the given concentration ; it follows from the equation a = cq where a = quantity diffusing through area q , c = concentration difference . 1906 . ] On Ionic Migration in Natural Diffusion . 367 , An inspection of the foregoing tables shows\#151 ; ( i ) The diffusion marked by the growth of ah in Tube A was almost identical with the only diffusion observable in the Tubes A ' and A . A sharply marked colourless strip , corresponding to ac , separated the boundary of pink coloration in the methyl orange Tube A " . This strip did not appreciably widen . ( ii ) Comparing the Tube A with C\#151 ; i.e. , normal HC1 with if/ 3*7 HC1\#151 ; it appears that the fall in the constant value ( Stefan 's law ) from 7'78 to 5*38 was not accompanied by a corresponding narrowing of the yellow-red band ac , nor by any appreciable shortening of the purple-red region ad . ( iii ) Comparing the Tube A with A " it is evident that a marks the diffusion front , in other words , the band ac falls behind the boundary reached by the acid . In the Tubes D and E next considered the same jelly was used . The concentration of the acid diffusing was N/ 9 and N/ 27 . Tube D.\#151 ; N/ 9 HC1 . Time . 1 ab . be . ac . ad . abj +ft % bej \ft . be/ ac . hours . mm. mm. mm. mm. app . 24 16 12 -5 3-5 7*0 3-26 2*55 3/ 57 Jelly protruded and was cut off 52 24 20*0 4-0 12 -0 3-33 2-77 5*00 76 29 24-0 5 -0 14-0 3*32 2-75 4-80 I 100 34 28 -5 5*5 15 5 3*40 2-85 5-18 1 116 36 30-5 5-5 17 -0 3*34 2-83 5-54 J Mean ... ! 3 35 2-80 5 12 Tube E.\#151 ; N/ 27 HC1 . 1 Time . ab . be . ac . . 1 ad . \ ab1V t. bej V t. be lac . p f | hours . mm. mm. mm. Tnm . 24 9 6-5 2-5 app . 8-5 1 *80 1 33 2*60 Jelly protruded and was cut off 52 13 10'0 3*0 9-0 1-80 1 -38 3 " 33 ] 76 17 13 5 3 5 10*0 1 '95 1-55 3 -85 L 100 20 16 -0 4*0 15 -0 | 2-00 1-60 4-00 f 116 21 17 -0 4*0 15 -0 1-95 1*57 4-25 J 1 1 Mean ... 1 1 95 1 52 1 3*86 368 Mr. R. G. Durrant . [ May 2 , In comparing the results of the observations in the Tubes A , C , D , and E all with the same jelly\#151 ; ( i ) The band ad appears to be independent of the concentration . ( ii ) The band ac , which was very similar in A and C , diminished in D and still more in E. ( iii ) The ratio bc/ ac became smaller as the concentration diminished , and appeared to rise steadily in E as time went on . ( iv ) The values ab/ s/ T in the four concentrations became less as the concentration diminished , thus\#151 ; In A. In \amp ; In D. In E. Relative concentration ... ... . 27 : 7*3 : 3 : 1"\ Relative value #5/ \/ 1 ... ... . 4 : 2'76 : 1*72 : 1J Since hydrobromic acid is known to diffuse at about the same rate as HC1 , experiments were made to ascertain if these acids behave similarly as regards the formation of bands . In the first four tubes , the mixture used was gelatine , 10 grammes in 150 c.c. , with a little caustic potash and not much litmus . No bands were observed corresponding either to ac or ad . These four tubes F , F , Gf , G , were placed respectively in N/ 2'17 HC1 , N/ 2-17 HBr , N/ 6'51 HC1 , N/ 6'51 HBr . Tube F.\#151 ; N/ 2-17 HC1 . Time . Diffusion . ab1 Vt constant . hours . mm. 18 32 0 7-51 42 49-5 7-64 74 65 -0 7-56 116 -5 81-0 7-50 144*5 89-0 7-41 Mean 7-52 Tube G.\#151 ; N/ 6*51 HC1 . Time . Diffusion . ! abj */ t constant . hours . mm. 18 23 5-40 42 37 5-71 74 47 5 -46 116 -5 59 5 -46 144 -5 67 5-58 Mean 5-62 Tube F'.\#151 ; N/ 217 HBr . Time . Diffusion . Constant . hours . mm. 18 31 -5 7-42 42 49-0 7-50 74 63 -5 7 -38 116 -5 80-0 7*41 144 -5 88-0 7 *33 Mean 7'42 Tube G'.\#151 ; N/ 6 51 HBr . Time . Diffusion . Constant . hours . mm. 18 23 5-40 42 . 37 5-71 74 47 5 -46 116 -5 59 5-46 144-5 67 5-58 Mean 5-52 1906 . ] On Ionic Migration in Natural Diffusion . 369 These results showed that the two acids behaved very similarly as regards diffusion at these concentrations . In the next four tubes\#151 ; H , IT , I , I'\#151 ; the following mixture was used :\#151 ; Ten grammes gelatine , 130 c.c. water , 10 c.c. neutral litmus , 0*3 gramme KHCO3 , the whole kept below 70 ' C. and filtered . The same acids and of the same strength were allowed to diffuse , using 25 c.c. of the acid in each case . In no case did a band ac ( yellow-red ) appear until after 110 hours . Nine observations were made for each tube , extending over 426 hours . The band ad ( due to hydrogen ) was seen at once , and grew regularly from 4 mm. to 26 mm. for the N/ 2T7 acids and from 5 mm. to 25 mm. for the acids of 1/ 3 of the concentration ( N/ 6'51 ) . After 141 hours in each case a band ac was observed which , though it became more distinct as time went on , did not grow appreciably . It widened from 4 mm. to 5 mm. only with the N/ 2T7 acids and from 4 mm. to 6 mm. with the acids of 1/ 3 concentration . The mean diffusion constants were\#151 ; N/ 2-17 HC1 , 6-55 , N/ 2T7 HBr , 6-65 , N/ 6-51 HC1 , 4*85 , N/ 6*51 HBr , 4 65 , whence the ratio of diffusive rates for the HC1 N/ 2*17 to N/ 6'51 were T35:1 , and for the HBr N/ 2*17 to N/ 6'51 , 1*41 : 1 . Details of the tubes I and I ' are given on next page , and show the further formation of bands , which began to appear after 426 hours . As the actual weight of litmus was not known in the H and I tubes , a third set of tubes , J , J ' , K , K ' , were filled with the following mixture , calculated for 1 c.c. of the jelly : Gelatine , 0*0666 ; KHCO3 , 0*00066 ; litmus , 0*0006 . This solution was purple and did not show the band ad . The four tubes were watched for 159*5 hours , seven readings each . The band ac showed at once , increasing regularly . It was of the same dimensions for HC1 and HBr throughout , and in the 1/ 3 concentration kept almost exactly 1 mm. wider than in the stronger acids . Tables appended on p. 371 . As the result of 76 readings of these 12 tubes in which the diffusion constants ( ab ) were taken\#151 ; half for HC1 and half for HBr\#151 ; it seemed worth while to compare the results , allowing for differences of the mean temperatures during the periods of observation . Mr. R. G. Durrant . [ May 2 , co o o W \4 a CO $H \amp ; 0 \#169 ; , S Is O CQ \lt ; D a S fa bC co cb r ^ 9 a ' S \#169 ; ^ rH JS I s jfe . S p-H *73 pL \lt ; D ho o a c0 GQ be -\#177 ; 3 .a a fl . 3 S o \#171 ; P o co ? H ^ . Sh T3 cO P H pP -4-3 fl #o *co 0 ) *43 a cO \amp ; a O O PQ w tH lO cb S ' eg fl .2 GO $3 PH o H i\#151 ; i lO ? b S ' \#171 ; g s .2 os 5S A ffl * A s fl .3 *0Q I ft abjbe . % p\#169 ; , \#151 ; -a.\#151 ; i Diff. | const . ! ab . CO Tf\#171 ; Tfi Tft xP ^ S 1 dipooo ? ?^ 9 p4lO CO lO CO 05 O H H C3 pH pH rH H ( N 0Q Average ... C C3 3 1 | | | 9^^ g I l i I tP ^ ^ \#166 ; S \amp ; S ^ '\#171 ; S a isl'S.I9^ s ^.^gigisg ^ rt a \lt ; 35 . \gt ; p ip o o o o o i. 1 383933$ i * lO ic g ip j\gt ; oq 2 1 sisssigg ^ HHHH p*H .3a ip ip lO H H H nd -2 : W q3 r\#151 ; i i O 3 *0 pH IQ g3 qd 00 00 ^p co co oqi ^P ^P Tp 9 \#169 ; O op s *0 Q0 CO \lt ; N \lt ; M CO jp ip 9 o l\#169 ; Q0 00N lO ip o o 5 . co co O H \lt ; M rH rH rH 9 poo s COHO rH ( M CO rH pH pH i i a : ? ! -c \#169 ; S CO N CO o \lt ; M 05 00 CO ^ iO CO ab/ be . \amp ; i . / \#151 ; *\#151 ; i a 1 \#166 ; S ft 18 CO 1\gt ; Q J\gt ; i\gt ; rH 00 O 00 00 00 00 00 op ^P nfl ^ ^ ^ ^1 1 a p4iO oq U5 1O00 O H g O-i rH pH pH rH O ) ( M S$ . C3 0 1 1 1 | 9 99 g 1 1 1 1 ^ ^ mm. Not distinct enough to measure 54-0 58 0 63 5 t a CqO54\gt ; rH00Cqr^ a ( N CO 'H1 iO ro CO CO Time . hours . 21 5 63-75 92-25 110 141 166 189 CD bD 03 \#169 ; p-H Id .p\#153 ; a .3 w cot\#187 ; 00 O H N \gt ; p \gt ; p us pH pH pH I 1*883 ^ \amp ; 1 15 JS 05 \#187 ; 0 OS S \#174 ; N 00 00 rO tP 05 00 05 00 05 05 Tp T ? ^ 8 \#171 ; 50N Cq CO CO 9 ip tp o 50 CD I\gt ; J\gt ; 9 ip ip O s Cq pH 05 \#187 ; H ( M ( M pH rH pH 8 05 05 CO rH ( N CO rH r^l rH r-l cq CDO 05 GO CO \#166 ; 3 io co r* Average ... 4*92 Average ... 1'6T J Tube.\#151 ; N/ 2-17 HC1 . J ' Tube.\#151 ; N/ 217 HBr . 1906 . ] On Ionic Migration in Natural Diffusion . 371 bc/ ac . lONOOOHN t'* rH 9 00 O b* ! \gt ; . XO I\gt ; J\gt ; 00 00 00 00 S Hf 1833888 CO CO t ? iO IO Diffusion constant ab . lO ^ CO ( M ( N CO O 00 C5 05 O CD CO CO CO CO CO 98-9 u CQ Diffusion constant ab . 883832S iO iO iO iO iO iO iO 8 iO S 9909000 ^r}UOU501\gt ; 05 Mean ... ri W rH 1C cb L-- 0 \#171 ; V3 *P " 5 9 \#187 ; 9 9 Tf U5 CO i\gt ; 00 O Mean ... | \#163 ; 9 9 9 9 9 99 OOOONHIMHO \lt ; M Cq CO lO CO \#169 ; rO rH r\#169 ; wwousooo EH e ' 9 9 9 9 9 9 9 \lt ; M \lt ; N CO 00 00 00 ( M CO ^ ^ O CO 00 M $ 99"3"3V399 8388388 Time . qd 99999 ^COOOOiCOHiOO O H N CO iO rCj rH Time . \#163 ; 99999 JS88$\#163 ; g8 " rH be jac . hN^QiOHOO CO *\gt ; 00 00 00 00 00 9999^98 CO CO T ? H* *0 10 10 1 Diffusion constant ab . \lt ; M l\gt ; \lt ; M 05 \lt ; N CO CO 9^900999 CD CO CO CO CO CO X\gt ; CO Q Diffusion constant ab . 28388S38 iO iO O iO iO iO iO 5-12 i 9 9 9 9 9 9 9 CO ^ O CO . ! \gt ; 05 Mean ... w rH IO cb S ' 1 9999999 Tf \#187 ; o \#171 ; 5 CO 00 O Mean ... \#163 ; 9 9 9 9 9 9 9 CO 00 00 \lt ; N \lt ; N H 0 oq ( M CO ^ iO CO 00 $5 p H \#169 ; r\#169 ; 0999999 CO 00 l\gt ; 05 CO CO CO rH rH O 0Q CO iO i 9 9 9 9 9 9 9 CO \lt ; N CO i\gt ; 00 00 05 ( M CO ^ ^ io CO 00 M *\#169 ; C3 9099999 83883S8 Time . m 99999 PC0C005C0rHlO05 OrH(MCO^i\gt ; C5iO rH Time . g 99999 |S8S9\#163 ; 8S rd iH Mr. R. G. Durrant . [ May 2 , The mean temperature for the first four days is given in each case . N/ 2*17 HC1 . N/ 2*17 HBr . N/ 6-51 HOI . N/ 6-51 HBr . Mean temp. F 7 *52 F ' 7*42 O 5 *52 Gt ' 5 -52 'F . 52 -5 H 6*55 H ' 6 *55 I 4*85 V 4 -65 48-5 J 6*88 J ' 6 *86 K 5 12 K ' 5-09 50*5 Mean diffusion con- 6*98 6*94 5*16 5-09 50*5 stant for ab It will be seen that the mean temperature for the J and K tubes happened to be the mean of the other two mean temperatures , and that the mean actual observation for the J and K tubes differs but slightly from the total mean readings for the three sets of tubes . It would therefore appear that the diffusion constant for HBr is slightly less than for HC1 . Taking the mean readings ( each representing 19 observations ) and calling the diffusion rate of HC1 == 100 , the results are\#151 ; For N/ 2*17 acids ... . HC1 = 100 , HBr = 99*42 . " N/ 6*51 " ... . . HC1 = 100 , HBr = 98*64 . It would also appear that the diffusion constant for HBr is reduced by dilution rather more than is the case with similarly diluted HC1 . Comparative diffusion experiments with normal HC1 and normal H2S04 into jelly composed of 10 grammes gelatine , 2 grammes KHCO3 , and 140 grammes water with neutral litmus :\#151 ; Tube O.\#151 ; Normal HC1 . Time . ah . ac . ad . Diffusion constant . hours . 39*5 53 not well 6 8*44 67*75 70 marked 9 8*50 90-0 82 7 about 12 8*65 118 *5 94 6 " 15 8*64 Mean ... 8*56 In the case of the HC1 , after 90 hours 5 mm. jelly dissolved ; after 118*5 hours 8 mm. jelly dissolved . Tube P.\#151 ; Normal H2SO4 . Time . ab . ac . ad . Diffusion constant . Ratio H01 = 100 . hours . 39*5 41*0 not well 6 6*53 77*3 67*75 55 *0 marked 5*0 10 6*68 78*6 90*0 64*0 6*0 13 6*75 78*0 118 *5 72*5 6*0 15 6*66 77*1 160 *5 85*0 6*5 16 6*71 Mean ... 6*66 I 77*8 L Mean temp. 54-2 ' F. 1906 . ] On Ionic Migration in Natural Diffusion373 It will be seen that the H2S04 behaved in a similar way as regards formation of bands\#151 ; the band ac being better marked than with HC1 . This band , on the theory of ionisation , would be due to the ion S04 bleaching by oxidation . In order to see if the band ac is only produced in cases where by theory an ion capable of bleaching is produced , the tubes J , J ' , K , K ' , were inverted and tested simultaneously with normal solutions of HC1 , H2S04 , oxalic and acetic acids . Though these two last acids are believed to ionise slightly* their ions , C204 and C2H302 , would not be oxidisers . In neither case did any band corresponding to ac appear . The observations , give the relative diffusive rates . The tubes were now called Q , E , S , and T ( see p. 374 ) . In order to find the best proportions of ingredients for showing the bands ac and ad , several jellies were prepared\#151 ; the ingredients were calculated as weight per 1 c.c. Grelatine . 1 KHCO3 . KOH . '.Litmus " ( from blue extract ) . D O -058 0 -00128 0-0002 0-0008 E 0*06 0-0006 0-0002 0-00084 P 0-0664 0-00088 0-00026 0-00024 Gt 0*064 0-0014 0-0002 0 -000175 H 0-0664 0-00066 0-0002 0 -000182 Of these , D and E both gave very fair results , using N/ 2 HC1 solution . The results with these jellies were watched and recorded six times in 361 hours . With D the band ac finally reached 7 mm. and ad 26 mm. " E . " " 6 " 25 " and from comparative results it appeared that 0T gramme of KHCO3 in 100 c.c. of jelly retards the diffusion constant for N/ 2 HC1 by 4*5 per cent. A further set of seven jellies was treated with N/ 4 HC1 solution\#151 ; the best was No. 7\#151 ; ( it showed ad very well ) which contained in 1 c.c.\#151 ; Gelatine . KHC03 . KOH . Litmus . 0-05 0-0026 0-00023 0-0011 Four readings in each tube extending over 117 hours were made , from which it appeared that extra litmus did not appreciably retard the diffusion constant . The addition of a small quantity of KOH makes the jelly sufficiently blue VOL. lxxviii.\#151 ; a. 2 c Tube Q.\#151 ; Normal HC1 . Tube E.\#151 ; Normal Oxalic . Mr. R. G. Durrant . [ May 2 , \#169 ; " o ' N\#169 ; 10 -7 11 0 10*0 10 -7 \#166 ; Is*- \lt ; \#169 ; *\gt ; \#169 ; 00 5.0 \#169 ; ip pS " 00 QO 00 00 $ ^ \#169 ; *\gt ; 00 o h5 oo 40 \#169 ; \#169 ; ^ 40 ^ 00 X\gt ; \#169 ; ^* T ? \#169 ; *\gt ; \#169 ; Time . hours . 28*5 49 80-5 121 \#169 ; \#169 ; Mean temp. . . OQ 1\gt ; tH 00 W \#169 ; \#169 ; CO \#169 ; ' \#169 ; \#169 ; \#169 ; \#169 ; \#171 ; \#169 ; \#169 ; go \#169 ; 03 00 \#174 ; * II CO \#169 ; ^ CO co \#169 ; \#169 ; \#169 ; 3 w )\#171 ; ?* \gt ; H \#169 ; \#169 ; \#169 ; \#169 ; T ? 3 rg 40 \#169 ; \#169 ; 40 \#169 ; \gt ; *C5 \#169 ; \#169 ; 40 \#169 ; i $ \#169 ; \#169 ; \#169 ; \#169 ; CO CO \#169 ; \lt ; D a j Time . OD \#169 ; \#169 ; P 00 \#169 ; \#169 ; 1-H O \lt ; M rfl QO \lt ; M rP rH \#169 ; \lt ; N S* r\#151 ; l \#166 ; s TS \lt ; D 'S PA nd d . pH CD O \lt ; 1 o \#169 ; rQ P H o CO w a Pi o \#169 ; P H S Oh \#174 ; a 1 CO al | 0 \#174 ; S"S s 8 rH || O op \#171 ; OS \#169 ; II 3 8888 s H i^ : \gt ; \#163 ; 888 \#163 ; \#169 ; \#169 ; \#169 ; \#169 ; \#169 ; 8S38 I a S go .S H rf \#169 ; \#169 ; \#169 ; P(M^U\gt ; H H \#163 ; \#169 ; \#169 ; II go \#169 ; ^ go II fH \#169 ; 00 00 \#169 ; S bejac . \#169 ; ( fi go ih \#169 ; \#169 ; 00 \#169 ; os \#166 ; * \#169 ; rf\#171 ; \#169 ; J\gt ; \#169 ; ^^ \#169 ; 8 ? CO \#169 ; \#169 ; \#169 ; \#169 ; \#169 ; o \#169 ; op I S CO ^ \#169 ; \lt ; D P\ \#169 ; \#169 ; \#169 ; \#169 ; NO \#169 ; rH CO ^ CO ^ \#169 ; \#169 ; 1 CO \#169 ; \#169 ; rH CO ^ \#169 ; 1\gt ; Time . , OQ \#169 ; \#169 ; \#169 ; \#169 ; E . . . . 0 Tf \#169 ; \#169 ; \#169 ; O ( M ^ |\gt ; rH r0 rH 05 t \lt ; N O fi 13 fc srS a* SJ W \#174 ; 'SJ .fl , cs .sf -4^\gt ; \#169 ; QD \#169 ; Eh \amp ; iJ8 P -4-^ \#174 ; \#163 ; " 3 .S +s *1 03 \lt ; D PH -2 jS H O 05 a \lt ; N 2 fe*| a s sr*S PH PI 8'J eo a si J.S .s S H S i CD *1 PH 00 j\gt ; m \lt ; D \#169 ; H Ph nd S o .jH 08 m \amp ; D If \#166 ; 43 \lt ; D si 3 s o \amp ; a S :S \#174 ; . \#174 ; .SJ8 m \#166 ; +-\#187 ; * \#171 ; .\#171 ; J8 \#171 ; fl r-l ^ II ' \#166 ; \#163 ; 6 |w is 3 O rtJ OQ \lt ; D ll ? ! i\#171 ; o .g0 ? , a jxj a , .\#166 ; S*8 S \#174 ; a -a \#166 ; \#174 ; ft S \#163 ; \#163 ; PS EH'I I fl I sis\#163 ; So \lt ; D 1906 . ] On Ionic Migration in Natural Diffusion . 375 to observe the band ad . From these experiments the retarding influence of the KHCO3 ( 0-1 gramme in 100 c.c. ) appeared to be only 2'1 per cent , on the diffusion constant for N/ 4 HC1 . tomparative Experiments on the Diffusion of certain Acids and of the Formation of the Bands ac and ad . No. 2.\#151 ; N/ 5 HC1 with 10 grammes NH4CI No. 1.\#151 ; N/ 5 HC1 . in 50 c.c. Ime . ab . be . ac . ad . abj Vt. Belative diffusion rate HC1 = 100 . fairs . mm. mm. mm. mm. app . 15-6 33*0 31-0 2*0 10*0 6-29 \i -25 45*0 42 -5 2 5 13 -5 6-28 1 54*5 51 -5 3-0 14'0 6-34 i 67-0 62 '5 4'5 16 *5 6*22 1 -5 80*0 75 *0 5*0 17 '0 6-24 ii 91 *0 84-0 7-0 19 0 6 25 Mean 100 Time . ab . be . ac . ad . abj \/ t. Relative diffusion rate . hours . mm. mm. mm. mm. app . 27-6 48 46*0 2 -0 7 9-14 144-0 51*25 66 63 5 2-5 9 9-22 146-0 74 79 77 -0 2 -0 10 9-19 145 -0 116 98 95 -0 3-0 12 9-09 146-0 164 -5 117 112 -5 4-5 15 9-12 146-0 212 133 127-0 6 0 15 9-13 146-0 Mean 145 -6 No. 3.\#151 ; N/ 5 H2S04 . No. 4.\#151 ; N/ 5 HN03 . db\ V tf Relative Relative me . db . be . ac . ad . diffusion Time . ab . be . ac . ad . ab\ V t. diffusion rate . rate . -urs . mm. mm. mm. mm. hours . mm. mm. mm. mm. app . app . 96-0 f -6 27 25*0 2-0 10 *0 5-14 81 -0 27 32 -0 29 *7 2 -3 10 6 09 1 '25 37 34-5 2-5 14 -0 5 -16 82-2 51 43 *6 41 *5 2-0 12 6-07 96-6 L 44 41 -5 2*5 14 -0 5 -12 80 -7 74 62 -5 51 -0 1 '5 13 6-10 96-3 55 51 -0 4-0 16 *5 5-11 82-1 116 65 -0 63 -0 2-0 16 6-03 97-0 4-5 66 61 -0 5-0 18 -0 5'15 82-5 164-5 78 -0 Line 21 6-08 97-5 $ 74 68-5 5*5 22 -0 5-08 81 -3 212 88 -0 indistinct 21 6-04 96-7 Mean 81 '6 Mean 96-7 2 c 2 Mr. R. G. Durrant . [ May 2 , No. 5.\#151 ; Formic Acid . No. 6.-N/ 2 H2S04 . Time . ab . be . ac . ad . abj Vt. Relative diffusion rate . hours . mm. mm. | ! mm. mm. app . 60'0 62 -2 27 51 20 '0 28 '0 \gt ; " d 9 15 3*81 3'91 74 35 '0 5 i 15 4'07 64*2 116 44*0 rO 18 4'08 65 '7 164 *5 212 54 '0 61 '5 O ft 19 20 4*21 4'22 65 '5 67 *6 Mean 64*5 Time . ab . be . ac . ad . ab\ Vt. Relative j diffusion rate . hours . mm. mm. mm. mm. app . 27 32 -5 ' 30 *5 2-0 8 -0 : 6'19 97 '5 : 51 \#166 ; 44 -5 42 -0 2*5 12 -0 6 '21 1 98'8 74 53 -5 50 -0 3*5 12 -5 6'22 98 -2 116 66 5 62 -0 4-5 14 *5 6'17 99 -2 164 5 79 0 73 '5 5*5 17 -0 6'16 98 -7 I 212 90'0 84'0 6-0 17 -0 6'18 98-9 Mean 98'9 Composition of this jelly was in grammes per cubic centimetre : 0 '00125 " litmus , " 0 '00073 KHCOs ... ... ... . . 0 *06 gelatine ( Coignet's)- , 0 '000102 KOH j- a deep purple blue , called the " a * ? \#166 ; jelly . It appears from these comparative experiments in " a " jelly\#151 ; ( i ) That the purple hand ad was independent of the nature of the acid 1 and of its concentration\#151 ; indeed the readings for N/ 2 H2S04 were less than j for N/ 5 H2SO4.* ( ii ) That the yellow-red hand ac was apparent in all the acids except | formic acid ( whose ion , CHO2 , is non-bleaching ) . ( iii ) That addition of ammonium chloride to N/ 5 HC1 , to an extent \ equivalent to making it a 4 N solution as regards chloride , increased the 2 diffusion rate in the ratio of nearly 3 : 2 . Arrhenius has previously shown | that with very concentrated ammonium chloride the rate may be increased * as 2'24 :1\#151 ; and the result is believed to be due to the higher concentration fl of hydrions , NH4CI = NH3 + H + Cl occurring to a certain extent.f ( iv ) Comparing the N/ 5 acids only , the relative diffusion rates come out # : HC1 , 100 , HN03 , 96-7 , H2SO4 , 81*6 , formic acid , 64-5 . * Although the band ad seemed rather shorter with N/ 2 than with N/ 5 H2S04 , the : * total distance bd was considerably greater , and again was almost identical with the jH distance bd for N/ 5 HC1 . t Voightlander 's values at 20 ' C. are\#151 ; HC1 , 100 , HN03 , 101*9 , H2S04 , 58-9 , formic acid , 42'1 ( ' Zeits . fiir physikal . Chemie/ 1889 , vol. 3 , p. 316 ) . Table given in Whetham 's 6 Solution and Electrolysis/ p. 53 , actual values HC1 , 2-06 , HN03 , 2-10 , H2S04 , 1*21 , formic acid , 0*867 . The difference is due probably to .the greater dilution in these N/ 5 solutions , which \#187 ; thereby become most nearly " isohydric . " | 1906 . ] On Ionic Migration Natural Diffusion . 377 ( v ) It would seem that an H/ 2 H2S04 solution becomes , in the jelly tube , approximately " isohydric " with an 1ST/ 5 HC1 solution . A seventh determination with H/ 2 H2S04 was made , at the same time , in which the acid was placed in a wide tube above the jelly , the tube being corked . The object of this determination was to see if by any chance the , purple band ad , hitherto assumed to be due to hydrions , was really due to C02 ascending . The table here given is put side by side with that already shown ( Ho. 6 ) . j. 6.\#151 ; H/ 2 H2S04 diffusion ascending . Tie . ab . 4 , ac . ad . abj a/ t. Relative diffusion . 8 . 7 32 *5 30-5 2 *0 app . 8*0 6 19 97 -5 I : 44-5 42-0 2 5 12 0 6 -21 98 -8 a 53 5 50*0 3 -5 12 *5 6 22 98 2 6 66 5 62 -0 4-5 14 -5 6 17 99*2 14 79 0 73 5 5-5 17-0 6-16 98-7 12 90*0 84-0 6 0 17 -0 6 18 98 -9 Mean ... 98 9 Ho. 7.\#151 ; H/ 2 H2S04 diffusion descending . Time . ab . | be . ac . ad . i-u 1 Relative diffusion . hrs . 27 33 *0 31 -0 2-0 app . 9 1 6*29 100-0 51 45 *0 42 5 2*5 14 6-28 100-0 74 53 -5 51 *5 3*0 14 6-22 98 -2 116 67 -0 62 *5 4-5 15 6*22 100-0 164 80 -0 74 -5 5 *5 18 6-24 100-0 212 90 -0 83 *5 6*5 18 6-18 98 -9 Mean 99-4 This result shows that the band ad forms equally well when the diffusion is descending . The diffusive rate appears to be slightly increased , but otherwise to be identical in its phenomena . It is highly improbable , if carbonic acid gas is set free from the bicarbonate used in these experiments , that this gas would act to form the purple band equally whether it ascends or descends . After a further interval these tubes with the " \#171 ; " jelly were examined , and the late forming bleached band began to develop in the H/ 5 HC1 , H/ 5 HC1+AmCl , H/ 5 H2S04 , and H/ 2 H2S04\#151 ; but not in the H/ 5 formic acid . In the case of the H/ 5 HHO3 the lower part of the jelly dissolved so that observations were impossible . In the H/ 5 HCl + AmCl tube , though the band was observed after 623 hours , later on a gas was formed which forced the jelly out from the lower end of the tube . 378 Mr. R. G. Durrant . [ May 2 , The following were the measurements recorded ( July 10\#151 ; 24 , 1904):_ S1 S-8-B-i ; m ? \gt ; . M O $ ( D \amp ; 8 i SI Time . ab , Ic . ac . ad . abj Vt. be . \#165 ; \#166 ; No. 1.\#151 ; N/ 5 HC1 . hours . 623 140 -5 132-5 8-0 30 5 -63 90 Ill app . O Hot / 793 163 0 155 0 8-0 36 5-78 103 indistinct weather L 961 185 -0 176 -5 8-5 blocked 6-00 127 \#187 ; No. 3.\#151 ; N/ 5 H2S04 . 623 I 115 107 8 I 28 | 4-61 90 joins ac . s Hot r 793 135 125 10 37 4-79 99 weather 1 961 1 152 140 12 | 45 1 . 4-90 104 a Q ) . No. 6.*\#151 ; N/ 2 H2S04 623 140 133 -o 7 -0 30 5 61 88 112 app . Hot f 793 162 155 -0 7-0 27 5 -75 99 . 123 " weather L 961 185 176 -5 8-5 blocked 6-00 114 indistinct $$| The diagram represents the diffusion of N/ 2 H2SO4 after 793 hours . The chief interest attaching to these observations taken on the 26th , 33rd , and 40th day after the diffusion was started is\#151 ; ( i ) The N/ 2 H2SO4 continued to keep pace with the N/ 5 HC1 . ( ii ) The lower , sharply-marked boundary of the bleached band e made its first recorded appearance at points nearly identical in each case , \#151 ; for N/ 5 HC1 at 90 mm. , for N/ 5 H2SO4 at 90 mm. , for N/ 2 H2SO4 at 88 mm. , from the bottom of the tube . ( iii ) The progress of this point e , however , varied , and its position after the 40th day ( 961 hours ) was for N/ 5 HC1 at 127 mm. , for N/ 5 H2SO4 at 104 mm. , for N/ 2 H2SO4 at 114 mm. , from the bottom of the tube . If , as it has been already suggested , this late forming bleached band is due to the anions Cl and SO4 , then the rates of progress here observed are what would be expected , because SO4 is known to have a lower mobility than Cl. The table due to Kohlrausch and Holborn , and given on p. 102 in Lehfeldt 's " Electro-Chemistry , " shows that the relative molecular conductivities for HC1 and H2SO4 at 200 L dilution ( 18 ' C. ) are\#151 ; HC1 : H2SO4 : : 1 1*77 , or HC1 : \#163 ; H2S04 : : 1 : 0-885 . 1906 . ] On Ionic Migration in Natural Diffusion . 379 The values for e on the 40th day for N/ 5 HC1 and for N/ 2 H2S04 were 127 mm. and 114 mm. , or\#151 ; HC1 : \#163 ; H2S04 : : 1 : 0'898 . This comparison is made on the assumption that the 1ST/ 5 HC1 and the IST/ 2 H2S04 became , in the jelly tubes , practically isohydrie , because their diffusion rates were equal . If this was the case , then the movement of the anions Cl and S04 in the dilute acid jelly would be equally affected by the movement of the hydrions also present , and thus the progress of the anions would be comparable . A number of experiments ( not all cited ) were made with litmus jellies not containing salts other than those in the jelly and litmus employed . In these experiments there was hardly any appearance of the bands ad and ac . This npn-appearance would seem to be in keeping with the conclusions arrived at by Walker , McIntosh , and Archibald :\#151 ; * . The conclusion we feel justified in drawing from these observations is that in at least a great number of cases , if not in all , combination with the solvent is the necessary precursor of ionisation , although such combination does not necessitate ionisation . " Conclusions . The results as given in the present paper would appear to afford a considerable body of data tending to support the theory of Nernst and Planck . So far as the author is aware , the method of studying band boundaries has been almost entirely confined to experiments in which batteries have been employed , as in the work of Orme Masson and of Steel . The earlier experiments in jellies and the later experiments with silver nitrate and calcium chloride show that very fairly sharp bands are obtainable without batteries . The evidence goes to show that hydrogen ions move in advance of the diffusion front , whereas other ions produce thief various " effects " in the rear of the diffusion front . * " Ionisation and Chemical Combination in Liquid Halogen Hydrides and Hydrogen Sulphide , " ' Chem. Soc. Journ. , ' July , 1904 , CXII , vol. 85 , 4D , p. 1105 .

rspa_1906_0083

0950-1207

The action of radium and certain other salts on gelatin.

380

384

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

W. A. Douglas Rudge, M. A.|Professor J. J. Thomson, F. R. S.

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6.0.4

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10.1098/rspa.1906.0083

Chemistry 2

Biochemistry

Chemistry

380 The Action of Radium and certain other Salts on Gelatin . By W. A. Douglas Budge , M.A. ( Communicated by Professor J. J. Thomson , F.R.S. Received June 7 , \#151 ; Read June 21,1906 . ) [ Plate 7 . ] The action of radio-active substances on gelatin media has recently attracted attention . In ' Nature '* there appears a letter by J. B. Burke , in which the writer states that certain " bacterial-like " cells are obtained as the result of the action , the cells grow up to a certain stage and subdivide , they contain a nucleus , and appear to be highly organised bodies . The author has made numerous experiments on this subject , and has made several communications to ' Nature ' and to the Cambridge Philosophical Society . The present paper deals chiefly with the results obtained by the aid of photography , which obviously is a much more satisfactory method of recording than mere drawing . The word " growth " is used to indicate the action , but must not be taken to imply that anything of the nature of living growth has occurred . Two methods of working were employed : ( 1 ) for unaided eye observation ; ( 2 ) for microscopic examination . In the first method small Soyka flasks with parallel sides were employed to hold the gelatin culture medium . The flask was about hall ' filled with the gelatin and sterilised in the usual way by steaming . A few specks of the radium salt were then placed on the surface of the gelatin and the effect watched . At once a whitish patch was seen to develop round the . speck , the patch rapidly increasing in size , so that at the end of 10 minutes it appeared like a growth of ordinary mould . Plate 7 , fig. 1a , represents the appearance of the growth at the end of about an hour . The patch continued to grow , but at a much slower rate , and in some cases reached a maximum in less than a day , the time required depending upon the stiffness of the jelly and upon the class of gelatin used . Several samples of radium salts of different degrees of purity were used , and it was seen that the rate and amount of growth did not depend upon the amount of radium present in the sample . Solutions of the salts were sometimes used , but the solid material was more satisfactory ; the general * Yol . 72 , p. 78 . The Action of Radium and certain other Scdts on Gelatin . 381 result was , however , the same . As radium salts are composed in the main part of barium salts , it seemed likely that the latter might have some effect upon the gelatin , and this was found to be the case , a growth being produced which seemed identical with that produced by the radium salt ( fig. 1b ) . Fig. 2 shows the extent to which the growth had penetrated after 36 hours , and after which it ceased to increase . A systematic examination was next made with all kinds of metallic salt , with the result that only those of strontium and lead , besides radium and barium , gave any decided effect . As these metals are those which form insoluble sulphates , it seemed likely that the growth originated about the precipitates which form with the sulphur compounds present in the gelatin . As the use of the gelatin in the culture material is simply for the purpose of localising the growth , by keeping it more or less fixed , the effect of using other glutinous or mucilaginous substances instead of gelatin was tried . The substances thus employed were agar-agar and several varieties of starch and gums , sufficient being added to the meat solution to cause it to solidify . When this was done it was found that if distilled water was used in making up the jelly , no growth could he seen , but if tap water was used a slight growth made its appearance , and if a soluble sulphate was previously added , then a very dense growth appeared . It thus was quite evident that the presence of a sulphate was necessary for the formation of the growth , and attention was then directed to the gelatin to ascertain whether sulphuric acid or a sulphate was usually present . Between 30 and 40 samples of gelatin were examined and , with three exceptions , all contained sufficient sulphuric acid to give a distinct , sometimes a dense , precipitate with barium chloride in presence of nitric acid.* ' The gelatin solutions were prepared by washing the sample six times with distilled water , allowing it to soak for some time before decanting , then dissolving in sufficient distilled water to make a thin jelly . Two samples of commercial Bussian isinglass and one sample of gelatin prepared by the author from fresh calf skin failed to give a precipitate with barium or radium salts , but in each of these cases a growth could be obtained by adding a soluble sulphate . If a barium salt gave no precipitate with the gelatin , then radium salt failed to produce a growth . It thus seemed clear that the growth originated about the precipitate of barium sulphate . The growth continues to extend for some time into the gelatin , but after a while it stops . The reason for this extension of the growth from the point of contact appears to be as follows : the gelatin allows of a slow diffusion of the * The precipitate was analysed in several cases , and was found to consist of BaS04 . Mr. W. A. D. Rudge . Action [ June 7 , barium salt through it , and as there is only a small amount of sulphuric acid present the barium is in excess and , therefore , after forming a precipitate in the first layers of the gelatin , sufficient barium salt is left , which , diffusing onwards , causes further precipitation in the succeeding layers , but eventually all the barium salt is used up by combining with the sulphuric acid and then the growth reaches its limit . A proof of this theory is given by the fact that , with samples of gelatin containing a ( relatively ) small amount of sulphuric acid , the growth , although much less dense , extends for a greater distance . Figs. 3 and 4 are photographs of two flasks containing very pure gelatin . To 3 there was added a small amount of calcium sulphate solution , to 4 twice the amount was added . The growth can be seen to extend much further into the gelatin in 3 than in 4 , although it is much less dense . Many observations confirm this . As the experiments conducted in the flask did not admit of the action being watched from the beginning , another method was adopted which allowed of continuous observations being made . This method consisted in placing a little of the melted jelly upon a glass slip and , after allowing it to solidify , adding a speck of the salt whose action was to be studied and then covering with a thin glass circle . A modification of this plan was to place the cover glass upon the still liquid gelatin and allow it to solidify under the cover . A speck of the salt was then placed at the edge of the cover glass , and the growth worked its way through the thin layer of gelatin enclosed between the glasses . Many hundreds of preparations were made in this way , using all kinds of salts , and the results obtained have been the same as in the flask experiments , viz. , that radium , barium , strontium , and lead salts are the only ones which produce any effect . ( t might be expected that calcium salt should behave in the same wav as barium and strontium , but the calcium sulphate is so much more soluble than the sulphates of the other two metals that it does not form a precipitate under the conditions of the experiments . Very careful search was made in the case of uranium salts , but not any growth could be obtained , negative results also following the use of thorium salts , pitchblende , and uranium metal . There is thus no connection between radio-activity and the formation of the growth . A number of photographs were taken of the preparation made by the latter method at periods from a few minutes after contact with the gelatin to several days and in some cases weeks . The apparatus used for this purpose was supplied by Zeiss , and for direct observation magnifying powers up to 1500 diameters could be employed . 1906 . ] Radium and certain other Salts on Gelatin . For photography and projection magnification up to 6000 or 7000 diameters could be obtained without undue distortion . Photographs were taken with magnifications of 400 , 1000 , and 4000 . The first effect of the action of radium salt was to cause an evolution of gas in the form of minute bubbles , owing to the decomposition of the water ; the evolution soon ceased , but simultaneously a nebulous growth was seen to proceed from the point of contact of the salt with the gelatin . The growth consisted of tiny particles of precipitate which increased in size rapidly up to a certain point , and then expanded much more slowly , and in many cases did not increase at all after 10 hours . This precipitate has , undoubtedly , a sort of cellular structure , as is clearly shown in the photographs taken with the higher powers . Figs. 4 to 8 show the progressive stages of the growth during 85 minutes , the magnification being 400 diameters . Many " pairs " of cells can here be seen , but the grouping is purely fortuitous . Fig. 9 represents a portion of the same preparation taken with a magnification of 1200 diameters . Here the cellular character is clearly seen . This same preparation was used to see whether any increase of size took place after one day . For this purpose the slide was fixed firmly to the stage of the microscope , and the objective , 1/ 12 oil immersion , focussed upon a large cell which had a well-defined shape . This was photographed at intervals of a day for four successive days in order to determine whether there was anything of the nature of " cell division " or growth , in the usual sense , taking place ( figs. 10 to 13 ) . The photographs absolutely negative this idea . Observation could not be carried on for a longer time on account of the drying of the immersion oil . It is important to observe that there is no trace of a , even on pushing the magnifying power by projection up to 12,000 ! ! , this figure being , of course , a long way past the limit of " useful " magnifications . A series of photographs was taken with barium salts instead of radium , with the results shown in figs. 14 to 17 . Fig. 14 shows the nature of the growth after 15 minutes at 400 diameters , fig. 15 after 30 minutes , fig. 16 the appearance at 1200 after one hour , and fig. 17 at 4000 . It appears that there is not much difference between the result of the radium and barium salts ; in fact , it is often impossible to say which metal has caused a particular growth . There is a considerable variation in the effect of both radium and barium salts , owing to the varying nature of the different samples of gelatin , and to the amount of water present , etc. 384 The Action of Radium and certain other Salts on Gelatin . Fig. 18 shows the result at 4000 diameters of the action of strontium nitrate , and fig. 19 that due to lead nitrate upon the gelatin . If these experiments are conducted upon gelatin from which the sulphuric acid has been removed no growths are obtained . A sample of gelatin from which the sulphuric acid had been removed was sealed up with some radium salt in September last , and at the present time no signs of growth have made their appearance , but if to a portion of the gelatin a soluble sulphate is added a growth at once appears . It thus seems to be quite clear that the cellular growth cannot be produced by radium or barium unless a sulphate is present , and other metals , save Sr and Pb , fail to produce any result , because the^ do not form insoluble sulphates . The cellular form of these precipitates is probably due to the circupistance that the gelatin is liquefied by the actions of the salt , and each particle of precipitate is formed about a core of gelatin , so that the layer of barium sulphate forms a kind of sac or cell which is surrounded by the solutions of the salt in the liquefied gelatin . This cell may be permeable to the liquefied gelatin containing a salt in solution , which , passing through the cell wall , causes an expansion to take place , the limit of growth being controlled by some surface tension effect . The conclusions which are drawn from a study of the photographs and direct examination under the microscope with high powers are that:\#151 ; 1 . The cells form round a precipitate of an insoluble sulphate , and the energy of the growth of the cell depends upon the amount of sulphate present . 2 . Radium has no specific action in forming cells , any effect produced being due . to the barium associated with it , and the purer specimens of radium salts are less satisfactory as cell-formers than the impurer ones . Probably pure radium salt would have no action except that of causing an .evolution of gas . 3 . The cells do not divide or bud or show anything resembling \#166 ; " karyokinesis , " their growth very quickly reaches a maximum , and they do not decay or split up , save as a consequence of the drying of the gelatin . If the cover glass is sealed down with cement , the cells have been observed to suffer no alteration in the course of four months . 4 . Eadio-active substances , unless they contain barium , do not give rise to the formation of cells . Rudge . Roy . Soc. ProcA 78 , Plate 7 .

rspa_1906_0084

0950-1207

The composition of Thorianite, and the relative Radio-activity of its constituents.

385

391

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

E. H. B\#xFC;chner, Ph. D.|Sir William Ramsay, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0084

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10.1098/rspa.1906.0084

Chemistry 2

Biochemistry

Chemistry

385 The Composition of Thorianite , an the Relative Radio-activity of its Constituents . By E. H. Buchner , Ph. D. ( Communicated by Sir William Ramsay , F.R.S. Received August 23 , \#151 ; Read November 8 , 1906 . ) [ . Prefatory Note by Sir William Ramsay.\#151 ; When the cubical mineral from Ceylon , sent to me by Mr. Holland in December , 1903 , and named by Professor Dunstan " Thorianite , " was analysed by several of my students , it was evident that although in the main , as shown by the analysis made by Mr. G. S. Blake under Professor Dunstan 's supervision , it consisted of the oxides of thorium and uranium , its composition is by no means simple . The analyses referred to were made by Dr. R. D. Denison , by Mr. Gimingham , and by Mr. Le Rossignol ; they are as follows ( for convenience of reference-Mr . Blake 's analyses are also appended ) :\#151 ; The extraction of radiothorium by Dr. 0 . Hahn , * and various other investigations carried on in my laboratory , made it evident that under the heading " lead , " for example , various other metals were included , and Dr. Buchner undertook to carry out an analysis on a larger amount , so as to ascertain what elements were present in the analytical groups into which , the constituents of the mineral had been roughly divided by previous * ' Jahrb . f. Radioakti vitat , ' vol. 2 , 1905 . Thorium oxide , T1i02 ... ... ... Cerium oxide , Ce203 ? ... ... . . Lanthanum oxide , La203 ... ... Didymium oxide , Di.203 ... ... . Uranium oxide , U308 ... ... ... . Ferric oxide , Fe203 ... ... ... . Lead oxide , PbO ... ... ... ... . . Calcium oxide , CaO ... ... ... ... Zirconium oxide , Zr02 ... ... . . Loss on ignition ... ... ... ... . Helium , He ... , ? ... ... ... ... . . Residue on fusion with HKSO , ... Denison . Giming- ham . Le Ros- Dunstan and Blake . signol . i. 2 . 3 . 72 -24 76 -22 78 -86 76 '4 77 -52 77 -07 [ 6 39 t 0-51 | 8'04 1 -02 14-9 13 -23 12 -95 11 *19 12 -33 15 -10 6-1 2-79 2-77 1 92 0-35 0-46 2 -0 3-42 2 -41 2-25 2-87 2-59 \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; 1 13 * 1 '63 1 63 3-68 0-20 \#151 ; \#151 ; \#151 ; \#151 ; 0-39 0-7 2-02 1 2-60 0-41 0T2 100 -i 100 -61 99 -43 98 -59 99 -93 99 -75 * Ignited mineral analysed . 386 Dr. E. H. Bucliner . Composition of [ Aug. 23 analysts . Another of the objects of his research was to determine how the radio-activity of thorianite is distributed over its various constituents . Assuming , as looks more than probable , that the radio-active constituents of thorianite , like those of similar radio-active minerals , are in process of change , it is to be expected that by working on comparatively large quantities these bodies and their products can be identified , even though in themselves they may not display the property of radio-activity . ] The methods employed in the chemical analysis of thorianite , together with the results obtained , will form the first section of this account , and the second part will deal with experiments relating to the radio-activity of the several fractions into which the mineral was separated . The total quantity of mineral taken for analysis was 24*373 grammes . On treatment with concentrated boiling nitric acid the greater part of it dissolved . After decantation , the residue was once more boiled with fresh acid , and only a small quantity remained insoluble . The solutions were then mixed , evaporated to dryness , heated to 130 ' to render any silica present insoluble , and redissolved in dilute hydrochloric acid . The residue , which was dried , ignited , and weighed , was non-volatile on treatment with hydrofluoric and sulphuric acids ; on testing it , it proved to be zirconium oxide , which had separated out as a basic salt . Sulphuretted hydrogen was then passed through the hot liquid ; the precipitated sulphides were treated with a solution of sodium sulphide , in which a portion dissolved . The residue dissolved almost completely in dilute nitric acid , only a trace remaining , which was soluble in regia after excess of acid had been removed by evaporation it was dissolved in water , and could be reprecipitated by sulphuretted hydrogen . Its amount , however , was too small to prove undoubtedly that it was mercuric sulphide ; mercury , however , has been found ( by Miss Evans ) in residues from a larger amount of mineral . Sulphuric acid was added to the nitric acid solution , and the precipitated lead sulphate was filtered off , dried , and weighed . Ammonia was then added to the filtrate ; this should have precipitated bismuth as hydroxide ; the colour of the precipitate , however , was reddish-brown , and it was practically insoluble in hydrochloric acid ; its quantity was also too small to permit of further investigation . Copper was then precipitated by Eivot 's method by addition to the filtrate of ammonium sulphocyanide , after reduction with sulphurous acid . The filtrate from the cuprous sulphocyanide gave traces of a brown precipitate with sulphuretted hydrogen , not in the least resembling cadmium sulphide . 1906 . ] and the Relative Radio-activity of its Constituents . 387 The solution of the sulphides in sodium sulphide , which should have contained arsenic , antimony , and tin , and other elements capable of forming sulpho-salts , was analysed* according to the methods of Bunsen and Clarke . A large excess of sulphurous acid was added to the liquid , and it was boiled for a long time . Arsenic is dissolved , antimony and tin remain behind . The insoluble residue was then suspended in water ; ammonium persulphate and oxalic acid were added , and sulphuretted hydrogen was once more passed through the solution . After a repetition of this operation , the solution should have contained only antimony , and the residue , tin . The antimony sulphide , after excess of sulphur had been removed by carbon disulphide , had an almost black colour , probably due to the presence of selenium , which has been discovered by Professor Ogawa in this laboratory , in course of work on larger quantities of residue . The solution , which was supposed to contain arsenic , was treated with sulphuretted hydrogen ; to the precipitate , after solution and oxidation , ammonia and magnesia mixture were added , but no arsenate came down . On passing sulphuretted hydrogen , however , a small quantity of a black substance was precipitated . To the filtrate from the sulphuretted hydrogen group ammonia was added after oxidation . The precipitate was redissolved in hydrochloric acid and , after adding a little concentrated nitric acid , a solution of oxalic acid was poured into the solution . The oxalates of the rare earths separated in a granular state , and were separated by filtration . This precipitate was then treated , according to Brauner 's method , with a solution of 20 grammes of ammonium oxalate in 40 grammes of water , and boiled for about 10 minutes ; the liquid was then diluted with about 800 c.c. of water . The thorium remains in solution ; the ceria , etc. , are precipitated . This process was repeated , and the solution was then evaporated to dryness and ignited ; the thorium oxide was then weighed . The original solution in hydrochloric acid , however , still contained thorium and cerium ; it was , therefore , partly evaporated and neutralised with ammonia , and oxalic acid was again added ; the precipitate obtained was treated in the same way as has been already described . No attempt was made to separate ceria from the other earths , though they were present , as is proved by the red-brown colour of the C62O3 . The ammonia-group further contained iron , aluminium , and uranium , which are not precipitated by oxalic acid . They were separated by the usual methods ; if the solution contains excess of ammonium carbonate , only iron and aluminium are precipitated by ammonium sulphide , and uranium is left in solution ; after precipitation by evaporation , and re-solution in dilute * 388 E. H. Buchner . Composition of Thorianite , [ Aug. 23 hydrochloric acid , it was thrown down by ammonium hydroxide and weighed as U308 . The aluminium and iron were separated by treatment with excess of caustic potash . The filtrate from the ammonia-group was evaporated to dryness in a platinum basin , and the ammonium salts were expelled ; the residue dissolved almost entirely in hydrochloric acid ( residue co ; see experiments on radioactivity ) . After neutralisation of the excess of hydrochloric acid , calcium oxalate was precipitated ; the filtrate was again evaporated , and heated to redness . A residue was left , which was weighed , and submitted to several tests . Part of it dissolved on boiling with concentrated hydrochloric acid ; the solution was evaporated , diluted with water , and treated with excess of caustic soda ; the resulting precipitate was soluble in hydrochloric acid . After neutralisation , sodium phosphate gave a white precipitate ( \lt ; \#163 ; ) ; on addition of ammonia to the filtrate , another precipitate came down in very small quantity ( magnesia ) . The solution , which contained excess of soda , was evaporated and heated ; on dissolving in water , a residue was left , soluble in hydrochloric acid , and precipitable by hydrogen sulphide with a brownish-red colour . None of these precipitates have been investigated more closely . The portion of the mineral insoluble in nitric acid was fused with hydrogen potassium sulphate ; the fused mass dissolved almost completely in hot water ; on addition of a little hydrochloric acid , however , a precipitate was formed . After this had been removed by filtration , a further quantity of a white substance separated . Sulphuretted hydrogen was passed through the filtrate from this second precipitate , when a red-brown precipitate was thrown down , which was treated in the same manner as described for the soluble part of the mineral . Mercury was again present in traces , as well as substances which came down in place of bismuth and cadmium ; these were probably identical in nature with those found in the ' other portion . After the supposed cadmium had been filtered off , the solution was evaporated and heated ; a residue was left ( p ) . The ammonia-group consisted only of aluminium , iron , and uranium . To the filtrate from this group ammonium carbonate was added ; no precipitate came down , until after 24 hours , when a white substance separated . The filtrate left no residue after it had been evaporated and heated . The precipitate mentioned above , which was obtained by adding hydrochloric acid to the solution of the fused mass , was once more fused with bisulphate , and dissolved in hot water ( solution y ) ; a residue remained , which was partly soluble in concentrated hydrochloric acid ( solution a ) , and a white residue was left . Sulphuretted hydrogen was then passed through 1906 . ] and the Relative Radio-activity of its Constituents . 389 solution a , and after 24 hours ' standing , a brownish-red precipitate was formed , the filtrate from which was mixed with solution / 3 , obtained in the following way:\#151 ; The solution y had become turbid , and deposited a white precipitate ; this was removed by filtration . Sulphuretted hydrogen was passed through the filtrate , and gave a precipitate similar in appearance to that formed in solution a ; after filtering and allowing to stand , saturated with sulphuretted hydrogen for 24 hours , another quantity of what was apparently the same substance was obtained . The mixed solutions a and / 3 were then oxidised , precipitated with ammonium hydroxide , and the precipitate dissolved in dilute hydrochloric acid . No precipitate was produced with ammonium oxalate , but only a slight turbidity , which passed away on addition of a few more drops . The oxalic acid was removed from this solution by evaporation and ignition , and the oxide was weighed . Qualitative tests showed that it consisted of oxide of titanium with traces of oxide of zirconium . A separate quantity of the mineral was heated to redness , in order to determine the loss on ignition . It proved to be considerable , and chiefly due to the presence of water . The gas evolved was collected over mercury , and the carbon dioxide absorbed with caustic potash ; the only other gas present was helium . From 1 gramme of the mineral 8*2 c.c. of helium were obtained at normal temperature and pressure . The results of the analysis are given in the table ( p. 390 ) , where the measurements of radio-activity of the various precipitates are also given , contrasted with that of the mineral taken as 100 . For determining the radio-activity of the precipitates , a month was allowed to elapse after they had been obtained ; about 10 milligrammes of the substance , if as much was available , was weighed out and placed in an electroscope . It was sometimes necessary , however , to place precipitate and filter together in the electroscope . The time in which the leaf moved over 20 divisions of the scale was noted , and from this the number of divisions per hour was calculated , allowance having been made for one hour 's leakage , had exactly 10 milligrammes been placed on the copper plate . The figures thus obtained are given in the third column of the table , and in the second column the activity of the total quantity of the precipitate , obtained by multiplying the numbers in the third column by the weight of the substance , is recorded . The last column shows the percentage activity , that of the original mineral being taken as 100 . The mineral possesses 83*3 per cent , of the activity of standard uranium oxide , a sample several years old . It is also to be noticed that the activity is associated almost entirely with the soluble part of the mineral ; while the VOL. LXXVIII.\#151 ; A. 2 D 390 Dr. E. H. Biichner . Composition of Thorianite , [ Aug. 23 , Per cent. Total activity . Activity per 10 milligrammes . Activity : mineral = 100 . HsrO traces Soluble porti\lt ; 284 m. Not weighed PbO 2 *42 72061 8360- 95703 125 145 166 1 '9 2-2 2 *5 CuO 0-08 10 0 05 none Sb204 0 T1 16 BiV)'p 0*21 2153 4144 421s \#151 ; 0-6 P traces 72 CdO ? FcoOq 2-05 17,5306 21,380 ' none 351 428 4-6 5*7 ALQ . 0-15 TJ , Oa 13*12 24,9153 35,490s 216,190 8680'0 9650'1 78 111 6-6 9-4 ^3^8 Th02 70 *96 125 57-2 CeoOo 1 *96 178 198 2-3 2-6 0 *23 924 16512 163'3 0-2 CaO 0 *13 108014 122515 343 388 0-3 0-3 [ Residue 1 *50 6590 1 -8 HsO traces Insoluble port 49 don . Bi2(V 0*15 124 44 and 16* CdO ? traces Fp\#171 ; 0.f 1 *30 66416 10101 ' 21 32 0-2 0-3 Abo* } 0*06 none m - ZrOo 0*02 traces 21 40 Ti02 0 *45 none Unknown substance Po0- 0*040 traces 66 none COo 0*10 He " 0 *15 HoO 3*20 98 -84 75 -7 80 -3 Original mineral ... ... ... ... . 155 Standard uranium oxide ... ... . 186 Original mineral ... ... ... ... . 155 Standard uranium oxide ... ... . 186 Dates.\#151 ; 1 ft Feb. ; 2 27 Feb. ; 3 23 Mar. ; 4 8 Feb. ; 5 24 Mar. ; 6 13 Feb. ; ' 5 Mar. ; 8 15 Feb. ; 9 6 Apr. ; 10 16 Feb. ; 11 28 Mar. ; 12 8 Feb. ; 13 28 Mar. ; 14 14 Feb. ; 15 27 Mar. ; 16 13 Feb. ; 17 13 Mar. * This precipitate came down in two portions , which were filtered off and kept separate ; the first had the smaller activity . ratio of the weights of the soluble to the insoluble portion is 40 to 1 , the ratio of the activities is about 300 to 1 . Again , comparing the activity of constituents common both to the insoluble and soluble portions , such as iron oxide , and bismuth ( ? ) oxide , the samples from the soluble portion are much more active than those of the insoluble portion . In the case of iron the ratio is Vl to 1 . Nearly all the precipitates obtained from the soluble portion proved to be radio-active , although some had only a very slight effect on the electroscope . A remarkable exception is furnished by the alumina , which , although closely 1906 . ] and the Relative Radio-activity of its . 391 allied to the strongly active iron group , is absolutely inactive . The active constituent of the iron group is therefore insoluble in excess of caustic potash ; as farther experiments showed , it gives off an emanation , the rate of decay of which , although not accurately determined , appears to point to its being due to that of radiothorium , separated by Hahn* which always comes down with iron . The activity of several precipitates had not reached a maximum at the last measurement ; those of lead , iron , uranium , cerium , and calcium were still increasing , while the activity of bismuth ( ? ) , thorium and zirconium did not change . On the other hand , several precipitates showed activity originally , which decreased and even disappeared , e.g. , co , insoluble in hydrochloric acidf ( see p. 388 ) . When originally obtained , it was placed in the electroscope along with its filter , and showed an activity of 30,000 to 40,000 . After destroying the filter , and dissolving the precipitate with aqua regia , and evaporating the solution to dryness , the activity had decreased to 250 , and it seemed then to be permanent at that value . It may be assumed , therefore , that this precipitate is a so-called X-substance ; its chemical behaviour somewhat resembles that of a platinum-metal . After evaporation , the solution in aqua regia left a yellow crystalline residue , which turned black when gently heated . This black residue was insoluble in hydrochloric acid , but soluble in aqua regia ; the solution showed again the same properties . The next most active precipitate was found in the filtrate from the ammonia-group . Several very active minute traces of substance were collected on filters . The substance ( f\gt ; , mentioned on p. 388 , obtained by addition of sodium phosphate , weighed only 8 milligrammes , and had a total activity of 3400 , which increased to 3900 after standing for six weeks . Although this precipitate forms only ( K)2 per cent , of the total weight of the mineral , it possesses 1 per cent , of the total activity . In connection with this it may be remembered that Rutherford , | during his early experiments on thorium and thorium-X\gt ; also found a strongly active constituent in his thoria , precipitable by sodium phosphate after removal of the thoria . He was not always able to detect it , however , and ascribed it to the presence of an impurity in commercial thoria . In conclusion , it is my pleasant duty to express my hearty thanks to Sir William Ramsay for his kind assistance and advice . * ' Jahrb . f. Radioaktivitat , ' vol. 2 , 1905 . t The residue , p ( p. 388 ) , was also initially very active , but lost its activity in a short time . X ' Chem. Soc. Trans. , ' vol. 81 , p. 345 . 2 d 2

rspa_1906_0085

0950-1207

Experimental investigation as to dependence of gravity on temperature.

392

403

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

L. Southerns| Professor W. M. Hicks, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0085

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0085

10.1098/rspa.1906.0085

Thermodynamics

Measurement

Thermodynamics

392 Experimental Investigation as to Dependence of Gravity on Temperature . By L. Southerns , Whitworth Scholar . ( Communicated by Professor W. M. Hicks , F.R.S. Received September 13 , \#151 ; Read November 8 , 1906 . ) Few experiments have been made with a view of detecting with accuracy any alteration in the weight of a given substance which may accompany variation of its temperature . The recent experiments of Professor Pointing and Mr. Phillips described in the 'Proceedings of the Royal Society , ' September 13th , 1905 , led to a null result.* At the time of the publication of this result the Author had been engaged for about a year on a similar line of research , and as the two methods of experiment were entirely different , it was thought advisable to continue with this work in order that the results obtained by the two methods might be compared . Further reference will be made to this matter in the sequel ; but it may be noted here that in their experiments a mass of gunmetal was heated externally , while in the present ones a mass of paraffin oil was heated internally . Original Apparatus and Method of Experiment . The apparatus in its original form was constructed several years ago by Dr. Hicks . It consisted of a specially made balance , carrying at one end of the beam a calorimeter , and at the other end a magnetic counterpoise . The calorimeter consisted of a light aluminium vessel containing refined paraffin oil , in which was immersed a coil of fine platinum wire of about 1100 ohms resistance , wound on a mica frame . Two other aluminium vessels surrounded the inner one , and the spaces between them were packed with cotton wool ; the vessels themselves were made airtight by sealing up with wax . Leads from the coil passed up a tube to the suspension pieces of the calorimeter . A magnet was suspended from the other end of the beam as counterpoise , so that by passing a small current through a coil fixed in the balance case the magnet could be attracted or repelled , and the balance thus brought to its zero position and calibrated while within its closed case . The beam consisted of two parallel brass arms fastened together by means of a block of insulating material . The knife-edges were of hardened steel , * It is interesting to remember that Count Rumford attempted this experiment , and concluded from its negative results that heat could not consist of a ponderable fluid ( of . ' Life and Works of Count Rumford , ' vol. 3 , p. 1 ) . Investigation as to Dependence of Gravity on Temperature . 393 and they rested on steel plates which were connected to binding screws outside the balance case . Each knife-edge was electrically connected to the centre of one of the parallel brass arms of the beam ; thus a current could pass from one binding screw through the knife-edge and one conducting arm of the beam , thence by a steel point to the suspension piece of the calorimeter , through the heating coil immersed in the mass of oil , and back again through the other part of the beam and its knife-edge to the other binding screw . The heating coil could also be used as a platinum thermometer for ascertaining the temperature of the oil before and after the passage of the heating current . A mirror fixed to the beam enabled observations to be made from a distance by means of telescope and scale . The advantages of this design of calorimeter and method of heating are that the heating is very rapid ; that it takes place while the balance is swinging on its knife-edges ; and that the outer envelope of the calorimeter is not heated , and only slowly becomes warm , so that air currents , etc. , are reduced to a minimum . Also , the complete experiment can be conducted from a distance by the observer . A number of experiments were made with this apparatus , using a heating current of about 0'2 ampere , alternating . The diagram A shows the results of a typical experiment plotted in the form of a curve , the abscissae of which represent times and the ordinates scale readings , deflections of the balance beam . The length of the vertical line A B in the diagram represents an increase of weight of 1 milligramme , the weight of oil heated being about 250 grammes . During the period C D observations were taken previous to heating , the balance being left free to swing on its knife-edges . D E represents the period of heating ( one minute in this case ) , and E F part of the period of cooling , during which observations were also taken . In all these experiments a large apparent increase of weight took place very soon after the period of heating , although the changes during the heating were very small . In order to investigate the cause of this , a platinum thermometer was inserted in the balance case near the calorimeter , and its temperature observed from time to time during an experiment . Diagram B shows the temperatures indicated plotted to the same time base as the balance deflections . The ordinates of the temperature curve ( shown dotted ) are proportional to the temperatures indicated , and approximately represent in magnitude the diminution in the buoyancy of the air , supposing the air surrounding the calorimeter to be at the temperature indicated by the thermometer . This is , of course , only a rough approximation to the truth , but the general similarity of the curves indicates that the effect is largely due to diminution of buoyancy of the air caused by escape of heat from the Mr. L. Southerns . Investigation as to [ Sept. 13 } 4-0 TIME 12-30 1906 . ] Dependence of Gravity on Temperature . calorimeter . As the temperature of the oil was only raised four or five degrees in these experiments , it was obvious that this effect must be greatly reduced before trustworthy observations could be made of any change in weight which might occur during the heating period if considerable increments of temperature were to be used . It was then decided to make the weighings in a partial vacuum in order to reduce this buoyancy effect . Modifications of the Apparatus . After some preliminary trials with a temporary vacuum chest , the apparatus was rearranged and set up in a constant temperature room in the basement of the new Physical Laboratory at Sheffield . This room was for the purposes of this experiment divided into two portions by a partition , the balance being set up on one side and observations taken from the other . The general arrangement of the apparatus is shown in fig. 1 . In the figure A A represents the partition , to which are fixed various instruments , resistances , etc. , not indicated in the figure . B is a brick pillar , which has a rubber course at its base , resting on a concrete slab C. The balance Mr. L. Southerns . Investigation as to [ Sept. 13 , is placed on a cast-iron tray D D , and over it is lowered a cast-iron cover E provided with circular windows . The bearing surfaces of cover and tray are faced with rubber , and the joint is rendered airtight by pouring mercury around it . An enlarged section of this joint , which can he made and broken with the greatest ease , is given in the figure . F shows a portion of the cover with its strengthening flange Gr , H the tray , J the mercury space , and K the rubber facings . Keturning to the main figure : L L represents a trestle from which pulleys are slung for raising the cover E. M is a tube to which are connected a water pump and a Fleuss air-pump for exhausting the balance case , and also a gauge which indicates the stage of exhaustion . Copper wires , sealed into glass tubes , which are in turn sealed into holes through the tray D , form the electrical connections for conveying the current into the balance case ; one of these is shown at N. P is the observing telescope fixed to a stand Q set up inside the portion of the room cut off by the partition so as to be free from sudden variations of temperature , vibration , etc. The scale is placed at S S , and is illuminated by means of a lamp T , with lens U , and mirror Y. Many instruments and practical details are left out of the figure in order to avoid complication . ' It was also necessary to construct a new calorimeter , as the original one was not designed to support the internal pressure produced when the balance case is exhausted . This is shown in fig. 2 , which will be described in due course . Also a closed vessel having a volume equal to that of the inner vessel of the calorimeter was attached to the magnetic counterpoise . The new apparatus was first tested at full atmospheric pressure , a current of 035 ampere being used for heating . It was found that motions of the balance were produced by the passage of the current ; thus deflections of 03 to 2-5 mm. were observed while the current was passing , but the balance nearly resumed its original position when the current was cut off . About 60 experiments under varied conditions were made in order to ascertain the causes of these disturbances . They were found to be due to induced currents , chiefly in the magnetic counterpoise coil , to self-induction in the beam and other parts of the circuit inside the balance case , and to some source of error due to the passage of the current through the knife-edges . It was , therefore , necessary to make further alterations in the apparatus . The magnetic counterpoise had to be sacrificed , and the current was made to pass by two stout copper wires fixed near each other to the beam , instead of by the brass arms of the beam , which enclosed a considerable area . These wires were pointed and made to just dip into two mercury cups attached to the supports of the balance so that the points of contact of wire and mercury were in the same straight line as the central knife-edges . The 1906 . ] Dependence of Gravity Temperature . L__________J Fig. 2 . A A. Copper calorimeter , 9 cm . x 8 cm . , made in two halves soldered together , containing oil to about the level shown . Weight of the copper = 53 grammes ; of the oil 233 grammes ; of the total heated mass , including solder and coil , about 300 grammes . \#163 ; B. Brass tube soldered to top of calorimeter . The leads from coil pass up this tube , which is sealed airtight with khotinski cement . C C. The dotted lines indicate shape of frame on which the fine platinum wire coil is wound ( non-inductively ) . The wire is distributed fairly uniformly throughout the mass of the oil . D D. Aluminium vessels packed with cotton wool . The outer one is airtight , but the inner one is not . E. Ebonite tube , closed at top , which retards loss of heat from B B , and carries the suspension plates . F. Suspension plate , with glass bearing slip underneath . One lead from coil is attached to F. G. Tinfoil strip connecting F to the conducting rod for conveying current to the coil . H. Conducting rod fixed rigidly to beam by an ebonite clip not shown . J. Mercury cup attached to balauce case into which the pointed end of H dips to make contact with external circuit . The point is in same straight line as knife-edges . K. Part of beam with bearing point . F , G , H , J , K are in duplicate . L. Gauge ( not shown in its true position ) containing mercury . This allows air to be drawn from the spaces between ADD when the balance case is exhausted , but the thread of mercury falls back and prevents escape of residual air from calorimeter during an actual experiment . Mr. L. Southerns . Investigation as to [ Sept. 13 , calorimeter terminals were connected to these wires by tinfoil strips . These precautions almost entirely did away with the disturbances . The arrangements are shown in fig. 2 . The counterpoise was also provided with an external vessel and gauge like that of the calorimeter . With the modified apparatus a series of observations was taken , the pressure of air in the balance case ranging from 1-6 to 5'0 cm . of mercury . In one case 6 mm. was used , but a discharge took place within the balance case , fusing the tinfoil strips . In this particular case the pressure was reduced by means of a bulb containing cocoanut charcoal , connected to the exhausting tube and cooled by liquid air . The low vacuum , however , not sufficiently insulating the leads , the method was not repeated . Final Experiments . The table ( p. 399 ) gives a record of the final experiments made with the modified apparatus . Observations were taken for a considerable period before and after heating ; the curves showing some of these are given in the diagrams indicated by letters in the last column of the table . It should be noted that all the deflections marked in the table are temporary only ( except No. 8 ) and the balance righted itself in one or two minutes in all cases . This effect plainly could not be due to an actual difference of weight due to alteration of temperature , or it would have persisted longer , for the fall of temperature in two minutes was very small\#151 ; always less than 1 ' C. Experiment No. 8 is abnormal , no doubt some accidental disturbance took place . In calculating x in Column 9 the temperatures given in Column 7 have been used . The calculation is as follows:\#151 ; Total weight heated = 300,000 milligrammes . 1 scale division corresponds to n milligrammes ( Column 8 ) ; .\ 1 " " to 1 in 300,000/ w ; . ' . 1/ 10 " " to 1 in 3,000,000/ w ; and if rise in temperature = 6 ' , 1/ 10 scale division corresponds to 1 in ( d x 3 x 106)/ ?i per degree rise of temperature , and as this is the smallest measurable deflection , we have x = ( 36/ n ) x 106 . In nearly all cases a very slight oscillation of the beam took place during the passage of the current . It seems reasonable to assume from the results of these experiments that any variation of weight which may occur is less than 1 part in 108 per degree rise of temperature . The fact that all the small displacements observed were 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 . 11 . 12 . 13 . 14 . No. of experiment . Date . Pressure in balance case . Current ( alternating ) . Time of passage of current . Rise of temperature by platinum thermometer.* Rise of temperature by specific heat of the oil.* Sensitiveness of balance , 1 mm. of scale = n milligrammes . Smallest measurable alteration of weight expressed as 1 part in x of total mass heated , per degree rise of temperature . Alteration of weight during heating , in millimetres of scale , -f = increase , \#151 ; = decrease . Alteration of weight during heating , expressed as 1 part in y , per degree rise of temperature . Time , after cutting off current , taken by balance to resume its former position . Remarks . * The temperatures were taken by using the heating coil as a platinum thermometer , and by calculation from the known heating effect and specific heat of the oil . The difference is probably due to non-uniformity of heating , as well as to an actual difference of temperature between the wire and the liquid in which it is immersed . A in Column 10 indicates a quantity too small for measurement . Refer to the curves marked with [ these letters . i 1906 . May 30 cms . of Hg . 2*5 amps . 0-35 secs . 30 'c . 11 -8 'c . 9-0 n. 1 -o X. 2 -7 x 10 ? mm. 0 iV . mins . No effect . c 2 " 31 1 -6 0-35 30 11 -8 9 0 1 -o 2 -7 x 10 ? 0 \#151 ; \#151 ; 3 ' June 11 1 -6 0-35 30 11 -8 9 0 1 *0 2 -7 x 10 ? \#151 ; A \#151 ; 1 Minute temporary deflection . 4 " 16 \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; Experiment spoiled by mercury in 5 " 22 1 9 0-35 30 11 -8 9-0 0-7 3 -8 x 10 ? 0 _ Gauge L , fig. 2 , going over . No effect . 6 " 23 1 9 0-35 30 11 -8 9-0 0-7 3 -8 x 10 ? -A \#151 ; 1 to 2 Minute temporary deflection . 7 July 23 3-2 0-35 30 11 8 9-0 0-86 3 -1 x 10 ? 0 \#151 ; \#151 ; No effect . 8 " 24 2 -4 0*35 45 \#151 ; 13 -5 0-86 4 -7 x 10 ? -o-l -4*7 x 107 10 Bad result . The only one which gave D 9 " 25 2 6 0-35 60 22 -5 18 -0 0-86 6 -3 x 10 ? 0 a permanent deflection with heating . No effect . E 10 Aug. 2 \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; \#151 ; Experiment spoiled as in No. 4 . 11 " 3 2-7 0-35 50 \#151 ; 15 -0 0-5 9 -0 x 10 ? \#151 ; A \#151 ; 1 Minute temporary deflection . F 12 " 4 2-6 0-35 60 22 -5 18 -0 0-5 1 -08 x10s -o-i -1 *08 x 10s 2 Small temporary deflection . 13 3 5 0-35 60 22 -5 18-0 0-49 1 -1 x 10s1 0 \#151 ; \#151 ; No effect . 14 " 14 4 6 0-15 360 \#151 ; 20 -0 0-6 1 -0 x 10s 0 \#151 ; \#151 ; j ) a 15 " 15 3-8 0-31 90 22 -8 21 1 0-6 1-05 x10s -0 1 \#151 ; 1 *05 x 108 1 Small temporary deflection . H 16 " 16 3-9 0-27 140 26 -4 25 -2 0-6 l -26 x 10s 0 \#151 ; \#151 ; No effect . J 17 \#187 ; 17 5-0 0-27 170 32 -5 30-6 0-72 1 -27 x 10s 0 \#151 ; \#151 ; \gt ; \gt ; K 1906 . ] Dependence of Gravity on Temperature . 399 Mr. L. Southerns . Investigation as to 10-30 10-30 11-30 1906 . ] Dependence of Gravity on Temperature . 401 in one direction lias given rise to the suggestion on the part of Dr. Hicks that while no permanent effect is produced by rise of temperature , it is just possible that the body may be slightly lighter during the actual development of heat . The present apparatus , however , is inadequate for the investigation of these minute effects ; some of them may be due to motions in the oil itself during the process of heating . Comparison of Results with those of Pointing and A few words may be said with regard to the two methods employed . The chief differences are , first , in the Birmingham experiments a much higher vacuum is employed ; secondly , the mass is of gunmetal , and is heated by means of an external steam jacket , and , thirdly , two experiments have to be performed , one with a solid mass and one with a hollow one , and the difference between the results taken , whereas in the present method only one is needed to give the complete result . The advantages gained by the internal method of heating are , first , the actual experiment itself is completed in two or three minutes , whereas in the external method two experiments , lasting 8 to 48 hours each , are required , during which time the balance is swinging on its knife-edges . This gives time for various disturbances due to external causes to interfere with the results of the observations . Secondly , the external envelope of the calorimeter does not sensibly rise in temperature during the critical part of the experiment , and there is no necessity to use a high vacuum in the balance case . This means that radiometer effects are not brought into play ( as is the case in the other method ) , whilst air currents are , nevertheless , practically or entirely absent . Thirdly , the balance case , supports , beam , etc. , do not become heated , therefore there is no connection such as that which has to be applied on this account in the case of the external heating method . In the experiments of Pointing and Phillips , the result is given as no variation of weight within 1 part in 109 per degree rise of temperature , while in the present paper a degree of accuracy of 1 in 108 only is recorded . The Author , however , thinks that in point of delicacy the present experiments are probably at least equal to the above , on account of the fact that no corrections need to be applied to the results . It would appear to be extremely difficult to apply satisfactory corrections for alterations of temperature of the balance case , and this has had to be attempted by them , on account of the considerable length of time occupied by an experiment . On December 8 , 1904 , for example , the correction curve appeared to be 17 times as steep as on the day before . Fig. 3 is plotted from the table on * 'Roy . Soc. Proc. , ' A , vol. 76 , September 13 , 1905 . 402 Investigation as to Dependence of Gravity on Temperature . p. 451 of the paper referred to and gives the correction for the hollow mass . The observations made on particular days are connected by dotted lines . The firm line shows the gradient deduced from the points marked by the method of least squares\#151 ; the application of this method , however , would appear to be superfluous in this case on account of the irregular disposition of the points . The nature of the diagram will show how uncertain such a correction must be . Also , the gradient is deduced from observations lying between 12a7 C. and 15 ' C. , but it is applied to all temperatures from 10o,45 C. to 170,45 C.* i.e. , over a range three times as great as that for which the observations for the correction were made . At the higher and ! ( fbal\amp ; rvc* . Cclojl . . Fig. 3 . lower temperatures the corrections must be still more uncertain . In some cases the correction deduced from a mean curve like that shown in fig. 3 ( it being impossible to obtain a fresh correction curve for each experiment ) amounted to over 60 times the final actual result ( 1 in 6 x 109 ) and in many cases to over 30 times this amount . Again , it is impossible to measure directly the temperature of the gun-metal masses , and it appears probable that these would not assume the extreme temperature of the jacket , especially in the case in which cooling by liquid air was employed , when the time allowed for cooling was rather short . * ' Koy . Soc. Proc./ September 13,1905 , p. 453 . There is evidently a misprint on line 3^of this page , which should read : Correction for temperature of case \#151 ; 0T3 division per 1 ? . Continuous Rays in Spark Spectra of , etc. 403 The vacuum between the jacket and the mass would act as an efficient nonconductor of heat . We may , however , probably conclude with considerable certainty on the combined testimony of the two series of experiments that , within the limits of temperature used , no variation of weight occurs greater than 1 part in 108 for a rise in temperature of 1 ' C. Note on the Continuous Rays observed in the Spark Spectra of Metalloids and some Metals . By W. N. Hartley , D.Sc . , F.R.S. ( Received October 17 , \#151 ; Read November 8 , 1906 . ) In a paper published in the ' Proceedings of the Royal Society , '* reasons were given for believing that the back-ground of continuous rays in the spark spectra of the metalloids , for instance , tellurium , arsenic , antimony , and bismuth , was caused by the light emitted by an incandescent oxide , whether in a state of vapour or solid , having its origin in the cooling of the dense vapour of the element in an atmosphere containing oxygen . The spectra of metals which are not oxidisable did not show it , namely , gold , silver , and platinum , neither did those of the easily volatile metals such as mercury , indium , f thallium , zinc , and cadmium . It was visible on photographed spectra of metals belonging to the iron group , but at the points of the electrodes only , where a non-volatile oxide is formed . As the original explanation has not been accepted as satisfactory ! I have recently submitted the question to a special examination . It must not be overlooked that spark spectra with continuous rays are yielded by the metals lead , tin , and cadmium , if the exposure of the photographic plate be increased to double that sufficing for the line spectra , and that sparks passing between electrodes of these metals in air deposit their oxides on all objects near to them ; in hydrogen , films of metal are deposited on the walls of the containing vessel , and when air is substituted for hydrogen there is at first a deposit of oxide , and subsequently one of * Yol . 49 , pp. 448\#151 ; 451 , 1891 . t This word is misprinted t : iridium " in the ' Proceedings . ' X See Kayser 's ' Handbuch der Spectroscopie , ' vol. '2 , p. 286 ; also P. Lenard , ' Annalen der Physik , ' 1905 , vol. 17 , pp. 208\#151 ; 212 . '

rspa_1906_0086

0950-1207

Note on the continuous rays observed in the spark spectra of metalloids and some metals.

403

405

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

W. N. Hartley, D. Sc., F. R. S.

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6.0.4

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10.1098/rspa.1906.0086

Atomic Physics

Thermodynamics

Atomic Physics

Continuous Rays in Spark Spectra of , etc. 403 The vacuum between the jacket and the mass would act as an efficient nonconductor of heat . We may , however , probably conclude with considerable certainty on the combined testimony of the two series of experiments that , within the limits of temperature used , no variation of weight occurs greater than 1 part in 108 for a rise in temperature of 1 ' C. Note on the Continuous Rays observed in the Spark Spectra of Metalloids and some Metals . By W. N. Hartley , D.Sc . , F.R.S. ( Received October 17 , \#151 ; Read November 8 , 1906 . ) In a paper published in the ' Proceedings of the Royal Society , '* reasons were given for believing that the back-ground of continuous rays in the spark spectra of the metalloids , for instance , tellurium , arsenic , antimony , and bismuth , was caused by the light emitted by an incandescent oxide , whether in a state of vapour or solid , having its origin in the cooling of the dense vapour of the element in an atmosphere containing oxygen . The spectra of metals which are not oxidisable did not show it , namely , gold , silver , and platinum , neither did those of the easily volatile metals such as mercury , indium , f thallium , zinc , and cadmium . It was visible on photographed spectra of metals belonging to the iron group , but at the points of the electrodes only , where a non-volatile oxide is formed . As the original explanation has not been accepted as satisfactory ! I have recently submitted the question to a special examination . It must not be overlooked that spark spectra with continuous rays are yielded by the metals lead , tin , and cadmium , if the exposure of the photographic plate be increased to double that sufficing for the line spectra , and that sparks passing between electrodes of these metals in air deposit their oxides on all objects near to them ; in hydrogen , films of metal are deposited on the walls of the containing vessel , and when air is substituted for hydrogen there is at first a deposit of oxide , and subsequently one of * Yol . 49 , pp. 448\#151 ; 451 , 1891 . t This word is misprinted t : iridium " in the ' Proceedings . ' X See Kayser 's ' Handbuch der Spectroscopie , ' vol. '2 , p. 286 ; also P. Lenard , ' Annalen der Physik , ' 1905 , vol. 17 , pp. 208\#151 ; 212 . ' 404 Prof. W. N. Hartley . Continuous Rays observed [ Oct. 17 , metal when the oxygen has been exhausted . In 1905 , having again sought for the most convenient source of a continuous spectrum extending as far into the ultra-violet as wave-length 2144 , the subject of the continuous rays was re-investigated by passing sparks between metallic electrodes in a closed vessel containing different gases . The conditions of the experiment , such as the size of the electrodes , the length of spark , and the period of exposure were identical for each gas and for each metal . The exposure was five minutes in a spectrograph with quartz lenses of 20 inches focus , and Cadett and Neall 's spectrum plates developed with ferrous oxalate . The spectra were taken , one below the other , on the same plate , and close together so that they could be easily compared . The results shortly are as follows:\#151 ; The emissive power of cadmium , as measured by its action on a photographic plate , stands first in hydrogen , second in nitrogen , third in air , and fourth , weak in carbon dioxide . This order applies particularly to the lines , but if we consider the continuous rays , the spectrum in hydrogen is the strongest , then those in nitrogen and air are about equal , but less strong than in hydrogen , the spectrum in carbon dioxide is very feeble . The result appears different when the electrodes are of lead . Thus the emission spectra both of lines and continuous rays are equal and very strong in hydrogen and nitrogen : they are equal , but very feeble , in carbon dioxide and air . The lines are a little stronger in nitrogen than in hydrogen , the continuous spectrum in both is strong and of equal intensity ; the lines in carbon dioxide show less intensity , and the continuous spectrum is of about half the intensity of that in the hydrogen and nitrogen ; in air the lines and the continuous rays are both enfeebled . In order to ascertain whether the metalloids give stronger spectra of continuous rays when they are exposed to the influence of hydrogen , arsenic and antimony were experimented upon . It is necessary to quote only the case of arsenic . It became of interest to ascertain whether by the action of the spark on this element in hydrogen a characteristic hydride could be obtained which would prove a delicate test for its presence . The results showed that the lines are very sharp and distinct in hydrogen while the continuous rays are feeble , but with air the lines are more feeble wThile the continuous rays are practically non-existent , or at most barely visible in any part of the spectrum . The result was similar with antimony . Ho evidence of any importance was obtained showing that the spectrum was other than that of arsenic or antimony as observed in the spectrum of air . On reviewing the facts we s ee , first , that the nature of the gas surrounding the electrodes appears to have a distinct influence on the spectra ; , that it operates somewhat differently on different metals ; thirdly , that the 1906 . ] in the Spark Spectra of Metalloids and some Metals . 405 continuous spectrum is not caused by oxidation , because in every case it is strongest when the electrodes are immersed in hydrogen or nitrogen . All the spectra are weakest in an atmosphere containing oxygen , whether free or combined , such as air or carbon dioxide , and the conclusion is inevitable that oxidation destroys or weakens the spectrum , for even in the carbon dioxide atmosphere the reversible interaction C02 ^ CO + 0 may liberate oxygen in greater quantity than that which is present in the same volume of atmospheric air . The continuous rays are clearly not due to the emissive power of any incandescent oxide , either gaseous or solid . On the Use of Metallic Electrodes as a Source of Continuous Rays.\#151 ; Particulars of trials made with various metallic electrodes were given on p. 473 of the ' Phil. Trans. , ' Part II , 1885 ( " Absorption Spectra of the Alkaloids , " ) and need not be recapitulated . E. Pauer also experimented in the same manner 12 years afterwards and arrived at the same conclusion , namely , that the continuous rays of cadmium answered the purpose better than copper , iron , or nickel electrodes.* At various times a number of flame spectra have been examined , as , for instance , those of sulphur and of phosphorus burning in oxygen , of carbon disulphide in nitrous oxide , phosphine in oxygen , ether and hydrogen with oxygen burnt from a blowpipe , also acetylene with oxygen burnt in the same manner . The inverted Welsbach incandescent gas-light used without a glass , the zirconia , magnesia , and lime lights have all been tried . Of the flame spectra the best effect is obtained with acetylene and oxygen , the rays are quite continuous and of equal intensity from the red to beyond wavelength 2700 . There are some difficulties attending manipulation with flames , particularly on account of their great heating effect , and I have therefore returned to the use of the cadmium spark spectrum for special observations on the spectra of hydrocarbon vapours , with results that I propose to make the subject of another communication . * ' Wiedemann 's Ann. , ' 1897 , vol. 61 , p. 363 . VOL. LXXVIII.\#151 ; A.

rspa_1906_0087

0950-1207

The refractive indices of water and of sea-water

406

409

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

J. W. Gifford|W. A. Shenstone, F. R. S.

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6.0.4

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10.1098/rspa.1906.0087

Tables

Thermodynamics

Tables

406 The Refractive Indices of Water and of Sea-water . By J. W. Giffokd . ( Communicated by W. A. Shenstone , F.R.S. Received May 9 , \#151 ; Read June 28 , 1906 . ) 1 . Method of Observation.\#151 ; Measurements of the refractive indices of water have been made by Fraunhofer , Gladstone , Yan der Willigen , Dufet , Pulfrich , and many others . Those now offered were made by the new method previously described.* 2 . Instruments.\#151 ; In addition to the instrument used for measuring the refractive indices of fluorite quartz and calcite , *f* a larger goniometer has been employed , especially for determining the temperature-refraction coefficients and for the critical part of the work generally . This instrument has quartz objectives of 3 inches diameter and 27'5 inches focal length , and quartz-calcite objectives of 2*375 inches diameter and the same focal length , and it has a divided circle of 18 inches diameter . There are two micrometers with reading microscopes , one on each side of the circle . These micrometers are similar to that of the smaller goniometer before described , ! and readings were taken in the same way . The hollow prism ( by Hilger ) used to contain the water has a clear aperture 1*675 inches by 2*375 inches , and is entirely of quartz . It can be used on either instrument ( see Appendix ) . 3 . Temperature.\#151 ; A standard thermometer , interchangeable with the stopper , was kept with its bulb in the water during each measurement and , subject to the precautions for maintaining an approximate temperature of 15 ' C. before described , ! readings were taken at the commencement and at the close of each measurement , and the mean taken . In no case did the variation between these exceed 1 ' C. By means of the temperature-refraction coefficients , which were found in both cases for three wave-lengths , the coefficients for the other wave-lengths were interpolated , and all the indices in the table corrected for a mean temperature of 15 ' C. 4 . Material.\#151 ; I am indebted to the kindness of Mr. W. R. Bousfield for the special examples of distilled water used . That for the experimental work on the variation of index due to impurities was supplied in a platinum bottle , that for the remainder of the work in a large bottle of special green glass , but little soluble . One cubic centimetre of this latter evaporated in a polished silver dish left a slight residue which was shown by subsequent experiment to have little effect on the index . For the specimen of sea-water * ' Roy . Soc. Proc. , ' Feb. 13 , 1902 . t Loc . cit. The Refractive Indices of and of Sea-water . 407 I am indebted to Lieutenant E. E. G. Evans , R.N. , who took it in blue water , 5 miles south of the Royal Sovereign Lighthouse ( off the coast at Eastbourne ) . It was surface water and was collected in another large glass bottle of the same kind . 5 . Standard W\lt ; ave-lengths.\#151 ; Rowland 's have again been adopted whenever possible . 6 . Measure of Error.\#151 ; This is the same as already described.* The approximate estimate made from group deviations is as follows:\#151 ; Water.\#151 ; There are 26 measurements in the table , in 5 of which a = less than S " corresponding value of index = 0-0000025 11 IF J5 = 0-0000050 8 J ) = 5 ) 2f " 5 ? V = 0-0000098 1 " = more than 2"-861 55 = 0-0000098 1 " = as much as H " n = 0-0000202 Sea-water.\#151 ; There are 12 measurements in the table , in 5 of which a = less than S " corresponding value of index = 0-0000025 5 " = " H " " " = 0-0000050 1 " = " 2S " " " = 0-0000098 1 " = as much as 2"-688 " " = 0*0000103 Owing to the additional difficulties , especially with sea-water , the accuracy is not so great as with solid bodies ; but these indices may be taken as correct to the fourth decimal place , and it is believed that in all cases the error does not exceed 0-000025 , and in most is not more than 0 000015 . Appendix.\#151 ; Special experimental work . In order to determine the disturbing effect due to the double refraction of the quartz plates forming the sides of the hollow prism , at the suggestion of Dr. Glazebrook a complete measurement was made on the large goniometer , and then , each plate having been rotated through 180 ' in its own plane , another complete measurement of index for the same wave-length ( line E ) was made . The results , reduced to 15 ' C. , were as follows:\#151 ; Plates normal . Plates rotated through 180 ' . 1-3356125 1-3356185 Want of parallelism in the faces of the plates was tested for by registering the position of the image of the slit ( collimator and telescope being in line ) without a prism , and then interposing the empty prism in its normal position and noting the effect . The difference of position of the image was not measurable . To determine the extent and influence of impurities in solution , a specimen * Loc . cit. 2 e 2 Mr. J. W. Gifford . Refractive [ May 9 , of ordinary distilled water , kept in an ordinary glass bottle , a cubic centimetre of which gave considerable deposit on evaporation , was measured . Mean result , reduced to 15 ' C. = 1'3355798 . Table of Refractive Indices at 15 ' C. Wave-length . Water . Sea-water . 7950 *0 Rb 1*32855 7682*45 Ka(A ' ) 1*329183 1*335652 7065 *59 He(B ' ) 1 *330443 1*33689 6563 *04 Ha(C ) 1 *331562 1*338062 5893 *17 Na(T ) ) 1 *333433 1*339959 5607 -1 Pb(A ) 1*334289* 1*340938 5270 *11 Ee(E ) 1*335643 1*342298 4861 *49 H/ jfP ) 1 *337501 1*344260 4678 *35 Cd 1*338515 1*345315 4340*66 Hy(Gf ' ) 1*340723 1*34763 3961 *68 Al 1*343959 1 *3509281* 3610*66 Cd 1*347915 3302*85 Zn 1*352699 3034*21 Sn 1*358337 2748 *68 Cd 1*36675 1*37494 2573 *12 " 1*37390 2445 *86 A g ' 1*380979 2312*95 Cd 1*389262 2265 *13 " 1 *39309 1*402880 2194 *4 " 1*39937 Absorption begins 2144 *45 " 1*40455 Absorption 2098 *8 Zn 1*409702 5 J 2062 *0 " 1*414543 5 ) 2024 *2 " 1*41996 J\gt ; 1988 *1 Al 1*425663 ) ) 1933 *5 " 1*4361 5\gt ; 1852 *2 " Absorption 53 Note.\#151 ; The number of figures in each index indicates the estimated freedom from errors of observation . The following interpolated indices are in all probability more correct for those referred to* 1 *334294 + 1 *35094 . A specimen of the special distilled water referred to ; kept in a platinum bottle and prepared in platinum vessels , 1 c.c. of which , when evaporated in the silver dish , left a just perceptible residue , was then measured\#151 ; Result , reduced to 15 ' C. = 1-3356359.* This specimen was then boiled and measured again\#151 ; Result , reduced to 15 ' C. = 1-3356338 . * There is a difference of reading for line E , resulting in 0*0000076 in the index between the two goniometers used , which it was difficult to account for . On testing the division of the two circles by readings from various zero points , I find that the large one stands the test almost up to the unit in the sixth place of decimals in the value of the index , while the smaller just begins to show discrepancy at five places : thus it is the smaller circle that is in fault . The experimental measurements here given were made on the large goniometer , but , for the sake of uniformity with previous measurements of index , Indices of Water and Sea-water . lft06 . ] Finally , the same specimen was frequently agitated with air while standing for a week , and three measurements were then made\#151 ; Mean reduced to 15 ' C. = D3355777 . During the measurements of sea-water the prism was emptied and refilled for every complete measurement to prevent errors due to rise of density from evaporation and to the displacement of the sides by salt crystals . Temperature Eefraction Coefficients . Wave-length . Water . 1 Sea-water . 1 5893 ( D ) -0-0000801 -0-0000785 2748 \#151 ; -0 -0000747 2265 \#151 ; ( -0 -0000758 ) 2145 -0 -0000724 1988 -0-0000687 all those given in the table have been made on the smaller instrument . But they agree well with other observers . The index for the mean D line in the table is 1'333433 . This , brought to its value at 20 ' C. by use of the temperature coefficient , becomes 1'333032 . Dufet ( 'Recueil de Donn6es Numeriques,5 vol. 1 , p. 83 ) gives the mean value of the measurements of this line at 20 ' C. by 29 observers as 1'33303 .

rspa_1906_0088

0950-1207

On a compensated micro-manometer.

410

412

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Bertrand J. P. Roberts|Sir John I. Thornycroft, F. R. S.

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6.0.4

http://dx.doi.org/10.1098/rspa.1906.0088

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10.1098/rspa.1906.0088

Thermodynamics

Fluid Dynamics

Thermodynamics

410 On a Compensated Micro-manometer . By Bertrand J. P. Roberts . ( Communicated by Sir John I. Thornycroft , F.R.S. Received August 14 , \#151 ; Read November 8 , 1906 . ) The accompanying sketch shows a form of fluid-pressure gauge or micromanometer , intended for use as an anemometer and for the indication and measurement of small pressures.* To source erf pre\amp ; our difference . / C. index bubble Ratio : approximately 10 : 1 diameter of bores . A design for a sensitive pressure gauge , or micro-manometer . Anti-evaporative attachment for use with volatile fluids ; one should be connected in series with each side of the gauge\#151 ; only one shown . A Woulff 's bottle with three necks would be a convenient substitute . Cal . chlor . tube should be used also in case of hygroscopic fluid in gauge . The two limbs A and A ' of a U-tube are connected by a tube of finer bore B , and this tube B contains an index bubble\#151 ; preferably of air , C , the bends at E form a trap , to prevent the accidental loss of the bubble . The small separate part is an arrangement for preventing loss by evaporation in the case of volatile fluids\#151 ; it does not need description . The sensitiveness of the gauge obviously depends on the ratio between the bores of the limbs and the connecting tube\#151 ; this is approximately 10 : 1 in the example shown ; also to some extent on the fluid employed in the gauge , and the fluid used should depend on the intended application and on the degree of sensitiveness desired . * The feature in which this arrangement differs from Sir W. Siemens ' bathymeter is the compensation . On a Compensated Micro-manometer . The length of the index bubble C should be approximately equal to the distance between the centres of the limbs A , A ' ; it will then be found that the gauge is practically indifferent to changes of position or level , as the effect of the air bubble ( while in the lower horizontal tube ) will counteract the effect due to any change of level of the limbs A and A ' ; it is , of course , not possible to exactly compensate for this , as the length of the bubble will vary slightly with the temperature and the barometric pressure . Any tendency to error in the readings from these two last-mentioned causes can be obviated by observing both ends of the index bubble : but , as it is not necessary to read very minutely , owing to the multiplying effect , this source of error can generally be neglected . It is not advisable to employ a larger bore for the tube B than 2 mm. , and 1^ mm. is preferable , as the surface tension is insufficient ( with most fluids ) to prevent fluid from passing the air bubble in larger bores ; the limit to the smallness of the bore depends on the viscosity of the fluid and the rapidity of readings desired . For the same reasons it is not practicable to use pure water as the working fluid , as owing to its high surface tension the zero point is very indefinite ; water can be used , however , if some substance , such as glycerine or calcium chloride , is added to lower the surface tension . The writer cannot say definitely what is the limit of sensitiveness that can be reached\#151 ; this depends on the resistance offered by the surface tension and viscosity of the fluid to the motion of the index bubble\#151 ; making its movements very slow , so that in returning to zero it may take five minutes or more , with a very sensitive form\#151 ; using alcohol . To reduce this effect as much as possible it is necessary to use either alcohol or ether ( and perhaps pentane ) for the most delicate results . The air bubble acts practically as a piston , and no fluid can be seen to pass it at a normal rate of movement , but fluid can be caused to pass in a thin film if the bubble is forced to move rapidly . There seems to be a critical speed\#151 ; for each size of bore and fluid\#151 ; above which the surface tension is unable to overcome the adhesion of the fluid , to the walls of the tube , quickly enough . In connection with this I have noticed an interesting effect\#151 ; showing well the rapidity of the motion of fluid in the centre of tubes , and the almost stationary condition of the layer next the sides . If a small bore\#151 ; say 2 mm.\#151 ; tube , similar to the gauge described above , and containing an air bubble , filled with uncoloured alcohol , be taken , and some coloured alcohol is added to one limb , then the air bubble moves at the average velocity of the fluid , but the coloured alcohol entering the tube will 412 Dr. Orme Masson and Mr. E. S. Richards . [ June 25 , be seen to be drawn , or rather pushed , out in a long conical point , moving much more rapidly than the bubble , and eventually overtaking it and turning over ; the fluid at the sides will be still quite uncoloured until mixed by diffusion ; to a certain extent the effect is reversible , and the cone of coloured alcohol can be drawn back without mixing very much . The device shown for preventing evaporation should be in duplicate , one to each limb ; only one is shown , as an example . On the Hygroscopic Action of Cotton . By Orme Masson , D.Sc . , E.R.S. , and E. S. Richards , B.Sc. ( Received June 25 , \#151 ; Read June 28 , 1906 . ) In an earlier paper by one of us* an account was given of the behaviour of dry cotton-wool when immersed in air saturated with water vapour , and the relation between the hygroscopic absorption and the change of temperature which the cotton manifests was investigated . It was shown that , so long as the surrounding air is saturated , the absorption process appears to be unending , though its velocity continuously diminishes ; or , in other words , true equilibrium between such an atmosphere and cotton wool , however moist , appears to be impossible , just as it would be impossible between the same atmosphere and an aqueous solution , however dilute . It was pointed out , however , that " if placed in an atmosphere containing water vapour at anything less than saturation pressure ( e.g. , in the open air ) the cotton would in time reach a state of equilibrium , either by absorption or by evaporation , according to its initial condition . " As we could find no record of any complete investigation of such relationship , it seemed desirable to determine the amounts of vapour absorbed by a given quantity of cotton in atmospheres of various known degrees of humidity . This has been done ; but it has been found necessary to determine the true equilibrium values by approaching them from both sides , by absorption and by evaporation , since neither process becomes really complete in any practicable time , though each leads in a few hours to what might be mistaken for true equilibrium . Reference must here be made to the interesting work published by Clayton Beadle , in 1894 and 1895 , f which was unfortunately entirely * ' Roy . Soc. Proc. , ' vol. 74 , pp. 230\#151 ; 254 . + 'Nature , ' vol. 49 , p. 457 ; 'Chem . News , ' vol. 71 , p. 1 ; vol. 73 , p. 180 .

rspa_1906_0089

0950-1207

On the hygroscopic action of cotton.

412

429

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Orme Masson, D. Sc., F. R. S.|E. S. Richards, B. Sc.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1906.0089

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1906_0089

10.1098/rspa.1906.0089

Thermodynamics

Tables

Thermodynamics

]\gt ; 412 Dr. Orme Masson and Mr. . S. Richards . [ June 25 , be seen to be drawn , or rather pushed , out in a long conical point , moving much more rapidly than the bubble , and eventually overtaking it and turning over ; the fluid at the sides will be still quite uncoloured until mixed by diffusion ; to a ce , ltain extent the effect is reversible , and the cone of coloured alcohol can be drawn back without mixing very much . The device shown for preventing evaporation should be in duplicate , one to each limb ; only one is shown , as an example . On the Hygroscopic Actio of Cotton . By ORME MASSON , D.Sc . , F.R. , and E. S. RICHARDS , B.Sc. June Read June In an earlier paper by one of an account was given of the behaviour of dry cotton-wool when immersed in saturated with water vapour , and the relation between the hygroscol ) absorption and the change of temperatul.e which the cotton manifests was investigated . It was shown that , so long as the surrounding air is saturated , the absorption process appears to be , though its velocity continuously diminishes ; or , in other words , true equilibrium between such an atmosphere and cotton wool , however moist , appears to be impossible , just as it would be impossible between the same atmosphere and an aqueous solution , however dilute . It was pointed out , however , thal " " if placed in an atmosphere containing water vapour at anything less than saturation pressure ( e.g. , in the open air ) the cotton would in time reach a state of equilibrium , either by absorption or by evaporation , according to its initial condition As we could find no record of any complete invesbigation of such relationship , it seemed desirable to determine the amounts of vapour absorbed by a given quantity of cotton in atmospheres of various known degrees of humidity . This has been done ; bub it has been found necessary to determine the true equilibrium values by approaching them from both sides , by absorption and by evaporation , since neither process becomes really complete in any practicable time , though each leads in a few hours to what might be mistaken for true equilibrium . Reference must here be made to the interesting work published by Clayton Beadle , in 1894 and which was unfortunately entirely 'Roy . Soc. Proc vol. 74 , pp. 230\mdash ; 254 . ' Nature , ' vol. 49 , p. 457 ; 'Chem . News , ' vol. 71 , p. 1 ; ibid. , vol. 73 , p. 180 . 1906 . ] On the H.ygroscopic Action of Cotton . overlooked by Masson his attention was called to it after publication of the paper already referred to . endle seems to have been the first to observe the striking elevation of temperature that dry cotton undergoes when exposed to damp air and to study the ress of absorption and the course of the temperature change . He , , did not atmospheres of constant and known humidity and temperature , but used the open air of the laboratory , so that his curves are affected by considerable ularities . Apart from these , his results arc in general character similar to those we have since obtained . The experimental method employed by us in this was similar to that already described by one of us . * The Vool e was the purified material sold as " " absorbent\ldquo ; and was wash several times with boiling distilled water before used . A suitable quantity , after was wound round the bulb of a thermometer , which with a ubber stopper that closed a jacket-tube in lvhich it could be By means of this stopper the thermometer could also be inserted into a tube in the cover of a desiccator phosphorus . It was proved that 24 hours ' exposure in this desiccator sufficed to bring the cotton to a constant weight , and this method of drying was adopted hout in preference to the heating method previously used , as it was suspected that frequent heating to above cause some alteration in the condition of the cotton . The atmospherc of known humidity obtained in the following way . A glass jar of about 1500 . capacity was provided with a plate-glass cover , ground and lubricated to fit accurately , and a short wide tube was cemented vertically through a central in covel A cylindrical porous pot of nearly 500 ) acity ( cleaned 1 ) previous extractions with acid ) was fixed by rubbel } ) inside the so as to leave a clear space around and below it . The porous pot were filled with sulphuric acid solution of known , covered , and placed in a thermostat of such depth that only the top of the tube in the cover showed above the water level . The jar was rhted with lead so as to keep it steady when submerged , and the water of the thermostat had free circulation all round and underneath it . Before an experiment the porous pot was emptied by a siphon operating through the central tnbe , hich then served for the admission of the cotton-covered tbermometer and also a duplicate instrument without cotton , which vays treated simultaneously and served as a counterpoise in hing . These were suspended from fixed and could be read accurately to at least a twentieth of a degree by means of a telescope with microlneter scale . Dr. Orme Masson and Mr. E. S. Richards . [ June The interior of the porous pot was kept constant as to humidity by evaporation from its walls , through which filtration of acid occurred , but this infiltration was slow enough to allow of the thermometer hanging for more than 24 hours without risk of the liquid reaching the cotton-wool . The exact strength of the acid in each experiment was determined by taking the density of the sample pipetted from the Pot , the percentage strength being then read from a curve drawn from Pickering 's values for the same temperature . * This being known , the corresponding vapour pressure was read from a curve drawn with percentage of as abscissae and relative vapour pressure ( that of water at the same temperature taken as unity ) as ordinates . were used in constructing this curve , and they were supplemented by the very concordant values obtained by a different method by Helmholtz . a curve , drawn for C. , is practically correct also for all es , as the relative vapour pressure of a given acid solution is almost constant . Two sets of apparatus were kept in alternate use so that each porous pot could soak for several days in a new acid solution before tests were made with it . A third apparatus was reserved distilled water so as to provide a saturated atmosphel.e when required . The huric acid employed ? making up the solutions was subjected to a preliminary treatnlent for complete removal of oxides of nitrogen . Unless this is done , the cotton is to some extent alfected by exposure over the higher of acid ; it tends to become brittle and its hygroscopic power is sensibly diminished . For convenience , our results are discussed in the sequel under six heads . 1 . The Iation of Conditions for Jquilr.\mdash ; In order to ascertain the of absorbed moisture which puts a of cotton into true equilibrium with an of given humidity , it is not sufficient to expose the dry cotton to the action of that atmosphere till its weight becomes apparently constant , for the rate of absorption , which rapidly diminishes , becomes almost inappreciable , while the absorption itself is certainly incomplete . This is ploved by supersaturating the cotton by previous exposure over water or a more dilute acid and then immersing it in the original atmosphere . It now loses moisture by evaporation till it once more attains an apparently constant weight ; but this is considerably greater than that previously reached by absorption . The thermometer on which the cotton is wound serves the useful purpose of the 'Chem . Soc. Trans vol. 57 , pp. 152\mdash ; 156 . Quoted in ' Carnelley 's Tables , ' vol. 1 ] , p. 750 . 'Wied . Ann. , , p. 508 . On the Hygroscopic Action of Cotton . progress of either change ; for the absorption test it rises rapidly for a few minutes and then falls with diminishing velocity towards the temperature of the thermostat as previously described this process is reversed during the evaporation test when the thermometer falls quickly to a minimum and then rises with diminishing velocity towards the temperature of the environment . In order to render these indications accurate , it is necessary to suspend the thermometer protected by its jackettube in the apparatus for an ] ) or two before the test is begun , so that it may have the same temperature as the thermostat at the moment of exposure . The ures given in Table I and the corresponding curves ( fig. 1 ) illustrate the chal.acteristic behaviour of dry cotton and of supersaturated cotton . The acid used in these tests contained per cent. of to a relabive vapour pressure of . The acid strength was proved to remain constant throughout the series . Each point in the absorption and evaporation curves was obtained by an independent meant . The excess moisture required for each evaporation test was by exposure over water , the time necessary for imparting a definite quantity of moisture being read off from a curve drawn from previous nents to show the course of absorption in a saturated atmosphere . It is possible in this way to predetermine the imparted moisture accurately to within Table of cotton exposed oyer acid of 40 per cent. . Bath at C. . Mean value of absorption and evaporation results . cit. 416 Dr. Orme Masson and Mr. E. S. Richards . [ June 25 , about a milligramme . The quantity here used was rather less than double that indicated for true equilibrium , viz. , 114 instead of 118 milligrammes . As is seen the results , this true equilibrium value must lie . somewhere between the apparent limits of absorption and evaporation , and their arithmetic mean may be taken as sufficiently correct . The time allowed for absorption or tion in any particular case has depended on the strength of the acid , and has varied from four hours in the driest to 24 in the most humid atmospheres employed , experience showing that longer exposure within practicable limits would not appreciaffect the results . As a rule , the initial moisture imparted before an evapol'ation test was about double that required for equilibrium ; but an deviation from this rule produces no sensible difference in the final result , as it merely hastens or retards the initial evaporation and is thus in measure self-compensating . To avoid circumlocution , the following symbols are used in the sequel:\mdash ; is the weight of dry cotton employed . is temperature of the apparatus . 1906 . ] the Hygroscopic Action of Cotton . is the actual pressure of water-vapour in the atmosphere employed . is the saturation pressure of water-vapour at the same temperature . is the of moisture absorbed by the sample of dry cotton of weight after exposure in the apparatus till further absorption appears ible . is the weight of moisture retained by the same sample after it has been supersaturated by exposure over water and then allowed to evaporate in the apparatus till further loss appears negligible . is the arithmetic mean of and , and is taken as indicating the amount of absorbed moisture which is required to establish true equilibrium . 2 . The Influence of mperaturo.\mdash ; The values obtained with a given sample of cotton depend on the strength of sulphuric acid over which it is . exposed , but not upon the temperature . In other words , they depend upon the relative vapour pressure ( the saturation pressure of water-vapour taken as unity ) , and not on the absolute vapour pressure of the enveloping- atmosphere , for the relative vapour tension of any given sulphuric acid solution is practically independent of the temperature . It seems , therefore , that cotton containing a definite proportion of moisture resembles an aqueous solution in that it also follows Babo 's law , i.e. , exercises a vapour tension which is at different temperatures a constant fraction of that of pure water . The following tests ( Table II ) illustrate this . They were all made with the same sample of cotton . It was subsequently shown to ] lave been somewhat altered by previous exposure over impure sulphuric acid , and was Table II . ( 1 ) Acid of density at per cent. ( 2 ) Acid of density at per cent. Dr. Orme Masson and Mr. E. S. Richards . [ June 25 , } ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. ( 3 ) Acid of density at per cent. therefore , not used in further work , but this does not affect the conclusions drawn here . The values of are given in milligrammes and those of in millimetres of mercury . 3 . If quantities of the same of cotton be employed , the weight of moisture required to establish equilibrium with an atmosphere of given humidity is in constant atio to the weight of the cotton . In the following tests not only the weights of cotton-wool were varied , but also the mode of wrapping it , some samples being wound tightly and others more loosely round the supporting ometer . This makes no sensible difference in the final value , though , of course , it may to some extent influence the velocity of absorption or evaporation by ecting the freedom of access of . moist air to the surface of the fibres . Table III.\mdash ; Acid of density at C. ; per cent. of ; in rammes . These results , taken in conjunction with those iven in the last section , suffice to show that , for a given quality of cotton wool , the value of depends only on that of 4 . The Influence of Surface.\mdash ; It is obvious that the weights of different samples of the same cotton wool , having the same average dimensions of fibre , are proportional to the extents of surface exposed to the hygroscopic action , and so that the constancy of the ratio in their case gives no proof that is really a function of the mass of cellulose rather than of its surface . It may , of course , be both . To test this question properly it is desirable to employ cellulose preparations having various known ratios of surface to mass . This is , however , not very easily done . The individual 1906 . ] On the Hygroscopic Action of Cotton . fibres in any given bundle of cotton vary confiiderably , and only a very laborious microscopic examination could give a reliable estimate of the average dimensions . Moreover , for a fair comparison , all the samples would require similar previous treatment in order to obviate not only errors due to residual impurity , but also such unequal alterations of the cellulose molecule itself as are at least possible in the case of so complex a substance . For this reason , experiments with amorphous cellulose , obtained by one of the solution methods , might give results not fairly comparable with those from cotton fibre , even if all ordinary impurities were eliminated . Such experiments , if carried out with all precautions , might , , afford information of value and help to settle the question of whether the surface film of moisture does , as gested by one of u diffuse osmotically into the substance of the cellulose and form with it a solid solution . A few tests already made with pure filter paper may be cited . The used was Schleicher and Schull 's ash-free , No. 589 . Three papers of 7 cm . diameter were wrapped tightly round the bulb of a thermometer and secured with a few turns of cotton thread , and then well washed and dried before use . The dry weight of paper ( and thread ) was gramme . The values were determined over three different of acid , and may be compared with the values for cotton wool , which lave been read from the curve shown in fig. 2 . It will be seen that they somewhat , weight for weight , in the case of the filter paper , but that the difference is not great . Table \mdash ; Tests with Filter Paper . ramme ; bath at C. 5 . The relation betwe ( tloe content and the of any given preparation of pure cotton may be shown by a cnrve , as abscissae and as ordinates . The experimental llethod employed is applicable over a large range , but becomes when ) exceeds about , since there is in practice a limit to the that can be given Dr. Orme Masson and Mr. E. S. Richards . [ June for absorption or evaporation over acid or for supersaturation over water a preliminary to the evaporation test . It is , however , obvious that the method must in any case be inapplicable to that value of ( if there be one ) which corresponds to the full saturation pressure , for exposure over water for any length of time would , at the best , only , which is less than , and it would be impossible to supersaturate the cotton and then determine the value by evaporation over water . These considerations support our previous contention that no true equilibrium is possible between cotton , however moist , and saturated aqueous vapour . In other words , the approach of the curve in fig. 2 to the saturation pressure is probably asymptotic . In this connection it is instructive to contrast the timeabsorption curve in an unsaturated atmosphere ( fig. 1 ) with that showing a 12-hours ' absorption over water.* The first series of experime1lts made for the purpose of testing the variation of with was spoilt by the use of insufficiently purified sulphuric acid , for it was found that the cotton had become brittle and so altered in the course of the work that points re-determined did not fall on the curve . A better result was obtained in the series given below . Here lo different strengths of specially purified were used in the order indicated in the table , and the fact that the first two points determined lie practically on the curve formed by joining the later ones is sufficient guarantee that no appreciable change in the hygroscopic power of the cotton Table Hygroscopic Tests with gramme of Pure Cotton over Sulphuric Acid tions ( at Acidemployed . * See ' Roy . Soc. Proc vol. 74 , p. 244 . On the Hygroscopic of occurred in the course of the work . The general form of the curve was quite similar in the first series , though the exact values were not trustworthy . It is obvious that such a curve indicates the relative water-vapour tensions of cotton of different degrees of moistness . The numbers in the fourth and eighth columns of this table have been used in plotting the curve shown in fig. 2 . Clmt . 6 . A New Method of initial velocity with which any given sample of dry cotton wool absorbs moisture at the moment of its exposure must depend on the pressure of water-vapour in the atmosphere to which it is exposed and on conditions of surface , etc. , which are constant for that particular sample . Now it has already been shown by one of us that the heat production is always proportional to the amount of hygroscopic absorption ; and as , at the first moment of exposule , when the cotton is dry and at the same temperature as its environment , the heat produced may be regarded as entirely consumed in raising the temperature of the cotton , it follows that the initial rate of that rise is directly to the VOL. LXXVIII.\mdash ; A. 2 Dr. Orme Masson and Mr. . S. Richards . [ June 25 , pressure of vapour . Adopting the same notation as in the paper , time since exposure of the dry cotton , difference of temperature between the cotton and its environment , weight of moisture absorbed , pressure of water-vapour in the atmosphere surrounding the cotton , we llay express above conclusions briefly thus : Now it was shown*that the whole temperature curve , in the case of immersion of dry cotton in saturated vapour , is expressed with very fair accuracy by the equation where is the maximum value attained by , and is the corresponding value of . Later results confirm this , and it follows that at any moment ( t ) ; and therefore that If this equation holds also for cases of immersion in unsaturated watervapour , we arrive at the conclusion that should be proportional to , or that , where is a constant for the particular sample of cotton , or rather for the instrument , which consists of the thermometer and its cotton covering This conclusion is fairly justified by the following observations . The first set was designed to test the constancy of when the air in the apparatus was saturated with water-vapour at different temperatures . The results are shown in the following table for temperatures between and C. Above . appeared to diminish ; but considerable error is probably caused when there is a difference between the temperature of the thermostat and that of the outer air , especially as a short exposure of the thermometer to the latter is unavoidable when it is being withdrawn from its jacket-tube before immersion . The next series of tests was made with a different thermometer and covering of cotton wool . Elevell tests in air saturated with water-vapour at gave for this instrument a mean value of 0140 , the extremes 1906 . ] On the Hygroscopic Action of Cotton . Table \mdash ; Dry Cotton-covered Thermometer exposed over Water at various Temperatures . and . The same instrument was used for the determination of the values already quoted in Table , and simultaneous determinations of the and values were made during the exposures over the sulphuric acid solutions used for that purpose . In the case of the three acids , atmospheres less han one-fifth saturated , the errors due to the unavoidable exposure of the instrument to the outer air at ] start and to other causes bulk too largely for any reliance to be placed on the results , but in 11 tests with more dilute acids is seen to have a mean value of with extreme values of and , and is thus not far from constant and equal to its value in saturated air . These results are shown in the table :\mdash ; Table \mdash ; Dry Cotton-covered Thermometer ( ' ' exposed over Water and Sulphuric Acid Solutions at C. mercury)minutes ) 424 Dr. Orme Masson and Mr. E. S. Richards . [ June 25 , 424 Dr. Orme Masson and Mr. E. S. Richards . [ June 25 , The figures in the last horizontal line are the means of those obtained from 11 determinations by exposure over water . A third series of tests was made with the same instrument in order to ascertain whether the value of is different when the dry cotton is exposed in the open air from that already found by exposing it over water or sulphuric acid solutions the experimental apparatus . For this purpose observations were made on 10 consecutive days ( December , 1905 ) by exposing " " \ldquo ; to the air of the laboratory and simultaneous readings of wet and dry bulb thermometers , which were interpreted by Apjohn 's formula so as to give the pressure of aqueous vapour . All readings were made by telescope so as to ayoid errors which arise from proximity of the observer , and the necessary corrections vere applied after comparison of the thermometers with a standard one . The results are shown in the following table:\mdash ; Table VIII . Cotton-covered Thermometer exposed to the Air of the Laboratory with Simultaneous Wet and Dry Bulb Hygrometry . From these tests it is seen that varies between and , with a mean value of , which agrees well with the mean values obtained by exposure over water and over varying strengths of sulphuric acid in the porous pot of the experimental apparatus . It follows that such an instrument supplies us with a method of hygrometry which is fairly accurate and easy to use . The method may be worked in the following marmer . A suitable thermometer is passed through the bore of a rubber cork , which is fixed in a convenient position on the stem . About a gramme of cotton wool is then wound round the bulb and secured by a few tur11s of cotton thread . Filter paper may be used instead of cotton wool , and is perhaps more convenient , being less bulky . desiccator is conveniently constructed by placing a quantity of phosphorus 1906 . ] On the Hygroscopic Action of Cotton . pentoxide at the bottom of a large wide-mouthed bottle , closed by a rubber stopper through which passes a short glass tube wide enough to admit the thermometer and be closed by its rubber cork . With this arrangement there is no risk of the cotton wool into contact with pentoxide . The instrument is always kept in the desiccator except when in actual use , and if observations are taken once in 24 hours the interval is sufficient to ensure dryness . When an observation is to be made , the ermometer is read through a telescope . It is then removed from the desiccator and hung near it , a stop-watch started at the moment of exposure . The rise of temperature is noted and , as this slows down , a few readings of time and temperature are made al short intervals ; and these are repeated as the same temperatures are passed during cooling from the maximum . Two or three points in the neighbourhood of this maximum are sufficient . The thermometer is then replaced in the desiccator , which is left in position for the next observation . The difference between initial and maximum temperatures gives . The corresponding time , which cannot be directly observed with sufficient accuracy , is calculated by the rule involved in the equation for the curve , already discussed , that , where and are the two observed times at which the same } ) ature ( near to ) is passed . The following example will illustrate the method:\mdash ; Hence and ( mean value ) . In order to find the pressure of aqueous vapour in the atmosphere from uch observations , the value of in the equation must be once for all determined for the particular instrument employed , and this may be done with sufficient accuracy by taking the average result of a few exposures in atmospheres with values of \mdash ; say over water at known temperatures . It is not claimed that this method of hygrometry is to be preferred to the usual wet and dry bulb method for ordinary purposes , but it may prove useful in special cases . Dr. Orme Masson and Mr. E. S. Richards . [ June of Results . 1 . quantity of hygroscopic moisture required by a given quantity of cotton to put it in true equilibrium with an atmosphere of given humidity , below the saturation value , can be ascertained by taking the mean of the apparent equilibrium values reached by absorption ( cotton initially dry ) and evaporation ( initially over-moist ) . The progress of either change can be followed by observing the characteristic temperature curve given by a thermometer the bulb of which is coyered by the cotton . 2 . The vapour tension of any sample of cotton containing a definite quantity of moisture is at different temperatures ( at least within ordinary atmospheric range ) the same fraction of that of water . The law here is similar to that familiar ( Babo 's ) in the case of aqueous solutions . 3 . Different of the same cotton have the same vapour tension when they contain the same percentage weights of hygroscopic moisture . The results are not influenced by tight or loose packing . 4 . Filter paper gives results very similar to those obtained with cotton wool ; i.e. , the same vapour tension corresponds to but slightly different percentage weights of hygroscopic moisture . 5 . The vapour-tension curve of moist cotton wool , in which the relative vapour tension ( thaL of water taken as unity ) is plotted against percentage weight of roscopic moisture , has been determined from to P. Its approach to is probably asymptotic . 6 . A new method of hygrometry has been tested , and is described , which is based upon the observations of the rate of rise of temperature of cotton when first exposed to moist air . Postscript.\mdash ; Since the aforegoing paper was written , we have received the last number of the ' Proceedings of ths Society ' ( No. A 517 ) containing a paper by Professor Trouton and Miss Pool on ' The Vapour Pressure in Equilibrium with Substances holding Varying Amounffi of Moisture which was read at the Society on January 25 . As the questions dealt with in the two papers are essentially the same , though the methods employed are different , we may be allowed to state that our experimental work ( except the few tests with filter paper recorded in Table ) was done during 1905 in Melbourne , and in norance o the fact that Professor Trouton was similarly engaged . Trouton 's method differs from ours in that he seeks to ascertain the vapour pressure corresponding to a predetermined quantity of moisture , while we have sought to ascertain the amount of hygroscopic moisture which balances 1906 . ] On the oscopi Action of Cotton . a predetermined vapour pressure . Trouton and Pool have used flannel , which is not a pure material , but in a footnote state that cotton wool has given similar results . Perhaps the most of their results is the meant of the law which been discussed in the second section of this paper , viz. :\mdash ; that the ratio of the vapour tension of a hygroscopically moist substance to that of water is independent of the temperature , and of this they give much fuller evidence than we have adduced . In another respect the results obtained by the two methods are in agreement , , as to the form of the lower part of the curve for vapour tension and weight of moisture , where a characteristic change of curvature is exhibited . Trouton , however , finds that a parabolic formula fits the upper portion of his pointing to the attainment of the full vapour tension of water itself by material containing only a limited amount of moisture , while our values cannot be so expressed and we incline to doubt the possibility of any such true equilibrium with saturated water-vapour . No exact quantitative is possible between Trouton and Pool 's values and ours because , though they give the weight of the flannel in grammes , they state the quantities of added water in terms of an albitray unit , , the contents of a capillary tube the dimensions of which are not given . This is all the more that their paper opens with the statement that " " the knowledge of the quantity of water held under varying circumstances by substances of an absorbent character , such as cotton or woollen material , in an atmosphere of any given humidity , is not only of importance in hygrometry , but is also of general interest in connection with the processes used in drying such materials . No investigations , , of this subject seem , up to the present , to have been ever published Surely such ations , when made , lose much of their value when the results are given in terms of units that cannot be interconnected . Perusal of the paper , however , suggests the probable explanation , viz. , that Trouton believes that the whole hygroscopic moisture is permanently retained as a surface film , in which case it would be useless to give its actual weight without a correct measure of the exposed surface , which can hardly be obtained . We gather this impression of Trouton 's views despite the fact that he himself calls attention , as we have done , to the similarity of the moist material to an aqueous solution in respect to the influence of lperature on vapour tension , and that he specially points out the eneral srity between the isothermals for water in flannel and for water in sulphuric acid . The fact should be emphasised , however , that more than a rough agreement veen these is not to be expected , even if the moist flannel be regarded as a species of aqueous solution , for the sulphuric acid case is , of On tloe Hygroscopic Action of Cotton . course , greatly complicated by ionisation , the effects of which are for the most part entirely unknown , but are certainly quite different in different parts of the curve . Aqueous solutions of such a substance as glycerine would be much more instructive for comparison , but , so far as we know , there are no data for a complete curve in that or any similar case . In our opinion the pure surface theory which seems to be held by Trouton is inconsistent with known facts and accepted views concerning the behaviour functions of cellulose and similar substances ; and , unless special evidence be adduced to prove that they are actually impermeable by watel , it is only onable to assume that the surface film of moisture does ( until equilibrium is reached ) penetrate and form a species of solution . We hope to offer further evidence on this point later . In the meantime , the following comps.rison of Trouton 's results for flannel ( second series ) and ours for cotton shows the extent to which they with or differ from one another . The values for the moisture corresponding to the same stated values of have in both cases been read from the curves and , as already explained , are in units that cannot be } ) ared ; but it will be seen that the atios in the last column of the table are fairly constant for middle values of pressure , but diverge at both ends . It seems to us that this divergence at the higher pressures is probably attributable to want of true equilibrium in Trouton 's experiments , for our own experience has shown that the attainment of such equilibrium within 12 hours\mdash ; or even a much period\mdash ; of the admission of water to roscopic material is not possible . This error would not interfere with the demonstration of the temperature law given by Trouton and Pool , for we could have based our proof of it on either the absorption or the evaporation tests as well as on the Catcium Absorbent of , etc mean ( true ) values ; but it would materially affect the other conclusions and especially the statement that the moist material attains to the full vapour tension of pure water when it contains a definite quantity of moisture . Unless very strong and direct evidence were forthcoming , we could not , after our own experience , believe that the whole of each " " feed\ldquo ; of water driven over into the space containing the flannel was uniformly distributed as hygroscopic moisture throughout that substance before the vapour pressure was measured , or that no part of the final ' ' feeds\ldquo ; was left as ordinary liquid water to exert its influence . Calcium Absorbent for the Production of Vacua and Spectroscopic Research . By FREDERICK SODDY , M.A. , Lecturer in Physical Chemistry in the University of Glasgow . ( Communicated by Professor J. Larmor , Sec. R.S. Received September 13 , \mdash ; Read November 15 , 1906 . Notes added November 20 , 1906 . ) CONTENTS . PAGE I. \mdash ; Introductory 429 II.\mdash ; Historical 430 III.\mdash ; Electric Furnace for Strongly Heating Reagents in Glass Vessels 432 \mdash ; Absorption of Gases by Calcium 436 V.\mdash ; Behaviour of Barium and Strontium 438 VI.\mdash ; Production of High by means of Calcium 439 VII.\mdash ; An Induction Method of Electrically Heating Calcium in Glass Vessels 441 VIII.\mdash ; Practical Considerations in the Use of Calcium as an Absorbent for the Production of High Vacua 444 IX.\mdash ; Quantity of Argon detectable by the Spectroscope 446 X.\mdash ; Misapprehensions regarding High Vacua 447 XI.\mdash ; Quantity of Pure Helium detectable by the Spectroscope 451 XII.\mdash ; Most Favourable Conditions for the Detection of Infinitesimal Quantities of Helium 452 I.\mdash ; Introductory . This paper contains an account of researches carried out by the aid of an electric furnace designed to heat reagents in soft glass tubes up to temperatures far above the softening point of glass , and has special reference to the use of calcium under these conditions as a valuable absorbent of gases . Recent work on the generation of helium from the radio-elements VOL. LXXVIII .

rspa_1907_0001

0950-1207

Obituary notices of fellows deceased.

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Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

P. F. F. |B. W. |A. N. |H. F. N. |E. D. |A. M. F. |A. M. |H. H. T. |J. E. S. |R. S. B.

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http://dx.doi.org/10.1098/rspa.1907.0001

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10.1098/rspa.1907.0001

Biography

Chemistry 2

Biography

OBITUARY NOTICES OF FELLOWS DECEASED . CONTENTS . PAGE Johannes Wislicenus ... ... ... ... ... ... ... iii George Johnston Allman ... ... ... ... ... ... xii Sir Isaac Lowthian Bell ... ... ... ... ... ... xiv Frank McClean ... ... ... ... ... ... ... xix Alexander William Williamson { withplate ) ... ... ... ... xxiv Sir William Wharton ... ... ... ... ... ... ... xliv Sir Charles W. Wilson ... ... ... ... ... ... xlix Otto Struve ... ... ... ... ... ... ... ... liv George James Snelus ... ... ... ... ... ... ... lx Charles Jasper Joly ... ... ... ... ... ... ... lxii JOHANNES WISLICENUS . 1835\#151 ; 1902 . There are few branches of science so indelibly associated with the second half of the last century as that highly-specialised study of the compounds of carbon , which is commonly called organic chemistry . The marvellously rapid development of this branch of chemistry will ever remain one of the greatest monuments to the enthusiasm and industry of scientific workers . Amongst the master-builders of this imposing edifice , one of the most conspicuous , was Johannes Wislicenus , who , over a period of more than forty years , devoted his great natural gifts and extraordinary energy to this work of construction . Although in 1853 , at the early age of 18 , we already find Wislicenus acting as assistant to Heintz , then Professor of Chemistry in the University of Halle , his further progress to academic distinction did not proceed on the stereotyped lines usually followed by those who succeed in gaining access to the select professorial caste of the German universities . Wisli-eenus ' early life is , in fact , of special interest , taking us back as it does to a time when liberty and freedom of speech were ideals for which serious sacrifices had to be made even in the countries of Western Europe . * Wislicenus was born on June 24 , 1835 , at Kleineichstad in Saxony , of which village his father , Gustav Adolf Wislicenus , was the pastor . He came of one of those stocks which betray their independent spirit and originality by finding themselves out of sympathy with the established religion of their fellow-countrymen , for the Wislicenus family , originally Polish , had , in consequence of their Protestant zeal , been forced to fly from Poland into Hungary , from where , in the 17th century , they passed into Germany . Eor several generations members of the family were engaged in the ministry at ( about 1875 ) . iv Obituary Notices of Fellows deceased . Sehonburg , near Naumburg . The inherited capacity of suffering for conscience sake , however , was again manifested in Wislicenus ' father , who , in consequence of belonging to a students ' society ( " Burschenschaft " ) for the promotion of liberal principles , was , in 1824 , condemned to twelve years ' imprisonment in a fortress , but was pardoned after suffering confinement for five years . Far from being crushed by this cruel punishment , he was again in 1844 identified with resistance to the persecution carried on by the orthodox party under William IY of Prussia , and for his liberal preaching he was in 1846 deprived of his living as pastor in Halle . He at once founded a free church in the same city , but was in 1853 condemned to two years ' imprisonment for publishing a work entitled " The Bible in the Light of the Culture of our Time , " to escape which he was obliged to fly to America . It would , indeed , be difficult to find a\gt ; more ideal ancestry for a man of science ! \#151 ; a line of forefathers in whom two hundred years of exile and persecution had been unable to extinguish the innate love of truth and heroic devotion to the cause of free thought . Through his father 's flight to America , Johannes Wislicen us ' studies at the University of Halle had to be interrupted at the age of 18 , for it was under his guidance that the family followed the father to the New World . Owing to limited resources they were obliged to set out across the Atlantic in a sailing ship , on which they embarked in England , but hardly had they got under way before cholera broke out on board , and the disease spread with such rapidity that the state of affairs soon became most serious . The writer well remembers the graphic description given him by Wislicenus of the scenes which ensued . The doctor , a Scotchman , proved himself wholly incapable of grappling with the situation ; he entirely neglected the steerage passengers , and had recourse to the whisky bottle . Young Wislicenus thereupon undertook not only the treatment but even the nursing of the wretched patients who had been left to their fate by the medical officer . The pestilence , however , assumed such dimensions that the ship was turned back to England , and the voyage abandoned . Owing to the family being provided with money but barely sufficient to carry them to America , the enforced delay in England entailed on them much hardship and suffering , and the bitter experiences of this dark time must have so impressed themselves on the youthful Wislicenus that it was not until thirty-four years later that he could be induced to revisit this country , notwithstanding the reiterated invitations of his many English friends . On ultimately reaching the United States it was again to Wislicenus , but little more than a boy in years , that the family looked for material support . He became assistant to Professor Horsford , of Harvard , and subsequently carried on practice as an analytical chemist in New York . Wislicenus used to relate many interesting episodes of his three years ' life in the States . On one occasion , as he told the writer , he was visited in his laboratory by two Americans , who requested him to analyse and report on a sample of water from a mineral spring which they wished to push for its therapeutic Johannes W v properties . They said they must have the analysis and report by the afternoon of the same day . This , said Wislieenus , was quite impossible , as the analysis would certainly take several days , and possibly longer . His visitors replied that they would , of course , be prepared to pay him more than the usual fee , but that the results of analysis must be in their hands by the afternoon . Their surprise was unbounded when Wislicenus declined to oblige them , and , saying that they guessed he must be a young greenhorn , they went to another chemist of high repute in the city , who duly furnished them with an elaborate analysis and report in the course of a few hours . This chemist subsequently informed Wislicenus , quite cynically , that , to meet the exigencies of the case , he had devised a method of analysing water by smell ! In such an atmosphere Wislicenus began to feel doubts as to his moral security , and he formed the resolve of returning to Europe as soon as he possibly could . In 1856 the family recrossed the Atlantic and settled in Zurich , where Wislicenus resumed his studies , and in the following year became private assistant to his former master , Professor Heintz , at Halle . Here he remained until 1859 , taking his Ph. D. degree in 1858 on an investigation which he had made of the basic decomposition products obtained by heating aldehyde-ammonia . This , and several other pieces of work , were published in conjunction with Heintz , whilst Wislicenus ' first independent papers appeared in 1859 and treated of the theory of " mixed types , " with special reference to the derivatives of glycerine and glycol . The next step in Wislicenus ' career should normally have been his " habitation as Privatdocent " at the University of Halle , but his participation in liberal movements , both political and religious , barred the way , and he was informed that unless he left public politics entirely alone he would not be permitted to place his foot on this next rung of the academic ladder . Wislicenus was , however , not the man to be coerced by such methods , and , preferring freedom in a foreign country to bondage in his own , he migrated to Zurich , and became Privatdocent at the University there . There is probably no city in Europe which has such a broadening influence on the human sympathies as Zurich ; its atmosphere is unique . The intellectual centre of the Swiss Republic , it has become the asylum of many distinguished refugees and malcontents from the despotic states of the Continent , whilst its geographical position leads to its being traversed by a continuous stream of visitors of all nationalities throughout the year . In this international colony of free thought and uncompromising originality , and placed amidst the purest of democracies , there is no soil for the growth of those privileges attaching to birth and wealth with which so many other states are honeycombed . In Zurich you will not see " Liberty , Egalite , Fraternity , " inscribed on the public buildings and posted up at the street-corners , but you will see these principles actually practised , and the man who is unwilling to conform to their spirit will find this city a very undesirable dwelling place . vi Obituary Notices of Fellows deceased . The thirteen years ( 1859 to 1872 ) which Wislicenus spent amongst these surroundings were in many respects the most important of his life , and the experience he gained during this time must have largely contributed to the building up of that rare personality which always made him such a marked figure amongst his academic colleagues . Wislicenus ' career in Zurich was an extraordinarily rapid and brilliant One , more and more responsible posts in quick succession being entrusted to him by the Swiss G-overnment . In 1861 he was made Professor of Chemistry and Mineralogy in the Cantonal School , in 1864 Extraordinary Professor , and in 1867 Ordinary Professor at the University , whilst in 1870 the still higher office of Professor at the Polytechnikum was conferred on him , and of this famous institution he became , in the following year , Director . It was in Zurich that Wislicenus carried out some of his most memorable researches , and began to display his great power of correlating isolated facts in support of wide generalisations . Thus in 1862 he published important papers referring to the constitution of the lactic acids , and supported his views by the experimental synthesis both of ethylene and ethylidene lactic acid . Then followed a long series of investigations on oxyacids , which had a most important influence on the development of structural organic chemistry , and ultimately led to a complete elucidation of the remarkable phenomena of isomerism exhibited by the lactic acids . Thus , when Wislicenus had proved that there were three isomeric lactic acids , whilst structural formulae predicted only the existence of two , he did not hesitate to hazard the opinion before the " Naturforscher Versammlung " at Innsbruck in 1869 , that this isomerism would be explicable by a consideration of the grouping of the atoms in space and by the use of solid model formulae . In his own words c( Derlei feincre Isomerieen wiirden sich wohl durch iiber die Grugypirung dev A.tome , also durch Modellf deuten lassen . ( Berichte d. deutschen chem . Gresellschaft , 1869 , pp. 550 and 620 . ) This pregnant suggestion was a few years later developed by Le Bel and Ya n't Hoff into an entirely new domain , now known as , with most important and far-reaching consequences . This branch of chemistry has attracted an ever-increasing number of workers , by whose labours a vast amount of experimental material has been accumulated , the subject being one of surpassing interest , largely owing to its intimate connection with the chemistry of vital processes.^ To this field of enquiry Wislicenus himself again returned about twenty years later , and made some most important contributions both theoretical and practical , which are summarised in his classical memoir , " Ueber die raumliche Anordnung der Atome in organischen Molekiilen und ihre Bestimmung in geometrisch-isomeren ungesattigten Verbindungen , " published before the Kongl . sachsische Gesellsch . der Wissenschaften in 1887 . A most eloquent discourse on this subject was delivered by Wislicenus before Section B of the British Association in the same year , and formed one of the most memorable features of the Manchester Meeting . Johannes Wislicenus . Vll During the Zurich period of his career , Wislicenus carried out , in conjunction with his friend Adolf Fick , then Professor of Physiology at the same University , what must be regarded as one of the most important and fundamental physiological experiments ever made , revolutionising as it did the doctrine introduced by Liebig , that albuminoids were the exclusive source of muscular power , and that the energy contained in the fats and carbohydrates was only employed in maintaining the temperature of the body . By climbing the Faulhorn ( Bernese Oberland ) , on August 30,1865 , taking food only from which albuminoids were carefully excluded , and also determining the " total nitrogen excreted during the climb , Fick and Wislicenus conclusively proved that the muscular energy was principally derived from the oxidation of fats and carbp-hydrates . In fact the energy liberated in the oxidation of albuminoids ( as measured by excreted nitrogen ) did not amount to one-third of that required to perform even that minimum of work involved in raising the body through the vertical height of the . mountain . This classical experiment was shortly afterwards supplemented by the late Sir Edward Frankland 's determinations of the heat of combustion of muscular fibre , and of numerous nitrogenous and non-nitrogenous food-stuffs , which threw quite new light on the total possible energetic values of these materials . ( See Frankland 's ' Experimental Researches , ' London , 1877 , pp. 918-959 . ) Wislicenus having thus , by the fertility of his labours on foreign soil , won his way into the front rank of living chemists , it was not surprising that in 1872 he should have been called to Germany to occupy the Chair , rendered vacant in the University of Wurzburg by the death of the celebrated Adolf Strecker . The filling of chairs by those who have distinguished themselves as university teachers in foreign lands has been of not unfrequent occurrence in Germany , and has proved a great source of academic strength to the country . , The thirteen years ( 1872 to 1885 ) which Wislicenus spent in Wurzburg , were those during which his rare gifts were probably displayed to the greatest advantage . They were the thirty-seventh to the fiftieth years of his life . This period was principally occupied in a long series of investigations bearing on the constitution , reactions , and synthetic uses of that marvellous substance , acetoacetic ester , which had been independently discovered by Geuther , and by Frankland and Duppa some ten years previously . It would be difficult to say how many publications concerning this classical body emanated from the Wurzburg laboratory during the Wislicenus regime , whilst still more difficult would it be to enumerate his pupils who were enabled to append the magic letters , " Ph. D. , " to their names as the outcome of investigations which they had made on this fertile compound of carbon . These researches led not only to the elucidation of the constitution and reactions of acetoacetic ester itself , but to important fuither advances , such as the uses of malonic ester by Conrad , Bischoff , and Guthzeit , the synthesis of succinyl-succinic ester by F. Herrmann , the production of viii Obituary Notices of Fellows deceased . polymethylene rings by W , H. Perkin , junior , and the synthetic formation of the pyridine ring by Hantzsch . All these achievements must be regarded as the direct result of the Zeitgeist prevailing in the laboratory , and of the inspiration derived from the master . Of other investigations which emanated from the Wurzburg laboratory during Wislicenus ' tenure of office , mention may be made of the synthesis of hydantoic acid from cyanic acid and glycocoll , the synthesis of ethyl-malonic acid by the action of potassium cyanide on the a-bromo derivative of normal butyric acid , researches on benzoin , on biuret derivatives , on the constitution of phosphorous acid , on the production of guanidines by the interaction of mercuriphenylammonium chloride on thiocarbamides , and studies on the isomeric crotonie acids . During the later years also a number of his pupils were engaged in researches on the aromatic and camphor compounds . Prom this brief survey it will be sufficiently apparent that the investigations in his laboratory were spread over an unusually wide field of organic chemistry.* Although during the Wurzburg period Wislicenus was not actually engaged on any work relating to stereochemistry , the magnetic eloquence of his discourses on this fascinating domain doubtless led several of his Wurzburg pupils\#151 ; Hantzsch , Bischoff , Purdie , and others\#151 ; to subsequently devote their best energies to extending its boundaries in various directions . The remarkable strength of the University of Wurzburg at this time , in the Faculties of Science and Medicine , may be gathered from the fact that Wislicenus numbered amongst his colleagues such men as Adolf Pick ( physiology ) , v. Kolliker ( anatomy ) , v. Bergmann ( surgery ) , v. Gerhardt ( medicine ) , Kohlrausch ( physics ) , and Sachs ( botany ) . On the death of Kolbe , in 1885 , Wislicenus was called to the Chair of Chemistry in the University of Leipzig , where the duty devolved on him of directing the energies of an even larger school of chemistry than at Wurzburg . The demands made upon a professor of chemistry in one of the large universities of Germany can only be realised by those who have studied there , as they have no parallel in the present academic system of our own or any other country . The duties can only be properly performed by a man who combines commanding ability , extraordinary capacity for work , and iron physique . This period of Wislicenus ' career , which only closed with his death in 1902 ( December 5 ) , was distinguished by many researches of great importance , more especially those relating to the configuration of unsaturated organic molecules ( fumaric and maleic acids , the crotonie acids , angelic and tiglic acids , the stilbenes , etc. ) , and to the synthesis of cyclic compounds ( reduction of diketones to cyclic pinacones ) . In respect of its influence on the progress of organic chemistry , Wislicenus ' * For a complete list of Wislicenus ' publications , see 'Berliner Berichte,5 vol. 37 ( 1905 ) , pp. 4928\#151 ; 4946 , these eighteen pages being covered by the enumeration of their titles , joint authors5 names , and references alone . Johannes Wislicenus . IX work falls into three parts , which are broadly coincident with his academic activity in Zurich , Wurzburg , and Leipzig respectively . His work in each of these centres was destined to produce a far-reaching effect . The investigations on the lactic acids , carried out in Zurich , were , as already pointed out , largely responsible for the fertile speculations of Va n't Hoff , and may thus be regarded as the foundation stones of structural stereochemistry . In his work at Wurzburg on acetoacetic ester , the extraordinary value of this substance as a synthetic agent was displayed in a great variety of ways , and led not only to its extended use , but also indirectly to the discovery of numerous other agents of a similar character , and thus to a great multiplication of the methods available for building up carbon compounds . Lastly , by the speculative and experimental work in the domain of stereochemistry , which distinguished his tenure of the Chair at Leipzig , he provided the widest and most consistent explanation yet given of the phenomena of isomerism manifested by numerous unsaturated carbon compounds . It will be evident , therefore , that Wislicenus ' influence is discernible far and wide in that extraordinarily rapid development of organic chemistry which took place in the latter half of the century that is just past . That the great merit of Wislicenus ' work was recognised by the world during his lifetime is attested by the public honours which poured in upon him . In this connection it will be sufficient to mention that he received high orders from the rulers of Bavaria , Saxony , and Norway , two of which carried with them the patent of nobility . It was , however , characteristic of the man that he consistently declined to make use of the titles which Courts had thrust upon him . He was elected a Foreign Member of the Chemical Society in 1888 , and a Foreign Member of the Royal Society in 1897 , receiving the Davy Medal in the following year . Of much greater value to Wislicenus than the prizes of scientific societies and the favours of princes was the knowledge of the feelings of love and respect entertained for him by his pupils , and indeed by all who came into personal relations with him . Certainly it would be difficult to conceive of anyone more liberally endowed by nature with precisely those qualities which are calculated to win the hearts of men . The majestic form and classical features might have well served Phidias or Praxiteles as a model foi the Olympian Zeus . His mellow voice and wonderful command of language , guided by . artistic intuition and the purity of his spirit , led him to be acknowledged as one of the most magnetic and inspiring orators of Germany . His lofty idealism and unswerving devotion to duty he carried into every phase of life , and his aspirations he had the power of communicating to those with whom he came into contact . Without any touch of Puritanism m the ordinary sense of the word , for he was full of good-fellowship and the friend of conviviality , he was one of those men who purify all their surroundings . In Wislicenus ' presence it was almost impossible for anyone to harbour a mean or unworthy thought , his searching though optimistic gaze irresistibly drawing forth the good and banishing the evil . x Obituary Notices of Fellows deceased . A man who thus combined such high qualities of heart and mind with a living enthusiasm for his science , could not fail to be a stimulating teacher . He gave the most conscientious attention to all students , from the beginner upwards , and sought in his daily visitation of the laboratories to awaken interest and sharpen the powers of observation and reasoning in his pupils , rejoicing with those that were successful in their investigations and encouraging to renewed effort those whom some failure had depressed . It was by means of this contagious enthusiasm and warm sympathy of the master that the great hives of industry at Wurzburg and Leipzig were kept humming , and not by any visible disciplinary measures which are the resort of those who , although placed in authority , were never born to rule . It was inevitable that one so full of human sympathy and with so much instinct for practical affairs as Wislicenus , should have been deeply interested in the momentous political changes through which Germany passed during his lifetime . The key to the political sentiments of his later life is to be found in the circumstance that he was at the still impressionable age of thirty-five in those stirring times when a united Germany was forged out of incoherent fragments by the determined men who brought to such a successful issue the great struggle of 1870 . This united Germany , which had-been the dream of the liberal idealists of the previous generation , was rendered an accomplished fact by a man , who , trusting in material strength alone , had no sympathy with liberal aspirations . Nevertheless , the great work actually accomplished by Bismarck and his iron associates in the drama of 1870 , secured the unbounded admiration of Wislicenus , as it did also of so many other Germans who were both by nature and by tradition imbued with liberal principles . Such men felt that the ideal but abortive aspirations of 1848 must be sunk for the time at least , and that their immediate energies should be directed to the consolidation and expansion of the great empire which had been built upon the throne of the Hohenzollerns as a base . Thus in the latter half of his life we find Wislicenus an enthusiastic admirer of the Iron Chancellor , of the Emperor William , and of the military system , he was one of the founders of the " Alldeutscher Verband , " and was amongst the first to urge upon his countrymen the necessity for increasing the strength ot the German navy . In giving his unqualified support to these men and to these measures , it is evident that Wislicenus must have been drawn into that chauvinistic vortex which now for a generation has hung over the civilise world like a great storm-cloud of ever-increasing density , but in which at length a small rift is beginning to appear in the shape of the newer idealism of those who dream not of empire but of the universal brotherhood of man . Could another decade have been added to the life and activity of Wislicenus , t ere can he little doubt that his powers of advocacy would have been enlisted m promoting that great work , which has already begun , of restricting e use , l not of limiting the power , of the sword on the earth . Any account of Wislicenus would be wholly incomplete without a reference to his family life , the circumstances of which are responsible for the manifes Johannes Widicems . tation of some of his greatest qualities . Soon after settling in Zurich , he married Katharine Sattler , who belonged to a Bavarian family remarkable for talent and originality , and who herself was possessed of great gifts as an artist . Her grandfather was with Buss , the inventor , in 1814 , of the well-known pigment , Schweinfurt-Gtreen . Wislicenus ' domestic happiness was , however , destined to be of only short duration . In 1866 his brother Hugo , Privatdocent of German Archaeology in Zurich , was killed in a mountaineering disaster on the Todi , and a few years later his wife , to whom he was most devotedly attached , developed an incurable mental disorder , from which she suffered for upwards of thirty years . She died in 1904 , and thus survived her husband by more than a year . Wislicenus had four sons and two daughters , to all of whom lie was attached with something more than fatherly affection , the bond of union being strengthened by the crushing sorrow resting upon the otherwise high-spirited and joyous children , over whom he watched with a mothers solicitude . Of the four sons , two were taken from him Conrad in the first bloom o youth , and Alwin , who displayed extraordinary talent as a painter , under most painful circumstances in early manhood . Of the remaining two sons , the elder , Professor Wilhelm Wislicenus , was called to t e lair o e at Tubingen shortly before his father 's death ; whilst the .v0 , inSc ' ' ~ Hans Wislicenus , had already some years previously been appointed to the Chair of Chemistry at the Agricultural Academy m iaran ' father whom daughters , the elder , Emilie , devoted herself absolutely U , " er she loved so well , and for whose wt'she wasTw quahhed . murmur or hesitation , the artist s career or w i tjc ndents , married The second daughter , Marie , likewise endowe home Dr. Adolf Fick , the well-known opbthalmo o^ ami ^ ^ ttt Zurich , as well as the homes of his two soi , c^.es amj sorrows of \#171 ; hi his later years the holiday retreats in w . j radiant fact^ an*l lifetime could be forgotten for a few weeks amidst innocent prattle of grandchildren . beginning to decline hvauu* That Wislicenus ' powerful physique conti"ued his lectures \#171 ; ui\#171 ; apparent several years before Ms death bu he c ^ ^ " attended to his other university dut.es unt:.U^ .inch vacation he sought re^f treatment did not to he had long been troubled , ielded to the injunctions \#187 ; . results hoped for . He relucta ) 7 hoie 0f the ensuing j ol , advisers and deputed his work ^f^ed too far for ^ The mischief had , however , of cerebral December 5 , 1902 , he succumbed diatingui*^ sixty-eighth year of his life . w Iogt 0ne of ^ patriot . In Wislicenus the scientific a great orato ever r^h chemists of the 19th " ^TnT the ^ of \#166 ; *\#171 ; \#171 ; friends and relatives a strong \#166 ; _ of 8trength with counsel or sympathy , ana v xii Obituary Notices of Fellows deceased . tribulation . Lastly , his numerous pupils lament the loss of the master who not only fired them with enthusiasm for their science , but who also , by his great example of unswerving devotion to duty and of resolute fortitude in bearing adversity , inspired them to lead a higher and a nobler life . P. F. F. GEORGE JOHNSTON ALLMAN . 1824\#151 ; 1904 . George J. Allman , born in Dublin on September 28 , 1824 , was a younger son of William Allman , M.D. , who was Professor of Botany in the University of Dublin from 1809 to 1844 . Dr. William Allman was one of the most distinguished botanists of his time , and was the first professor in the British Isles to introduce ( in 181.2 ) , and lecture on , the Natural System of Linnseus . George J. Allman entered Trinity College , Dublin , at an early age , and during his undergraduate course uniformly obtained high honours in Mathematics , pure and applied . He graduated in 1884 as a Senior Moderator and Gold Medalist in those subjects , along with the late Professor Samuel Haughton , F.R.S. , who obtained the First Senior Moderatorship of that year . In 1853 he married Louisa , daughter of Mr. John S. Taylor , of Corballis , Co. Meath , and in the same year was appointed Professor of Mathematics in Queen 's College , Galway ; there he had among his colleagues Sir Thomas W. Moffett , late President of the College , George Johnstone Stoney , F.R.S. , John E. Cairnes , the distinguished Political Economist , D'Arcy Thompson , and other men of celebrity . He was made a Member of the Senate of the Queen 's University in 1877 , and was nominated by the Crown , in 1880 , one of the first Senators of the Royal University of Ireland , a position which he filled until the end of his life . The degree of Doctor of Science { honoris was conferred on him in 1882 , and he was elected F.R.S. in 1884 . He was sent by the Council of his College as a delegate to the University of Bologna on the occasion of the celebration of its Octo-centenary in 1888 . The work by which Dr. Allman 's name will long be known is his " History of Greek Geometry from Thales to Euclid , " which first appeared in the form of successive articles in various numbers of the Trinity College periodical , entitled ' Hermathena , ' and afterwards ( in 1889 ) was published as a volume in the Dublin University Press Series . George J. Xlll To this work Dr. Allman devoted many years of indefatigable study , learned research , and original thought . In it he traced the rise and progress of the sciences of Geometry and Arithmetic , comprising the labours and discoveries of the three great schools of the period , known respectively as the Ionian , the Pythagorean , and the School of Athens . As remarked by Mr. J. S. Mackay at the end of a critical review in the ' Academy , ' June 1 , 1889 , " Nothing so painstaking , so lucid , and so satisfactory has been written on the history of geometry during the period selected , even in laborious Germany . " The work was hailed with high praise by scientific and literary iournals at home and on the Continent ; it was recognised , as having thrown a laroe amount of new light on the different steps in the early development of science , by distinguished foreigners , such as Tannery , of Pans ; Zeuthen , of Copenhagen ; Loria , of Genoa ; Hultsch , of Dresden ; Gunther , of Munich , Cantor , of Leipzig , and other well-known mathematical scholars . Dr Allman had earlier published several mathematical memoirs , among which was an account of Professor McCullagh 's lectures on the " Attract:lou of the Ellipsoid , " which was reproduced in the collected works of McCullag , published ( 1880 ) in the Dublin University Press Series . At a later period.he contributed to the 9th Edition of the ' Encyclopaedia Bntanmea articles on Thales , Pythagoras , Ptolemy , and other Greek philosophers . Dr. Allman died of pneumonia in Dublin , on May 9 , 1904 . In every relation of life he was estimable , and his loss will be long felt by a large circle of college and other deeply attached friends . To the latter he was endeared by his affectionate , frank , and genial disposition ; and no person who came m close contact with him could fail to be impressed by the integrity , sincerity , and strong sense of duty which were among his marked characteristics . B. W XIV Obituary Notices of Fellows deceased . SIR ISAAC LOWTHIAN BELL . 1816\#151 ; 1904 . The father of Sir Isaac Lowthian Bell , Mr. Thomas Bell , came to Newcastle in the year 1808 . By birth he was a native of Cumberland , and he entered the offices of a Cumbrian firm , Messrs. Losh and Company . As it was in the employment of this firm that , some 30 years later , Sir Lowthian Bell was to take the first step of his business career , a few particulars of the work in which they were engaged may not be considered out of place . Messrs. Losh and Company had carried on a general merchants ' business in Newcastle , but at the time when Thomas Bell joined them they were launching out into other and wider directions . They had just started the Walker Alkali Works , using Le Blanc 's process , and were , in addition , manufacturing malleable iron at Walker , obtaining the pig iron in Scotland . A few years after his arrival in Newcastle , Thomas Bell married a Miss Catherine Lowthian , and in the year 1816 their son , Isaac Lowthian Bell , was born . His early education may be said to have been very thorough . It began at that famous fount of learning , Dr. Bruce 's Academy in Newcastle-on-Tyne . At that time most Newcastle youths of a certain standing seem to have attended Dr. Bruce 's school . Many became very distinguished men , and though , in latter day Newcastle , their place knoweth them no more , yet the old school and its master are by no means forgotten . From this place young Bell passed first to Denmark and then to Germany ; next to Edinburgh University , and finally to France . He studied in Paris for a time , and then wTent to Marseilles , where he learned a new process for the manufacture of alkali . On ' his return from France , being by this time 19 years old , he entered the offices of his father 's firm , Messrs. Losh , Wilson , and Bell , in Newcastle . He only remained for about a year in Newcastle , and then was sent to Walker-on-Tyne to manage the firm 's rolling mills there . His labours at Walker , and incidentally his connection with Messrs. Losh , Wilson , and Bell , seem to have lasted for about the next eight or ten years . This period may be said to have completed his education , if such an expression be permitted of one who continued to acquire knowledge during the whole of his life . Certainly during this time he was taught , and taught himself , a great deal . He had the advantage of considerable intercourse with Lord Dundonald in connection with the manufacture of railway wheels , which the firm were making under the latter 's patent . Lord Dundonald , so well known to history in other spheres of distinction , was not only a man of alert intellect , but also one of considerable scientific attainments . Probably of all Lowthian Bell 's instructors , a Mr. John Yaughan , with whom he first came into contact about Sir Isaac Loivthian xv the year 1842 , was the one to whom he owed most . Mr. Vaughan must have been a very remarkable character . He came from Carlisle to look after the rolling mills at Walker . He was , of course , a professor of rule of thumb , but at the same time one imagines that he knew in his own way practically all that was then known about iron . It is an interesting picture , which we have from the pupil 's own lips , of these two at their work . They would sit in the mill and watch the work going on , most of the day and often half the night , the elder man expounding , and the youth absorbing , information , which later on he was to translate into the language of science . In the meantime Mr. Bell had married Miss Margaret Pattinson , and had removed from Newcastle to a house at Benton . His father-in-law , Mr. Hugh Lee Pattinson , was a Fellow of the Royal Society , and was interested in the Felling Chemical Works . It seems to have been at about this time , or a year or two later , that Mr. Bell severed his connection with Messrs. Losh , Wilson , and Bell . In the year 1844 , with two of his brothers , Thomas and John Bell , he took a lease of Captain ' Blackett 's blast furnaces at Wylam-on-Tyne , a venture which , as it turned out , had the most far-reaching results . It was this combination which , in a few years ' time , was to become famous as Messrs. Soil Bros* Their business started upon a moderate scale . Their iron ore was obtained at first from Hareshaw in Northumberland , and afterwards ironstone was collected on the beach at Whitby . Subsequently they used material from the mines at Skinnergrove in Yorkshire . \#166 ; , _ , There is a curious story in connection with this phase , of the firms existence . It was while the Messrs. Bell were working the mines at Skmner-grove that Mr. Bewick , the geologist , told them that he knew where an ironstone bed , 10 feet thick , existed . He refused to disclose its exact locality , as he said that it was far from any railway , and would rum them if they tried to work it . As a matter of fact , it was at Skelton in Yorkshire , and subsequently Messrs. Bell Bros , became lessees of it About the year 1850 Mr. Lowthian Bell assisted his father-in-law to stai the Washington Chemical Works . He was connected with this concern for a number of years ; in fact , for nearly twenty he lived at Washington but m spite of this it does not appear that he took quite the same interest in t e Washington business as he did in that of Bell Bros. __ He eventually , in 1874 , parted with his shares in the Washington Company to his two brothers-in-law , Mr. Newall and Mr. Beaumont . In so many ways , from about the year 1850 , is Mr. Lowthian Bell s history the history of Bell Bros. , that it would perhaps be easier to trace-at first at all events the progress of the firm rather than that of the mdividua At this time , then , the great Cleveland ironstone bed had just been discovered , and , in the year 1852 , Messrs. Bell Bros , became lesse^of %P'rt3 of it on the Normanby estate , which was the property of the Ward-Jackson family . After they had obtained , with no little difficulty , this lease , Bell xvi Obituary Notices of Fellows deceased . Bros , determined to open furnaces in closer proximity to their supply of ironstone . This necessitated a great deal of negotiation and a great deal of arrangement , but ultimately the Clarence Works were started on the north bank of the Tees , at what was afterwards to become the town of Middlesbrough . The exact reason for the choice of this spot is believed to have been on Mr. Balph Ward-Jackson 's account , who was one of the owners of the ISTormanby estate . Further difficulties arose in connection with the railway transport of the ironstone , but eventually the firm obtained an Act of Parliament for the construction of the Cleveland Bailway . This result , however , was not reached without severe fighting , for even after the Parliamentary conflicts , which in themselves were memorable , the opposition was not at an end ; but the railway was completed at last , and the ironstone was thus brought direct to the furnaces . In 1854 , three furnaces at the Clarence Works were put into blast . There were only two rival establishments on the Tees at this time , Messrs. Bolckow , Vaughan and Company and Messrs. Cochrane and Company . For the first few years the company seem to have done extremely well . Prices for pig iron were high , and the business was very ably managed . In 1858 , owing to the growth of the Clarence Works , the Normanby supply of ironstone was found to be insufficient , and in consequence of this the firm obtained a lease of a larger tract of country on the Skelton Castle estate . This , it will be remembered , was the El Dorado mentioned by Mr. Bewick . But lean years were to follow , and in 1861 we hear of pig iron at 44s . instead of 7ls . , -as in 1854 . However , Messrs. Bell Bros , managed to carry on their works , owing to the careful manner in which their business had been conducted during the prosperous times . It was at about this time that the West Hartlepool Harbour and Bailway Company , who were deeply interested in several collieries in the county of Durham , found themselves , owing to the general depression in trade , unable to carry on their business . The actual railway and harbour works were sold to the North-Eastern Bailway Company , of which Mr. Lowthian Bell was made a director in 1865 , and Messrs. Bell Bros , were able to purchase a portion of their colliery property . Thus , in 1864 , they became proprietors of the Page Bank Colliery , and in the same year they sank the Brownie Colliery on a large tract of coal which they leased from the late Lord Boyne . This does not , by any means , exhaust the list of their colliery properties , but will suffice to show that Messrs. Bell Bros , were expanding very rapidly . And in each step of their progress one traces the careful guiding hand of Mr. Lowthian Bell , for it is impossible not to be impressed by the shrewdness and prudence of the policy of the firm . In fact , throughout Mr. Bell 's life , one notices the same far-sightedness in connection with almost everything with which he had to do . * In 1874 the firm of Bell Bros , became a limited liability company , and of Sir Isaac Lowthian Bell . xvn its history from this point onward a few words will suffice for the purpose of this memoir . Mr. Lowthian Bell did not in any way lose interest in his works ; indeed , so far from this being the case , in the course of the next 20 years he acquired practically the whole of the shares in the company . However , the subsequent development of Bell Bros , is better known than its earlier history , and any worthy account of it would occupy too much space to be here introduced . A word may be permitted , however , with regard to the Clarence Works of the present day . They represent , under favourable conditions of trade , an output of about 1000 tons of iron a day . Their rolling appliances are capable of dealing with some 1500 tons of steel ingots , and the number of men employed is about 5000 . monumentum might well be said . Having dealt , though not by any means fully , with Sir Lowthian Bell 's commercial career , his scientific achievements may now be considered . From almost his earliest years he had a considerable leaning towards chemistry . As we have seen , he devoted much of his time to the scientific side of alkali making . And there can be little doubt that , but for his subsequent researches on iron , which rendered him so famous , and which fully occupied him , his work on this subject would have earned for him the highest consideration as a practical chemist . But , as has been stated , it was in connection with the metallurgy of iron that his chief work was accomplished . For the last 50 years of his life he had few superiors in general knowledge of the subject , and as far as the blast furnace is concerned he was probably without equal . He it was who first endeavoured to explain the actual conditions which exist inside a blast furnace , and to his investigations was due , to no small extent , the discovery of the Thomas-Gilchrist process . In 1872 he published that standard work of reference , for all who are interested in the manufacture of pig-iron:\#151 ; " Chemical Phenomena of Iron Smelting : An experimental and practical examination of the circumstances which determine the capacity of the blast furnace , the temperature of the air and the proper condition of the materials to be operated upon . " Twelve years later he published a second work , " Principles of the Manufacture of Iron and Steel . " These two books made his name as a metallurgist in scientific circles , and it is not surprising that numerous honours from the learned societies of England and America fell to his share . Among others may be mentioned the Gold Medal of the Society of Arts and the Bessemer Gold Medal of the Iron and Steel Institute . Of the latter body he was ever a warm supporter . He was instrumental in its foundation , and in 1873 succeeded Sir Henry Bessemer as its third President . He was an Hon. D.C.L. of Durham University , LL. D. of Edinburgh and Dublin , and D.Sc . of Leeds University . Of his municipal and political work , little need be said . He was for many years a Councillor , and then an Alderman , of Newcastle-on-Tyne , and was xviii Obituary Notices of Fellows deceased . Mayor of the city on two occasions , one of his terms of office being for 1863 , when the British Association visited Newcastle , Lord Armstrong being President . As a Liberal he sat in Parliament for a short time , representing the Borough of Hartlepool , and previous to this he had unsuccessfully contested the Northern Division of the County of Durham . Apart from his own business he devoted much of his time , especially towards the end of his life , to the affairs of the North-Eastern Bailway Company . Only a short time before his death he published an exceedingly usfeful volume , the result of his investigations on the life of a steel rail . He served on more than one Boyal Commission , and was a Government Commissioner or Juror for most of the International Exhibitions for the last thirty years . In the year 1885 , to mark his services to the State , he received the honour of a baronetcy . Little remains to be said : his latter years were spent at Bounton Grange in Yorkshire , a place which he purchased early in the seventies . Time seems to have dealt very gently with him , and though he reached a great age , his faculties , with the exception of his eyesight , were almost unimpaired . During the last year of his life he failed somewhat , and finally on December 20,1904 , in his eighty-ninth year , he passed away full of years and of honour . ' A. N. FRANK McCLEAN , 1837\#151 ; 1904 . Frank McClean , who died at Brussels on November 8 , 1904 , was born at Belfast on November 13 , 1837 . He was the only son , in a family of six , of John Robinson McClean . Mr. McClean , senior , was a civil engineer and Fellow of the Royal Society . His eminence in his profession and his reputation as a man of sound judgment are indicated by the fact that he was a member of several Royal Commissions . His advice was also sought by the Emperor Louis Napoleon about improvements in the City of Paris , and he was one of the English engineers who urged the completion of the Suez Canal at a time when the abandonment of that great work was contemplated by the Khedive . Frank McClean was educated at Westminster School up to the age of sixteen , and went thence to Glasgow University , where he came under the influence of Sir William Thomson , now Lord Kelvin . In 1855 he entered at Trinity College , Cambridge ; he became a scholar of the College and was a Wrangler in the Mathematical Tripos of 1859 . Immediately after taking his degree he became a pupil of Sir John Hawkshaw and was employed on the drainage works of the Fen Districts of the Eastern Counties . In 1862 he was made a partner in the firm of McClean and Stileman and assisted his father in the survey made for the railways in*Moldavia . Shortly afterwards he became resident engineer of the Barrow Docks and of the I urness and Midland Railway and acted in this capacity for about four years . In 1865 he married Ellen , the daughter of Mr. John Greg , of Escowbeck , Lancaster , and for the next four or five years lived in London , working in the office of the firm ; but in 1870 he withdrew from the active pursuit of his profession and went to live at Ferncliffe , Tunbridge Wells . Here he found quiet and leisure for congenial studies and for scientific research , and he devoted himself quietly and methodically to work . As an example of his thoroughness , it may be mentioned that on finding his studies seriously impeded by his ignorance of foreign languages , he mastered both French and Italian in his thirty-fifth year , and he read widely in ancient and modern history . He travelled much on the Continent and knew the principal galleries and museums intimately . His own super collections of ancient coins , manuscripts , early printed books , enamels and ivories were made methodically ; he did not collect in a haphazard way , e had an ordered plan , and as far as he could he chose his specimens to illustrate evolution in art . He did not often talk of these matters , but and then he would open out and let one see the value he^ attached to t e humanizing influence of art , his delight in some finished piece of workmanship and his knowledge of its position and value in the history o artistic xx Obituary Notices of Fellows deceased . development . He thought that scientific men were often too much absorbed in their own special work . Perhaps he felt that his own method of research left him somewhat isolated ; for he never employed an assistant , but carried out all the laborious details of his scientific work with his own hands ; thus , for instance , in his very brief account of his study of the spectrum of high and low sun , he gives details of the methods he himself employed for the sensitisation of the photographic plates . So , also , his many portfolios of photographic enlargements which he himself made from his original negatives of spectra show how systematically he carried out the tedious processes of manipulation for the sake of being able to put into the hands of other investigators the material which he had gathered together by his own industry . The same sort of activity and system are evidenced by the choice collections which he bequeathed to the University of Cambridge for preservation in the Fitz-William Museum . The manuscripts which he bequeathed are 200 in number and range in date from the eighth to the eighteenth century ; and there are besides 230 early printed books . By his bequests the resources of the Museum have been nearly doubled in each of these departments . Mr. McClean 's earliest scientific paper is a note of two pages on the Equations of the Motion of the Moon , published in the ' Quarterly Journal of Mathematics ' in 1860 ; but he did not pursue this line of research , and it is in connection with spectroscopy that he made his mark in science . His first experimental work related to electricity ; in 1872 he spent much time in devising and making coils and other electrical appliances , and he made use of them later in his researches on the spectra of metals . Meanwhile , about 1875 , he invented the simple and efficient star spectroscope which bears his name . He used it in connection with a 15-inch reflector in making visual observations of star spectra at Ferncliffe . This form of spectroscope is a direct-vision instrument ; it is furnished with a slit , which , however , may be dispensed with in stellar observations ; in place of the usual plano-convex lens a cylindrical lens is inserted between the slit and the prism , and thus a lengthened image of the slit is formed in its principal focal plane . The observer thus sees a broad spectrum in which the lines can be much more readily detected than in the linear spectrum of a star . Mr. McClean has not given any published account of this instrument , but he had it constructed by Browning ; and by reason of its compactness and efficiency , and the ease with which it could be manipulated , it was and still is widely used . Mr. McClean 's first published paper on spectroscopic matters is one relating to his photographs of the red end of the solar spectrum between the lines D and A ( 'Monthly Notices , Royal Astronomical Society/ 1889 , vol. 49 , 122-124 ) . He had been for several years previously working at solar observations , and for three years at least , 1879-81 , had made records of the positions and drawings of the forms of the notable prominences on the sun 's limb . These records survive unpublished , but it is only from a question put to Father Perry at a meeting of the Royal Astronomical Frank McClean . xxi Society in January , 1888 , that we learn that he had paid attention to solar phenomena for nine years previously . He remarked at that same meeting that his observations afforded some evidence of the recurrence of prominences at fixed solar longitudes , and that there seemed to be indications that prominences were of a more permanent character than sun-spots . The records , which are fairly numerous for 1879-81 , seem hardly to he sufficient to establish this view ; the systematic nature of the observations was no doubt interrupted by his building a new house at Rusthall , Tunbridge Wells , whither he moved in 1884 . He had arranged the spacious attics of the house , so as to serve as a laboratory , with electrical and other appliances . In the roof was fixed a polar heliostat which reflected sunlight down a telescope which pointed to the pole . By a second reflection the light passed into a diffraction grating spectroscope . This installation was designed for solar studies and for researches on the spectra of the metals . At the west end of the house he erected an observatory containing an equatorial of 8 inches aperture . It was in 1887 , very shortly after the completion of his new house and laboratory , that Rowland 's map of the solar spectrum first appeared ; this map exhibited the spectrum from wave-length 3200 to 5790 . Now Mr. McClean had worked much in the red region of the spectrum , and this part was not delineated in Rowland 's first map . In fact , nearly one-half of the visible spectrum remained to be photographed . Mr. McClean devoted himself to carrving out this work , and gave a brief description , in the paper of 1889 referred to above , of the photographic methods adopted , and issued a portfolio of enlargements of the solar spectrum from D to A in seven sections corresponding to those of Angstrom 's normal solar spectrum . This work was completed in December , 1888 , almost simultaneously with the publication of the final edition of Rowland 's map , which covers the range 3100-6950 . Mr. McClean 's work was done with a Rutherford grating from 1879 until 1890 . In 1890 he substituted a Rowland plane grating . Mr. McClean next embarked upon a more extensive piece of work , part of which he carried out and published in the form of a portfolio of Comparative Photographic Spectra of the Sun and the Metals . Series I relates to the platinum group of metals , and shows the solar spectrum and the spectia of iron , platinum , iridium , osmium , palladium , rhodium , ruthenium , gold , and silver . The range of spectrum shown is from 3800 to 5750 ; it is divided into six sections corresponding to the sections of Angstrom s chart , the scale of the plates being 1 mm. per tenth-metre throughout . Series II deals in similar manner with the metals of the iron-copper group , viz. , iron , manganese , cobalt , nickel , chromium , aluminium , and copper . He had begun the work by taking comparative photographs of the sun , iron , and iridium ; iridium was chosen in order to get a full spark spectrum of air ; iron was chosen " on account of its close correspondence with the solar spectrum , and its thus furnishing the best means of co-ordinating the spectra of the other metals with the solar spectrum . " xxii Obituary Notices of Fellows deceased . In November , 1890 , Mr. McClean had completed his " Comparative Photographs of High Sun and Low Sun Spectra , " showing the absorption lines due to the earth 's atmosphere . This paper is the last which he published dealing with solar phenomena . In 1895 , Mr. McClean set up in the observatory on the roof of Eusthall House a fine twin refractor made by Sir Howard Grubb . It was of the pattern used for the astrographic chart and consisted of a 10-inch visual telescope coupled with a 12-inch photographic ; it carried also an objective prism of 12 inches clear aperature with an angle of 20 ' . It was thus in his fifty-ninth year that Mr. McClean embarked with this instrument on a systematic survey of the spectra of the stars brighter than 3| magnitude in the northern heavens . This survey was completed in 1896 , and the general results , together with 17 plates reproducing the spectra of 160 stars , were published in the * Transactions ' of the Eoyal Society in May , 1898 . Meanwhile Mr. McClean had completed the survey of the whole sky by taking his objective prism to the Cape of Good Hope , where Sir David Gill put the astrographic telescope of the Eoyal Observatory at his disposal . With this he had in six months secured 292 photographs of the spectra of 116 stars . In the Northern Survey one of the results of interest was that the bright helium stars were more numerous , relatively to other stars , near the galactic plane than near its poles . This point was amply corroborated by the Southern Survey . A further result of interest in the latter survey was the discovery of the fact that oxygen is shown by the visibility of several characteristic lines in the spectrum to be present in many of the helium stars . The Gold Medal of the Eoyal Astronomical Society was awarded to Mr. McClean in 1899 for the achievement of this remarkable piece of work . Among his other work may be noticed his researches on the spectrum of the variable star / 3 Lyrse , published in 1896 , and his work on Nova Persei , carried out in his sixty-fifth year , and published in 1905 , after his death . Of the inner history of the many munificent gifts and bequests which Mr. McClean made for the advancement of science , it is not easy to speak , for he was reticent about such matters . He showed his affection for his Alma Mater Cambridge by several endowments . First of all , in 1890 , he founded the Isaac Newton Studentships ; and it was characteristic of him that he declined to allow his own name to be attached to these endowments . The Isaac Newton Studentships were intended to encourage post-graduate study and research in astronomy ( especially gravitational , but including other branches of astronomy and astrophysics ) and physical optics . The studentships afford opportunities for men to devote themselves for three years to research at a time in their lives when , under ordinary circumstances , it would be necessary to search for other paid employment . The records of the holders of the studentships afford a remarkable testimony to the success of the endowment . Again , it was Mr. McClean who , as an anonymous donor , gave a considerFrank Me Clean . xxiii able sum in 1903 for the augmentation of the stipends of two distinguished mathematical lecturers at Cambridge . By this endowment the Stokes and Cayley lectureships were founded . In 1894 Mr. MeClean proposed to Sir David Gill to provide a large photographic telescope fitted with very complete spectroscopic appliances for the Eoyal Observatory at the Cape of Good Hope , in order that the attack on celestial problems might be carried on with greater power in the Southern Hemisphere . This equatorial , with large circumpolar motion , is a twin refractor , by Grubb , consisting of an 18-inch visual telescope coupled with a 24-inch photographic telescope . The design embodies suggestions made by Mr. McClean himself . An excellent dome fitted with hydraulic appliances for raising the floor was also provided . At Mr. McClean 's desire , the telescope was called the Victoria telescope ; he was in hopes that it would be completed in the year of the Diamond Jubilee of the late Queen ; but sundry alterations were found necessary in the instrument , and it was only formally installed a couple of years later . He had intended to accompany the British Association to South Africa in 1905 , principally with the object of seeing his telescope in use . Unfortunately this intention was frustrated , for he was overtaken by illness at Brussels on his way home from abroad ; pneumonia unexpectedly developed , and he died at Brussels on November 8 , 1904 , in the 67th year of his age . It was not merely during his lifetime that he was a generous benefactor of science . On his death it was found that he had left large bequests to be devoted to the improvement of the astrophysical equipment of the Cambridge Observatory : to the University of Birmingham ( in which he had already shown his interest by liberal subscriptions during his lifetime ) for the department of physical science : to the Eoyal Society : to the Eoyal Astronomical Society : and to the Eoyal Institution . Mr. McClean received the honorary degree of LL. D. from the University of Glasgow in 1894 . He was elected a Fellow of the Eoyal Society in 1895 , and was for many years a Fellow of the Eoyal Astronomical Society , and a member of the Institute of Civil Engineers . H. F. N. XXIV Obituary Notices of Fellows deceased . ALEXANDER WILLIAM WILLIAMSON , 1824-1904 . Among the chemists engaged , in the middle of the nineteenth century , in developing the molecular theory of chemical reactions , it was Alexander William Williamson who established that theory on a foundation of experimental facts . His earlier researches on bleaching salts and on Prussian blue are of exceptional value and interest , but it is for the effect upon chemical theory of his other researches and essays that Williamson 's name will remain eminent in the annals of chemistry . Williamson did all his memorable work well within the first half of his life , indeed almost within the first third . His communications to learned societies concerning this work occupy so small a volume , notwithstanding their great significance , that an analysis of their contents can fortunately be included in this account of his life , without altogether exceeding the limits within which it must be confined . Usually , in preparing a biographical notice , famous investigations may be taken to be well enough known to make mention of them all that is necessary , but of Williamson 's work a more particular account than that seems called for . There is , it would seem , at the present time , an insufficient realisation of what exactly Williamson did for chemistry , attributable , no doubt , to the fact that his efforts were directed to the replacement of notions , now almost obsolete , by those which have become part of the accepted theory of chemistry , as well as to the fact that the substances upon which he worked are among those which are best or most familiarly known , namely , bleaching powder , Prussian blue , and alcohol . Of Scottish descent , Williamson was born at Wandsworth , in London , on May-Day , 1824 . His father , a man of unusual force of character , was a clerk in the India House , but must have retired , with pension and private means , some fifteen years after the birth of his son . Williamson 's mother was the daughter of William McAndrew , a city merchant ; from her training and example he acquired that delicate sense of honour for which he was noted . When Williamson was six years old , the family removed from Camberwell to a house which his father had purchased in Wright 's Lane , Kensington . James Mill and his son , John Stuart Mill , lived close by , and the two families formed an intimacy which was maintained for years afterwards . The old residences and gardens in Wright 's Lane have long since been destroyed and their sites built over . At a date unknown , but probably coincident with that of his father 's retirement from the East India Company 's service , the family went abroad and resided for many years , first in Paris and then near Dijon . He attended day schools in Kensington , and apparently in Paris , and was a pupil at the College at Dijon . At Dijon also he and his sister , Antonia Helen , two years his senior , had private lessons . Concerning these , the tutor 's report was that the young lady had worked steadily , but that of her ALEXANDER WILLIAM WILLIAMSON . Alexander W. Williamson . xxv brother as much could not be said.* Later on , Williamson spent a winter at Wiesbaden , working diligently at German . He spent three years ( 1841-4 ) at Heidelberg , where he went to study medicine at the wish of his father . He attended Tiedemann 's lectures there ; but the professor was then very old , and Williamson , finding the lectures intensely dull , spent much of the hour in conversation with Moleschott ( to be well known later as a physiological chemist ) and other fellow-students . On the other hand , he became greatly interested in his work in Gmelin 's laboratory and with the lectures on chemistry . From the very first Gmelin was most kind and courteous , and later on he took the greatest interest in his successes . Williamson always spoke of Gmelin with the greatest respect and affection , and soon informed his father that he wished to be a chemist . The latter showed much annoyance , but , seeing that his son was determined , he wrote home to a relative to ask him whether there was any opening for a chemist in England . It will excite no surprise to hear that the answer returned was\#151 ; \#171 ; Hone at all . " Williamson was also discouraged at first by Gmelin himself , who told him that it was not likely that he could succeed as a chemist , because of certain bodily imperfections . From earliest infancy he had lost much of the use of the left arm through stiffness of the elbow ; and he had also been deprived of sight in one eye , and left very short-sighted in the other . It was not long before Gmelin had changed his opinion , and therefore allowed himself to tell " Williamson 's mother that her son would be chemist . The mother being won over to her son 's wishes , the father at length gave Williamson next went to Giessen to study under Liebig . In six weeks ' time ( May , 1844 ) he was working daily in Liebig 's laboratory , and rising early each day to attend Bischof 's lectures on physiology , then his favourite science next to chemistry . During his stay in Giessen he boarded with the family of Dr. Hillebrand , Professor of Literature in the University . His associates were always his seniors , and his letters to his father at this time exhibit him as the serious and hard-working student , to whom even his recreations counted more as aids to better working than as enjoyments . It must be remembered that he had had no English school or college life wort considering , and that he was not bodily fitted to join in youthful sports . ^ ^ Referring to Liebig in one of his letters , Williamson expresses the opinion that the eminence which that chemist had then reached , was due as much to his pleasing manner as to the undoubtedly great importance of his discoveries . There was to be added to this , he continues , that everyone coming in immediate contact with him could not but be captivated by the expression of benevolence or of affection which a look of his cou C'Thirty years afterwards , in his Presidential Address at Bradford to the * In the obituary notice of Williamson in the 'Journal of the Chemical Society , Professor Carey Foster gives an interesting reminiscence of the striking personality o Antonia Williamson , to whom her brother through life showed the warmest attachmen . xxvi Obituary Notices of Fellows deceased . British Association , soon after the death of Liebig , he said of him and of these days in his laboratory , " I think it is not too much to say that the Giessen laboratory , as it existed some thirty years ago , was the most efficient organisation for the promotion of chemistry which had ever existed . Picture to yourselves a little community , of which each member was fired with enthusiasm for learning by the genius of the great master , and of which the best energies were concentrated on the one object of experimental investigation . " First Paper : Bleaching Salts , Catalytic Action.\#151 ; While , at Giessen , Williamson , at the age of 20 , published in London , in the Memoirs of the Chemical Society ( 1844 ) , the results of his first research . More as an exercise than for purposes of investigation , Liebig set him to work upon the subject of the " bleaching salts " which had recently been receiving attention in France , and even in Germany in the Giessen laboratory itself . He soon obtained results quantitatively at variance with those recorded by others , and came upon a fact which , in his own words in a letter to his father , " will throw a much-needed light upon the composition and properties of one of the most interesting salts , not only to the chemist but to the public . " To Williamson 's mortification , Liebig at first discredited these results as too improbable , but he was eventually convinced , exclaiming , to his pupil 's delight , " Ei , das ist ja eharmant , das ist allerliebst ; jetzt bin ich erst uberzeugt . " It may be of interest to record some words of Williamson 's concerning the execution of this research . Writing of his solitary walks on Saturday afternoons , he says : " I often find such a walk of as much real service to me in my progress as a whole week 's labour ( in the laboratory ) . The great difficulty in a research such as that I am now pursuing consists not so much in performing the experiments once fixed upon , as in inventing and choosing from those most calculated to attain the desired object . " The great value of this paper , which is entitled " Decomposition of Oxides and Salts by Chlorine , " as a contribution to the knowledge of the way in which bleaching salts in solution pass into chlorate , seems to have been entirely overlooked . Yet no one , after Balard and Gay-Lussac , has thrown more light upon the chemistry of chlorine in interaction with bases than Williamson . As ordinarily carried out , the production of a chlorate is the result of the catalytic action of chlorine upon the hypochlorite present in the solution of ( so-called ) chloride of lime or similar bleaching salt ; this Gay-Lussac had already explained . But Williamson succeeded in showing , in the first place , that , after the chlorine in presence of water has combined with an alkaline earth or an alkali to form chloride and hypochlorite of the metal , still as much more of it can be made to dissolve in the solution by converting the hypochlorite itself into chloride , along with hypochlorous acid , and with but very little formation of chlorate . In the next place , he found that this solution of metallic chloride and free hypochlorous acid can be made by heat to pass into that of chlorate equivalent in quantity to half of the Alexander W. Williamson . \#166 ; XX . V11 chloride , with the liberation of as much chlorine as had been absorbed by the bleaching solution . To make his proof of this the more convincing , he dissolved some potassium chloride in a strong solution of hypochlorous acid , and by heat changed this chloride into chlorate and free chlorine , thus establishing what had seemed to Gay-Lussac ( 1842 ) to be most unlikely . To-day , the possibility of such a remarkable change will be admitted without much hesitation ; but 60 years ago , quite possibly , chemists hesitated to accept results obtained by a 'prentice hand in chemistry which were not in accordance with the opinion of such an authority as Gay-Lussac . Nearly 40 years later ( 1883 ) , Lunge and Naef , evidently unaware of what Williamson had done , succeeded in showing that , even in the cold , hypochlorous anhydride freely decomposes solid hydrated calcium chloride by converting part of it into hypochlorite . Finally , Williamson proved ( contrary to what Liebig had with approval allowed his English pupil , Detmer , to publish in the ) that hypo- chlorous acid , which so readily decomposes a chloride , cannot decompose a dissolved alkali carbonate or bicarbonate . By this , as he pointed out , it is shown that , in the copious production of a chlorate which may follow upon the passage of chlorine gas through a solution of potassium or sodium bicarbonate , the production of the chlorate depends solely upon t e interaction of the first-formed alkali chloride and hypochlorous acid . This research of Williamson 's appears to be the first successful attempt to throw light upon the nature of a catalytic action , such as had been here presented by Gay-Lussac . It was soon to be followed by a second one in the case of what is known as etherification . , , Ozone.\#151 ; A second paper quickly followed that on chlorine . It is entitled , " Some Experiments on Ozone , " * and purports to have proved that ozone is a peroxide of hydrogen . Ten years afterwards , however , Andrews and Tait proved that ozone is not a compound at all . Williamson had worked with a mixture of ozone and oxygen eleetrolytically obtained , and these mixed gas , we must assume , had not been kept quite free from electrolytic hydrogen . Prussian Blue.\#151 ; Very , soon after the appearance of the paper on ozone , Williamson published his important research on the composition of i iussia blue . This beautiful preparation was then of special interest as a ea . , ,m constitution of whioh one and the same element , iron , functions part y basic and partly as acid radical . It had been easy to ascertain that it composed of both ferrous and ferric cyanides and o P " " T\#171 ; ko teen that the proportions of these cyanides are inconstant in it It had also be nossihle to foresee , with some confidence , that among its component suh-stancest there must be present the two cyanides of iron , formulated respec tively by Fe , CiaNie and Fe6Ci2N12 , but it had hitherto no een pos verify this inference . For , Prussian blue , being amorphous ^highly colloidal , is incapable of being separated into the several which it is a mixture . \#166 ; * 'Mem . Chem. Soe . , ' 1845 , vol. 2 , p. 395 . xxviii Obituary Notices of Fellows . Williamson succeeded in actually preparing both the above indicated iron cyanides in a state remarkably near to purity , notwithstanding their colloidal nature . He also produced a new blue salt , a constituent likewise of Prussian blue , a double cyanide of iron and potassium , KFeaCeNe , by the limited oxidation of the insoluble , nearly white , potassium ferrous cyanide K2Fe2C6lSr6 , known as Everitt 's salt . The new salt , since obtained in various ways , has proved to be of perhaps greater interest than either of the other constituents of Prussian blue , namely , Turnbull 's blue , Fe5Ci2]Sr13 , and the substance , FeyCigNig , which chemists often still call " Williamson 's blue . " One thing which gives it interest is the fact that it is the parent salt of both Turnbull 's and Williamson 's blues , being always , as Skraup has shown ( 1875 ) , * the precipitate first to form , whether a ferrocyanide be mixed with a ferric salt or a ferricyanide with a ferrous salt , so that , as a consequence , well-washed and freshly prepared Prussian blue is always a mixture of these three blue salts and of these only . Another point of interest about Williamson 's new salt is the remarkable readiness with which it usually passes into a form freely soluble in water . It appears to be possible , indeed , to get all three blue constituents of ordinary Prussian blue into solution in water , but such dissolution of two of them only exceptionally occurs ; whereas the other one , that obtained by Williamson , KFe2CeH6 , is usually found to be so soluble in water as to have become known as " soluble " Prussian blue , and is only obtainable in a form insoluble in pure water when it is prepared by Williamson 's method . Oiie other matter of importance comes out from Williamson 's researches on this subject , which is that , when potassium ferrocyanide in solution is digested with Prussian blue , the ferric cyanide in each of the three blue salts which together constitute it , will always take potassium cyanide from the ferro-cyanide and thus become potassium ferricyanide in solution , whilst in its place there will be left an insoluble pale blue substance containing all the ferrous cyanide together with some of the potassium cyanide of the potassium ferrocyanide , apparently as Everitt 's salt . Williamson proposed in this way to manufacture potassium ferrieyanide in a state of purity . From the account just given it will be seen that this paper on the compounds of cyanogen and iron must be ranked as a classic memoir on the subject . It was read at the meeting of the Chemical Society , held on March 16 , 1846 . After carrying out the three researches just described , Williamson left Giessen and took up residence in Paris in July , 1846 , where he remained until his return at last to London in June , 1849 . Arrived in Paris , and being already familiar with the French language , he at once arranged for lessons in mathematics with Auguste Comte . Writing to his father in eulogy of Comte , he said , " If my experience of Comte 's superior powers were insufficient to convince you that his lessons were worth their price , John ( Stuart ) Mill 's * Recent valuable work by Karl Hofmann and his colleagues on Prussian blue ( 1904-5 ) is essentially confirmatory of that of Williamson and of Skraup . Alexander W. Williamson . xxix saying that he * would prefer him to any man in Europe to finish a scientific education , ' ought to carry the point and to induce you to consent to my continuing as I have begun . " Williamson seems to have made good use of these lessons , for before the end of the year he was himself teaching an English youth mathematics . Comte was much pleased at this , and remarked that teaching was the best possible means to perfect one 's own knowledge . During Williamson 's three years in France he published nothing of importance and seems not to have attempted any chemical researches . But it was probably in these years that he began that cordial acquaintance with Laurent , Gerhardt , Dumas , and other French chemists which continued throughout their lives . After his marriage , there was a close intimacy between the Williamson and the Wurtz families and also with the Berthelots , and with Cornu . On the death of Fownes , Williamson , in 1849 , was unanimously elected to the Professorship of Practical Chemistry in University College , London , and thus came under the influence of Thomas Graham , who at that period held the Chair of General Chemistry . ... During the next five years he elaborated the great work of his lifetime publishing the results of it in varying detail at meetings of the British Association , the Chemical Society , and the Royal Society , and in the ' Philosophical Magazine ' and the ' Chemical Gazette . ' Of these researches , first came those included under etherification , and later those on the constitution of salts . . . Etherification ( 1850-52).\#151 ; The expectation that in chemical reactions substances would generally beget others similar to themselves , induced Williamson to make an experiment , soon to become celebrated , in which 1 was anticipated that a new alcohol could be derived from ordinary a coho . To his " astonishment , " it yielded him common ether instead of a new alcohol . The experiment had been a simple one , its result had not met his anticipations and it had not even been productive of a new substance ; but the nature o his interpretation of the result of it quickly made his name famous with chemists . To begin with , he had seen that his experiment had solved , for him at least , the long-vexed question of the relation of three substances of such fundamental importance in organic chemistry as alcohol , ether an water , and thereby had determined the true proportions of their atomic quantities or , as we now say , their molecular quantities . It h^ afforded , besides , a confirmation and proof of the views of Diurent andGerhardt , comparable to that which was , long after , to be g't^n o e , , theory of the periodicity of the elements by Leeoq de Boiebaudran s disco y of gallium . In this way it was destined to do more than anything else in showing how futile was any further opposition by the old schooll of \lt ; *emis to the adoption of Gerhardfs system of equivalent quantities now known as molecular quantities . Next , it gave Williamson the basis of his theory of etherification , in which is contained the origin of chemical , dy\#153 ; \#153 ; 08\gt ; theory of ionisation , the theory of catalytic action , and the grounds fo xxx Obituary Notices of Fellows deceased . reconsidering Berthollet 's law of mass action , which had fallen into neglect . Lastly , but perhaps before all in ultimate importance , it led Williamson to form his theory of the constitution of salts , in which is included the foundation of the doctrine of valency and the linkage of radicals . Some account of his experiment must be given , in order to make his theory clear . He had converted some alcohol partly into ethyl iodide and partly into potassium ethoxide ( or ethylate ) , the former being reconvertible to alcohol by means of moist silver oxide , and the latter by merely dissolving it in much water . He then found that these substances interact with each other in proportions derived from equal quantities of alcohol , and that the products are the substances , ether and potassium iodide . Either of these is derived from both ethyl iodide and potassium ethoxide , and therefore its quantity is chemically equivalent to that of the ethyl iodide or that of the potassium ethoxide . But the two reacting substances are each equivalent to the quantity of alcohol from which they are derived . From this it follows that two equal quantities of alcohol are concerned in the production of ether , and that the quantity of it produced is equivalent to either of the two quantities of alcohol . Nowadays , for equivalent the word molecule is used , but the sense is unaltered . Williamson 's experiment would doubtless Jby itself not have proved convincing to many chemists at that time . They would have met it with the apparent contradiction afforded by the fact that alcohol is decomposed into ether and water , in quantities together equal to it in weight and composition , when it is run into sulphuric acid already mixed with alcohol and water in such proportions as to allow the heated mixture to boil at 140 ' . For , from this fact it would seem just as reasonable to assume that the alcohol , which decomposes into equivalent quantities of ether and water , is itself equivalent in quantity to that of either of its educts , as it is to assume that the ether produced in Williamson 's own experiment is but one equivalent or molecule instead of two . But Williamson 's papers forestalled in two ways the bringing in of this fact as adverse evidence ; first , by the accounts of other experiments which they contain , and , secondly , by the theory of etherification put forward in them . It is important , however , that it should be recognised that the result of his single experiment is really sufficient to establish his point . That experiment in itself indicates that , in the ordinary ether process , there are to be recognised two molecules , two equal and distinct quantities , of alcohol which , by their mutual exchange of ethyl and hydrogen , give rise to the ether and water , one molecule of each . The results of Williamson 's other experiments strengthen the argument , but are themselves unconvincing if the result of his first experiment is so . One set of these experiments , in which he prepared mixed ethers , such as methyl ethyl oxide , consisted in letting the iodide derived from one alcohol interact with the potassium derivative of another alcohol . The other set was made up of those in which , in different ways , the mixed ethers are obtained , by using two different alcohols in carrying out the ordinary or continuous etherification process by means of sulphuric acid . Alexander W. Williamson . xxxi The production of mixed ethers , substances which prove themselves by their composition to be derived from the two alcohols used , shows the propriety of regarding ordinary ether as being all derived from both the ethyl iodide and the potassium ethoxide , instead of half of it coming exclusively from one of these substances and half of it exclusively from the other . Their production served another purpose , because Williamson had found that the same mixed ether was produced , whichever of the two alcohols was used as the potassium or as the iodine derivative . For , from this fact it follows almost necessarily , that the ethers are oxides of two hydrocarbon groups and not of a complex of the two . Williamson has not indeed expressed his views in this way , but as he started his experiments under the belief that the hydrogen of alcohol is or may be all united directly to the carbon , herein following Berzelius , he must have been influenced by some such reasoning when he represented alcohol as the oxide of ethyl and hydrogen , and ether as the oxide of two atoms of ethyl . The molecular weights thus found by Williamson for alcohol and ether were the same as those assigned to them by Gerhardt on the assumption that molecular quantities of different substances have the same volume in the gaseous state under like conditions . They therefore gave such support to Gerhardt 's views as to weaken greatly , as was just now said , the doubts entertained as to the substantial correctness of these views . Other experimental verifications , as is well known , quickly followed , so that- in a few years Gerhardt 's assumption led to the revival in full force of the rule or hypothesis of Avogadro which , at the time of Williamson 's experiments , was well-niah forgotten , so little had it appealed to chemists for want of sufficient experimental support . It was also largely due to the effect produced by Williamson 's experiments and the interpretation he gave of them that the notion of molecules as being the true equivalents , and of their component atoms as being subordinate to them , obtained general acceptance , a notion tor the conception of which chemistry is also indebted to Avogadro . Catalysis or Contact Theory.\#151 ; When Williamson made his famous experiment there were in the main two views current as to the nature o t e process of making ether from alcohol by means of snip uric ac* . Mitscherlich 's view , upheld by Williamson 's colleague , Graham , was t at y contact with hot sulphuric acid ( or perhaps by contact with sulp ovimc aci ) , and by virtue of a catalytic force rather than by the influence of any play o chemical affinities , the alcohol decomposed into water and ether , the catalysing acid , whichever it was , remaining chemically unchanged . The other view was that the production of ether was due to decomposition , by heat , o su p ovimc acid ( ethyl hydrogen sulphate ) into sulphuric acid and ether , o owe } e production of fresh sulphovinic acid by the union of alcohol with sulphuric acid . This view was Liebig 's , in whose laboratory Williamson had been trained . Both accounts were made up of facts , hypothesis , and error ; neither could be dignified with the name of theory , for neither offered any sufficient explanation . In propounding his theory , the one and on y t eory a as xxxii Obituary Notices of Fellows deceased . been framed , Williamson was careful repeatedly to point out that he was combining the theories of his two eminent seniors in his own , but it is clear that the enunciation of his own theory implies the rejection of the essential points in both of their theories . The catalytic phenomenon is a patent fact ; but the existence of a catalytic force , and the activity of a contact which brings about chemical change without the contact substance being affected , are both , to be cast aside as baseless fancies . The production of sulphovinic acid is also a fact not to be denied ; the decomposition of the acid into ether , by heat and by itself , is only imaginary . Williamson 's description of etherification is that a molecule of alcohol reacts with a molecule of sulphuric acid to form ethyl hydrogen sulphate and water , and that then a second molecule of alcohol reacts with this ethyl hydrogen sulphate to become ether and sulphuric acid again , this pair of reactions being ever and again repeated , so long as the conditions are that the ether and water produced are being removed and replaced by fresh alcohol . In this way it is made evident that the quantity of alcohol which gives a molecule of ether and a molecule of water must be treated as being not one but two molecules . Here , it will be seen , is given , for the first time fully ( but see p. xxvii ) the form of explanation , now universally accepted , of all catalytic action . Chemical Dynamics.\#151 ; To complete his theory , Williamson points out that whilst the two double decompositions involved are , in themselves apart , perfectly conformable with others , the fact of their alternations and continuous successions is something obviously independent of the exercise of chemical affinity , and inconsistent with the supposition that the atoms of a compound are in a state of rest . There must therefore be a dynamical treatment of chemical phenomena , in which the degree and kind of motion possessed by atoms must be studied , and the element of time be taken into consideration . The alternating changes of sulphuric acid and sulphovinic acid into each other cannot be attributed to any exercise of superior affinity , for one moment sees replaced by hydrogen the ethyl which during the preceding moment had replaced a hydrogen atom . Nor can it be referred to the action of some occult catalytic or contact force . It happens because the atoms are not at rest and confined within the molecule , but are constantly changing into other molecules , there taking the place of like or similar atoms . In completing his theory of etherification in this way , Williamson , as is universally admitted , placed the dynamical idea of chemistry on a definite concrete foundation . In a lecture on the subject at the Eoyal Institution , he expressed himself , as follows , in words which recall the opinion pronounced by Eobert Boyle in the infancy of the science:\#151 ; " The dynamics of chemistry will commence by the rejection of the unsafe and unjustifiable supposition that the atoms of a compound are in a state of rest , will study the degree and kind of motion which atoms possess , and will reduce to this one fact the various phenomena of chemical change . " In another place in this lecture he says:\#151 ; " There are many primd facie evidences that time is necessary for Alexander W. Williamson . xxxiii chemical action , but this fact has not as yet entered into the explanation of phenomena . " Ionisation.\#151 ; It is evident , too , that in the theory of etherification he foreshadowed the modern notion of ionisation . This may be seen in what precedes , but the following quotation seems too interesting as an illustration of the point for it to be omit bed:\#151 ; " A drop of hydrochloric acid being supposed to be made up of a great number of molecules of the composition C1H , ... each atom of hydrogen does not remain quietly in juxtaposition with the atom of chlorine with which it first united , but , on the contrary , is constantly changing places with other atoms of hydrogen or , what is the same thing , of chlorine . . . . Suppose we mix with the hydrochloric acid some sulphate of copper , the basylous elements , hydrogen and copper , do not limit their change of place to the circle of the atoms with which they were at first combined , the hydrogen does not merely move from one atom of chlorine to another , but in its turn also replaces an atom of copper , forming chloride of copper and sulphuric acid . " More might be quoted with advantage , but what is here given will be enough to show that , whatever may be the ultimate view adopted on the subject of ionisation , Williamson played an important part in the development of the conceptions on which the theory is based . Mass Action.\#151 ; Following up his illustration , just quoted , with another in which sulphate of silver is used instead of sulphate of copper , for the sake of the example it affords of the- precipitation of an insoluble compound , he refers to Berthollet 's view about mass action , and gives new life to it by accounting for the existence of mass action between substances constituted of atoms as an action due to the innate motion of these atoms carrying them from molecule to molecule . Structural or Positional Formulce.\#151 ; In discussing the facts concerned in the production of ether , Williamson showed , for the first time , how chemical formulae might be so written as to represent chemical constitution as an arrangement and interdependency of atoms , formulae thus constructed being what are now known as " structural " formulae . He then developed the subject in papers on the constitution of salts , the anhydrides of monobasic acids , and sulphuryl hydroxy chloride.* This method , of expressing by symbols the conclusions to be drawn from the results of experiments as to the chemical constitution of substances , has turned out to be a veritable " calculus of chemical operations , the importance of which to the progress of chemistry can hardly be overestimated . When Williamson began to publish his views , Gerhardt had already introduced his unitary synoptic formulae , the nature of which may , perhaps , be best indicated by calling them " agnostic " formulae . For they were * " On the Constitution of Salts " ( 1851 ) ; " On Gerhardt 's Discovery of Anhydrous Organic Acids " ( 1853 ) ; " Note on the Decomposition of Sulphuric Acid by Pentachloride of Phosphorus " ( 1854 ) . d xxxiv Obituary^Loti Follows formulae , the purpose of which was to make no vain attempt to indicate chemical constitution , but to express as simply as possible only the ultimate chemical composition of equivalent quantities of substances . Gerhardt and Laurent did not deny that substances do have atomic structure , but they denied that we could expect to make out anything about it . Such notions concerning chemical constitution , as that nitre consists of and contains potash and nitric acid , and that alcohol consists of ether and water combined together , had been shown by them to be unwarranted assumptions , but were still current . What Willliamson wanted\#151 ; instead of Gerhardt 's synoptic formulae of reactions , and of the ill-conceived constitutional formulae which they were intended to replace\#151 ; were such formulae as might* be used as an actual image of what we rationally suppose to be the arrangement of constituent atoms in substances , between which decomposition may be effected by the exchange of a radical in the molecule of one substance for a radical in the molecule of another substance . Now , in order to describe , by means of a chemical equation , the process by which the change is effected , in the reaction of one substance with another , that change should be represented by the juxtaposition of the formulae of the reacting substances , aDd by then indicating in these formulae what takes place in the interchanging substances . The adoption of such a method necessitates a reference to types , from which , by the replacement of certain elements or radicals , the constitution of substances of increasing complexity can be deduced . Williamson took the constitution of water to be the structural type of salts and of classes of substances apparently allied to them , and constructed formulae for water and for each of these substances in which the three symbols or , in case there were more , three groups of symbols , are so spaced out as to represent by their relative positions always the same structural relation , whatever that may be , in each of them . Thus N02 no2 0 , are his formulae for water , caustic potash , potassium oxide , nitre , nitric acid , and nitric anhydride . Similarly , to alcohol , ether , acetic acid , acetic anhydride , and ethyl acetate , he gave the formulae C2H c2h 50 , C2H3On H M* C2H30 c2h3o 0 , C2H30o C2H5 U These triangulated formulae are now usually unfolded into straight-line formulae , thus HOH , K0(N02 ) , ( C2H5)OH , ( 02H5)0(C2H30 ) ; but are otherwise unaltered . The Linkage and Valency of Radical.\#151 ; It was the significance given by Williamson to the relative position , to the " juxtaposition , " of the three * The next 11 lines are almost in Williamson 's own words . Alexander W. Williamson . xxxv symbols or groups of symbols , which constituted the essential novelty and the importance of these formulae as constitutional formulae . It is clear what that significance was to him . For instance , as regards alcohol , it was that one-sixth of its hydrogen is " held " united to the carbon and rest of the hydrogen by its atom of oxygen ; that in potassium acetate , half the oxygen serves to " hold together " the potassium with the rest of the salt . Again , sulphuric acid is a dibasic acid , because the radical sulphuryl ( S02 ) holds together two atoms of hydroxyl . Carbonyl ( CO ) is given by him as another example of a radical which , in the carbonates , replaces two atoms of the hydrogen of a doubled molecule of water , and thus holds together the two substituted water residues or metalloxyls , thus , j^qCO . Thus was enunciated for the first time the fundamental part of the doctrine of the linkage of atoms and the valency of radicals . Later on , he gave experimental evidence that sulphuryl is bivalent in sulphuric acid , of the same convincing kind as that he had given of the bivalency of oxygen in alcohol , ether , and water . It consisted in the application of the discovery he had made of sulphuryl hydroxychloride , and of its production from sulphuric acid by means of phosphorus pentachloride ( p. xxxvi ) . In his description of this production , he showed himself already ( 1854 ) discarding anything there might be in the presentation of the water type which is outside this theory of the existence and linking power of multivalent radicals . Again ( later in 1854 ) he showed the same thing , when he pointed out that the remarkable substance , ethyl orthoformate , " may be equally well conceived to be a body in which the ( oxylic ) hydrogen of three atoms of alcohol is replaced by the tribasic radical of chloroform , as ( to be ) one in which the chlorine of chloroform is replaced by peroxide of ethyl ( ethoxyl ) . " Confining , as he did , his attention to the water type , the only elemental atom or radical he exhibited , as exercising linking power , was oxygen . Odling and , pre-eminently , Frankland extended the conception to several other elements , but it was not till Kekul4 recognised that , in the case of carbon in organic compounds , atoms of the same element may be united directly together , that the real and supreme value of Williamson s conception became evident , and the reference to compound radicals and types to be no longer necessary . Gerhardt added three other types to Williamson 's water type , but all were to him no more than " types of double decomposition , " and wanted therefore that structural significance which they had for Williamson . Just as the latter was led by his water-type formulae to differentiate one atom of the hydrogen of alcohol from the other five , so was he quickly afterwards led to separate the oxygen of acetic acid into one atom as being that of water , and the other as being within the radical , acetyl ( his " othyle " ) . This procedure was at once justified by the discovery ( by a method similar to that employed by Williamson in connection with ether ) yyyvi Obituaryffoticezs of of the monobasic acid-anhydrides by Gerhardt , who had himself previously deemed their existence impossible . To bring out the fact more strongly that Gerhardt 's type formulae were no anticipation of Williamson 's structural formulae , it may be here recalled to mind that , in 1863 , Playfair advocated the reference of salts to the type of hydrogen peroxide as more appropriate than Gerhardt 's reference of them to the type of water , giving a sufficiently plausible presentation of the subject , quite worthy of consideration until the views of Williamson as to atomic structure are applied to show the futility of Playfair 's proposal . It is of interest to note further that Gerhardt , before Williamson had worked upon etherification , had gone so far as to regard ether and alcohol as the normal and acid esters of water , water being treated as a dibasic acid , and yet had wholly missed the point of the relationship afterwards brought out and formulated by Williamson . Gerhardt wrote the formulae of ether and alcohol as ( C2H4)2 , OH2 and C2H4 , OH(H ) , in order to represent this view of their relationship . These instances from Gerhardt 's writings serve to illustrate how entirely original were Williamson 's notions concerning the chemical constitution of salts and other substances . Kekuffi , who spent the session 1853\#151 ; 54 in Stenhouse 's laboratory at St. Bartholomew 's Hospital , and passed much time in intimate companionship with Williamson , carried out at that time a research* on thiacetic acid , which afforded a beautiful confirmation of the correctness of Williamson 's action in formulating acetic acid with half its oxygen in the radical , acetyl or " othyle . " Kekuffi showed that by acting upon acetic acid , or its anhydride , or its ester , with phosphorus tersulphide or quinquesulphide , compounds were produced in which only half the oxygen was replaced by sulphur and which had much resemblance to the original acetic compounds . Substance , Distinct from Radical of same name.\#151 ; Concerning the radicals which he introduced into chemistry , such as sulphuryl and acetyl , and others such as ethyl , the existence of which he accepted , Williamson was careful to point out that they are not to be confounded with the substances or bodies in the free state , which would be indicated by the same names and formulae . Extending this important distinction , too often still neglected , to metallic and other elemental radicals , he wrote \#151 ; " To say that metallic zinc is contained in its sulphate is an expression authorised by usage , but is only strictly true by abstraction from most of the properties of the metal . The material atom which , under certain circumstances , possesses the properties which we describe by the word . zinc ' is no doubt contained in the sulphate but with different properties , and in the chloride with properties different from either ; so also of the compound radicals . " Sulphuryl Hydroxychloride ; Dibasic Acidsf ( see p. xxxv).\#151 ; In spite of the work of Laurent and Gerhardt , the majority of chemists at that time still preferred to consider potassium sulphate as a salt which , like nitre , contains * 'Roy . Soc. Proc , , ' 1854\#151 ; 5 , vol. 7 , p. 37 . + " Decomposition of Sulphuric Acid by Pentachloride of Phosphorus , " 1854 . Alexander W. Williamson . XXXYll only one atom of potassium , and the acid salt as being potassium sulphate in combination with sulphuric acid . Williamson now placed it beyond dispute that , just as potassium hydrogen sulphate is intermediate to potassium sulphate and sulphuric acid ( hydrogen sulphate ) in there being replacement of hydrogen by metal or the reverse , so sulphuryl hydroxychloride is intermediate to sulphuryl chloride and sulphuric acid ( sulphuryl hydroxide ) , in the interchange of hydroxyl and chlorine:\#151 ; H0(S02)0H , H0(S02)0K , K0(S02)0K H0(S02)0H , H0(S02)C1 , C1(S02)C1 . Gerhardt , who had just then prepared chlorides of dibasic acids , had not succeeded in bringing his facts into line with the theory of monobasic acids , which he had adopted from Williamson . The latter 's discovery of the substance intermediate to sulphuric acid and its chloride ( sulphuryl chloride ) , and his recognition of its nature as such , rendered evident how this was to be done , and demonstrated the fullness with which the water-type theory met the case . In this way , a material impulse was given to the general adoption of structural or valency formulae.* In 1854 , several papers upon subjects worked out in his laboratory by assistants and other students , all bearing the impress of his directing mind , were brought by Williamson before the Eoyal Society . Some of them are of great interest , but space cannot be given for notice of them here . Also , in this year , he read a note before the Eoyal Society on the magnetic medium . In 1855 , when Graham resigned the Chair of Chemistry in University College on becoming Master of the Mint , Williamson was unanimously chosen in his place , the Senate having decided , at Williamson s strongly urged wish , to combine the Professorships of Chemistry and Practical Chemistry in one person . His researches on bleaching salts and on Prussian blue had gained him his first professorship ; now , it was those upon etherification which contributed very largely to his success in getting the second and higher appointment . These researches had just before led to his being made a Fellow of the Eoyal Society . Three weeks after he had obtained his new position he married Emma Catherine Key ( third daughter of his colleague , Professor T. H. Key , F.E.S. , also Head Master of University College School ) , to whom he had been engaged for more than a year . In 18o7 , he was for a month almost deprived of sight by an explosion in the laboratory . The session ending with his appointment to the Professorship of Chemistry was the last in which Williamson published papers upon the lesults of researches by himself , or carried out at his instigation , with the nota e exception of those by Sakurai , in 1880-81 . This abstention from researc work , however greatly to be regretted , is not perhaps much to be wondere at . His mind , indeed , at this time and for years afterwards , teemed with suggestions which , had they been carried out with his own hands , would no * Williamson 's papers on Etherification and the Constitution of Salts have been republished in the convenient form of an Alembic Club Reprint ( 16 ) . xxxviii Obituary Notices of Fellows deceased . doubt have sometimes been fruitful of results though not always those expected . But having to be left to others , competent though they probably were , the facts reached generally caused him to discontinue the pursuit of one idea for that of another , so that a research was rarely brought to a satisfactory conclusion . The same may be said of his later attempts in the applications of chemistry , carried on at his Willesden works . His professorial position made , indirectly , great demands upon his time . He took an energetic interest in the affairs of University College , among other things in forwarding through it the movement to get the University of London to grant Degrees in Science . On the Council of the Chemical Society he served continuously from 1850 , becoming President in 1863 ; and he look a prominent partin the then somewhat frequent and elaborate discussions at its general meetings . In 1859 he began his first term of office on the Council of the Eoyal Society . In all co-operative work his opinions had great weight with his colleagues and others , in consequence , apparently , of the extent to which he at once saw through difficulties , and of his not being dismayed by opposition . Indeed , as a strenuous advocate of any cause he took in hand , he was always a force to be reckoned with , in movements to be undertaken in which he might be interested . He generally came to occupy a forward , if not the front , place in such a movement . Williamson was one of the most hospitable of men , and after his marriage was seldom without one or more friends at his table . He frequently entertained foreign guests , among whom may be mentioned J. P. Cooke , Wurtz , Berthelot , Cornu , and Cannizzaro . Everyone at once felt at home with him and Mrs. Williamson , both blessed with the most kindly dispositions . There is yet another reason , and no doubt the essential one , for his comparative neglect , from this time forward , of the field of chemical research , hitherto so brightly illumined by him . From 1854 , for several years to come , his mind became occupied with the possibility of generating steam for mechanical purposes in a more satisfactory way than was then being followed . By 1859 he had invented a water-tube boiler , or " tubulous " boiler as he suggested it should be called , to distinguish it from the common form with the fuel gases passing along tubes through the water . He then wrote of his invention as important and as fast approaching completion . Again , in 1862 , he called it the best and most important work in his life . This was just after he had taken out letters patent for it . The claim in his patent runs , with slight abridgment , as follows : " The construction of boilers wherein a number of slanting or vertical tubes , each acting as a separate steam generator , are firmly connected to a foundation at their lower ends , and are there made to intercommunicate by having connecting pipes attached to them for supplying the feed water , whilst the upper ends have no rigid connections , and are free to expand in the direction of their length , the steam being conducted , by small curved pipes attached to their upper ends , into main steam-pipes . " Stacks of such pipes formed the side-walls of the combustion chamber , and allowed the hot gases to circulate Alexander W. Williamson . xxxix round the pipes , so as to raise steam and superheat it . As to what extent Williamson 's invention is to be considered as an anticipation of the water-tube boilers now in use with marine engines , it is beyond the competence of the present writer to offer an opinion . Early in 1863 , writing to his father , he referred to his patent and appealed for further pecuniary assistance . His father showed himself unsympathetic and refused help , advising him to leave the invention alone and devote all his abilities to the duties of his professorship . Towards the end of that year ( 1863 ) Williamson received from Mr. Hugh Matheson , of Lombard Street , an offer to send him five young Japanese to be boarded and looked after in matters concerning their education . He was unable to take in more than three of these as boarders , but undertook the general supervision of the education of them all . These young men were destined soon to play important , in some instances most important , parts in the great and practically bloodless revolution whereby the Imperial House of Japan was restored to power , and the country led to adopt and build upon much that it found good in European arts and sciences , forms of government , commerce , manufactures , and education . One of these , now the Marquis Ito , framed the present Constitution ; a second , ( now Count ) Inouye , gave direction to the development of commerce ; a third , also named ( Yiscount ) Inouye , established the railway system ; and a fourth , ( Yiscount ) Yamao , acting as the first Minister of Public Works , introduced , with the aid of instructors from this country , a system of technological training which has Later on , the Prince of Satsuma sent over a party of 16 young Japanese to be placed under Williamson 's care , among them being Mon , who became Minister Plenipotentiary both to London and Hew York , and afterwards a member of the Cabinet in Tokyo . Also of the number , and later on representing their country abroad , were Yoshima and Sameshima . Williamson took a keen interest in all the work of these pioneers a , n some of their successors in the development of Japan on the European si e u-c Po^onlarlv was he resr\gt ; onsible for the selection of the start o proved to be eminently successful . By the use of the pressure tube , xl f Obituary Notices of Fellows deceased . therefore , the necessity of correcting for atmospheric pressure and temperature is avoided and the process of analysis greatly facilitated . A preliminary notice of the apparatus appeared in the * Proceedings of the Royal Society ' for 1857 , but it was not fully described in an improved form until 1864 in the 'Journal of tjie Chemical Society . ' Williamson 's courses of lectures to the students of University College were always of an impressive , suggestive , and interesting character , in spite of the fact that he did not do much to modify them as time went on , in order that they should continue to reflect the rapid developments which chemistry is ever undergoing . He used to say that he had come to look upon his early lecturing as having been much too elaborate and advanced , and to believe in the wisdom of greatly simplifying his teaching . A small text-book published by him , in 1865 , served to illustrate what his notion was as to the ground to be covered by a general course of lectures . The courses of practical chemistry , entailing as they did hard work and continuous attention , he had after a few years to leave to be given by his assistants , several of whom have since become eminent . He was emphatically a great teacher , honoured and revered by his pupils . Williamson gave several lectures at meetings of the Chemical Society : in 1855 , on certain processes for the decomposition of fats by water at high temperatures ; in 1859 , on gas analysis ; in 1861 , on thermodynamics in relation to chemical affinity ; in May , 1864 , on the classification of the elements according to their atomic weights ; in December , 1864 , on chemical nomenclature and notation ; and in 1869 , on the atomic theory . The last three of these are contained in the Journal of that Society . The subject of the classification of the elements had suggested itself to him through the proposal of Cannizzaro to readopt most of the atomic weights used by Berzelius . Cannizzaro had based his proposal mainly on physical grounds , and Williamson proceeded to summarise the chemical evidence in support of Cannizzaro 's system of atomic weights . In this lecture there occurs Williamson 's statement of the grounds for rejecting Kekul4 's contention that the atomic valency of each element must be constant . Thoroughly convinced as to chemical valency being variable , Williamson did not hesitate some years later in his address to Section B of the British Association in 1881 , and elsewhere , to enlarge the notion in applying it to the multivalency of the dominant element in metallic double salts . He thus , to some extent , anticipated Werner 's conception of the " co-ordinating " power of such elements . Representing by symbols the well-known alkali double salts of auric and platinie chlorides as compounds of quinquevalent gold and octovalent platinum , AuCLtNa and PtCleKs , he pointed out the converse analogy of the former with sal-ammoniac , NH4CI , explaining that the atom of sodium is not to be regarded as directly united with the atom of gold , but indirectly with it through the chlorine . The lecture on chemical nomenclature and notation appears to have been Alexander W. . xli given after the attempt at agreement , by a committee of Section B of the British Association appointed to consider the subject , had failed . His recommendations were largely adopted by chemists , and are followed even now to some extent . Williamson was a convinced believer in Dalton 's atomic theory , and held that the results of modern research sufficed to prove its truth . Giving his lecture on the atomic theory from a handful of unarranged notes , he filled the whole time of the meeting with an eloquent assertion of the truth of the theory , holding his large and distinguished audience in unflagging attention . After the summer vacation , another meeting was given up to the discussion of the subject of the lecture . It was a memorable and interesting evening in the life of the Chemical Society . Both lecture and discussion are reported at length in the Journal , but the reports give no adequate reproduction of what was said . Frankland , Brodie ( in the chair ) , Allen Miller , Tyndall , Carey Foster , Odling , Mills , C. R. A. Wright , and others took part m the discussion , and the excitement ran high at times . But nothing came of it all , and chemists remain not much less divided on the subject now than they were then . , In 1862 Williamson was the recipient of one of the Royal medals , awarded by the Royal Society in recognition of his work on etherification . In 1863-4 and 1864-5 he was President of the Chemical Society , the latter being the year in which he delivered two of the lectures just noticed . He was again President of that Society in 1869-70 and 1870-71 . He had thu ? the opportunity of inaugurating the Faraday Memorial lectures , of which the first was given in 1869 by Dumas . The next year he made " perhaps the most memorable year in the history of the Society , " by starting the publication , m its Journal , of monthly reports in the form of abstracts of all papers of a chemical nature , " a work second only in importance to that accomplish^ by the establishment of the Society . No steps could have more direct y promoted the main objects of the Society . _ . Soon after 1870 he established at Willesden some experimental works tor improving and inventing chemical manufacturing processes , an con them for about eight years . Although his outlay must have been considerable , he arrived at no profitable results . Among other things , improvenmnts the manufacture of sodium hydroxide are said to ave even ue . attempted the economic recovery of gold , platmum , and other rar from pyrites , by roasting with salt and in other ways . * In 1863 , at Newcastle , he presided over Section B of_ the British ' ciation , his address being upon recent progress m chemis ry . President of the British Association itself m Bradford , m_1873 , ( taking the subject of his address the meaning and use of scientific what can be done to encourage it for the advancement of science , .He.used chemistry to illustrate his views , and gave the atomic theory asi the has its development and wonderful progress . He again presided o . of the British Association meeting in York , in its Jubilee year in 1881 , in xlii Obituary Notices of Fellows deceased . order that he might trace in his address the history of chemistry since the foundation of the Association , in accordance with the plan of giving that year in each of the sections a history of the science with , which it was concerned . From 1874 to 1891 he was the General Treasurer of the British Association . After serving on the Council in 1859-61 and in 1869-71 , Williamson was made Foreign Secretary of the Royal Society in 1873 , and continued to hold that office till 1890 . He was a particularly able linguist . His earlier papers on chemistry were written by him in German , being intended for but not published in Liebig 's Annalen , and then translated into English for publication in the Memoirs of the Chemical Society . In 1876 he was appointed by Sir C. Adderley to succeed Dr. Letheby as Chief Gas Examiner under the Board of Trade . The Birkbeck Laboratory of University College had for many years proved quite insufficient for the needs of the various classes , to which had been added those in Applied Chemistry . The laboratories now in use were therefore put up under Williamson 's direction , and he moved into them in 1880 . In this year also a research was carried out under his direction , which was interesting not only on account of its results , but of the Japanese nationality of its author , and of the part which Williamson had already taken in promoting the spread of scientific knowledge in Japan . The research was by Sakurai , now well known to chemists , and eminent in Japan among University , professors . He published three papers in the 'Journal of the Chemical Society ' on the subject of metallic compounds of multiyalent hydrocarbon radicals , two of which were worked out in University College laboratory and the third in Japan . The monomercuric iodide derivative of methane was already known , but Sakurai unexpectedly succeeded in obtaining the compounds , \#151 ; CH2(HgI)2 , CH(HgI)3 , ( the metallic analogue of chloroform , CHC13 ) , and other derivatives which as compounds of bivalent and tervalent radicals were of a new order . During 1884 and 1886 , Williamson took an active part in the discussions about a teaching university for London . In 1888 he resigned his active appointments at University College where he had been a professor for 39 years , and was elected Emeritus Professor of Chemistry . A portrait of him , by Collier , which hangs in the Council Room of University College , was presented on behalf of the subscribers by Sir Henry Roscoe . Another portrait , painted by Mr. Biscombe Gardner , was presented , 10 years later , to the Chemical Department of the College . A short time before his retirement , that is , in 1886 , he had gone to live at High Pitfold , Haslemere , and there began to devote most of his time to farming on scientific principles , only now and then visiting London , but much enjoying the occasional visits of his children and grandchildren to Haslemere . Very slowly his health began to decline , and from this cause he had to absent himself from the Jubilee Meeting of the Chemical Society in 1891 . Seven years later , however , he was able by a great effort to attend Alexander W. Williamson . xliii a banquet given by the Chemical Society on November 11 , 1898 , to him and the five other Past Presidents , who had then been Fellows of the Society for at least 50 years . He not only attended the dinner , but spoke , as did his colleagues , to the toast of the evening . The President ( Professor Dewar ) spoke of his services to chemistry in glowing terms . A seniority of four months in Fellowship of the Society made Professor Odling 's turn to speak precede Williamson 's , who was in years considerably his elder , and Odling made happy use of the opportunity to refer to his brother guest . He said , " I have always looked upon myself ... . as a follower of Williamson . It has been my pride to reckon myself one of his adopted pupils\#151 ; a disciple of his ideas more perhaps than many of those who were his actual pupils . He was always very decided in his notions . Sometimes , indeed , I turned a little restive , but was always soon pulled up into form again\#151 ; sometimes more abruptly , perhaps , than was quite agreeable at the moment . At one time I laboured under the sad suspicion of being a little unsound as to the Atomic Theory . " In 1901 Williamson gave up his office of Gas Referee under the Board of Trade , his health having then utterly broken down . He died in May , 1904 , eighty years old , and was buried at Brookwood , in Surrey . Besides his widow , closely associated with him for half a century in almost every incident of his public and private life , with its many hospitalities , his daughter , Mrs. Fison , and her three children , and his son , Dr. Oliver Key Williamson , survive him . Williamson was Ph. D. ( Giessen ) ; LL. D ( Dublin and Edinburgh ) ; D.C.L. ( Durham ) ; Hon. F.R.S.E. ; Fellow of the Uniyersity of London ; Hon. M.R.I.A. ; Hon. Member of the Literary and Philosophical Society of Manchester ; Hon. Member of the German and American Chemical Societies ; Corresponding Member of the French Institute ( Academy of Sciences ) ; Corresponding Member of the Royal Turin Academy of Sciences ; Extraordinary Member of the Accademia dei Lincei , Rome ; Extraordinary Member of the Royal Berlin Academy of Sciences . He was a Member of the Athenaeum Club , elected by the Committee without ballot . To know Williamson was to love him for his truly affectionate disposition . He was a true and constant friend . But there were many acquainted with him who never got to know him . There was a reserve about him which seemed to turn away advances and which made him appear indifferent to forming new friendships . This reserve , however , was all unreal and its appearance wide of the truth . His manner was largely attributable to his -near-sightedness , which , firstly , in his youth led him to find his own company sufficient , and which , secondly , interfered always with that ready recognition of persons and faces which is necessary for the full enjoyment of social life . Far from being really reserved , he had an open and most sympathetic disposition . But , again , to his cost , he was an outspoken , severe , and caustic critic of doctrinal views in chemistry , and in this capacity he seemed to repel men of softer mould . It was always the doctrine he was hard upon , never the man who , to him , was foolish enough to hold it . Qf no one xliv Obituary Notices of Fellows deceased . was he a keener critic than of himself , and it was at times disconcerting to his followers to hear him dilate upon the weakness and uncertainty attaching to views which he was himself habitually defending . To some he seemed not to brook contradiction . It was not really so ; he was only the strenuous advocate , and , however discomposed he felt for the moment , he gave and received blows without any trace of personal ill will . E.D. SIR WILLIAM JAMES LLOYD WHARTON , 1843\#151 ; 1905 . William James Lloyd Wharton , second son of Mr. Robert Wharton , County Court Judge of York , was born in London on March 2 , 1843 . In August , 1857 , having been previously educated at Burney 's Academy , Gosport , he entered the Royal Navy on board H.M.S. " Illustrious , " at that time recently commissioned as a training ship for Naval Cadets , stationed at Portsmouth . Passing out of the " Illustrious " with great credit , he was appointed midshipman of H.M.S. " Euryalus " in April , 1858 , on board which ship Prince Alfred , afterwards Duke of Edinburgh , was also serving . In November , i860 , he was appointed to H.M.S. " Jason , " and , while serving in her on the North American and West Indies Station during the summer of 1861 , he was lent to H.M.S. " St. George , " employed on fishery duties in Newfoundland . Having completed his time as midshipman , on January 13 , 1863 , he passed his examination in seamanship for the rank of lieutenant . The " Jason " returned to England to pay off at the close of 1864 , Wharton having received his commission as Acting Lieutenant of her two months previously . He now had the opportunity of completing the necessary qualifying examinations in gunnery and navigation , in which he acquitted himself brilliantly , a ; nd was confirmed in his rank March 15 , 1865 . In December he was awarded the Beaufort Testimonial for passing the best examination of the year in Mathematics , Nautical Astronomy , and Navigation . In the meantime , in July , 1865 , he had been appointed to H.M.S. " Gaunet , " a sloop commissioned partly for the general duties of the fleet and partly for surveying service on the North American and West Indies Station , but acting entirely und'er the orders of the Commander-in-Chief . In that ship he acquired his first experience in the work to which his life was afterwards devoted , showing great ability and aptitude for surveying duties , and receiving the commendation of the Board of Admiralty for the zeal displayed by him in the work performed in the Bay of Fundy . The " Gannet " paid off in November , 1868 . The Commander-in-Chief , Vice-Admiral Sir James Hope , had already realised Wharton 's abilities , shown as much by his practical work on board Admiral Sir William xlv the " G-annet " as in the distinction he had gained in passing his examinations ; consequently , when the Admiral was about to hoist his flag at Portsmouth , Wharton was offered the appointment of Flag-Lieutenant . The Hydro-Grapher meanwhile had promised to submit his name as 2nd Lieutenant of H.M. Surveying Vessel , " Newport , " and Wharton , considering himself pledged to the surveying service , was prepared to forego Sir James Hopes offer* although he was fully aware he would thereby sacrifice the prospect of certain promotion at the end of three years . Fortunately , however , Sir James Hope took another view , and , speedily arranging matters with the Hydrographer , Wharton was appointed as his Flag-Lieutenant on March 1 , 1869 . Whilst so employed he wrote " The History of H.M.S.'Victory , ' " which still commands a steady sale to the public , the proceeds being devoted to the Royal Naval Seamen 's and Marine Orphans ' Home , Portsmouth . HMS . " Urgent " being temporarily commissioned in November , 1870 , to convey a scientific expedition to the neighbourhood of Gibraltar to observe the forthcoming total eclipse of the sun , Lieutenant Wharton was gratified at being appointed to her as 1st Lieutenant for the cruise . On March 2 , 1872 , he was promoted to Commander on Sir James Hope striking his flag , and the following month was appointed to the command of H.M. Surveying Vessel , " Shearwater , " on the Mediterranean Station , and afterwards on the East Coast of Africa . His work in the Mediterranean was chiefly distinguished by a valuable contribution to Science in the form of an investigation of the surface and undercurrent in the Bosphorus , setting at rest the many controversies respecting the exhaustless flow of water from the Black Sea to the Sea of Marmora by proving that an undercurrent existed as strong as that on the surface , but which invariably flowed m exactly an opposite direction . His report , which was officially published , may be considered as prescribing the method for similar enquiries . ^ . , Whilst at Rodriquez , in the South Indian Ocean , he took part m observing the transit of Venus in 1874 . , " , , . The " Shearwater " was paid off in July , 1875 , and m June the following year he commissioned the " Fawn " for surveying service in the Mediterranean Red Sea , and East Coast of Africa . Starting with a staff of officers , most of whom were wholly inexperienced , Commander Wharton set himself to train them after his own ideals , and succeeded in imbuing his assistants with something of his untiring energy and love of the work . Whis exacting the utmost that each individual was capable of giving to the service , he exercised unremitting patience and forbearance , and throughout a prolonged commission of four and a-half years , endeared himself to all who had the happiness to serve under him . He was sympathetic and considerate towards both officers and men , and entered heartily into all schemes for their recreation when opportunity offered . This commission of the Fawn was perhaps one of the most successful , as it certain y was one o e happiest , ever spent by a surveying vessel in modern times . The las two xlvi Obituary Notices of Fellows deceased . years were occupied with the survey of the Sea of Marmora , an excellent piece of work for which he and his officers received an expression of the approbation of the Lords of the Admiralty . On January 29 , 1880 , Wharton was promoted to Captain , and the " Fawn " was paid off at Malta at the end of the year . " Hydrographical Surveying " was written by Captain Wharton during the interval of leisure which now followed , and immediately on its publication it was recognised as the standard work on the subject . As such it is still in use in both British and Foreign navies , its value being thus well proved despite the characteristically modest tone of its author 's preface . In March , 1882 , Captain Wharton commissioned H.M.S. " Sylvia , " for surveying service in the River Plate and Straits of Magellan . He successfully observed the transit of Venus for the second time in December that year . The work in the Straits of Magellan was pushed on rapidly in spite of hardships and difficulties which had to be encountered , with the result that the survey was completed within the allotted time , but two seasons ' work carried on in such an inhospitable climate , and in such dangerous waters as the western part of the Straits of Magellan , told so considerably upon Captain Wharton , that during this time he aged much in appearance . Before he left England it had been an open secret that on the retirement of Sir Frederick Evans , Captain Wharton should succeed him as Hydrographer of the Navy . On the return of the " Sylvia " to Montevideo in March , 1884 , it became necessary therefore that he should leave the ship and proceed to England by mail steamer . On August 1 , 1884 , he was appointed Hydrographer , at an age younger than that of any officer preceding him in the office . This closed his career afloat . Wharton 's administration of the hydrographic department of the Admiralty continued uninterruptedly for 20 years with constantly increasing credit , and to the great advantage of our own Navy , as well as of the whole maritime world . This period covered the enormous expansion that took place both in the 'personnel and maUriel of the Fleet , causing corresponding accessions to the labour of departmental work . During the same period the number of chart-plates was largely increased , and the number of charts printed annually for the Fleet and for sale to the public multiplied threefold . Gifted with an extraordinary capacity for work , Wharton never spared himself ; the sound judgment , and wide scientific attainments , which he constantly brought to bear upon the infinite variety of subjects with which he was daily called upon to deal , secured for him the respect and confidence of successive Boards of Admiralty , to whom he was an ever true and inestimable adviser in all matters hydrographic . Not the least important part of his work at the Admiralty was the advice he was called upon to give on naval engineering works generally , and particularly on the great engineering schemes which have been proceeding during the last ten years under the Naval Works Acts . Admiral Sir William Wharton . xlvii In dealing with such questions , his clearness of thought , the breadth of his general knowledge , his keen appreciation of engineering difficulties , and his broad and far-seeing view of Naval requirements were of the utmost value in framing the general lines of the schemes , as well as maturing their details . Always willing to give his advice and assistance to his colleagues at the Admiralty , his general remarks and criticisms afforded information of the greatest value to them , and in general conversation on professional subjects all those with whom he was brought in contact could realise how wide his knowledge was . The part he played in settling the main principles upon which the Naval Defences of the country are now based can only be known to and appreciated by those with whom he was associated at the time . It was one of his marked characteristics that the mass of information he had acquired on all sorts of subjects was at once available on the spur of the moment . No matter what difficult question might arise in any part of the world , he was ever ready with the proper answer ; yet although his mind was such a storehouse of valuable and instantly available knowledge , he remained to the last the same simple and modest sailor as he began . As ex-officio member of the Meteorological Council he attended its meetings assiduously and rendered important service to the advancement of Ocean Meteorology . His personal interest in the surveying service was unceasingly manifested in the voluminous semi-official correspondence he maintained with the officers in command of surveys . Scientific subjects of every kind bearing on hydrography always claimed his attention . His strong desire was ever to make his work thoroughly scientific , and to ensure that the same ideal was kept before the surveying officers of the Navy . Thus he took great pains to have a new and revised edition of the ' Admiralty Manual prepared , and he sought as coadjutors in this task the most distinguished and experienced men of science in each branch of investigation treated of in that excellent work . So anxious was he to furnish the surveying staff with all the available assistance in their work that he applied to the Director-G-eneral of the G-eological Survey for a list of the more typical and frequently recurring minerals and rocks , and he had a series of collections of specimens made and distributed among the surveying vessels . He wished that every naval officer , besides being thoroughly trained to do the official work entrusted to him , should be taught to use his eyes in observing Nature , and be encouraged to communicate his observations to headquarters . Nowhere could these communications be more sure of a kindly and sympathetic reception than at the hands of the Hydrographer . He used to write appreciative letters to the authors of them , and where the observations seemed to be of sufficient novelty and importance he spared no pains to have them published either by the Admiralty or in the pages of some scientific journal . In 1886 Captain Wharton was elected a Fellow of the Royal Society , xlviii Obituary Notices of Fellows deceased . serving on its Council from 1888 to 1889 , again from 1895 to 1897 , and lastly from 1904 until his death . As a Fellow of the Royal Astronomical Society , as well as of the Royal Geographical Society , of which he was Vice-President , and as member of numerous committees , he rendered services only less important than his official work at the Admiralty . His first contribution to the publications of the Royal Society was the investigation of the great waves produced by the eruptions of Krakatoa in 1882 , which had been begun by the late Sir Frederick 'Evans and left unfinished at his death . In 1893 he edited the journal of Captain Cook during his first voyage round the world . At the meeting of the British Association at Oxford in 1894 , he presided over Section E. Many contributions to ' Nature ' appeared from time to time from his pen , the investigation of the origin and formation of coral reefs being a subject of especial interest to him . On this question he advanced a theory , based upon the result of the surveys of a large number of these reefs , that the effect of wave action was mainly accountable for the striking uniformity of depth so frequently met with over the interior of coral banks in the open ocean . He insisted that the erosive influence of the waves in open oceans extends to greater depths than had previously been considered possible . As a member of the Coral Reef Committee of the Royal Society , he was largely responsible for the selection of Funafuti as the atoll to be investigated by sounding and boring operations , and he was instrumental in securing the co-operation of the Admiralty in the work , which has produced such valuable results in the monograph published by the Royal Society . He was keenly interested in the project for Antarctic exploration , but more particularly in its bearing upon terrestrial magnetism , and he took an active part as a member of the Joint Committee of the Royal and Royal Geographical Societies appointed to organise it . He was placed on the retired list in 1891 , in accordance with the regulation respecting non-service at sea . Promoted to Rear-Admiral on January 1 , 1895 , on the Queen 's birthday that year he was nominated as C.B. On the occasion of the Diamond Jubilee in 1897 he was created K.C.B. On July 31 , 1904 , Sir William Wharton resigned the office of Hydrographer . For some years previously he had suffered much inconvenience and pain owing to an injury to his right wrist received whilst serving in the " Shearwater " ; for this and other causes he determined to relinquish the appointment . In July , 1905 , after a visit to Aix-les-Bains , he accepted with some hesitation the reiterated invitation to go out to South Africa with a party of members of the British Association , and he presided over Section E at Cape Town . Unfortunately he fell ill on the return journey from the Victoria Falls , and could not return to England , as he intended , with his friends . His illness , which was at first thought to be a chill , proved to be enteric fever complicated with pneumonia , and although no effort was spared to effect his recovery he died at the Observatory at Cape Gen. Sir Charles W. Wilson . xlix Town on September 29 , where he was the guest of his old and valued friends Sir David and Lady Gill . He was buried at the Naval Cemetery at Simon 's Town on October 1 , with naval honours , H.M. the King being represented by the Commander-in-Chief of the station . He was married in 1880 , to Lucy Georgina , daughter of Mr. Edward Holland , of Dumbledon , in Gloucestershire , and by her , who survives him , he had two daughters and three sons , two of whom are now serving in H.M. Navy . A. M. F. SIE CHARLES WILLIAM WILSON . 1836\#151 ; 1905 . \ Charles William Wilson , second son of Edward Wilson , Esq. , J.P. , of Hean Castle , Pembrokeshire , was born in Liverpool , March 14 , 1836 . He received his education , first at St. Davids , and later at the Liverpool Collegiate Institution , at Cheltenham College , and the University of Bonn . In his nineteenth year he entered the Royal Engineers , gaining second place in the open competition and was gazetted Second Lieutenant , September 24 , 1855 . His special fitness for pioneer work was early recognised , and in 1858 he was selected to serve as Secretary and Superintendent of transport and commissariat arrangements to the Commission for the Survey of the boundary between Canada and the United States . By the Treaty of 1846 , the parallel of 49 ' N. had been constituted as the boundary line , but the earlier surveys made from the Atlantic coast had only been carried as far west as the meridian of 95 ' W. , ending at the Lake of the Woods , close to the western extremity of the Province of Ontario . The survey party of 1858 , under the command of Colonel Hawkins , the Chief Commissioner , began their operations at Boundary Bay , on the Strait of Georgia , and worked eastward through the difficult and uncivilised region of swamps , forest , and mountain , as far as the meridian of 114 ' , ending at the eastern boundary of British Columbia , on the eastern range of the Rocky Mountains . In the latter part of the work much of the superintendence of the actual survey was committed to Lieutenant Wilson , and on the completion of the survey in 1863 he received the thanks of the Secretary of State for Foreign Affairs , and was promoted to the rank of Second Captain . In August , 1864 , Captain Wilson undertook the task of making a survey of Jerusalem and the surrounding country , in connection with the scheme originated by Miss Burdett Coutts for providing a supply of pure water to that city . This work he accomplished with signal success , and he carried his survey through the country to the east of Jerusalem , as far as the Dead Sea , of which he determined the level . Owing to local intrigues , the project of the water-supply was not then proceeded with , but the maps and plans , made by Obituary Notices of Fellows deceased . him are of permanent value and have been the groundwork of all subsequent topographical research in this region . He published descriptive notes explanatory of his maps at the time , and at a later date he wrote a short paper on the water-supply of Jerusalem . The interest aroused by the researches of Captain Wilson , as well as his direct personal influence , led to the organisation , in 1865 , of the Palestine Exploration Fund , and the Executive Committee of that body appointed him as the first Director of the Exploration . In this capacity he returned to Palestine in 1865 , and made a preliminary survey of a large part both of Judaea and Galilee . He made plans and drawings of many ancient sites and ruins , and carried a line of Azimuths from Banias to Jerusalem . From this work he was recalled to take part in the Ordnance Survey of Scotland in 1866 , and was succeeded by Captain ( now Sir Charles ) Warren . In recognition of the value of his survey he was elected member of the Executive Committee of the Palestine Exploration Fund , and later he was awarded the Diploma of the International Geographical Congress at Antwerp , in 1871 . While connected with the Scottish Survey he acted as Assistant Commissioner on the Borough Boundaries Commission in 1867 . In 1868 he again visited the East to make , in conjunction with Captain Palmer , a survey of the Sinaitic peninsula , a difficult task which he accomplished in less than six months . His notes of this exploration were published in the following year . On his return he was appointed Executive Officer in the Topographical Department of the Wkr Office , and in 1871 , on the expansion of this branch into the Intelligence Department , he became its Director , with the rank of Assistant Quartermaster General . He was in this year elected Member of Council of the Hoyal Geographical and of the Biblical Arehseology Societies , and in 1872 received the decoration of C.B. ( Civil ) . In the following year he was promoted Major of Royal Engineers . He was elected a Fellow of the Royal Society in 1874 , and in that year was President of the Section of Geography of the British Association . The next task entrusted to him was the compilation of the map of Afghanistan for the India Office . For this work , which he completed in 1875 , he received the thanks of the Secretary of State for India . In the following year he was appointed to the Command of the Ordnance Survey of Ireland , in succession to Lieutenant-Colonel Wilkinson , and held that office until 1879 . During his tenure of this office he also served on the Royal Commission for the Registration of Deeds and Insurances , and while in residence at Mountjoy Barracks he was a frequent and welcome guest at the Council breakfasts of the Royal Zoological Society , and took much interest in the work of that Society . # . In 1878 he was again ordered abroad to serve as British Commissioner for the delimitation of the boundaries of Servia under the Treaty of Berlin . For his services in that capacity he received the thanks of the Government , and was promoted Brevet Lieutenant-Colonel in 1879 . On account of his remarkable knowledge of Eastern affairs he was Gen. Sir Charles Wilson . li appointed in 1879 to the responsible post of Consul-General in Anatolia . While he held this office he travelled through little-known parts of Asia Minor , and was sent on special missions to Bulgaria , Macedonia , and Roumelia . Much of the information which he thus collected is embodied in the " Handbook to Asia Minor " and the " Handbook to Constantinople , " edited by him for Murray 's Series . For these services to the Foreign Office he was accorded special thanks , and he received the Order K.C.M.G. in 1881 . In that year he was also promoted Regimental Lieutenant-Colonel . On the outbreak of the rebellion of Arabi Pasha in 1882 he accompanied the force under Sir Garnet Wolseley to Egypt , and took his share in active military service . On the suppression of the insurrection he served under Sir Edward Malet , and was put in charge of several important matters ; among others he was appointed to superintend the prisons in which the political prisoners were confined , and to watch their trial , on behalf of the British Government . In the discharge of these duties there were many difficulties to be overcome , but these he surmounted with much tact and discretion , and received the thanks of the Government and the rank of Brevet-Colonel in 1883 . When Lord Dufferin 's Commission was sent for the reorganisation of the Egyptian Administration , Colonel Wilson was appointed on the Staff , and in this capacity his attention was directed to the affairs of the Soudan , where the Mahdi Mohammed Ahmed had proclaimed himself as the prophet foretold by Mohammed and had raised the standard of rebellion against the Egyptian Government in August , 1881 . On this subject Colonel Wilson made a report in 1882 to the Consul-General , and recommended that a British force should be sent to Khartoum to examine and report on the steps which were required for the quieting of the native unrest . In accordance with the suggestion in this report , Colonel Stewart was sent thither and made his report in 1883 , but the recommendations made therein were shelved , although by that time the rebellion had become a formidable menace to Egypt after the crushing defeat of Assuf Pasha . Meantime Sir Charles Wilson was recalled home to his former post as Director of the Irish Ordnance Survey . The British Government imperfectly realised the gravity of the situation , and sent , in 1884 , General Gordon for the purpose of withdrawing the isolated garrisons of Egyptian troops from the Soudan . The subsequent events are matters of history , and need not here be detailed.-When the Government realised the necessity of sending an expedition for the relief of Gordon , Sir C. Wilson was appointed Chief of the Intelligence Department with Lord Wolseley 's force , and joined the Army in September , 1884 , with the rank of Deputy Adjutant and Quartermaster-General . The expedition reached Korti , south-east of Dongola , on December 16 , 1884 , and on January 8 Sir Herbert Stewart and Sir Charles Wilson were sent on with the Camel Corps to communicate with Gordon , and to let him know that a relief expedition was on the way . The instructions were explicit that Wilson was only to stay long enough to confer with General Gordon and to return e 2 HI Obituary Notices of Fellows deceased . then at once with Lord Charles Beresford to Matammeh . In his book on the expedition " From Korti to Khartum " ( 1886 ) , Sir Charles Wilson has given a graphic account of this disastrous journey and of the chapter of accidents which delayed it . As Sir Herbert Stewart was wounded at Abu Klea the command devolved upon Sir Charles Wilson , and he started from Gubat at the earliest possible opportunity , on the 24th January , for his four days ' journey up the Nile , only to learn that Gordon had been killed on the 26th . Even had he arrived two days earlier with the small and undisciplined force under his command , he would have been unable to alter the course of events , and would most probably have shared Gordon 's fate . For his services in this expedition he received from the Secretary for War a telegram of " warm recognition of Government of brilliant services of Sir Charles Wilson , and satisfaction at gallant rescue of his party . " He was specially mentioned in Lord Wolseley 's despatches , and was created K.C.B. in 1885 . Shortly after his return home he was appointed Director-General of the Ordnance Survey , and began the revision of the Irish Survey maps on the 1/ 2500 scale , as well as the Survey of Yorkshire and Lancashire on the same scale . He also carried on a general revision of the small scale maps , so as to bring them up to date . He initiated a scheme for the organisation of Survey sections for service with an army in the field . He continued in command of the Survey until 1894 , having been promoted Major-General on February 15 in that year . In the next year he was appointed Director-General of Military Education , an office which he held until 1898 , when he retired under the age clause of the Boyal Warrant . While discharging these duties he found time to write a " Life of Lord Clive , " for the " English Men of Action " series published in 1890 . Sir Charles Wilson served on the Council of the Eoyal Society , 1889-90 , and his work was recognised by the conferring on him by Oxford of the honorary degree of D.C.L. in 1883 , by Edinburgh of the degree of LL. D. in 1886 , and by Dublin of the degree M.E. in 1893 . Through all the stages of his varied career he kept up his interest in the work of the Palestine Exploration Fund , and on the retirement of Mr. Glaisher he was unanimously elected Chairman of its Executive Committee . The duties of this office he discharged with unremitting zeal , keeping himself in touch with the progress of the work of exploration in the field , visiting the excavations both at Tell Zakariyeh and later at Gezer . For the last year of his life his work was hindered by a severe affection of the eyes , but he continued to edit the " Quarterly Statement " of the Fund and to attend its committee meetings almost to the end . The last research on which he was engaged was an exhaustive study of the evidence as to the site of the Holy Sepulchre , and he had almost finished the revision of his manuscript when he was laid aside by his last illness . This book will soon be published by the Palestine Exploration Fund under the supervision of Sir Charles Watson , who has succeeded him as Chairman of the Executive Committee of the Fund . He died on October 25 , 1905 , at Tunbridge Wells . Gen. Sir Charles W. Wilson . liii Sir Charles Wilson married , in 1867 , Olivia , daughter of Colonel Adam Duffin , Bengal Cavalry , who survives him ; he also leaves a daughter and four sons , three of whom are officers in the Army . He was in manner quiet , courteous , dignified , and remarkably unobtrusive , but one could not be long in his company without realising his quick and correct judgment of men and affairs , his wisdom and firmness of purpose , his kindness and consideration for others , and his extraordinary store of accurate knowledge . Those associated with him on the Committee of the Palestine Fund learned to rely implicitly on his advice , and willingly to accept his decisions as final . They feel that they have lost a wise and judicious friend indeed , and have stated in their last published report that his death is " the severest personal loss that the Fund has ever sustained . " In addition to the published works referred to , Sir Charles Wilson was also the author of : 1 . " The Becovery of Jerusalem , " 1871 . 2 . " Jerusalem the Holy City , " 1889 . 3 . " Picturesque Palestine , Sinai and Egypt , " 4 vols . 1880 . 4 . " The Pilgrimage of the Bussian Abbot , Daniel , " 1895 . The writer is deeply indebted to Sir Charles Watson for much of the information embodied in this biographical notice . A. M. liv Obituary Notices of Fellows deceased . OTTO STRUVE . 1819\#151 ; 1905 . The death of Otto Struve on April 14 , 1905 , closes more than one chapter in the history of Astronomy . One such chapter might be headed " The Pulkowa Observatory , " and we should find Otto Struve 's name on almost every page from the first to the last . At the foundation of the Observatory in 1839 , he went as assistant to his famous father ; within a very few years he began to perform some of the Director 's duties , and long before he officially succeeded his father in 1864 he had been practically the head of the Observatory . When at last he left Pulkowa after 50 years spent in its service , the " Pulkowa Observatory " officially ceased to exist* and became the " Observatoire Central Nicolas . " Changing our historical arrangement a little , and classifying by lines of investigation rather than by localities , there is a great chapter on " Double Stars " written by the two Struves , following that written by the Herschels . Otto 's name does not occur here till nearly the middle of the chapter ; unless perhaps we find room on the first page , when mentioning the publication of W. Struve 's first Catalogue of 727 stars in 1820 , to record the recent birth of the son who was to be so worthy an assistant and successor . Once again , regarding not the doings of a single observatory or the history of one branch of astronomy , but taking a more general outlook on the spirit of the times , we realize that in Otto Struve there passed away a commanding figure of the " old school " of astronomers . An attempt to define too closely the characteristics of this school would inevitably result in error and failure : but it is significant that the fourteen volumes of observations published under Otto Struve 's Directorate all relate to the 'positions of stars , and contain no allusion to the spectroscope or the photographic plate . Nevertheless ( and there could not be a better illustration of the dangers of being too definite ) we must at the same time remember that the very existence of the department of Astrophysics at Pulkowa is due to him , and that he only established it after considerable trouble . Struve began work at a time when it was scarcely dreamed that Astronomers would ever use the spectroscope or take photographs , and his * The description of the Observatory published by F. G. W. Struve in 1845 is entitled ' Description de l'observatoire astronomique Central de Poulkova . ' Fourteen volumes of observations were published by Otto Struve , entitled ' Observations de Poulkova , publiSes par Otto Struve , Directeur de l'observatoire Central Nicolas , ' the last words being in quite small type . On Struve 's retirement a new series of volumes was started with the style ' Publications de l'observatoire Central Nicolas , Serie II . ' The last volume of Serie I to appear , numbered vol. 10 , is dated 1893 , and contains Struve 's name as " Ancien directeur . Otto Struve . lv first lessons were calculated to impress indelibly upon his mind the fundamental importance of work in which the spectroscope and the photographic plate have even yet taken no part . His early years were devoted to a determination of the constant of precession , and the value he obtained was adopted for general use . His observations led him to side with Herschel , and against Bessel , on the question ( at that time new ) whether the Solar system was moving in space . Moreover , he witnessed the determination , about the same time , of the constant of aberration by his father , and of that of nutation by his colleague Peters . He saw the Pulkowa Observatory take a leading place in the astronomical world for its accurate measures of stellar positions , and it was his own life work to help in raising it to that place and maintaining it there . He lived long enough to see a new constant of precession suggested for adoption , after his own had been in use for half a century , and died just as evidence* was being published in support of his old value as against the proposed change . Otto Wilhelm Struve was born on May 7 ( April 25 , O.S. ) , 1819 , at Dorpat , where his father was Professor in the University and Director of the Observatory . He was the third iD a family of 18 children . He completed his gymnasium and university course early and was already an assistant to his father when the latter was summoned to found and direct the great Pulkowa Observatory . Otto took his place as assistant in the new Observatory with three colleagues , 0 . Puss , G. Sabler , and C. A. F. Peters . The programme adopted at the outset was the determination of three astronomical constants , aberration by W. Struve , nutation by Peters , and precession by 0 . Struve ; and the success attained has already been mentioned . Other observations of an orderly kind were also carried on , but there was no attempt made to publish them for many years . This fact was lamented by Airy in 1847 , and doubtless his representations had some weight in stimulating the ultimate publication of the first two volumes in 1869 . But this was after the directorship had passed from the hands of W. Struve into those of his son . It seems proper to recall here , alongside the mention of Airy 's action , that we owe to Otto Struve the movement for doing full justice to the observations made by a great Englishman . It was Winnecke , at Struve 's instigation , who first undertook the re-reduction of Bradley 's observations , though the work passed into t e able hands of Dr. Auwers at an early stage . For the determination of precession , which occupied his ear y years , a Pulkowa , Otto Struve received the Gold Medal of the Royal Astronomical Society in 1850 . The work had been completed nine years before , and this fact is apologetically mentioned by the President ( Airy ) in an interesting manner . " A rather unusual delay , he said , has occur m ie n\lt ; ? of this paper ( on precession ) . This has arisen partly from the delay which usually occurs in the printing and distribution of foreign memoirs , partly * ' Mon . Not . E.A.S. , ' vol. 45 , p. 443 . Dated March , 1905 , published April . Struve died April 15 . lvi Obituary Notices of Fellows deceased . from the time which is necessary for thoroughly reading a paper of such length ; but principally from the occupation of the minds of astronomers , as well within as without the Society , by the remarkable planetary discoveries made in several years past . " This was in February , 1850 , the discovery of Neptune having been made on September 23 , 1846 , while six new minor planets had just been found , after a barren interval of 40 years since the first four . The mention of the discovery of Neptune recalls the fact that Otto Struve was elected an Associate of the Eoyal Astronomical Society on the same day ( May 12 , 1848 ) as Gall , who actually discovered the planet ; and Struve 's death leaves Gall as the unrivalled doyen of the Society , which honoured him a dozen years before any existing Fellow was elected . But having completed his work on precession , Struve became henceforth a double star observer . We may no doubt trace this bent to his whole-hearted devotion to his father , which is writ large on every page of his published works . It was not in double star observing alone that this devotion found expression . In a memoir of his father left in MS . he has recorded that in 1845 ( when he was only 26 ) he had already practically taken over the duties of administration of the Observatory , though ' the official acknowledgment of the fact did not follow for many years . Possibly the strain of these early years may have contributed to the serious illness which overtook him in 1864 soon after he was actually appointed Director . The doctors actually gave him up , and though he recovered , he was so broken in health as to think of resignation . A winter in Italy , however , fortunately restored him ; and he returned to a long and prosperous term of office and activity . Indeed the length of his record as an actual observer is remarkable ; there are certainly one or two measures of double stars recorded as made by him at Dorpat in 1836 , and there are others dated 1889 . Few indeed can match a record of 53 years as an observer . But his veneration for his father fortunately did not cramp his originality . He selected for special study stars of a distinctly new type . W. Struve had deliberately chosen double stars with components not differing much in brightness ; what first suggested to his son to form a catalogue of stars having faint companions ? The difference may at first seem to be one of detail ; but it represents an important step taken in the study of double stars , preparing the way for the modern work of Burnham and others . Another important line struck out by Otto Struve for himself was the investigation of personal peculiarities of measurement . The idea of " personal equation " in a variety of forms is familiar enough to us now ; but in 1853 it was only recognized in transit observations , and was deduced from comparison of the observations themselves , not by any attempt at independent determination . Such comparisons of observations inter se were , in the case of double star observations , not available in sufficient number to determine personal differences , though there were enough to suggest them . Struve devised his famous artificial adjustable double star to Otto Struve . lvii investigate his own peculiarities . The actual separation and position angle of the artificial double were known ; and turning his telescope horizontally towards the distant model and measuring them as he would those of a real double , he found the systematic errors in his measures . The errors were large ( 13 ' in position angle in some cases ) and were not quite satisfactorily determined with the apparatus , as is intelligible when we remember that the stars in the actual sky are observed with a telescope which is anything but horizontal , and that they are liable to atmospheric disturbances . But Struve obtained at any rate a large measure of success , and was able not only to eliminate the main part of such systematic errors from his future observations , but by comparison to infer suitable corrections for observations already made . The summary of his life-work as an observer is to be found in Volumes IX and X of the Pulkowa Observations , Volume X being completed in 1893 . We must not forget to add the work he did in editing , jointly with Schiaparelli , the two volumes of Dembowski 's observations of double stars which appeared in 1883 . It would do scant justice to Otto Struve to regard him merely , or even chiefly , as a double star observer . The range of his interests and activities was very wide . In 1851 he read before the Academy of Sciences an elaborate paper on the Rings of Saturn , suggesting from a discussion of old and recent observations that they were spreading inwards to the planet ; ( this hypothesis has not been confirmed ) . Geodetic work absorbed much of his attention , and it was on his initiative that the 47th parallel of latitude , which had been selected for measurement , was given up in favour of the 52nd . By this change the arc was extended at both ends ; the eastern end became Arsk in Siberia , and ( what is of chief interest to us ) at its western end the arc crossed England and terminated in Valencia in the extreme S.W. of Ireland . Recent work on the longitude of Waterville carried out under the direction of the Astronomer Royal has a direct bearing upon the investigation as modified by Otto Struve . In another enterprise of international interest he was not so successful . He had succeeded in persuading the authorities of the advantages in adopting the Gregorian calendar in general use by other European nations ; and the change was under serious consideration in high quarters , when all chance of reform was abruptly destroyed by the dynamite explosion in the Winter Palace.* On the occasion of the Paris International Conference in 1887 , which led to the scheme for charting the heavens by photography , Struve was unanimously called to the chair . His opening address contains a paragiaph so characteristic of the man and of the epoch that it may fitly be quoted heie . " En effet , l'Astronomie pratique poss\amp ; de aujourd'hui , dans la Photographie , un instrument de la plus haute valeur et qui , probablement , avec le temps , * Y.J.S. ' Ast . Ges . , ' Jahrg . 40 , Heft 4 , pp. 298-9 . To this notice by M. Nyr6n the present writer is indebted for much , of the information here given . lyiii Obituary Notices of Fellows deceased . faeilitera 4norm4ment nos Etudes ^pineuses . Mais restons sobres dans nos provisions . Pour le moment , nous no devons regarder la Photographie que comme un instrument trOs prOcieux , mais dont l'Otude rest encore k complOter . Nous devons tocher d'elever la Photographie cOleste k ce degrO de perfection qui la rendra digne de concourir sous tons les rapports avec les mOthodes d'observation usitOes jusqu'k present , mOthodes qui ont valu \amp ; l'Astronomie pratique la position enviable dune science experimentale dont les conclusions peuvent rivaliser en rigueur avec les theories mathematiques . " These words remind us of those in which Wilhelm Struve opens his description of the Pulkowa Observatory ( 1845):\#151 ; " L'Astronomie , par la sublimite de son sujet , occupe un place 4minente parmi les sciences naturelles . Elle est , par excellence , la science naturelle exact . " It may be doubted whether Astronomy in its modern developments will be able to maintain this claim of an exactitude greater than that attainable in other sciences , if indeed it could ever rightly advance it ; but there is no doubt that to the Struves the claim was a righteous one , and was the source of no little inspiration . The Transit of Yenus of 1874 brought with it much work of organisation for Otto Struve . So too did the Total Solar Eclipse of 1887 . His own preparations for the latter event were characteristically all for observations of position , but some 40 astronomers of other nations visited Russia on the occasion , and Struve made the most hospitable arrangements and careful plans for their comfort . Nearly all of them passed through Pulkowa and were entertained by him at his own house . He took great interest in their proposed work , though much of it was clearly strange to him . For instance , he learned with obvious surprise of the time for preparation required by those desiring to make photographic or physical observations : he had estimated that no one would wish to be at his station more than 2 or 3 days altogether . But on realizing their requirements , he did all he could to secure the requisite facilities . The memory of those few days at Pulkowa , when at the same table , spread in the open air in order to make the most of the short northern summer , there were gathered astronomers from Italy , Spain , France , Germany , America , and England , to each of whom Otto Struve spoke in his own language ; when we caught a glimpse of the daily life of the little secluded community , with such special features as the disappearance of all the males in the afternoon to sleep , so that they might be regularly on the alert for observations till 3 a.m. ; when we were privileged at night to look through the great 30-inch refractor , which had not then been thrown into shade by the Lick and Yerkes telescopes ; the memory of these days will long remain with astronomers of many nations . They were almost the last days of Struve 's life at the Observatory . Two years later , in 1889 , there was again a great gathering of foreign astronomers to celebrate the Jubilee of the foundation of the Observatory : but Struve s resignation had already been accepted , although it had been decided , by the Otto Struve . lix express wish of the Ozar , that he should remain in office until the ceremony was completed . Otto Struve was twice married : first to Emilie Dyrssen , who died in 1868 ; secondly , to Emma Jankowsky , who died in 1902 . He celebrated the " silver-wedding " of both marriages . By his first wife he had several children , of whom 4 sons and 2 daughters reached maturity , though one died before her father ; by the second wife he had one daughter . Of the sons the two youngest are well known astronomers : Hermann , Director of the Berlin Observatory , who received ( in the third generation ) the Gold Medal of the Boyal Astronomical Society in 1903 for his brilliant work on the satellites of Saturn with the great Pulkowa refractors ; and Ludwig , Director of the Charkow Observatory , who followed in his father 's footsteps by determining the constant of precession and the movement of the solar system . The honours conferred on Otto Struve would make a long list , for he was a foreign or corresponding member of almost all European learned societies . The date of his recognition by the Royal Society is 1873 . In 1868 the Bonn University conferred a Doctorate upon him , honoris causa . After his retirement from Pulkowa he lived a few years in St. Petersburg ; later in Karlsruhe , on account of failing health ; though until recently he paid a visit to St. Petersburg every summer . He died without any serious protracted illness , in his 86th year , on April 14 , 1905 . By his own wish his ashes are to be taken to Pulkowa and laid under the stone on which his own special instrument , the 15-inch refractor , stood at the time of his observations . H. H. T. lx Obituary Notices of Fellows deceased . GEORGE JAMES SNELUS , 1837\#151 ; 1906 . The subject of this notice was born at Camden Town on June 25,1837 . He was originally trained as a teacher at St. John s College , Battersea , and subsequently , while following this profession , he attended lectures at Owens College , Manchester . It was here , under Professor Roscoe , that Mr. Snelus laid the foundation of his success by his study of Chemistry and Metallurgy . In 1864 he gained the first Royal Albert Scholarship , and consequently entered upon a three years ' course at the Royal School of Mines . Here he succeeded in obtaining the Associateship in Metallurgy and Mining , and was awarded the He la Beche medal for mining . At the end of his course he was recommended by Hr . Percy for the post of chemist at Howlais Works , and he remained there until 1871 . In 1869 he was elected a Member of the Iron and Steel Institute , and the brilliant series of papers , representing a large amount of true pioneering work , read before that body in the early seventies will secure for him a lasting place in the annals of the iron and steel trade . He was elected a Member of the Council in 1881 , and during the next twenty-five years no one attended the meetings more regularly or took a greater interest in the general development of that body . He became a Vice-President in 1889 . In 1871 Mr. Snelus was selected by the Iron and Steel Institute to visit the United States , and report on the chemistry of the Hank 's rotary puddling process , and the report , when completed , proved to be . the most important contribution ever published on the scientific features of the puddling process . Whilst at Howlais Mr. Snelus made observations which led him to the conclusion that phosphorus could be removed from iron while the metal was in the molten state . Experiments showed him that lime could be burned at a high temperature so as to be impervious to water , and it occurred to him that if he used lime so over-burnt as a lining for a Bessemer converter he would get a basic lining which would not be acted upon by basic slag , and so would be able to eliminate the phosphorus during the Bessemer process . He took out a patent for this in 1872 , and soon afterwards proved experimentally the correctness of his surmise . The invention , however , was not pushed forward or made a practical success in his hands , and it was not until the " basic process " had been developed by Messrs. Thomas and Gilchrist , with the assistance of Mr. E. P. Martin , Mr. E. W. Richards and his metallurgical staff , that it came into commercial operation . It is an undisputed fact that Mr. Snelus was the first to make steel in a lime-lined Bessemer converter . Por his invention in connection with the basic steel process Mr. Snelus was awarded a gold medal at the Paris Exhibition of 1878 , and in 1883 the Iron and Steel Institute recognised the part he had played in developing the process by awarding him , jointly with Mr. Thomas , the Bessemer medal . George James lxi For his discovery , and for his numerous and valuable literary contributions connected with iron and steel , Mr. Snelus was made a Fellow of the Royal Society in 1887 . During the period 1869\#151 ; 1885 he wrote and spoke on a great variety of matters connected with the manufacture of iron and steel , and he was really the first to bring to the notice of iron and steel works ' chemists in this country the true practical value of the molybdate method of determining phosphorus in iron and steel . Indeed , it was mainly due to the influence of Mr. Snelus that chemists in steel works learnt to make analyses sufficiently rapidly to be of value in controlling the manufacture of steel . He went to Cumberland in 1872 and took up the position of manager of the West Cumberland Iron and Steel Company , where he remained many years . Subsequently these works were discontinued and to a large extent dismantled . From that time Mr. Snelus did not undertake managerial work , although he was director of several companies engaged in the iron trade . Only quite recently he had invented a new process for the manufacture of steel , by which a basic-lined rotary furnace is employed . Whether this new process will prove a success remains to be seen . Much of his leisure time was devoted to Volunteering and rifle shooting . He served as a Volunteer for 32 years , and was , for many years , one of the best rifle shots in the country . He was for twelve years from 1866 a member of the English Twenty , and during that period gained a greater aggregate than any other member of the team . Mr. Snelus was also an enthusiastic horticulturalist and a staunch Conservative , and was keenly interested in local affairs , public bodies seeking eagerly for his services . He married Miss L. W. Woodward , daughter of Mr. David Woodward , of Macclesfield , and had three sons and three daughters . Mrs. Snelus died in 1892 . Mr. Snelus spent a busy life until his health broke down . After a long illness he died at Ennerdale Hall on June 18 , 1906 . ^ J. E. S* lxii Obituary Notices of Fellows deceased . CHAELES JASPEE JOLY , 1864\#151 ; 1906 . Chakles Jasper Joly was born in Tullamore , Ireland , on June 27 , 1864 . His father , the Eev . John Swift Joly , was a man of studious bent and author of archaeological studies of local interest . It can hardly be said that any of the more nearly antecedent ancestors of Charles Jasper foreshadowed his remarkable gifts . The family is French on the father 's side , having emigrated from France so long ago as the middle of the eighteenth century . If heredity is to be appealed to for Joly 's mental powers , it is necessary to go back to the seventeenth century , when Claude Joly . an author of distinction , appeared among his ancestors , but not in the direct line . The family claims , however , direct descent from Jacques Joly , a Secretary of State ( about 1640 ) , and from Eeginald , born 1375 , who was " Conseiller " in 1420 , as well as from Antoine Joly , of Blaisy-en-haut , a seigneurie in Burgundy , near Dijon , which was erected into a Marquisate in favour of the said Antoine . Charles Jasper was a brilliant boy at Galway Grammar School , appearing able , when so inclined , to win whatever medals and prizes he aspired to , and even several at one time . In the public Intermediate Examinations he took prizes and honours , but although possessed of this amount of reputation when he entered Trinity College , Dublin , in his eighteenth year , the exceptional powers which he subsequently developed were not indicated in his school career . Even as . a student in Trinity College there was nothing accomplished by Joly that has not been accomplished by many a man who subsequently remained without further distinctions through life . He took a mathematical scholarship\#151 ; by no means on specially brilliant marks\#151 ; and finally won a mathematical studentship , but , again , without the distinction of the " Large " gold medal . His second subject at this examination was Experimental Science . After leaving Trinity College he went to Berlin and entered Helmholtz 's Laboratory with the intention of making Experimental Physics his life study . There he worked under Koenig 's supervision , and would , doubtless , have carried out his intention of giving himself up entirely to the fascination of Physical Eesearch had not the death of his father recalled him to Ireland and rendered it necessary that he should seek some more sure road to a competency . That he altered his intention of devoting himself to Experimental Science was perhaps for the best . For , while he certainly never showed any exceptional originality in that direction , his after career fully justified his diversion to mathematics . The possibility of attaining to the Fellowship of his own College induced him to pursue the mathematical and mathematical-physics courses required for the mathematical side of this test . The severity of this competition is lxiii Charles Jasper intensified by the extraordinary arrangement permitting candidates in mathematics and classics to compete against each other ; the successful candidate being the winner of highest marks , where subjects , papers , examiners are different . For this ordeal it is not uncommon for men to read for five or seven years ; not , perhaps , acquiring fresh wisdom after the first two or three years ' reading , though gradually becoming more proficient in the art of scoring . Year after year Joly fell short of success . Year after year he read Dante and other masters of literature , and , led away by the facile charms of literary studies , he plunged , forgetful of everything else , into the real or unreal world of poetry and romance . It was at this period that my own more intimate friendship with him commenced . Besides the the of relationship , we had many tastes in common . In the course of our endless discussions and speculations there was revealed to me a mind both keen , critical , and honest ; a nature undemonstrative , sincere , and deeply affectionate . It was not till 1894 that Joly was successful in his efforts to gain Fellowship . He appears to have attained something more than Scholarship by the long and arduous preparation required for this trying test . He was injured neither in freshness of originality nor in bodily health . He set to work almost immediately he became Fellow on mathematical work , the only holiday intervening being the annual Swiss tour . A word must be said here on Joly as member of the Alpine Club . His development as mountaineer was as unexpected as his mental evolution . Delicate in appearance , pale in complexion and with rather stooped shoulders , no one would have predicted the athletic prowess he displayed . But two factors were in his favour : he possessed undaunted courage and a power of endurance which must have had its origin also in a marvellous nervous organisation . A very few years later I was with him in circumstances of considerable danger , when on the arete of the Eiger we made our way downwards in the midst of a furious snow storm . Joly led the way with a skill and nonchalance which even in the midst of our troubles claimed our attention . Later , climbing became a passion with him , and his holidays were passed in the Alps , ascending the most difficult peaks . The Dent Blanch , Kleine Zinne , and many others were ascended . ( See notice by Dr. George Scriven , 'Journal of the Alpine Club , February , 1906 , vol. 23 , p. 58 . ) . " The first work to appear from his pen , " The Theory of Vector Functions , was read before the Royal Irish Academy in the same year in which he got his Fellowship . A second paper on the subject of Vector Linear Functions appeared in the ensuing year , 1895 , and two others the next year . At this period his marriage with Jessie , daughter of the late Robert Mead , took place . . , Later in the year 1897 the Board of Trinity College appointed him to the Andrews Professorship of Astronomy and to the post of Royal Astronomer of Ireland . The appointment was a particularly happy one , although at the Ixiv Obituary Notices of Fellows deceased . time there was some difference of opinion as to his suitability for the office . But not only had Joly considerable training in manipulative scientific work , he was already recognised as highly accomplished in the Mathematics of Hamilton , and possessed of originality and activity . All through his reading for the Fellowship he had been more and more drawn to the use of Sir William Bowan Hamilton 's mathematical methods , and it was even stated at the time that his examiners had themselves some difficulty in following the young mathematician in his facile use of Quaternions . The election accomplished , Joly took up his abode in the historic house of Dunsink , wherein Brinkley , Hamilton , and Ball had done much of their best work . Joly now had the freedom from the too constant invasion of visitors and friends and the quiet and healthful surroundings favourable to mental activity . Never , indeed , had the life of a recluse any charm for him . He associated himself with some of the most important Institutions of the City of Dublin and never failed the committee which had a claim upon him . But he was spared petty interruptions . His teaching duties as Professor of Astronomy were light\#151 ; one Term in the Session\#151 ; and an able and careful Assistant was at hand to do the bulk of observational work . The mornings were generally free from disturbance , and , as will be seen , an amazing amount of work was done during the next few years of this quiet life . Many who read this brief memoir will know the beautiful precincts in which Joly and his predecessors have done such good work . The old House commands from the south windows an extensive view . The panorama of the Dublin Hills\#151 ; the rounded granite hills of Leinster\#151 ; rising one beyond the other , invite the imagination into the furthest distance . Between lies a broad and noble valley containing in the near distance the lawns and woods of Phoenix Park , and to the east the City of Dublin . The pastoral element predominates , however , and , seen from this view-point , Dublin might appear to be a city girt with peaceful lawns and forest trees . Further yet , beyond the " towers , domes , citadels , " the Bay of Dublin stretches to the horizon . A more varied sweep of mountains , forest , city and sea it would be hard to find . From the south window of the study an observer lifting his eyes can , at a glance , review it all . Around the house is the fruit garden and shrubbery , planted by Brinkley and Ball , and the old-fashioned box-trimmed flower garden merging into the orchard . Tall trees line the shady walk leading to the gate in the wall where suddenly is revealed to you , across steeply sloping fields , the same majestic panorama of mountains and woods seen from the study window . In this home Joly lived to the end of his brief life , its quietness and its beauty contributing to his work and to his happiness . A period of ever-increasing mental activity followed upon his appointment . The great work of editing ' Hamilton 's Elements of Quaternions and bringing this vast treatise up to date was already upon his hands . It had now to be completed , but its completion did not hinder Joly from continuing the publication of papers on various mathematical subjects . Thus we . have a Charles Jasper Joly . lxv paper on " The Associative Algebra Applicable to Hyper-space " in 1897 ; one on the Congruency of Curves in 1899 ; and still others in 1900 and 1901 . In 1900 he accompanied the Eclipse Expedition sent out by the Royal Dublin Society and the Royal Irish Academy , to Spain , and obtained some exquisite photographs of totality . In 1899 the first volume and in 1901 the second volume of the new edition of Hamilton 's Elements appeared . What the editorial work involved in patient and brilliant scholarship will only be appreciated by those acquainted with the vast and difficult literature which had to be analysed and embodied in the new edition . About 150 quarto pages of new matter were added . During the couple of years succeeding this editorial work Joly was mainly occupied in extending his reading in Astronomical Science . Two other papers on mathematical subjects , however , appeared during this interval , and the laborious work of editing a new edition of Preston 's ' Treatise on Light ' was accomplished . In December , 1902 , Joly 's paper on " Quaternions and Projective Geometry " was communicated to the Royal Society by Sir Robert Ball and appeared in the ' Transactions . ' We ourselves know that the writer regarded this as a great advance and as a hopeful extension of the utility of Quaternions to new fields of investigation . His name was put up for Fellowship in the Royal Society in 1904 and his election followed the same year . In the year 1905 the Manual of Quaternions appeared . I have omitted reference to various mathematical papers which preceded this work . The Manual appeared in the centenary year of Hamilton s birth . The work was written in a marvellously short space of time\#151 ; about a twelvemonth . He however , wrote mathematics , worked out examples , and pursued his reasoning with the facility and ease with which a ready writer of fiction might develop the events of a novel . This , about his last great work , was received with commendation on every side ; a reception all the more flattering as those who were admirers of Tait 's treatment of the subject had to adapt themselves to a somewhat different mode of development before they could appreciate the new writer 's work . Indeed , the Hamiltonian method of establishing t e laws of Quaternions is here in part abandoned . In this work the s^ut oi makes use of a wonderfully extensive knowledge of the mathematics of every branch of Physical Science . . \#166 ; . In 1905 he took part in the visit of the British Association to South Africa . It was shortly after his return that first his little daughter and then he himself contracted the illness ( typhoid ) which , after a piotrac e period of many weeks , during which his strength was slowly sapped , gave rise to a complication ( pleurisy ) against which he could no C01* n To the last moment of consciousness he showed the same unselfish consideration for others which was one of his most lovable characteristics . . a 1 e after midnight\#151 ; 'early on January 4 , 1906 he passed away unconscious y. In the last year of his life he acted as secretary to a Committee appointed by the Board of Trinity College to enquire into the mode of election o lxvi Obituary Notices of Fellows deceased . Fellowship in Trinity College . A serious constitutional evil is undoubtedly existent in the exclusively examinational nature of this mode of selection . Joly never mentioned this matter without disapproval , and the Committee was appointed largely at his request . He gave much time and thought to its work , but the recommendations of the Committee led to no remedial measures . The appointment of a Government Commission , to which he had often looked forward as probably the only hope of drastic reform of this and other constitutional evils , took place a very few months after his death . It would be hard to estimate how much of the time and thought of distinguished Trinity men have been absorbed upon this hitherto fruitless subject of contemplation . It must be remembered that the constitution of their University regulated the lives and surroundings of these men . Every feeling of loyalty to their University as well as every disinterested desire to benefit the higher education of their country , acted to urge into action men of the stamp of FitzGerald and Joly . His extraordinary powers of mathematical head-work are known to his more intimate associates . The problem stated , Joly 's blue eyes sparkled with an expression which might more readily be taken for mirth than for abstraction . A characteristic gesticulation in'these moments of thought was the stroking of his short beard . In an astonishingly short time the solution often came\#151 ; perhaps more than one\#151 ; and not till then was pen and paper resorted to that the enquirer might have it put before him . Men of very considerable mathematical training who had sought in vain for the solution and got it in this way were naturally impressed . There was undoubtedly a comprehensiveness in his learning which has rarely been excelled even by the greatest of mathematicians , and it must be remembered that almost his entire work was accomplished within the short space of 10 years ; far the greater part within the last five years of his life . This rapidity of production indicated both thoroughness of knowledge and swiftness and sureness of reasoning . The remarkable powers of head-work were but the expression of these accomplishments and gifts . He possessed , in common with FitzGerald , a wonderful power of abstraction from immediate surroundings . Much of his work was done while conversation was going on around him . Joly generally reclined on a sofa when writing . The paper was held on his knee . The actual work was done in this attitude . A final copy was then typed . He wrote a clear and simple style of English , without effort or affectation . Most of his letters might be sent to press without a word of alteration . Full of point , too , are they , and of clever criticism . Much of his correspondence with Sir Eobert Ball will be preserved in the Library of Trinity College , Dublin . It largely refers to the Theory of Screws . It is beyond my powers to convey the impression which Charles Joly made upon me . His books and papers speak for his fare gifts ; and his best and most esteemed friend\#151 ; among many friends\#151 ; adds to this short notice an estimate of his mathematical work . * The circumstances of Joly 's early death are indescribably sad . He was Charles Jasper Joly . lxvii literally only beginning when life closed for him . A future excelling all his past was assured to him had the toil of youth but met its just reward and the harvest of life been his . The happy domestic life , the rare and precious gifts\#151 ; honours of life so meekly borne\#151 ; the whole bright future , all to be laid aside ! When he knew he was attacked by the dangerous illness which ended all , he wrote to a friend : " If the attack is as severe as Jessie 's ( his little daughter ) , I know quite well I cannot hold out . For myself I am content , though I should have given much to save they pain that others may feel . I confess also that I should like to be allowed to finish my life 's work . Many .unsolved problems might have some light thrown upon them if I had a little more time . I might have a useful influence in the affairs of College . I feel it would be a pity " \#151 ; . At the time of his death his hands were full of work . He had undertaken the article on " Quaternions " in the new edition of the ' Encyclopaedia Britannica , ' and had already entered upon the formidable duties of editing the whole of the articles on " Optics " for the same work . An unfinished Elementary Astronomy , having many features of novelty of development , remains behind , as well as a nearly finished Treatise on Solid Geometry . The latter promises to rank among his best writings . Joly was , at the date of his death , Secretary of the Boyal Irish Academy , Trustee of the National Library of Ireland , Member of Council of the Boyal Dublin Society , and President of the International Association for Promoting the Study of Quaternions and Allied Systems of Mathematics . J. J. Professor Joly 's paper on the " Theory of Linear Vector Functions " ( 1895 ) , T.B.I.A. , vol. 30 , p. 597 , was the commencement of a remarkable series of Memoirs on Quaternions , which has largely extended the applications of Hamilton 's splendid invention . At the close of this paper he gives for the first time the relation between the theory , of linear vector functions and the theory of screws . In 1899 the first volume of the Second Edition of " Hamilton 's Elements of Quaternions " appeared under the Editorship of Joly , and in 1901 this was followed by the second volume . The important work thus done in rendering Hamilton 's masterpiece accessible has been greatly enhanced by the numerous notes and copious appendices which Joly has himself supplied . Attention may also be given to the significant words in the Preface in which Joly says : " My task as Editor has convinced me of the extreme caution with which any endeavour should be made to improve or modify the calculus of Quaternions . " Joly , following to some extent the example of Tait , has made very extensive use of the linear vector functions . This beautiful part of the theory is shown to be admirably adapted to many different classes of physical investigation . In a remarkable appendix , Joly also shows how Quaternions provide the most natural method of investigating / 2 lxviii Obituary Notices of Fellows deceased . the systems of rays , which formed the subject of a famous Memoir of Hamilton in his early days and long before the Quaternions were thought of . Perhaps the part of the appendix which will be most generally appreciated is that on the operator A , of which many applications to hydro-dynamical and other problems are given . On the conclusion of this great work Joly turned his attention to the further development of Quaternions by continuing his original Memoirs . Such was his industry and so fertile was the method of Quaternions in his hands that in 1902 three important Memoirs appeared . The first contained an entirely novel development in which a Quaternion is represented as a point symbol . The point is supposed to have a weight equal to the Scalar of the Quaternion , while the vector of the point from a fixed origin is the quotient of the vector of the Quaternion by the Scalar . This was followed by another Memoir in which screws were represented as weighted points , and also by another on Quaternion arrays . The year 1903 was one of still greater activity . An important paper appeared in the * Phil. Trans. ' ( vol. 201 , pp. 223\#151 ; 327 ) on " Quaternions and Projective Geometry . " In this is developed the theory of the linear Quaternion function depending upon a latent biquadratic as the linear vector function depends on a latent cubic . The investigation exhibits the relation of Quaternions to Projective Geometry in quite a new light . Another Memoir in this year is on the Quadratic Screw System , in which a very large theory is most ably set forth . It was followed by a shorter Memoir on the Geometry of a New System of Screws . Here , again , the theory of linear vector functions is employed with much effect to set forth geometrical problems . But , doubtless , the most important work in Quaternions with which the name of Joly will be remembered is his " Manual of Quaternions " which appeared in 1905 . In this volume he follows at the outset a slightly different procedure from that adopted by Hamilton . Joly makes the result of the product of two vectors a matter of definition . There seems to be much gain from the point of view of the student in this modification . But the student , while he appreciates the facilities thus given at the beginning of his acquaintance with a new subject , will , as he advances , find it advantageous to turn to Hamilton and read his beautiful reasonings on the interpretation to be given to a product of two vectors . By the excursions which Joly takes into various departments of Mathematical Physics such as the theory of Strain , Spherical Harmonics , Hydrodynamics and Electro-magnetism , the student of the Manual of Quarternions is introduced to regions far beyond those discussed by Hamilton , though not perhaps beyond those to which he foresaw his calculus might be extended . Indeed , the present state of Quaternions , to the advancement of which Joly has so largely contributed , goes far to justify the aspirations of Hamilton himself . Writing fifty years ago to Humphrey Lloyd , afterwards Provost pf Tyinity College , Lublin , Hamilton , says ; \#151 ; Charles Jasper Joly . lxix " In general , although in one sense I hope that I am actually growing modest about the Quaternions , from my seeing so many peeps and vistas into future expansions of their principles , I still must assert that this discovery appears to me to be as important for the middle of the nineteenth century as the discovery of fluxions was for the close of the seventeenth . " R. S. B. * NOTE . Obituary Notices of the following deceased Fellows are in preparation for press , to appear in the B Series of the ' Proceedings . Sir John Burdon Sanderson , Bart. Henry B. Medlicott . William T. Blanford . Professor Thomas G- . B. Howes . Baron Ferdinand von Richthofen . Captain Frederick W. Hutton . George B. Buckton . Charles B. Clarke . Dr. Lionel Beale . Rev. Canon Tristram .

rspa_1907_0002

0950-1207

Calcium as an absorbent of gases for the production of high vacua and spectroscopic research.

429

458

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Frederick Soddy, M. A.| J. Larmor, Sec. R. S. |Arthur John Berry

article

6.0.4

http://dx.doi.org/10.1098/rspa.1907.0002

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1907_0002

10.1098/rspa.1907.0002

Thermodynamics

Atomic Physics

Thermodynamics

Calcium as an Absorbent of , etc. 429 mean ( true ) values ; but it would materially affect the other conclusions and especially the statement that the moist material attains to the full vapour tension of pure water when it contains a definite quantity of moisture . Unless very strong and direct evidence were forthcoming , we could not , after our own experience , believe that the whole of each " feed " of water driven over into the space containing the flannel was uniformly distributed as hygroscopic moisture throughout that substance before the vapour pressure was measured , or that no part of the final " feeds " was left as ordinary liquid water to exert its influence . Calcium as an Absorbent of Gases for the Production of High Vacua and Spectroscopic Research . By Frederick Soddy , M.A. , Lecturer in Physical Chemistry in the University of Glasgow . ( Communicated by Professor J. Larmor , Sec. R.S. Received September 13 , \#151 ; Read November 15 , 1906 . Notes added November 20 , 1906 . ) CONTENTS . page I.\#151 ; Introductory ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . . 429 II.\#151 ; Historical ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . 430 III . \#151 ; Electric Furnace for Strongly Heating Reagents in Glass Vessels. . 432 IV . \#151 ; Absorption of Gases by Calcium ... ... ... ... ... ... ... ... ... ... ... . 436 V.\#151 ; Behaviour of Barium and Strontium ... ... ... ... ... ... ... ... ... ... ... . 438 VI.\#151 ; Production of High Vacua by means of Calcium ... ... ... ... ... ... ... . 439 VII.\#151 ; An Induction Method of Electrically Heating Calcium in Glass Vessels ... 441 VIII.\#151 ; Practical Considerations in the Use of Calcium as an Absorbent for the Production of High Vacua ... ... ... ... ... ... ... ... ... ... ... ... ... 444 IX.\#151 ; Quantity of Argon detectable by the Spectroscope ... ... ... ... ... ... . 446 X.\#151 ; Misapprehensions regarding High Vacua ... ... ... ... ... ... ... ... ... ... 447 XI.\#151 ; Quantity of Pure Helium detectable by the Spectroscope ... ... ... ... 451 XII.\#151 ; Most Favourable Conditions for the Detection of Infinitesimal Quantities of Helium ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 452 I.\#151 ; Introductory . This paper contains an account of researches carried out by the aid of an electric furnace designed to heat reagents in soft glass tubes up to temperatures far above the softening point of glass , and has special reference to the use of calcium under these conditions as a valuable absorbent of gases . Recent work on the generation of helium from the radio-elements VOL. LXXVIII.\#151 ; A. 2 G Mr. . F. Soddy . Calcium as [ Sept. 13 , has shown the necessity for more simple , certain , and-powerful means of absorbing other gases and in particular nitrogen . The usual practice of Sir W. Ramsay and the writer when working together was to make provision for the removal of compounds of hydrogen , oxygen , and carbon , but to take the utmost precautions against the admission of air into the apparatus in the first place . If nitrogen was present in spite of the precautions taken , it was often possible , by gently running the spectrum-tube , to absorb it by the hot electrodes of aluminium , the lines of helium , if present , appearing as the nitrogen spectrum faded . The difficulty in absorbing nitrogen is that the usual absorbents , for example , a mixture of lime and magnesium , only react above the softening temperature of an exhausted soft glass tube , and the present researches had their origin in an attempt to enable higher temperatures and more powerful absorbents of gases to be used within soft glass apparatus . Lithium , it is true , absorbs nitrogen at a very low temperature , but its use introduces hydrogen . A good exarnple of . a very perfect train of absorbents* able to absorb all known gases with the exception of those of the " argon family , is to be found in the recent researches of Debierne* on the production of helium from radium and actinium . " Oxygen is absorbed by heated copper ; the absorption of hydrogen is secured by the action of heated copper oxide and phosphorus pentoxide , at the same time the copper oxide transforms gaseous carbon compounds into carbon dioxide , which is absorbed by potash , and finally nitrogen is absorbed by pure lithium . " Now such an apparatus serves but one experiment , and has to be built up afresh for each , because it is necessary to fill it after the absorption with mercury in order to compress the helium sufficiently to detect it . The labour involved during a lengthy investigation may be imagined . It is , therefore , very satisfactory to be able to state that I have found that a single reagent , namely , calcium , at the high temperature attainable by the use of my furnace , would serve instead of all the reagents employed by Debierne , and do the work far more effectively and rapidly . Calcium , under the conditions mentioned , is a universal absorbent of all gases with the exception of the argon group . ' II.\#151 ; Historical . Till recently calcium has been a very uncommon metal , while barium and strontium still belong to the category of chemical curiosities . Maquennef found that when amalgams of these three metals were heated in nitrogen , * ' Comptes Rendus , ' 1905 , vol. 141 , p. 383 . + 'Comptes Rendus , ' 1892 , vol. 114 , p. 225 . 1906 . ] Gases for the Production of High Vacua , etc. 431 the mercury was volatilised and nitrides of the metals were formed . The absorption took place at a lower temperature than in the case of the metals magnesium and aluminium . Barium was stated to lend itself best to the experiment . None of the alkaline-earth metals were investigated by Lord Bayleigh and Sir W. Bamsay in their examination of the known absorbents of nitrogen , * on account of the difficulties in obtaining large quantities of these metals at that time . After the discovery of argon , Maquennef showed that a mixture of calcium oxide and magnesium rapidly absorbed the oxygen and nitrogen of the air when heated in a hard glass tube , and attributed this reaction to the production of calcium in an extremely divided state . He states that a manometer attached to the apparatus showed a diminution of pressure from the atmospheric equal to 70 and even 73 cm . of mercury . This mixture is now commonly employed in the preparation of argon , and it is customary to accept Maquenne 's explanation of its absorbing power . It is , however , quite certain that the commercial calcium in the form of compact metal bars , produced by electrolysis , behaves in a manner entirely different from the " nascent calcium , " if such it be , produced by heating a magnesium and lime mixture , for the former , heated in a tube filled with air at atmospheric pressure , produces no noticeable absorption , even at the highest temperatures . Moissan first succeeded in preparing calcium in quantity sufficient to make an accurate study of its properties.^ His calcium was in finely divided crystalline condition , and was obtained by acting upon calcium iodide with excess of sodium . The calcium is deposited out from the sodium on solidification , and the latter is removed by the action of absolute alcohol , which does not attack calcium . He showed that at a dull red heat this calcium absorbs both hydrogen and nitrogen with incandescence , forming nitride and hydride respectively . The hydride heated to the softening temperature of a Bohemian glass tube in an atmosphere of hydrogen neither absorbed nor evolved gas . In a determination of its melting point the calcium was heated in a vacuum obtained by the use of a mercury pump . Moissan noted the evolution of small quantities of gas which were pumped off , " but as soon as the metal became dull red hot the last traces of gas are absorbed , and the vacuum stood at 1 mm. " This inconsistency might have been due to sticktion of the mercury in the gauge , or to an error in its reading , for , as Moissan himself remarks , the last traces of gas are absorbed under these conditions . * ' Phil. Trans. , ' A , 1895 , vol. 186 , p. 187 . + 'Comptes Rendus , ' 1895 , vol. 121 , p. 1147 . J 'Comptes Rendus , ' 1898 , vol. 126 , p. 1757 , and vol. 127 , pp. 29 , 497 , and 584 . Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 Calcium , electrolytically produced in the form of compact bars , free from mercury and oil , has been available for over two years , and has been the subject of much interest . Those who have examined it must have been more struck with its apparent disinclination to react than with any exceptional reactivity . Thus the attempts to replace the magnesium or magnesium-lime mixture by this calcium in the preparation of argon have never succeeded in my experience . Even when heated to 1200 ' C. in an electric oven it refuses , after a very slight initial action , to absorb nitrogen . It must be heated to a very high temperature in the blow-pipe before it ignites in the air , and then readily goes out . In one experiment a powerful arc was caused to pass between calcium points in air without inducing combustion.* Negative results of this character could be multiplied . Arndtf undertook a research on the melting point of commercial calcium , in which the metal was heated , as in Moissan 's experiment , in a vacuum of 1 mm. pressure to avoid chemical action . He noticed that the calcium began to volatilise below its melting point , and that the vapour reacted energetically with the residual air , so that the pressure on the manometer sank to an unreadable value . Absorption commenced at 700 ' C. , was rapid and accompanied by visible volatilisation at 730 ' , whereas the melting point was found to be 800 ' . When a Pliicker spectrum-tube was included , it was found that " the nitrogen spectrum faded rapidly , while the lines of hydrogen ( from a trace of water present ) remained behind with the lines of argon . " He found , that the vapour of magnesium did not exhibit nearly the absorptive power of calcium . With the use of the apparatus to be described I arrived independently at , and have confirmed , the observation of Arndt on the extreme rapidity of absorption of the oxygen and nitrogen of air by the vapour of calcium . In addition I have found that all the common gases can be absorbed equally well , although in some cases , as the above quotation from Arndt 's paper shows for hydrogen , complete absorption is not effected by simple heating alone . III.\#151 ; Electric Furnace for Strongly Heating Reagents in Glass Vessels . The apparatus usually employed depends upon the internal heating of the reagent by an electric resistance circuit and the protection of the glass walls * This , however , is partly due to the extraordinarily slight heating which electrodes of calcium experience when a discharge is passed through a gas between them . Of all metals calcium heats the least , and is in this respect far superior to aluminium . But for other difficulties it might be used to replace aluminium , ' with advantage , as the electrodes of vacuum tubes in the case of the inert gases . A steady arc can be maintained between calcium points in air with a very small ampdrage . + ' Ber . d. D. Chem. Ges . , ' 1904 , vol. 37 , p. 4733 . 1906 . ] Gases for the Production of High , etc. by a screen of porcelain placed between it and the enclosed furnace . It is shown to the scale of 6 inches to the foot , in section , in fig. 1 . Figs. 2 , 3 , 4 are transverse sections on the lines x , y , z respectively . The outer containing x\#151 ; \- \#151 ; y vessel is made out of soft glass tubing , and is in two parts , the upper B and the lower B2 , which are ground to fit together accurately at D. The lower part B2 has two mercury cups with platinum wires b2 sealed through the glass . The upper part B widens at the shoulder d , on which rests the Mr. F. So\amp ; die . Calcium as art Absorbent of [ Sept. 13 , porcelain shield-tube K. This is slipped into the tube , which is then constricted at A and joined to a narrow piece of tubing for connecting to other apparatus . The furnace-tube J , which carries the heating wire , slides through the ground-joint of B and passes inside the shield-tube For the upper part of its length it is grooved with an external screw thread of about 1 mm. pitch , and wound with a platinum wire of 0*25 mm. diameter . It passes through the holes jj into the inside of the tube , and is joined to stouter pleads of nickel , copper , or platinum , or is simply doubled on itself . The leads pass through the doubly-bored porcelain insulator 7 , which slips within the lower half of the furnace tube and the upper part of and are finally taken into the mercury cups . The lower end of the furnace-tube rests on , and is .supported by , the upper end of B2 , and itself surrounds and supports at its upper end a porcelain test-tube L , in which the reagent to be heated is placed , at C. The whole arrangement is readily taken to pieces at the ground-joint B for recharging , cleaning , or repairs . The end B2 usually carries between the two mercury cups a narrow tube , shown by dotted lines , to which is attached a bulb and tap , shown in fig. 5 , for th\amp ; purpose of admitting mercury into the apparatus without introducing air , and also for conveniently filling the mercury cups and other purposes . An oil or mercury seal may surround the ground-joint , but is not necessary if it is of good workmanship . For special work , where the possibility of leaks or the presence of vapour of grease is to be avoided , it is easy to dispense with the ground-joint D and to make the apparatus in one piece . In this case B is made long , so that it can be repeatedly opened and sealed , and the various parts are introduced through the upper end by suitable tongs . But these refinements are usually quite unnecessary if the ground-joint is of good workmanship , and is well lubricated , and if the leads are of sufficient conductivity not to heat the joint . In special work , too , the mercury cups may be dispensed with and the wires continued through the glass seal if the presence of mercury vapour is to be avoided . [ Added.\#151 ; An improved and thoroughly satisfactory method of working , applicable whether the ground-joint is used or not , is to dispense with the porcelain insulator 7 , and to bore two holes opposite each other at the lower end of the furnace-tube 7 , twisting one end of the doubled platinum heating wire through each hole , together with a length of " flexible " copper wire , and continuing the two flexibles , insulated if necessary in little glass tubes , into the cups bb , where they make good touching contact with the . platinum , without the . use of mercury . In this way a mechanically strong joint with the fine heating wire is secured , the presence of mercury inside the vacuum is altogether avoided , and the formation prevented of a mercury arc between 1906 . ] Gases for the Production of High , . the two cups when a high-tension discharge is passed through the vacuum , which in the first form of apparatus constituted an occasional source of annoyance and damage . ] With this apparatus reagents may be safely heated to temperatures far above the melting point of glass without injuring the apparatus . After nearly two years ' use of these furnaces I do not recall a single case where the heat has caused the glass to crack or break while in use , although , of course , the glass tends to get brittle and to break when being cleaned more readily after use than before . If required for prolonged heating at high temperature , it is an advantage to blow a bulb on the tube at the hottest part of the furnace , otherwise , when the porcelain shield-tube has become heated through , the glass is apt to melt . These shield-tubes never break . The furnace-tubes are more fragile , but stand extremely well , while , of course , the test-tubes containing the reagents require the most frequent replacement . Tubes made of thin iron would for many purposes have very many advantages over porcelain . But they must be gas-tight at the lower end , for the vapour of calcium would ruin the platinum wire if it came in contact with it . The limit of temperature attainable in this apparatus is fixed mainly by the volatility of the heating wire in the high vacuum usually maintained within the apparatus , and for this reason platinum or one of its alloys must be used . Iron or nickel volatilise and the wire is destroyed in a few minutes . Even with platinum the volatilisation of the metal is serious at a bright-red heat . In addition , a certain tendency to become brittle with loss of metallic qualities , which is noticeable in ordinary platinum resistance furnaces , thermometers , and thermocouples , and which prevents their prolonged use at temperatures above 1200 ' C. , appears to be far more marked and to take place at lower temperatures in the high vacuum , rendering occasional rewindings of the furnace necessary . The cause of this has not been fully explained . An examination of somewhat analogous phenomena in the case of nickel has been recently made by Dr. H. C. H. Carpenter in a paper read before Section G of the British Association this year , and attributed by him to gases in the nickel.* I am inclined to connect the phenomenon in the case of platinum with the vaporisation of the metal . If tantalum wire could be obtained , no doubt it would prove far more suitable than platinum . Naturally , a high vacuum within the apparatus tends greatly to conserve the heat and to diminish convection , and the risk of the outer vessel melting . In this respect the apparatus is the antithesis of the Dewar vessel for storing liquid air . * ' Engineering , ' August 17 , 1906 , p. 222 . 436 Mr. F. Soddy . Calcium as an Absorbent of [ Sept 13 , IY.\#151 ; Absorption of Gases by Calcium . If the apparatus described , charged with a small piece of calcium , and furnished with a Pliicker spectrum-tube , is exhausted by a Fleuss pump , and the furnace heated , gases , consisting of compounds of hydrogen , carbon , and oxygen are given out by the calcium . If connection with the pump is then shut off and the heating continued , absorption of the remaining gases , accompanied by volatilisation of the calcium , takes place , and the vacuum rises almost instantly to a point at which no discharge can be passed through the spectrum-tube . By a non-conducting vacuum is to be understood one of greater resistance than an alternative spark gap in air of 2 to 3 cm . , unless the length of the gap is given . If air is introduced into the apparatus , all but argon is rapidly absorbed , and quantities up to 10 or 20 c.c. can be thus dealt with . These experiments with air are , however , of interest from so many points of view that they will be dealt with in detail later . In a similar way it was shown that carbon monoxide , carbon dioxide , water vapour , hydrogen , acetylene , sulphur dioxide , ammonia , and the oxides of nitrogen ( nitric oxide , with deflagration of the calcium ) are all as readily and completely absorbed as in the case of the oxygen and nitrogen of the air . , Quantities of several cubic centimetres disappear within a minute after introduction , and the vacuum-tube becomes non-conducting . Finally , in order to put the power of the calcium to as severe a test as possible , several successive quantities of coal gas , each of several cubic centimetres , were introduced into the apparatus after the absorption temperature had been attained . Within a minute after each addition the spectrum-tube became non-conducting to the discharge . Calcium thus acts as a universal absorber of chemically valent gases . The case of hydrogen and its compounds alone calls for fuller treatment , for at too high temperature calcium hydride possesses an appreciable tension of dissociation . The same is of course true of calcium carbonate , but this compound does not appear to be formed when only small amounts of carbon dioxide are absorbed by the calcium . If hydrogen or its compounds are present in a gas in large quantity , the spectrum-tube , after the absorption of the other gases , shows still the hydrogen lines , and refuses to become nonconducting as long as the temperature of the furnace is maintained . But if the heat is reduced , the non-conducting stage is reached at once . In one experiment 1 c.c. of hydrogen was introduced , and the heat reduced . The spectrum-tube became non-conducting in 40 seconds . Careful experiments have shown that even after cooling an infinitesimal 1906 . ] Gases for the Production of High , etc. 437 quantity of hydrogen remains unabsorbed . Thus if , after cooling , mercury is allowed to fill the apparatus and compress the residual gas many hundred times into a tiny spectrum-tube , a very faint hydrogen spectrum can be seen , although the spectrum-tube , even after this concentration of the gas , is still of high resistance and fluoresces brilliantly under the discharge . This residual trace will be shown to be of great value in certain experiments . A point of very great practical importance arises out of the dissociation phenomena of calcium hydride . Different commercial specimens of electrolytic calcium exhibit differences in their behaviour which I have traced to the presence of hydride in some specimens and not in others . The presence of this hydride quite alters the characteristics of the absorption process , and although with sufficient experience it is possible to get good results in spite of the presence of hydride , this experience is apt to be dearly bought . When hydrogen is present the real absorption temperature is apt to be overstepped , for instead of a non-conducting vacuum being obtained , as it should be almost instantly with a proper specimen of metal , the dissociation tension of the hydrogen is sufficient to enable the discharge to pass . An inexperienced operator , or one accustomed only to the character of the purer metal , will , in consequence , continually increase the temperature , and the tension of the hydrogen of course increases , and may ultimately become quite measurable on a gauge . Before it is realised that the proper temperature has been far overstepped , the metal may have melted , subsequently to crack the crucible on cooling , the platinum wire may fuse or volatilise , and even the glass envelope may soften . Whereas , if instead of increasing the temperature the heat had been cut off , the non-conducting stage would have been reached in a few seconds . It was noticeable that of two specimens , one excellent and the other containing hydrogen and unsuitable , the latter was by far the more malleable and could be always detected by this test after it had accidentally got mixed with the other specimen . But this difference of properties may not have been due to the presence of the hydride . No one would use metal containing hydride wittingly , but it is well to know that by cutting off the heat , when the spectrum of the gas becomes that of hydrogen , quite satisfactory results are attainable . But the sacrifice of time and apparatus , destroyed by excessive temperature , was considerable before the differences between the specimens of metal were suspected , and the differences of behaviour understood . Experiments were tried to see if calcium which had been strongly heated and allowed to cool in an atmosphere of helium and argon , respectively , re-evolved any trace of these gases when reheated in vacuo , but in each case with negative results . 438 Mr. J ? . Soddy . Calcium as an [ Sept. 13 . Y.\#151 ; Behaviour of Barium and Strontium . Tested under the same conditions , barium and strontium show very analogous behaviour to calcium . The specimen of barium employed had been preserved under oil , and was in the form of a granular powder . It had been prepared from the amalgam and still contained mercury . It was given a preliminary heating in vacuo to remove oil and some of the mercury . It commenced to absorb gases without appreciable volatilisation at a temperature notably below that required in the case of calcium . A non-conducting vacuum was usually not obtained before the metal had been allowed to cool . In the work with both barium and strontium the hydrocarbon spectrum , reminiscent of the argon gases , was very frequently observed^ and was ! probably due to traces of the oil in which the metals had been preserved . This spectrum usually appeared when the metal was hot , and disappeared . on lowering the temperature , the vacuum becoming nonconducting . Coal gas was admitted to the heated barium to a pressure of 2 to 3 mm. , and was rapidly absorbed , and'a non-conducting vacuum obtained without difficulty . Air introduced to about 7 mm. pressure was rapidly absorbed , except for argon , exactly as with calcium . Barium can be heated to its absorbing temperature in a hard glass tube by a Bunsen burner , but the tube collapses and cracks on cooling . Under similar circumstances calcium requires a blowpipe to induce volatilisation and absorption , and the tube is completely melted and flows round the calcium in the process . Experiments with strontium were less complete on account of the difficulty of obtaining the real metal , and on account of the small quantities that had to be used . The first sample bought as strontium proved to be potassium amalgam simply , without sufficient strontium to give a precipitate with sulphuric acid . The metal , when it was obtained , proved to be similar in properties to barium and calcium. . On account of the cost only a decigramme at a time could be used , and it is very probable that its behaviour , as observed , was partly due to presence of alkali metals , oil , and mercury , and that electrolytic strontium in compact form , free from these contaminations , would exhibit a behaviour even more nearly allied to calcium . So far it has not been possible to procure this . Absorption with the sample employed seemed to start at a slightly higher temperature than with calcium , and at a high temperature some volatilisation of the metal appeared to occur . This was due probably-to a trace of alkali metal . It showed to a very marked extent the phenomenon1 of not giving a good vacuum until it had been cooled down , and of showing hydrocarbon spectra very strongly , but * this behaviour might 1906 . ] Gases for the Production of High Vacua , etc. not be shown by an oil-free specimen . It seemed hardly worth while to pursue experiments with a metal at once so costly and so impure , when a commercial process has been patented for producing the metal on a scale similar to that of calcium . But the experiments proved that , like barium and calcium , it can absorb coal gas and air , and give a non-conducting vacuum without difficulty . * . * '\#166 ; , \#166 ; , \#166 ; \#166 ; ' \#166 ; -- . v ' ' 3- -3 YI.\#151 ; Production of High Vacua by Means of Calcium . From what has been said it will be seen that the apparatus described affords a ready means of obtaining a high vacuum by the use of calcium as an absorbent . Arndt , in the paper referred to , suggested its use in the production of high vacua , on account of the energetic action of the vapour on the residual air . A little consideration , however , shows that since argon is not absorbed by the reagent , air must be as rigorously as possible excluded . As is well known , the real difficulty in the production of high vacua depends not so much on the removal of all the original air , which is comparatively easily and quickly accomplished even with a pump , but on the effective removal of the gases which are condensed on the glass walls of the vessel being exhausted , and which tend to recondense in the pump when driven out of the vessel , and to introduce a kind of steady vapour pressure until they have all been removed . The value of calcium as a means of producing the highest vacua depends on its power to absorb almost instantly the gases condensed on the glass walls as soon as the latter are expelled by heating . It is , as stated , necessary to replace all the air in the apparatus before the absorption with calcium takes place , or the residual argon will prevent the vacuum obtained from being really good . The importance of this is increased by the fact that articles for exhaustion have usually to be provided with a very constricted orifice , so that they can be sealed safely after the vacuum has been obtained . As a consequence , any argon accumulating in the absorption chamber dams back the flow of absorbable gas from the vessel being exhausted , and enormously increases the time required , as the contents of the vessels have to diffuse and mix through the constricted orifice , and this process may require some minutes . Hence , in this method of high vacua production , the customary precautions must be taken against the leakage of air , if really high vacua , as distinguished from the apparently high vacua later to be considered , are desired . If a Fleuss pump in good order is available , and new glass apparatus which has not before been exhausted is being dealt with , it suffices to continue the pumping while the apparatus in question is heated in the usual way to expel condensed gases , and so utilise the latter to replace the residual Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 , air remaining in the apparatus . Or , if a new charge of calcium , not previously heated in a vacuum , is employed , the same displacement of the air can be readily effected by the gases given out by the calcium before it attains its absorption temperature . In both cases the gases consist chiefly of carbon and hydrogen compounds and , being free from argon , serve well for the displacemement of the remaining air . In other caaes , or where more certainty is desirable , the complete replacement of the air may be effected by the use of a side tube containing a mixture of potassium chlorate and manganese dioxide , which evolves oxygen on warming . One or two small quantities of oxygen are admitted during the pumping , and the connection with the pump closed or sealed off before the calcium is brought into action . Fig. 6 shows , in diagram , an apparatus suited for the purpose of exhausting an X-ray bulb . C is the calcium heated by the platinum wire c within the glass vessel B. A is an X-ray tube , and is a tube containing the oxygen mixture . The Fleuss pump is connected with E , and the spectrum-tube E is a convenience both for judging of the degree of vacuum and the character of the residual gas . With this method , as in all methods of vacua production , the degree of , rarefaction attained is the balance between the rate of absorption or removal of the gas present , and the rate of supply of fresh gas from leaks or from condensed films , or from substances such as lubricating grease or mercury which have a vapour pressure . Since the rate of absorption 1906 . ] Gases for the Production of High Vacua , etc. is extremely rapid , good results can be obtained even under poor conditions . Conditions have to be very bad indeed for any difficulty to be experienced in the production of a so-called " X-ray " or " non-conducting " vacuum . But it will be shown in the sequel that these electric discharge phenomena may be produced in vacua which could not be described as high in any other sense . With proper care the very highest vacua may be obtained by the use of calcium , as is proved by the experiment quoted in Section IY , of filling the apparatus with mercury and compressing the gaseous contents several hundred times . Personally , in crucial experiments , I should use it preferably to any other , and in the research on the positive charge carried by the a-particle* it was the final court of appeal , by which results obtained by other methods were always retried . VII.\#151 ; An Induction Method of Electrically Heating Calcium in Glass Vessels . Calcium is an excellent conductor of electricity , being the fifth best if wires of equal length and diameter ( Ag , Cu , Au , Al , Ca ) , and the third best if wires of equal length and weight ( Xa , Li , Ca , Mg , K , Al ) are compared . Its volatility , relatively low melting point and low resistance are all against the possibility of heating calcium to its absorbing temperature by conducting a current through tit . But in the form of fairly massive discs or rings calcium may be heated to its melting point by induction through the glass walls of the containing vessel by means of alternating circuits outside the vessel . Por instance , if a bundle of iron wires , similar to the core of an induction coil , is put through a ring turned out of a bar of calcium , and the whole placed in an exhausted glass tube , the walls of which are protected from fusion by a porcelain shield-tube in the manner before described , and a bobbin of insulated wire traversed by an alternating current of high periodicity be slipped over the glass tube , the calcium may be readily heated to its absorption and volatilisation temperature . The arrangement is simply a step-down transformer , in which the calcium ring acts as the single short-circuited winding of the secondary , and , being of low resistance , a fraction of a volt induced in it by the magnetic flux suffices to cause the passage of a heavy current , probably of the order of a kilo-ampere , which heats it to the required high temperature . Pig . 7 shows one arrangement for this purpose . Pig . 8 is a transverse section on the line The iron core M is enclosed in a thin tube of Jena glass P , which is exhausted and sealed . This tube effects the double purpose of protecting the iron from excessive heat and retaining gases given off from the iron , but can be dispensed with . C is the * ' Nature , ' August 2 , 1906 , p. 316 . 442 Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 , calcium ring , K is the porcelain shield-tube , B is the outer glass containing tube , N is the external circuit through which the inducing current is passed . As the heat given out from the calcium is considerable and apt to injure insulating material , it is convenient to employ , instead of a bobbin of insulated wire of many turns , a Firt . 7 . few turns of stout , bare , copper bar or tube , and to obtain the inducing current from the secondary of a step-down transformer not shown in the drawing . Since the magnetic flux , and therefore the inducing voltage in C , varies as the square of the diameter of the core , while the resistance of G varies as the diameter , it follows that the larger the diameter of cross-section of the apparatus the easier it is to obtain the desired result . But the induced voltage depends also on the periodicity of the inducing current , so that the latter must be the higher the smaller the apparatus employed . The dynamo employed was specially constructed for the purpose and gave with variation of speed a periodicity from 200 to 400 cycles per second . The drawing shows the apparatus to the scale of 6 inches to the foot . Another form of apparatus is shown in fig. 9 , to the scale of 3 inches to the foot . It differs from the last mainly in that the magnetic circuit , composed of the iron strips or wires M M , is closed but for the two air gaps where the glass walls of the containing vessel penetrate it . The use of the step-down transformer is unnecessary , because the inducing bobbins , represented diagrammatically by the circuit M N M are far enough removed from the source df heat not to be damaged . \#151 ; w -Fiff . \lt ; 5 , 1906 . ] Gases for the Production of High Vacua , etc. Fig. .M ? ' 3 , Y Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 The part within the glass containing vessel is shown to twice the scale ( 6 inches to the foot ) in fig. 10 . Fig. 11 is a section of the same . Figs. 12 and 13 are transverse sections in vertical and horizontal planes respectively . Cis a disc of calcium bored with a central hole , through which passes the bundle of iron wires M M. are two porcelain crucible lids bored with central holes . Instead of the disc of calcium shown , a disc one-third the thickness between two similar discs of copper may be employed if it is required to increase the conductivity . Since in these induction methods of heating the heat is developed in the reagent itself , the latter is hotter than its surroundings , which is a great advantage , as far less screening of the glass walls suffices . The temperature of the metal can be very accurately judged by the eye , and must be kept below the melting point . A moderate red-heat just above the cherry-red stage is necessary for absorption of gases and volatilisation to occur . For experimental work where cost is not the primary consideration , and where frequent dismantling of the apparatus is rendered necessary , the resistance-furnace method of heating is to be preferred . But for prolonged work in which the object is simply to obtain a high vacuum , the induction method offers great advantages . YIII.\#151 ; Some Practical Considerations in the Use of Calcium as an Absorbent for the Production of High Vacua . There is no doubt that a low initial pressure , not exceeding a few millimetres of mercury , is as essential a condition in causing calcium to combine with gases as a high temperature . As Arndt showed , there is a slight initial absorption below the volatilisation temperature , and this is of great practical importance . For rapid and continuous absorption volatilisation is essential . But in a case where the initial pressure is above that at which volatilisation occurs the slight initial action is often sufficient to lower the pressure to the extent necessary for the formation of vapour . When this has once taken place subsequent absorption is much facilitated , for the film of volatilised metal continues , even in the cold , to absorb , although more slowly than the vapour itself . Hence once volatilisation has taken place there is present a tendency to re-establish the condition for further vaporisation . When , however , a mixture with an unabsorbable constituent , for example , air , is being absorbed , the accumulation of this constituent hinders the volatilisation and further absorption by the calcium . Another factor operating in the same direction is the increased loss of heat by convection currents in the presence of a gas , tending to lower the temperature of the reagent and furnace , and to lower the resistance of the latter . In the usual case , where 1906 . ] Gases for the Production of High , etc. this resistance is small compared to the external resistance in the circuit , the fraction of the electrical energy dissipated within the furnace is also lowered , and so the temperature falls from a double cause . If water vapour is present the action becomes extremely marked on account of the great conductivity of this vapour to heat . The current necessary to raise the temperature in this case may be so great that , unless promptly reduced when absorption commences , the heating circuit is apt to be destroyed . Under proper conditions of working the calcium should never be melted , although it may be volatilised completely and redeposited on the cooler part of the tube as a compact tube or ring difficult to remove by mechanical means . Used porcelain tubes should never be exposed to the air or treated with water or dilute acids , as they readily crack under this treatment . Immersion in concentrated hydrochloric acid usually serves to dissolve the volatilised metal without cracking the tube , but with the liberation of the spontaneously inflammable silicon hydride . If the calcium is melted in the tube the latter usually cracks on cooling , so that for many reasons suitable iron tubes would be better than porcelain . The narrow margin of temperature , 70 ' C. according to Arndt , between the volatilisation and melting point need , however , never be exceeded when experience has been gained and suitable metal is employed . The presence of hydride in the metal acts so prejudicially largely because the dissociation tension of hydrogen lessens the volatilisation and reduces still further this narrow margin , so that the melting point is the more likely to be overstepped . These conclusions as to the conditions under which calcium should be employed as an absorbent have been arrived at after over a year 's continuous use of the method . The following experiment on the effect of vapour of grease and of a very constricted orifice between the vessel being exhausted and the absorption chamber is instructive . An X-ray bulb was connected to the calcium absorption apparatus provided with a ground-joint . The latter was lubricated by the well-known mixture of rubber , paraffin-wax and vaseline , employed by Sir W. Ramsay . A spectrum-tube was provided and the apparatus exhausted by the Fleuss pump , and the connection with the latter sealed off . The calcium was brought into action and a vacuum corresponding to an alternative spark-gap of 15 cm . obtained in the X-ray tube . It was then left over night in connection with the furnace , so that the vapour from the grease of the ground-joint could exert its full effect . In the morning the vacuum was so low that there was no trace of green fluorescence in the tube . The calcium was heated and allowed to cool . In 40 minutes the 15-cm . alternative spark-gap was again attained . Then , hour by hour , the vacuum slowly deteriorated till the alternative VOL. LXXVIII.\#151 ; A. 2 H Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 , spark-gap was nil and the green fluorescence disappeared . This process of heating the calcium and leaving till the vacuum went right down was repeated day by day for a week . It was noticed that it always took 40 minutes after heating the calcium before the 15-cm . spark-gap was regained , and this period represented , as numerous experiments with the same tube show , the time taken by the gases to flow out of the X-ray bulb through the constricted orifice when a practically perfect vacuum existed on the other side . It happened that the constriction was unusually and unnecessarily narrow , such as an amateur not realising the importance of it would make , but the necessity of this constriction , where the tube is ultimately to be sealed off , imposes a natural limit on the time taken for the exhaustion , however rapid a method of absorption is employed . In this experiment the spectrum in the Pliicker tube , when the vacuum was low , was due to hydrocarbons , and nitrogen was never seen . That there was no appreciable leak of air was also shown by the fact that even at the end of a week no lines of argon could be seen . This shows that the deterioration of the vacuum was simply due to vapour being slowly given off from the grease used for lubrication . A properly constructed ground-joint is wonderfully air-tight . I may mention that in 1904 I constructed one of Strutt 's so-called radium clocks with a ground-joint similar to those employed in the furnaces . The period of the clock is the same now as when constructed , and it has worked continuously without re-exhaustion , proving conclusively that no trace of air has leaked through the ground-joint . Hence , in the calcium method , where the vapours of lubricants are absorbed with rapidity , as many taps , ground-joints and similar conveniences as desired may be employed without harm , provided they are well lubricated and never get heated , and that the apparatus being exhausted is sealed off as soon as the high vacuum is attained . IX.\#151 ; Quantity of Argon Detectable by the Spectroscope . If air is admitted to heated calcium the oxygen and nitrogen are absorbed almost instantly , and the argon and its companions in the atmosphere remain behind in a state of great purity and freedom from ordinary polyatomic gases . In the apparatus used an arrangement of two taps for admitting known small quantities of gas was joined to the apparatus for the absorption of gases by calcium . The space between the taps was 0T3 c.c. and the total volume of the apparatus was 123 c.c. The partial pressure of argon is 0D094 of the atmospheric , or 71 mm. Each quantity or " dose " therefore of 043 c.c. of air admitted to the apparatus corresponds to a pressure of argon of 0'0075 mm. of mercury . The vacuum-tube employed was an ordinary Pliicker tube , with aluminium electrodes , of about 4 5 c.c. capacity . It was found that no trace 1906 . ] Gases for the Production of High , etc. 447 of the argon spectrum could be seen in the tube , and no discharge would pass through until three doses of air had been admitted and absorbed . At this stage the group of greens and the orange line in the spectrum were faintly visible . With four doses the red lines were visible momentarily as the nitrogen spectrum faded , and with five doses these became permanent . After 10 doses ( 1'3 c.c. ) of air had been introduced , the whole argon spectrum was brilliant ; 4*5 c.c. were so added in small quantities and then 3 c.c. at once . In one minute the nitrogen spectrum began to clear and T5 minutes the argon reds were visible . In two minutes nitrogen had disappeared , and in under three minutes only argon and hydrogen were visible . The hydrogen disappeared when the heat of the furnace was reduced and the tube , giving a perfect argon spectrum , was sealed off as a memento of the experiment . In another experiment the volume of the apparatus was 100 c.c. , and 12 c.c. of air were admitted in one quantity after the calcium had been heated vacuo to the absorbing temperature . This was absorbed without difficulty . The residual argon must have exerted about 1 mm. pressure . Yet the spectrum-tube showed brilliant green fluorescence . A tap was opened and the argon allowed to flow into a similar volume of 100 c.c. which had previously been perfectly exhausted . The pressure was thus reduced to about 0'5 mm. , and at this stage the spectrum-tube had a resistance equivalent to an alternative spark-gap of 5 mm. It follows from these experiments that below a pressure of 1/ 50 of a millimetre no discharge can be sent through a tube containing argon . At this pressure the greens and orange become faintly visible , and at 1/ 25 of a millimetre the reds appear . At 0-5 mm. the resistance of the tube is still so high that the discharge prefers to jump an air-gap 5 mm. long , while at a pressure of 1 mm. the tube is brightly fluorescent . It was found that the substitution for the ordinary vacuum-tube of one of minimal volume with platinum electrodes did not much affect the pressure of gas at which the spectrum became visible . With a tube of 0'3 c.c. volume , which is as small as it is convenient to employ , a quantity of argon less than 1/ 100 of a cubic millimetre , measured at normal temperature and pressure , could not be detected by the spectroscope . This applies to the pure gas in the absence of almost every trace of the relatively far more conducting polyatomic gases . As in the case of helium , to be considered , smaller quantities of argon could be detected in presence of hydrogen or other polyatomic gas . X.\#151 ; Misapprehensions Regarding High Vacua . The foregoing experiments with argon , and others of a similar character with other monatomic gases , serve to show that the characteristics of the Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 , electric discharge may prove a very faulty guide to the degree of a vacuum . The terms " X-ray vacuum , " " fluorescent vacuum , " etc. , afford , apart from the knowledge of the character of the residual gas , no indication at all of the actual pressure . For if it happens that the residual gas is a pure monatomic gas , the fluorescent stage and even the non-conducting stage are reached at pressures within the range of the mercury barometer . These considerations serve to connect numerous isolated facts familiar to those who have worked with high vacua . Thus it is well known that to pump out a spectrum-tube with a mercury pump takes far less time if the gas pumped out is argon or helium than if air or hydrogen has been present . [ Added.\#151 ; It is also well known* that in vacuum-tubes filled with inert gases great heating of the electrodes occurs , even when these are made of aluminium , accompanied with the rapid disentegration of the electrode and the volatilisation of the aluminium . At the same time a rapid exhaustion of the supply of gas apparently takes place , the vacuum appears to rise , the tube rapidly becomes fluorescent with use , and the resistance increases to the non-conducting point at which no discharge can be passed through the tube . In the past this has been attributed to the absorption of the gas by the electrodes and the walls on which the volatilised aluminium is deposited . The advantages of aluminium over other metals , such as platinum , have been ascribed to a more rapid absorption in the case of the heavier metals.f Attempts to recover the gas supposed to be absorbed , by heating the apparatus , solution of the metal electrodes , etc. , have not been successful , as only a trace of the gas is recovered in this way . The true explanation of the phenomenon is quite different , and follows simply from the experiments given in section IX for argon , and similar ones in sections XI and XII for helium . The inert gases are not absorbed , but remain in undiminished quantity in the gaseous state in the tube , but the traces of ordinary chemically active gases always present , initially or introduced from the electrodes during the discharge , are absorbed , and the tube becomes in consequence non-conducting . The experiments of Skinner have an important bearing on this question , and in his most recent paperj he summarises his conclusions . When a current is passed through a vacuum-tube , entirely independently of the nature or amount of gas filling the tube , hydrogen is evolved from the cathode and absorbed by the anode at a rate initially equal to that required by Faraday 's law . Aluminium and magnesium cathodes give out hydrogen much more freely than the denser * Compare , for example , E. C. C. Baly , ' Phil. Trans. , ' A , 1903 , vol. 202 , p. 183 . t Compare Travers , * Study of Gases , ' p. 299 . % ' Phil. Mag. , ' November , 1906 , p. 481 . 1906 . ] Gases for the Production o f High Vacua , etc. 449 metals , but the rate of evolution from the cathode rapidly falls off as the supply of gas in the surface layers of the metal is exhausted . If the tube is allowed a rest the initial rate is recovered . When a continuous discharge is passed through any tube , therefore , the vacuum improves , for the rate of absorption by the anode gains on the rate of evolution from the cathode , and this should suffice to explain the well-known improvement with use in the vacuum of an X-ray tube . According to Skinner , helium and argon are not absorbed by the electrodes , hence the rapid exhaustion or " running out " of the tube and the advantages of the aluminium electrode are to be explained only in the manner indicated . It is intended to try , by passing a unidirectional current through a tube filled with inert gas , to what gas pressure the non-conducting stage can be pushed . It is not a little remarkable from the theoretical point of view that helium , which conducts so much more readily than any other gas under usual conditions at high pressure , should exhibit the peculiar behaviour it does at low pressure in a state of purity . Frequently in the work on the production of helium from radium , in conjunction with Sir William Eamsay , it was noticed when " running " a spectrum-tube to absorb nitrogen and reveal helium , if present , that , although a severe and prolonged running might be necessary to absorb the nitrogen , it always " ran out " first , and helium , however minute in quantity , showed itself , if present , as the nitrogen spectrum faded . When , however , the nitrogen spectrum had completely faded , which it did usually with great rapidity once it commenced to weaken visibly , the helium " ran out " almost instantly , if only in minute quantity , and the tube refused to conduct the discharge . This sharp preferential absorption , as it seemed , of the nitrogen first by the electrodes , so that , even after a quarter of an hour 's hard running , the helium would survive , instantly to disappear as soon as the nitrogen faded , always seemed to me almost providential , until , recently , the true explanation became obvious . } The explanation is also to hand why the presence of mercury vapour affects the action of the mercury pump so little . The vapour pressure of mercury at room temperature is between 1/ 500 and 1/ 1000 of a millimetre . In the case of hydrogen or carbon dioxide it is probable that this pressure would be sufficient to conduct the discharge and prevent the vacuum appearing very high to the electrical test . That " high vacua " can be obtained at all by the mercury pump is probably due to the fact that mercury vapour is monatomic . Similar considerations apply to the vacua so readily and simply obtained by the use of charcoal cooled in liquid air according to the method now largely used in scientific investigation and first employed by Sir James Dewar.* It * 'Roy . Soc. Proc. ' A , 1904 , vol. 74 , pp. 122\#151 ; 131 . 450 Mr. F. Soddy . ' Calcium as an Absorbent of [ Sept. 13 , happens here also , ais in the case of the calcium method , that the unabsorbed gases are monatomic . At liquid air temperature the helium and neon in the air remain very largely unabsorbed by charcoal . Sir W. Ramsay* has determined in this way the proportion of these gases in the atmosphere and found 17 parts per million of the two gases together . An earlier determination made by Dewar , f without the use of charcoal , was identical with this . The figures obtained by Eamsay , however , are for the total gases left uncondensed by charcoal at liquid air temperature , and have a direct bearing on the present question . Now , as Lord Blythswood and Allen J have shown , there is no difficulty in exhausting an X-ray bulb by the use of cooled charcoal from atmospheric pressure to the point at which it is difficult to force a discharge through the bulb . Yet the pressure of the helium and neon in the bulb must be 17 millionths of the initial pressure or about 1/ 75 of a millimetre . This result , although appearing strange by itself , is consistent with the experiment on the pressure of argon necessary to allow the discharge to pass . When any method of measuring the amount of gas remaining in the exhausted space other than the electrical is employed , the deficiencies of the non-conducting vacuum produced by cooled charcoal , when the vessel was originally filled with air at atmospheric pressure , become at once apparent . If , for example , the degree of vacuum obtained is measured by the rate of evaporation of liquid air in a Dewar flask , then the presence of these residual monatomic gases becomes all important . Experiments of a quantitative character on this subject are being made by Mr. Berry S in this laboratory . [ Added.\#151 ; Lord Blythswood and H. S. AllenJI after showing , in the first part of their paper , that an X-ray bulb could be exhausted by cooled charcoal from atmospheric pressure in one hour to " a vacuum so good that the tube had to be heated in order to allow the discharge to pass through it , " describe in the second part experiments in which the final pressures realised were measured by means of a McLeod gauge . When the apparatus was exhausted by a Fleuss pump initially to 40 mm. , the final pressure attained was 0*0009 mm. , whereas , starting from a pressure nearly atmospheric , the final pressure attained was ten times as great . They point out the importance of the preliminary exhaustion when an extremely high vacuum is required , owing to the presence of the less easily condensible gases , hydrogen , helium , and neon , in the air , but do not refer to the * ' Roy . Soc. Proc. , ' A , 1905 , vol. 76 , p. 111 . + ' Roy . Inst. Proc. , ' 1902 , vol. 17 , pp. 223\#151 ; 230 . | ' Phil. Mag. , ' October , 1905 , p. 497 . S See addendum to this paper . || Loc . cit. 1906 . ] Gases for the Production of High Vacua , etc. apparent inconsistency between the results with the McLeod gauge and their earlier ones with the electric discharge test . I was present at the meeting of the Philosophical Society of Glasgow ( March 22 , 1906 ) , when Mr. Allen showed experimentally the exhaustion of an X-ray bulb from atmospheric pressure by cooled charcoal , and I was much impressed at the time with the apparent inconsistency between this result and the recent measurements of Sir W. Eamsay already cited . The allusions in this section to the results of use of the charcoal method have reference solely to the phenomenon of the bad conducting quality of the residual inert gases that remain when air is absorbed from atmospheric pressure by use of charcoal or other methods . The question of the degree of vacuum produced under proper conditions for obtaining the best results is , of course , entirely different . Although the test of non-conductance , which has , so far , been relied upon too implicitly for gauging the goodness of the vacuum , * is useless , and may be actively misleading in the case of vacua obtained by the use of cooled charcoal without preliminary exhaustion by a pump , there is no doubt at all that , with suitable procedure , this method can give a very high degree of exhaustion.*]- ] XI.\#151 ; Quantity of Pure Helium Detectable by the Spectroscope . Mixtures of known composition were made of helium and oxygen , and known quantities introduced into the calcium absorbing apparatus of known volume . The pressure of the residual helium could thus be calculated . In one case 0T3 c.c. of helium was made up to 104 c.c. with oxygen , so that the mixture contained 1/ 8 per cent , of helium . Successive quantities , each of 0T3 c.c. , were introduced into the apparatus , the volume of which was 89 c.c. , including an ordinary Pliicker tube of volume 4*5 c.c. The following observations are extracted from the note-book . The " quantities " referred to are each 0T3 c.c. of the mixture , and the test of non-conductance was an alternative spark-gap of 2*5 cm . in air . 1st quantity.\#151 ; Glimpse of D3 for a fraction of a second as the oxygen spectrum suddenly cleared and tube became non-conducting . 2nd quantity.\#151 ; D3 clear while the tube conducted , which was but momentarily . 3rd quantity.\#151 ; D3 very pure and distinct , but tube became non-conducting . 5th quantity.\#151 ; D3 at first brighter than the mercury yellows . 6th quantity.\#151 ; D3 the brightest line at first except for the oxygen orange-red line . * Compare also G. Claude and Ren6 J. L6vy , ' Comptes Rendus , ' 1906 , vol. 142 , p. 876 . + Cf . the experiments described by Mr. Berry in the addendum to this paper . 452 Mr. F. Soddy . Calcium as tin Absorbent of [ Sept. 13 , 7th quantity.\#151 ; Just before the non-conducting point the general spectrum was plainly recognisable as helium . 8th quantity.\#151 ; The brighter helium red ( 6677 ) visible . 9th quantity.\#151 ; The two blues and violet seen . 10th quantity.\#151 ; -First glimpse of the peacock-green line ( 5016 ) . Tube took four minutes before it became non-conducting . 11th quantity.-\#151 ; Eight minutes before non-conductance . 13th quantity.\#151 ; The helium spectrum was now quite good while it lasted , but the tube became non-conducting in three minutes . The experiment was continued without much alteration up to the point at which 35 quantities had been added . The helium spectrum was plain , and indeed brilliant , so long as the tube conducted , but always a point was reached at which the discharge refused to pass . Diffusion was hastened by alternately heating and cooling the furnace . At the 35th quantity the tube conducted one way of the commutator and not the other , and this was taken as the limiting value . Later in the day and next morning the tube showed the same result . The discharge just passed , but the spectrum was feeble . The line D3 was clear and the peacock-green exceedingly faint . These were the only helium lines visible . The pressure of helium corresponding to each dose is 0*0014 mm. and to 35 doses 0*049 mm. It is thus clear that pure helium at a pressure of less than 1/ 20 mm. is non-conducting to the discharge , while far less than this can be detected in presence of other gases . Like mercury vapour and krypton , a very small trace is visible in the spectrum of another gas . In the above experiments the D3 line was visible plainly when only a single dose was added , so that to get the minimum quantity detectable a fresh series of experiments with more dilute mixtures was necessary . XII.\#151 ; Most Favourable Conditions for the Detection of Infinitesimal Quantities of Helium . Collie* states that in presence of large quantities of mercury vapour the blue helium line , 4922 , is the most delicate test for helium , and can easily be seen when none of the other helium lines are visible . It is likely , however , that the author mistook for helium a line in the spectrum of mercury which has the wave-length 4916*4 ( Stark ) and which is prominent in the mercury vapour-lamp spectrum . It is not often seen in the Pliieker tube , except when the latter is warm and liquid mercury is present , so that the vapour pressure of the mercury is considerable . Collie has suggested * ' Roy . Soc. Proc. , ' 1901 , vol. 71 , p. 25 . 1906 . ] Gases for the Production of High Vacua , etc. 453 for the calibration of spectroscopes a tube containing liquid mercury , helium , and hydrogen , as the spectrum consists of a large number of standard lines fairly equally distributed throughout the length of the spectrum . In such a tube I kept the blue line in question under close observation in a good spectroscope . With a feeble discharge , the tube cold and the mercury spectrum faint , this line was single and due to helium only . As the strength of the discharge was increased , and the tube warmed , the mercury spectrum intensified , and a second line became visible on the more refrangible side of the helium line and distant from it roughly about as far as D3 is distant from D2 . On still further increasing the strength of discharge the helium line disappeared entirely , and the line was again single and due to mercury only . On diminishing the discharge and allowing the mercury vapour to recondense , the less refrangible line reappeared and grew in strength as the other faded , and finally alone remained visible . Thus , it is clear that so far from enhancihg the strength of the helium line , 4922 , the presence of mercury serves to mask it completely even in presence of considerable quantities of helium . This line , 4916 , is seen equally well in a tube containing mercury in which no helium has been introduced . Under no conditions tried has the line 4922 been seen when D3 was invisible . The latter is by far the most delicate test for the presence of helium , and becomes visible with a quantity many times less than suffices to develop any other line in the spectrum . Some experiments with various kinds and sizes of spectrum-tube , some with aluminium and others with platinum electrodes , showed that with minimal quantities of helium at similar pressure it is slightly easier to detect the D3 line in the ordinary Pliicker tube of volume 4-5 c.c. than in a tube of minimum volume . But the difference is not great , and is mainly due to the sodium lines from the glass being more prominent in a tiny tube masking the D3 line . Certainly , when the object is to detect the smallest possible quantity of helium , the tube should be of as small volume as possible . A series of experiments was tried in which quantities of helium , far smaller than those necessary to allow the discharge to pass when in the pure state , were examined in presence of hydrogen and oxygen . A mixture containing 0'015 per cent , of helium with oxygen was prepared by the principle of successive dilutions . Known quantities were introduced into the calcium absorption apparatus of known volume . After the oxygen had been completely absorbed , connection between the spectrum-tube and the absorption chamber was closed , and traces of oxygen and hydrogen introduced into the gas in the spectrum-tube . This was accomplished by heating a trace of solid potash , previously fused and freed from water , Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 , in vacuo , ,or by momentarily raising to redness a spiral of platinum wire by means of a current . It does not appear to make much difference which gas is added to conduct the discharge . After the first momentary heating platinum gives oxygen free from hydrogen . The potash gives hydrogen , doubtless as water vapour . The function of this gas is merely to cause the discharge to pass . Once established , a large part , perhaps the larger part , of the current is carried by the helium , the spectrum of which , under these conditions , appears with extraordinarily minute quantities . With an ordinary Plucker tube and an apparatus of volume 111 c.c. after three doses , each of 0*13 c.c. of the 0'015-per-cent , mixture , D3 was but momentarily visible , and could not be again brought out by introducing oxygen or hydrogen . With four doses D3 was faint but clear and permanent , and this may be taken as the extreme limit of visibility . The partial pressure , due to the helium at this stage , is only 1/ 100 of that necessary to conduct the discharge when pure , being 0'0005 mm. as compared with 0'05 mm. for the case of the pure gas discussed in the last section.* If a vacuum-tube of 0*3 c.c. volume is used , it follows that a quantity of helium , 1/ 4000000 part of a cubic centimetre , measured at normal temperature and pressure , would be within the range of detection by the spectroscope . For safety a margin of twice this quantity should be allowed , or 1/ 2000 of a cubic millimetre . This quantity weighs 10~10 gramme , and contains-about 2 x 1013 atoms . The delicacy of the test may be indicated by the following consideration . It can be calculated on the assumption that the a-particle is an atom of helium , that a kilogramme of uranium nitrate would generate 1 c.c. of helium in a period of about 5000 years . The amount of helium produced in a single day should be within the range of spectroscopic detection . ^Researches on the production of helium from uranium and thorium have been in progress for some time , and it is hoped , now that the ground is cleared , that the matter will soon be put to a definite quantitative test . In the above experiments the actual quantity of helium used was , of course , many times the amount finally examined in the spectrum-tube . It is easy , however , to fill the absorption chamber after cooling completely with mercury , and to compress the gas into the spectrum-tube . In this * [ The point was raised in the discussion of the paper , how far it had been actually proved that the inert gases were not absorbed , at least in part , by the walls and electrodes . The last experiment answers this question , for in a tube containing only one-hundredth of the quantity of helium necessary to conduct the discharge in the pure state , the helium spectrum may be brought out afresh by introducing a minute quantity of hydrogen or oxygen , which would not have been the case if the helium had been absorbed when the tube became non-conducting . ] 1906 . ] Gases for the Production of High Vacua , etc. operation the minute quantity of hydrogen left unabsorbed by the calcium is , after the compression , just of the right amount to conduct the discharge and to reveal any trace of helium without any additional arrangement . As an example of an actual experiment , one may be taken from the note-book from an examination of the gases present in native platinum . On the view that the scarcity of an element , after prolonged and extensive search for it , justifies the suspicion that it may be a member of a disintegration series , it was thought possible that evidence of such disintegration might appear in the presence of rare gases in platinum , as is the case with the radio-active minerals . Messrs. Johnson and Matthey very kindly lent me as much native platinum as required , and I desire to acknowledge my indebtedness to them for their kindness . In one experiment a quantity of about 300 grammes was heated in a porcelain tube in an electric oven to 1200 ' C. , and the gases passed into a calcium absorption chamber of the usual kind provided with a tiny spectrum-tube at the upper end . A trace of carbon dioxide , from the walls probably , first came off . Then nitrogen appeared , and , as the temperature approached 800 ' C. , carbon dioxide in quantity . On closing the connection with the platinum and absorbing the gas with calcium , the spectrum-tube became quite non-conducting . These operations were repeated , the gas evolved being admitted and absorbed in stages . When the electric oven had reached a temperature of 1000 ' C. , a momentary glimpse of the D3 line was seen . At 1100 ' C. the peacock-green line was picked up , and the more prominent of the two reds seen extremely faintly . On forcing the discharge the argon greens could be faintly made out in a Eamsay pocket spectroscope . When the oven reached 1200 ' C. , a large quantity of carbon dioxide had accumulated . This was admitted to the absorption chamber , and the connection sealed and the heating of the platinum stopped . On cooling the calcium after absorbing the gases , the spectrum-tube was on the verge of non-conductance , but extremely faint helium could be detected . Mercury was admitted and the contents compressed completely into the tiny spectrum-tube . The helium spectrum was now reasonably bright , all the lines being visible , together with the hydrogen red and the mercury lines . With the pocket spectroscope argon could just be detected . It was estimated from the appearance of the discharge at various stages of the compression that about 1/ 5 of a cubic millimetre of helium was present , a quantity 400 times as much as could have been detected , yet only representing 1/ 15000000 per cent , by weight of the platinum . The experiment lasted but two hours , and is given merely as an example of the ease with which an infinitesimal quantity of helium may be separated from large amounts of other gases 456 Mr. F. Soddy . Calcium as an Absorbent of [ Sept. 13 , by means of calcium , and its quantity estimated with fair probability . No weight is to be put on the result as indicating the origin of the helium . As a matter of fact , the native platinum was quite distinctly though feebly radio-active , 300 grammes of it in an electroscope producing an effect equivalent to 0-07 milligramme of uranium oxide . Clevite usually contains about 2 c.c. of helium per gramme , and is usually of about the same activity as uranium oxide . The platinum contained about 3,000,000 times less helium , and was about 4,000,000 times less radio-active than clevite , so that there is no reason to go further to explain the source of the helium than to suppose that a trace of some radio-element is present in native platinum . Appendix.\#151 ; Results of Gauging High Vacua by the Evaporation Test . By Arthuk John Berry . In this note the results of some experiments , on the rate of evaporation of liquid air contained in a Dewar vessel exhausted in different ways , are described with the view to showing that this test may be used as a means of gauging the degree of vacuum produced by different processes . Owing to various causes the research has not been carried as far as it was intended , but one set of measurements , complete in themselves , have been obtained , which bear out in a clear manner one of the points discussed by Mr. Soddy in the paper preceding . Starting with a vessel filled with air at atmospheric pressure , there is no difficulty , by using the method of Sir James Dewar to produce a vacuum therein , in obtaining a vacuum apparently perfect , so far as the electric discharge test can indicate , provided that a sufficiency of charcoal is employed . It was of interest to compare the rate of evaporation of liquid air in a Dewar vessel exhausted in this manner with the rate in the same vessel exhausted also by Dewar 's method , but in which the air had been first removed by an auxiliary pump . Although the electrical test reveals no difference in the degree of vacuum obtained in the two methods , it is to be expected that the thermal test will show a far higher vacuum by the second method than by the first , owing to the residuum of non-conducting inert gases left by the first method.* This expectation has been fully borne out by the experiments . The vessel employed was of about 1 litre capacity , globular in form , and silvered on the two inner walls . During the exhaustions it was placed in an inverted position in an air oven , and the temperature maintained at * Compare Lord Blythswood and H. S. Allen , ' Phil. Mag. , ' October , 1905 , p. 497 . 1906 . ] Gases for the Production of High , etc. 457 350 ' C. A vacuum-tube served to indicate the progress of the exhaustion . At the completion of each exhaustion it was filled with liquid air , and kept in an ice chest to keep the external temperature constant . The vessel was weighed at regular intervals to determine the rate of evaporation of the air . Three different methods of exhaustion , designated throughout I , II , III , were employed . I. In the first the exhaustion was performed by the mercury pump . A Topler pump of ordinary pattern , worked by hand , was used , and pumping was continued from four to five hours while the vessel was heated in the air oven . The pump had a capacity of about 450 c.c. , and was provided with a phosphorus pentoxide tube and tap . The results of two similar experiments agreed well among themselves , and in the table the second of the two , which was slightly the better , is alone included . II . In the second method the apparatus was exhausted from atmospheric pressure by cooled charcoal . As in the experiments of Lord Blythswood and H. S. Allen * two separate charcoal bulbs were employed , the one with 97 grammes and the other with 70 grammes of charcoal freshly prepared from cocoanut shells . The first bulb alone reduced the pressure from atmospheric to the fluorescent stage in 30 minutes , and was then cut out and the second bulb , brought into action . The absorption was continued one and a-half hours further , and the vessel sealed off . No discharge could be sent through the vacuum-tube at this stage . III . The same vessel was exhausted by a duplex Fleuss pump of large size , mechanically driven , and during the action of the pump the charcoal was well heated . In this way carbon dioxide is expelled from the charcoal , and the last traces of air are swept out . It was found in a separate experiment that little or no difference was produced in the result by the displacement of the last of the air by oxygen during pumping . In this method only one charcoal bulb was used , which was connected direct by a glass tube without taps to the vessel being exhausted . The connection with the pump was sealed after the removal of the air was judged complete , and the absorption by charcoal continued for two and a-half hours . The following table shows the results of the three methods . Weighings were taken at intervals of either 6 or 12 hours . The first column shows the time in hours from the first weighing , and the total weight of liquid air initially present in the three experiments is indicated in the first line . The succeeding lines indicate the amount that has evaporated in the 6- or 12-hour interval from the previous weighing :\#151 ; * Loc . cit. 458 Calcium as an Absorbent of , etc. Hours . I* II . III . 0 972 grammes 954 grammes 979 grammes 12 2 x 54 *5 2x63 2 x 40 '5 18 54 62 40 24 54 60 39 36 2 x 54 *5 2x60 2x39 42 54 59 39 48 55 58 37 60 2x56 2 x 57 -5 2x37 66 56 67 37 72 57 56 37 84 2 x 58 *5 2x56 2x 37 90 58 55 38 96 59 ( 78 remaining ) 56 ( 18 remaining ) 36 108 \#151 ; 2x37 114 \#151 ; \#151 ; 38 120 \#151 ; .\#151 ; 36 132 \#151 ; \#151 ; 2x36 138 \#151 ; \#151 ; 36 144 _ 37 ( 78 remaining ) It will be seen at a glance that whereas the vacuum resulting in the second method , by cooled charcoal , but starting from atmospheric pressure , is inferior to that produced by a simple mercury pump , that obtained in the third method , by charcoal after removal of the air , is by far the best of the three . After six days 78 grammes of liquid air out of the original kilogramme remain in the vessel . In conclusion , I desire to take this opportunity of expressing my indebtedness to Mr. Soddy , at whose suggestion the research was undertaken , for placing the apparatus required at my disposal and for many valuable suggestions . * The slight increase in the rate of evaporation during this experiment is due to a shortage in the supply of ice in the ice-chest . In the other two experiments the chest was kept well filled .

rspa_1907_0003

0950-1207

The theory of the compositions of numbers.\#x2014;Part II.

459

460

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Major P. A. MacMahon, F. R. S., etc.

abstract

6.0.4

http://dx.doi.org/10.1098/rspa.1907.0003

en

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1907_0003

10.1098/rspa.1907.0003

Formulae

Tables

Mathematics

]\gt ; The Theory of the Compositions of Numbers . \mdash ; Part II . By Major P. A. MacMahon , F.R.S. , etc. ( Received August 23 , \mdash ; Read December 6 , 1906 . ) ( Abstract . ) This investigation was recently suggested to the author by Professor Simon Newcomb . A pack of cards is shuffled and then dealt out in succession , the cards being placed in one heap or pack so long as the numbers of pips on them are in ascending order ( equality in the numbers of pips as ascending order ) ; when there is a break in ascending order , a fresh heap or pack is commenced , and so on . In this way a set of packs will be formed containing cards respectively . If the total number of cards be , it is clear that the succession of numbers constitutes \ldquo ; composition\ldquo ; of the number into parts . Denote by the number of arrangements of the cards which yields the composition and by the number of ements which yields compositions into parts . The investigation is primarily concerned with the properties of the numbers ( 1 ) When no two cards in the complete pack have the same num'oer of pips ; ( 2 ) When the cards are numbered in any manner whatever . This investigation is essentially a contribution to the Theory of the Compositions of Numbers . The method employed is " " the powerful calculus of symmetric functions The associated differential operators are freely used , and a complete solution of the main problems of the paper is presented . Incidentally some useful and novel ideas in the pure theory of synumetric functions are reached and developed . The Theory of the Compositions of Numbers . In regard to the roots of the equation a new symmetric function is defined by impressing a multiplication theorem upon the elementary functions ; viz. , I write and generally ; and in regard to the homogeneous product-sums similarly , The main question concerning the numbers is solved by means of the symmetl.ic function ; and I obtain the important theorem where ) , are conjugate compositions of The composite conjugate to a given one is readily obtained from the nodal graph of a composition given for the first time in this paper . As an illustration , the graph of the composition is given by each row of nodes commencing vertically beneath the right-hand node of the previous row . The conjugate is thence obtained by reading the columns from left to right , viz.:\mdash ; ( 12111112 ) .

rspa_1907_0004

0950-1207

The theory of photographic processes, Part III: The latent image and its destruction. (Abridged account.)

461

472

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

S. E. Sheppard, D. Sc.|C. E. K. Mees, D. Sc.|Sir William Ramsay, K. C. B., F. R. S.

abstract

6.0.4

http://dx.doi.org/10.1098/rspa.1907.0004

en

rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1907_0004

10.1098/rspa.1907.0004

Biochemistry

Atomic Physics

Biochemistry

461 The Theory of Photographic Pro , Part III : The Latent Image and its Destruction . { Abridged Account . ) By S. E. Sheppard , D.Sc . , and C. E. K. Mees , D.Se . ( Communicated by Sir William Bamsay , K.C.B. , F.B.S. Beceived September 19 , __ Bead December 6 , 1906 . ) The following abridged account summarises the results of an investigation to be published in a more extended form subsequently . It deals with the formation of so-called " latent images " on photo-films , their destruction by chemical agents , and the bearing of these results upon the nature of the ight-product in silver halides and its function in promoting reduction . Part I.\#151 ; The Developable Condition in Halide Emulsions . The essential chemical reaction in development may be typified by the equation Ag + B'^Ag ( met.)-f-B ' . It is somewhat difficult to give a comprehensive and characteristic definition of development which shall distinguish it from normal reduction of silver ions to the metallic state , the more so that the word develop is used in such varied senses . For present purposes the following is probably sufficient . Developability is brought about when a preliminary treatment accelerates a subsequent reduction with reducing agents . It is , perhaps , impossible to draw a line of strict demarcation , but the inner mechanism will be clearer in the sequel . An investigation by one of the authors* has shown that the aforementioned reaction in development is reversible . Independently , then , of " developability " the reaction Ag+B'^Ag + B ' proceeds to a state of equilibrium . But it does not follow that metallic silver is precipitated . Unless the potential of the reducing ion is very high , the metallic silver may remain in solution . Two further eventualities are possible . A colloidal silver solution may be formed , stable under certain conditions , but liable to coagulation by electrolytes . Or there may be some cause lowering the meta-stable limit , so that metallic silver is precipitated . In the presence of solid silver with normal reducing agents complete reduction of the gelatino-halide grain is ensured , f in agreement with the " silver-germ " theory of development.^ Any cause tending to lower the meta-stable limit of the silver solution makes the halide developable . The aforementioned investigation showed that the reduction in * 'Chem . Soc. Trans. , ' 1905 , vol. 87 , p. 1317 . + 'Boy . Soc. Proc. , ' A , 1905 , vol. 76 , p. 217 : " Theory of Photographic Processes , Part TI . X ' Chem. Soc. Trans. , ' loc. cit. VOL. LXXVIII.\#151 ; A. 2 I Drs. S. E. Sheppard and C. E. K. Mees . [ Sept. 19 , development could be divided into two periods , an initial induction , the length of which depended chiefly on chemical processes , and a second period , in which the velocity depends chiefly on the supply of reducing ions to the affected grains . A number of substances , if introduced into the grain in very intimate mixture\#151 ; probably as a solid solution*\#151 ; can greatly shorten the induction period and bring about developability . We found that the following could act as " germs " for a dry-plate:\#151 ; ( a ) Silver , introduced as colloidal silver by treatment with silver nitrate solution and then Carey Lea 's ferrous citrate solution . Dilute HC1 was then applied , converting the colloidal silver to metallic , and in a developer reduction proceeded forthwith . ( b ) Gold , by the action of gold chloride on the gelatin film . ( c ) Platinum , to some extent as with gold , and better by the action of ferrous oxalate . ( \lt ; i ) Silver sulphide , by the action of polysulphides and of acid thiosulphate with ferrous oxalate . ( e ) Gas ions from flame gases with a plate soaked in developer . That the shortening of a chemical induction period by lowering the metastable limit is the essential factor in developability appears to be confirmed by the following . Gelatino-silver nitrate , jellified with 10-per-cent , gelatin , gave , with certain precautions , on treatment with ammoniaeal pyrogallol , or better , ferrous fluoride , rings of metallic silver deposited at regular intervals , in addition to a general coloured deposit . The former are the well-known Liesegang 's rings , f considered by Ostwald as a confirmation of his theory of a meta-stable limit , and quantitatively investigated for silver chromate by Morse and Pierce . } : Non-emulsified Silver Halide and the Function of Gelatin.\#151 ; An investigation of the action of light and reducing agents on pure precipitated silver bromide layers confirmed the statements of Abney and Schaum , S that gelatin mechanically or chemically retards reduction by developers . ; Now , Jaff6 , || in some studies on supersaturation , found that the " life " of a solution was always prolonged by repeated preliminary filtration . The removal of " germs " mechanically raised the meta-stable limit . Our experiments point to the gelatin functioning as a protective sheath against " germ infection , " thus * Cf . H. Weisz , ' Zeit . phys . Chem. , ' 1906 , vol. 54 , p. 305 . t ' Chemische Reaktionen in Gallerten ' ( Diisseldorf ) . 1 ' Zeit . phys . Chem. , ' 1904 , vol. 45 , p. 600 . S ' Zeit . wiss . Phot . , ' 1904 , vol. 1 , p. 377 . || 'Zeit . phys . Chem. , ' 1903 , vol. 43 , p. 565 . 1906 . ] The Theory of Photographic Processes . 463 mechanically retarding redaction . In part , also , it forms solid solutions with the halide , and complex ions with the silver ion , both additional helps to the stability of the halide . On the whole , the evidence tends to the conclusion that a necessary and sufficient condition for " developability " is the production in the silver halide grain of a new substance . How , the developable condition may be induced by the action of various energies , which we may group as follows* : \#151 ; ( a ) Ether vibrations , from infra-red to ultra-violet . ( b ) Kontgen rays , kathode rays , and the / 3- and y-radiation of radio-active bodies . ( c ) Mechanical stress or pressure . ( d ) Heat . ( e ) Chemical action . At present we will only consider the first , resulting in the ordinary photographic image . To deal critically with the various theories , physical and chemical , as to its nature , would take too much space . But it is almost impossible to account for the way in which the " latent " image interferes , with certain definite chemical reactions on any physical theory . Such are the aforementioned abbreviation of an induction in reduction , the existence of an image capable of development after fixation , and , in particular , the destruction of the " latent " image by halogenising and oxidising agents . We have made a somewhat extended investigation of the action of the latter and may collect our conclusions as follows . Part II.\#151 ; The Destruction of the " Latent " Image . Section A. The Action of Oxidisers Subsequent to Exposure . It has frequently been maintained that halogenising and oxidising agents do not actually destroy the latent image , but only retard development . Sterry , for example , considered that their effect was to delay what he termed " secondary development , " i.e. , an assumed intensification of a primarily formed image by silver from neighbouring granules . Our experiments with chromic acid subsequent to exposure led to the following conclusions:\#151 ; Plates were dipped by rotation in Cr03 solution for a given time , then rinsed by rotation , and developed.^ The plate-curve was distorted at the top , but * See also C. Lea , ' Phil. Mag. , ' 1891 , p. 320 . t J. Sterry , 'Phot . Journ. , ' 1904 , vol. 54 , p. 50 . X For the authors ' experimental methods , and for the meaning of the symbols log i and , etc. , see the previous papers , 'Roy . Soc. Proc. , ' 1904 , vol. 74 , p. 447 , and A , 1905 , vol. 76 , p. 217 . Drs. S. E. Sheppard and C. E. K. Mees . [ Sept. 19 , log i and y^were unchanged . The velocity-constant K of development was diminished , approximately in proportion to the logarithm of the strength of the preliminary Cr03 bath . Prolonged washing never entirely annulled the effect , but it was diminished . The values of K ( the velocity of development ) decreased with the time of immersion in Cr03 , ultimately reaching a minimum for each concentration , the function of the effect on K being independent of the concentration . From these facts we conclude that the Cr03 is irreversibly absorbed in the film , probably both to the film and to the silver halide , forming with the latter something of the nature of a solid solution . Freshly precipitated AgBr is coloured yellow by chromic acid , and the colour is not removed by long washing . The retained oxidiser then slows development by oxidising the developer in the film . This view was further confirmed as follows . Plates were treated , after " chromating , " with a solution of sodium sulphide , which restored K to its normal value by reducing the chromic acid . This " sulphite reaction " enabled us to decide without doubt that the prolonged action of Cr03 destroyed the latent image , both log i and yx were altered . After sulphiting , since K is now restored to its normal value , any change in y is due to a lessening of the mass of the latent image . The following table exemplifies the results for N/ 50 Cr03 , with a subsequent bath of N/ 10 Na2S03 , all developed in M/ 20 quinol for five minutes:\#151 ; t = time of immersion in Cr03 in minutes . t = 0 . 2 . 20 . 40 . 120 . 1-65 1-65 0-77 0*48 0-34 1*25 1-25 1*30 1*50 1-80 The rate- of attack on the latent image was found to increase very rapidly with the concentration of the Cr03 . The phenomena point to a re-oxidation ( possibly involving the release of halogen from a combination with gelatin ) of a reduction product , the latter being in solid solution in the normal halide . Section B. Desensitisers . Plates bathed before exposure in certain metallic salt solutions show a diminished sensitiveness to light , even after prolonged washing.* We find that salts of the following cations are effective , the anion being unimportant:\#151 ; Cu " , Hg " , Fe ' " . and ( UO2 ) " ' , whilst the following have no action :\#151 ; IT , K- , Ba " , Mg " , Mn- , Co " , Nr " , Fe " , Zu " , Mo " , Or- ( ? ) , Ag ' , Pb " , Th " " . If plates are dipped in CuS(\gt ; 4 immediately prior to development with FeC204 , there is no action . If left standing , yM is lowered , the latent image being destroyed in a * Luppo-Kramer , ' Wiss . Arb . auf d. Geb . d. Phot . ' ( Knapp , Halle ) . 1906 . ] The Theory of Photographic Processes . 465 manner similar to the action of chromic acid . But if dipped before exposure , the value of log iis greatly increased , i.e. , the sensitiveness diminished , but yx and K remain unchanged . The peculiar behaviour of desensitisers might be referred to two categories : either ( a ) it alters the sensitive salt prior to exposure ; or it occurs during exposure by reversal of the photo-chemical reaction . The first would agree with that theory of " ripening " which supposes this process produces a minute quantity of the photo-reduction product . The second requires that some of the desensitising salt be retained in spite of prolonged washing , a view confirmed by some experiments with metol development . The following experimental results , with ferrous oxalate development , fully bear out the theory that desensitisers act during exposure by reversal of the photochemical action , and not by any modification of the sensitive substance :\#151 ; ( i ) Moist and Dry Films.\#151 ; We have confirmed Sterry 's result : that moist films are less sensitive than dry ones , but have a higher \lt ; yx . ( ii ) Time of Immersion and Concentration.\#151 ; The effect , as measured by A log i , increases with the time of immersion , and on prolonged immersion weak solutions give the same effect as strong ones . Conversely , different solutions , acting for the same time but with long washing out , give the same effect . Otherwise this depends on the concentration and time . ( iii ) Fe-sensitising.\#151 ; By the action of a solution which combines with or reduces the desensitising ion , partial or complete resensitising may be obtained . With copper salts , quinine and benzaldehyde act in this manner ; with ferric ions , oxalate solution , the ferric complex not being so effective . Hence it appears probable that the desensitiser forms a solid solution or some combination with the silver salt , the maximum effect being for the limiting quantity absorbed . For the relative effect the following results were obtained :\#151 ; Plates bathed in . Water . CuS04 . ( U02)(N03)2 . FeCl3 . HgCl2 . Log i ... . . 1*95 0-50 0-59 P79 not \gt ; 2 Hence extent to which plate is made insensitive\#151 ; \#151 ; 3-6 44 69 \gt ; 100 The Mechanism of Desensitising.\#151 ; It is noteworthy that an effect may be obtained with very slight concentrations . Thus with M/ 100,000 C11SO4 , with two hours ' immersion before exposure , we obtained log i ( unbalhed ) T60 , log i ( bathed ) 2*25 . Drs. S. E. Sheppard and C. E. K. Mees . [ Sept. 19 , Hence , the desensitising effect of water is probably to be attributed to small quantities of impurities , and the action may give the clue to some of the troubles met with in emulsion-making , where the sensitiveness is sometimes found to drop for unknown reasons . Further , if a plate containing CuS04 be exposed long enough to overcome the resistance introduced by the CuS04 and so give a full density , after a time the image again disappears . A very small quantity of the desensitiser can thus continually destroy the latent image . The action may be described as catalytic . The metallic ions effective are all known to act as catalysts in oxidising and halogenising processes.* Substances such as stannous salts , quinine , mannite , etc. , f inhibit the positive catalysis by reacting with the catalytic ion , and hence acting as negative catalysts . The catalysis is to be referred probably to pseudo-catalysis or " Uebertragungscatalyse " ( Wagner , Ostwald ) , since the copper probably takes a definite part in the reaction according to some scheme of the form\#151 ; a ... ... . Cu " + Ag ( resp. Agy ) = Ag'-fCu* , b ... ... . Cu- + iOa = Cu " + 0 ' , the reformed Cu " again taking part in the destruction of the image . During exposure , this reversing action prevents the formation of the reduction product . The effect would be different after exposure , owing to the reduction product forming a solid solution in normal halide . This view of a catalysis of a reverse action was confirmed by an increase in the intermittency failure in presence of a desensitiser . Section C. The Spontaneous Decay of the Latent Image . Much evidence has been brought forward pointing to a spontaneous decay of the latent image , J with which we may associate the phenomena of " reversal , " and the failure of the Bunsen-Koscoe reciprocity relation , which states that the photo-chemical effect of an exposure E is the same whether the intensity or the time be altered , provided It E be constant . AbneyS and others have shown that this law does not hold absolutely for photographic plates , but that there is a range giving the maximum available energy . Repeating the work in a different manner , we used a very wide range of intensities . A typical table is as follows :\#151 ; * * * S * Bredig , 'Zeit . phys . Chem. , ' 1903 , vol. 46 , p. 502 ; Titoff , ibid. , 1903 , vol. 45 , p. 641 . + Bigelow , ' Zeit . pliys . Chem. , ' 1898 , vol. 27 , p. 585 ; and Titoff , loc. cit. f Cf . Baekeland , ' Zeit . wiss . Phot . , ' 1905 , vol. 3 , p. 58 . S 'Phot . Journ. , ' 1893 . 1906 . ] The Theory of Photographic Processes . I. t ( to give D = 1 ) in secs . It . log ( I x 1000 ) . 84 *5 0-204 17 -2 4-927 6-0 2 -59 15 -5 3-720 1-71 9-61 16 -4 3-232 0-452 34 -4 15 -5 2-655 0-130 120 15 -5 2-114 0'198 931 18 -4 1 -296 0-0074 4760 35 -1 0-869 0-0056 6400 36 -2 0-750 The deviations are best shown as follows : if the values of It , which gave an equal effect ( density ) be plotted against those of I , or , for convenience , log I , then the resultant curve will , if there be no deviation , be a straight line parallel to the x axis , but otherwise a curve showing the nature of the deviations . ( Compare Amagat 's pv-p curves . ) It was found that:\#151 ; ( a ) The failure is not a steady function of t. ( b ) Is independent of the total value of It . ( c ) Is relatively independent of the sensitiveness of the plate , i.e. , starts at the same point relatively to the inertia point.* The Intermittency Failure.\#151 ; Another form of reciprocity failure is with intermittent exposure , and this has been investigated by Abney and Englisch.f Our results are in good qualitative agreement with these observers ' , whilst practically they show that in sensitometry sector-wheels should not be driven at mote than 100 revolutions per minute , the error below this being negligeable . The general conclusions are:\#151 ; ( i ) The failure increases with the pause between each illumination , increasing as the sector-angles diminish . ( ii ) It increases with the rate of intermittency . ( iii ) It is greater with small intensities . Englisch attributes the failure to an initial induction and also to a " fading-loss " or deduction . This latter merits chief consideration . Various " molecular " and " strain " hypotheses have been suggested , but the peculiar nature of photo-chemical equilibria appears to give sufficient explanation . Abegg* has correlated these phenomena with the lessened photo-effect obtained when plates are exposed through the glass side . Erom the * This is opposed to Abney 's results , and possibly requires further confirmation ; our results are for plates of 20 and 200 H. and D. Experiments with " gasdight " emulsion are desirable , but difficult , owing to the great exposures required . + ' Schwarzungs-Gesetz phot . Platten . ' W. Knapp , Halle . 'Sitz.-Ber . Wien Akad . , ' 1900 , vol. 109 , p. 1 . 468 Drs. S. E. Sheppard and C. E. K. Mees . [ Sept. 19 , investigations of Luther* it appears that the continuous exposure of silver halides to light results in a state of equilibrium in which every light-intensity is balanced by a definite halogen potential ( whether expressed as gas pressure , solution pressure , or electric potential ) . Equilibrium is not usually reached in ordinary exposures because these are too short , whilst the halogen is removed by diffusion and combination with the gelatin . Diffusion is easier from the film-air side ; to this Abegg attributes the lessened effect through glass.f When the incident light is cut off , the reverse reaction is no longer opposed by the photo-dissociation , and the theory agrees well with the facts brought forward on the intermittency failure . The failure with small intensities is less easily accounted for , and is perhaps involved in processes antecedent to the dissociation of halogen , which will be mentioned later . Reversal.\#151 ; The peculiar phenomenon of reversal by very prolonged or intense exposure has not yet received a satisfactory explanation . Experiments with " retarded " development^ show that the characteristic plate curve does not give a complete epitome of the photo-chemical reaction . In the diffusion period of developmentS it is evident that an increase per grain of the photo-reduction product would not accelerate development , whilst if the bromine released were mechanically retained in the film it would oxidise the developer , as was found with chromic acid ( see p. 464 ) , hence leading to apparent reversal . The results of Precht|| with plates containing a developer ( edinol sulphite ) favour this view , since reversal is then much retarded . Weisz,1T in a comprehensive study of this phenomenon , has shown that " tanning " theories must be abandoned , and apparently considers that a modification of the physical state of the reduction-germ or nucleus is brought about . The Nature of the Reduction Product.\#151 ; So far the evidence only shows , if with some degree of conclusiveness , that the latent image consists of a substance containing less halogen . The " free silver " theory is negatived by the general behaviour of oxidising agents , and especially by that of nitric acid.** By the researches of Lutherff on the halogenisation of silver , the existence of the half-halides Ag2X is made very probable , as well as their * * * S ** * ' Zeit . phys . Chem. , ' 1899 , vol. 30 , p. 628 . t Loc . cit. f 'Chem . Soc. Trans. , ' 1905 , vol. 87 , p. 1317 . S Ibid. , p. 1316 . || 'Zeit . wiss . Phot . , ' 1905 , vol. 3 , p. 79 . IT ' Zeit . phys . Chem. ' ** 'Zeit . wiss . Phot . , ' 1905 , vol. 3 , p. 329 . tt Loc . cit. 1906 . ] The Theory of Photographic Processes . 469 identity with the visible and latent images , but later investigations by Gunter and Baur* show that the half-lialide must form solid solutions in all proportions with normal halide . The varying behaviour of different exposures to oxidisers may then be explained as follows : In consequence of the thickness of the film and the absorption of light by this , there exist layers of halide grains with varying amounts per grain of reduction-product . If n grains must be reduced to the metallic state to give a visible image ( Schwellenwert ) , the corresponding exposure will be shifted by reoxidation , progressively with time and concentration , but as the amount of subhalide falls , and its concentration in the grain is lessened , the potential of the oxidiser must be raised , or in the more exposed portions there will still be left sufficient grains with a sufficient minimum of half-halide to ensure developability . Paet III.\#151 ; " Ripening " and the Photo-electric Effect . Before summarising our conclusions on the photographic process we may interpolate a brief note on the process of ripening and on a probable action preliminary to any chemical action in exposure . Ripening or the raising of sensitiveness by " cooking " aggregates the particles in a well-known manner , f and increases the opacity to light . A possible explanation of the change involved is the following : The vibrations of light are considered to be of an electro-magnetic nature , and their absorption as conditioned by resonance . Previously mentioned researches by Quincke show that in a gelatino-halide emulsion the admixture is of the most intimate kind . Every electro-magnetic resonance is conditioned not only by the electric and magnetic properties of the resonators and of their surrounding medium , but also necessarily by their spatial distribution . In fact , the vibration period increases with the spatial extension of the resonators , with the closeness of their packing and with the dielectric constant of the medium.^ Zsgimondy , by the ultra-microscopic method , S has shown that gelatin consists of a homogeneous basis containing aggregates or " clumps , " the proportion being variable and influenced by the state of the gelatin . In an emulsion these clumps would give their form and distribution to the associated halide . They may be considered as forming the resonators or groups of systems of resonators postulated above , and their formation as one end in ripening . To this is also probably due the slow alteration in the viscosity of gelatin on cooking , noted by Schroder . * ' Zeit . phys . Chem. , ' vol. 45 , p. 618 . + Cf . Ostwald , ' Zeit . phys . Chem. , ' 1900 , vol. 34 , p. 495 . J CfLuther , ' Zeit . wiss . Phot . , ' 1905 , vol. 3 , p. 264 . S ' Zeit . Elektrochem . , ' 1902 , vol. 8 , p. 686 . Drs. S. E. Sheppard and C. E. K. Mees . [ Sept. 19 , The Photo-electric Effect.\#151 ; As is well known , certain metals and other substances , under the influence of ultra-violet light , lose a negative charge . The sensitiveness of the effect runs parallel with the absorption and is greatest for the region chiefly absorbed . The silver halides and many dye-stuffs used as sensitisers are highly photo-electric . It is assumed that the incident light sets free electrons or negative corpuscles , which at a bounding surface ionise the gas and are removed by diffusion and convection , or , if in an electric field , move in accordance . There is , however , another photo-electric effect . Many substances , and especially silver and the silver halides , give a difference of potential when immersed in an electrolyte and one pole exposed to light . M. Wilderman , * from a quantitative study of the phenomenon , concludes that the solution pressure of the exposed plate is increased . H. Schollf finds that silver iodide in light undergoes a species of dissociation which produces the ions of Agl and negative electrons . The latter are much more mobile than the electrolytic ions in solid silver iodide and impart metallic conductivity to this . Hence we must agree that in the plioto-film the electron is set free , not only at the ' bounding surface , but as far through the substance as the intensity of the light is sufficient . This may be regarded as the primary photochemical change . JolyJ has ably resumed the bearing of the photo-electric effect . He considers that the latent image is built up of ionised atoms or molecules and upon these the chemical effects of development are subsequently imposed . But the assumed stability of the free electric charges remains unexplained , S as also the destruction of the latent image by oxidising agents . Bather does it seem that the liberated electron brings about a chemical change ( if temperature and other conditions are favourable ) and that the product , when below the threshold of perception , forms the latent image . The process may be typified as follows:\#151 ; Ag- + Br ' + \#174 ; + G* = Ag ( met . ) + Br + G , or 2Ag . , etc. , \#151 ; Ag2 ' ( subhalide theory ) , where G is a molecule which becomes positively charged to G ' ( molion ) by the photo-electric process . Probably many of the phenomena of photographic induction may be susceptible of an explanation by this theory . In addition it accounts for the action of dyes as sensitisers for their own region of absorption , since the electrons liberated from the dye would act as before . * 'Roy . Soc. Proc. , ' 1904 , vol. 74 , p. 369 . + 'Ann . Phys. , ' 1903 [ 4 ] , vol. 16 , pp. 193 and 417 . J Address to Photographic Convention , 1905 . 'Brit . Journ. of Phot . , ' 1905 , vol. 52 , p. 551 . S Of . also Scholl , " On the Evanescence of Photo-electric Effect , " loc. cit. 1906 . ] The Theory of Photographic Summary . The photographic process , in brief , consists in the passage of ionised silver to the metallic state , with a sub-oxidation stage as probably intermediate . We may summarise our conclusions at the present stage as follows:\#151 ; 1 . Ripening due to\#151 ; ( a ) Formation of resonating systems . ( b ) Formation of ( intermediate ) reduction-product . Function of gelatin : forms resonators and assists reduction . 2 . Exposure , light absorbed and electrons set free which ionise the halide and surrounding gas . Function of gelatin : high dielectric constant , photo-electric , conserves electrons . Function of gas : according as it removes electrons or not , may diminish sensitiveness . Electrons may be emitted either from halide or from sensitisers . 3 . Ionisation leads to chemical reduction : electroly tically dissociated halide becomes discharged by interaction with electrons and positive atom or molions . Function of gelatin : combines with free halogen . The reduction probably results in a half-halide , AgsX , in solid solution . The action is reversible , a definite halogen pressure corresponding to each intensity of light . Destruction of latent image\#151 ; ( a ) Free halogen during and after exposure . ( b ) Desensitisers during exposure ; cyclic action with oxygen involved . ( c ) Oxidisers after exposure ; possibly halogen released from gelatin . ( d ) Reversal ( 1 ) halogen reconverts subhalide ; ( 2 ) halogen ( absorbed ) oxidises developer . 4 . Development : subhalide reduced to metallic silver , silver germ formed and complete reduction consequent on\#151 ; ( a ) Formation of silver germs : velocity chiefly dependent on chemical processes ; induction period . ( b ) Deposition on silver germ : velocity dependent on diffusion processes steady state . Very possibly subhalide occurs as an intermediate product in development also . Function of gelatin : filter against germs , so preventing fogging . Mr. A. Mallock . Relation between Breaking [ Dec. 4 , 5 . Fixation or removal of remaining halide.* In conclusion , the authors desire to express their great thanks to Sir William Ramsay , K.C.B. , F.R.S. , for his constant advice and interest in the investigation . The Relation between Breaking Stress and Extension in Tensile Tests of Steel . By A. Mallock , F.R.S. ( Received December 4 , \#151 ; Read December 13 , 1906 . ) A large number of the tensile tests of steel are now made with test-pieces , which are only a few diameters long ( fig. 1 ) . N. S , Fig- i. \gt ; \lt ; \ fl J -\#171 ; zl0 v When such a test-piece is broken by tension , it has a profile , as shown in fig. 2 . The usual records , made when the tests are carried out , include , among other things , " breaking stress " and " extension per cent. " " Breaking stress " here means the maximum tension applied divided by the original area of the test-piece ; and extension per cent , is taken as the percentage increase due to the strain , in the distance between two marks , one at either end of the test-piece , whose unstrained distance is known . The use of the term " breaking stress " in the above sense is convenient , from an engineer 's point of view , as showing what force a bar , etc. , of given sectional area will stand before giving way . The true breaking stress of a material , however , is the actual intensity of the stress at * 'Phot . Journ. ' ( Trans. Boy . Phot . Soc. ) , 1906 , vol. 46 , p. 235 : " On the Theory of Fixation . "

rspa_1907_0005

0950-1207

The relation between breaking stress and extension in tensile tests of steel.

472

478

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

A. Mallock, F. R. S

article

6.0.4

http://dx.doi.org/10.1098/rspa.1907.0005

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rspa

http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1907_0005

10.1098/rspa.1907.0005

Measurement

Tables

Measurement

]\gt ; onclusion , uthorsMr . Mallock . desire txpress their great thanks tetween B 5 . Fixation or removal of remalnlng halide . * William amsay , K.C.B. , F.R.S. , for his constant advice and interest in the investigation . The Relation between Strcss and Extension in Tensile Tests of Steel . By A. MALLOCK , ( Received December 4 , \mdash ; Read December 13 , 1906 . ) A large number of the tensile tests of steel are now made with test-pieces , which are only a few diameters long ( fig. 1 ) . When such a test-piece is broken by tension , it has a profile , as shown in . The usual records , made when the tests are carried out , include , other things , " " breaking stress\ldquo ; and " " extension per cent " " Breaking stress\ldquo ; here means the maximum tension applied divided by the original area of the test-piece ; and extension per cent. is taken as the percentage increase due to the strain , in the distance between two marks , one at either end of the test-piece , whose unstrained distance is known . The use of the term " " breaking stress\ldquo ; in the above sense is convenient , from an engineer 's point of view , as showing ) force a bar , etc. , of given sectional area will stand before giving way . The true breaking stress of a material , however , the actual intensity of the stress at ' Phot . Journ. ' ( Trans. Roy . Phot . Soc 1906 , vol. 46 , p. 235 : " " On the Theory of Fixation 1906 . ] Stress Extension in Tensile Tests of Sbeel . the broken surface , and is , of course , greater than the nominal breaking stress , because of the reduced area of the broken surface . To avoid confusion , I will call the true breaking stress the " " intrinsic strength\ldquo ; of the material . An examination of a very large number of observations made with the short test-pieces shows that , if the nominal breaking stress ( as defined bove ) is expressed in tons per square inch , the arithmetical sum , breaking stresselongation per cent. , remains constant , and equal to about 67 or 68 for all mild steels , which , at the beginning of the test , are free from internal mechanical strain , no matter what has been the heat treatment of hardening and annealing to which they have been subjected . The object of this note is to examine the reason for this : for , since breaking stress has the dimensions of a force \mdash ; an area , and extension per cent. is a pure number , it seems at first sight that no physical quantity could be represented by their sum . To determine the relation between breaking stress ( B ) , elongation per cent. ( E ) , and the intrinsic strength of the material , the form assumed by the test-piece when extended must be known . The experimental fact to be explained is constant or 68 , if is expressed in tons per square inch . Any relation which makes ensures the constancy of the sum of , and a variety of relations might be assunled which will do this approximately ; but the particular relation to be sought for is that which not only makes , but also makes the diameter calculated from correspond to the measured diameter , not only at the break , but along the whole length of the test-piece . When the extension is a small of the whole length , the contraction of the diameter is nearly uniform over the whole . As the extension proceeds , the local contraction appears , and breakage ultimately occurs at the narrowest part of the neck . Measurements taken from a number of test-pieces show that the extensions can be represented as being due to ( 1 ) a general and unifornl contraction of the diameter of the test-piece , and ( 2 ) , in to this , contraction of diameter , which at any given cross-section is a negative exponential function of the distance of that cross-section from the crosssection where the break occurs , the axis of the exponential curve being the generating line of the cylinder , to which the distant sections of the testpiece ( had it been long ) would have been reduced by ( 1 ) . The extensions corresponding to ( 1 ) and ( 2 ) will be considered separately . Mr. A. Mallock . between } Let 2 original length of test-piece , extended \ldquo ; original diameter contracted diameter extension ratio reckoned on extended length , , , , , original length , force applied to produce breakage divided by original area of cross-section . intrinsic strength of the material . Taking first the extension corresponding to ( 1 ) , since , as is well known , the density of the material is not appreciably affected by the extension , , so that Now ; thus . ( I ) If the unit of force in which is expressed is chosen so that units and 100 units tons per square inch , units identically , if is a constant . When is small , and are nearly equal , so that for small extensions units nearly . For the extension corresponding to ( 2 ) take the axis of X parallel to the axis of the test-piece ( 4 ) , and let , be the abscissae respectively of the broken end of the test-piece and the end ( or mark ) from which the extension is measured , and let be the diameter at The curye representing the diameter of the test-piece will be part of the curve , and the condition as to the constant density ( i.e. , invariable volume of the material ) ives the relation 1906 . ] Stress in sile Tests of Steel . Performing the integration , we have We may take / as nearly equal to , and if , for convenience , we put equal to being the yalue of for which , then To find the actual value of by computation is laborious , but a simple graphical method can be employed . We have on putting , and in ( II ) , a curve for , say , can be found for any assumed value of thus :From x subtract , and through the point on the axis of , and at an of to the axis , draw a line to cut curve in , then the abscissa of is In this way the has been constructed for test-pieces of the proportions which were used for measurement , viz. inch , inches ) . An examination of this diagram shows how nearly constant the sum of the breaking stress and elongation per cent. is on the assumption that the intrinsic th of the material is a quantity which is not altered by heat treatment , whether of hardening or annealing . It gives some evidence , however , that the intrinsic strength increases slightly as the material is extended , not more than about 5 per cent. for an extension of 30 per cent. The intrinsic strength of steel probably varies with the amount of carbon , . but since Professor Ewing gives 60 to 70 tons per square inch as the average tensile strength of high carbon tempered steel , in which the extension be small , the variation cannot be large . Any considerable addition of nickel or chrome , however , seems to the intrinsic strength , as the same authority gives 90 tons as the breaking stress of a 12-per-cent . nickel steel and 80 tons for a chrome steel of chrome not stated ) . * In saying that the intrinsic of all ordinary steels is about 70 tons per square inch , I exclude altogether case of drawn wire or rolled plates , and refer only to such steel as is fairly isotropic and eneous at the " " Strength of Materials Ewing , 1906 . Mr. A. Mallock . between Breaking [ Dec. 4 , 1906 . ] Stress and in Tensile Tests of Steel . commencement of the test . To compare the strength of a wire with the strength of the isotropic material is rather analogous to comparing the strength of a rope with strength of a felt made of the same fibre . The resistance of the rope to tension would be somewhat less than three times the resistance of the felt . The tensile strength of steel wire has been raised in some cases to more than twice the intrinsic of the material , but it is probable that , if the experiment could be tried , it would be found that the resistance to tension a diameter of the wire was inisbed . When the condition regarding eneity and freedom from initial strain is fulfilled , I think the constancy of the sum of the breaking stress and extension per cent. , and the approximation of this sum to 68 , may be looked on as a good test of the quality and soundness of the steel . If the sum is less than 68 , it is an indication either of or ties of structure , for it may be seen that the mere presence of parts havin a different degree of ductility , without any actual flaws , would lessen the extension , because the less ductile parts would either give first and so throw excessive stress on the rest , or if the harder parts did not extend with the rest the distortion of the neighbouring softer part would ) excessive , and so cause a breakage . It must be noted , however , that unsymmetrical holding of the test-piece in the testing machine would produce the same result , especially in the case of hard steels where the extension is small . See Nos. 14 to 19 and 21 to 23 in the Table , where the small extension is probably due , in part at any rate , to this cause . It occasionally happens that the sum is reater than 68 . This , I think , is due to the fact that what is called the breaking stress is the yreatest stress measured , which is not always the stress at the monlent of . With very extensible steels the material at the neck gives way at surface , while still holding on in the interior . Thus the working area at the moment of the break is somewhat less than the of the broken surface , and the interred breaking stress in such cases refers to a period of the test bef.ore the extension has reached its ultimate value . As far as I have observed the test-pieces rarely break in the middle of their length , and there is a tendency for a neck to be formed near both ends . gives the results of some measures of diameter which this . It is probably due to the sudden alteration in the diameter of the test-piece beyond the working part , which causes a non-uniform distribution of stress over the cross-sections in the neighbourhood . It should not appear in a testpiece where the diameter tapered entl to the working diameter . VOL LXXVIII.\mdash ; A. 2 478 Stress Extension in Tests of Steel . A Table is appended iving the numerical results of some of observations . The general conclusion which I draw from the relations observed to hold between breaking stress extension and contraction of area , is that the various treatments and chemical compositions of ordinary mild steels ( whether carbon nickel or nickel chrome ) , though operating powerfully on the limits distortion , have but little effect on the intrinsic strellgth of the material . E. Extension per cent. on a length of 2 inches . B. Breaking stress in tons per square inch of original cross-section . S. Sum of breaking stress and extension . D. Measured diameter at break . F. Intensity of stress at broken surface ( to the nearest ton per square inch ) on the assumption that B. was the stress at the time breakage occurred . denotes nickel steel . U. means that the axis of the test-piece was bent , as well as extended . This may be due to the want of homogeneity , but is more the result of the test-piece not being held symmetrically in the testing

rspa_1907_0006

0950-1207

An examination of the lighter constituents of air.

479

482

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Joseph Edward Coates, B. Sc.|Sir William Ramsay, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1907.0006

en

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1907_0006

10.1098/rspa.1907.0006

Thermodynamics

Atomic Physics

Thermodynamics

479 An Examination of the Lighter Constituents of . By Joseph Edward Coats , B.Sc. Wales . ( Communicated by Sir William Ramsay , F.R.S. Received November 29 , \#151 ; Read December 13 , 1906 . ) This research was undertaken with the object of ascertaining whether a large quantity of air , if systematically fractionated , would yield any constituent lighter than helium . It has been stated that " coronium " has revealed its presence in the gases emitted from the Solfatara of Pozzuoli by a line of wave-length 531-5\#151 ; 531'6 ; and that from some of the Vesuvian fumaroles gases have been obtained which give rise to new lines not coincident with any important lines in the neon or helium spectra.* Again , it has been stated by Dewar in a lecture delivered at the Royal Institution ( April 11 , 1902 ) , f that in the most volatile part of the atmosphere " a vast number of rays , generally less brilliant , are distributed through the whole length of the visible spectrum . The greater part of these rays are of , as yet , unknown origin."| A subsidiary object of the present research was to form a new estimate of the proportion of free hydrogen in air by the method of fractionation . The most important estimations have been made by Gautier , Rayleigh , and Dewar . Gautier , using the method of passing air over red-hot copper oxide , found 19*5 volumes of free hydrogen in 100,000 volumes of air , i.e. , about half as much free hydrogen as carbon dioxide . S Rayleigh|J discussed and , in part , repeated the work of Gautier ; he considered three parts per 100,000 as a maximum estimate , but regarded the question as still unsettled . Dewar , in the lecture mentioned above , stated that " air contains as a minimum not more than -I0^000th of free hydrogen . " The conclusions arrived at in this paper may be briefly stated : ( 1 ) there are no unknown lines in the spectrum of the lightest portions of the air , all thost observed being traceable to helium , neon , and hydrogen ; ( 2 ) the amount of hydrogen separable from air is much less than the maximum assigned by the above-mentioned investigators , for it amounts to about one volume per million and a-half volumes of air . The first stage in the fractionation was effected by means of the air- * Nasini , Anderlini , and Salvadori , ' Accad . dei Lincei , ' 1898 , vol. 7 , pp. 73\#151 ; 74 . t ' Proc. R. Inst. , ' vol. 17 , p. 225 . 1 See also Dewar and Living , ' Roy . Soc. Proc. , ' vol. 67 , p. 467 , 1900 , " Spectrum of the More Volatile Gases of the Atmosphere Condensed at the Temperature of Liquid Hydrogen . Preliminary Notice . " S 'Ann . Chim . Phys. , ' vol. 22 , 1901 . || ' Phil. Mag. , ' vol. 3 , 1902 , p. 416 . Mr. J. E. Coats . An Examination of the [ Nov. 29 , liquefying apparatus at University College , Gower Street . The air of the compressor room ( situated in the basement and well ventilated ) passed through the apparatus , and the portion which did not liquefy was collected in a large gas-holder . This , together with fresh supplies of air , was repeatedly circulated through the apparatus , with the object of making a preliminary concentration of the lighter portions . To avoid contamination with hydrogen , the gas-holder was well painted inside and the compressor cylinders lubricated with very dilute alkali . The total quantity of air dealt with in this operation amounted to about 73,500 litres . A second fractionation of the gas thus collected was obtained by liquefying about 70 or 80 litres at a time in a glass bulb immersed in liquid air boiling under reduced pressure.* Light fractions were boiled off and the process repeated several times until the volume was reduced to 4700 c.c. This portion ( 1 ) was separated , by the method of absorption in cooled charcoal , into three fractions , ( 2 ) not absorbed at about \#151 ; 190 ' C. , ( 3 ) not absorbed at about \#151 ; 110 ' C. , ( 4 ) discarded . Spectroscopic examination showed ( 2 ) to be almost pure neon and helium with faint hydrogen lines . An attempt was made to fractionate ( 2 ) and ( 3 ) at the temperature of liquid air boiling at ordinary pressure ( \#151 ; 190 ' C. ) , but , in the case of ( 3 ) , the fractions always showed the nitrogen spectrum ( see table of fractionations ) ; it was therefore decided to work at the temperature of liquid air boiling under reduced pressure , which represents a temperature of about \#151 ; 205 ' C. Table of Fractionations . \#151 ; 14 \#151 ; 15 \#151 ; 16 \#151 ; 19\#151 ; --8\#151 ; ----24 --9\#151 ; 22---- 3---- \#151 ; 10\#151 ; \#151 ; 21\#151 ; \#151 ; 11\#151 ; \#151 ; 12\#151 ; 23----- \#151 ; 13\#151 ; * A description of this piece of apparatus and its use has been given by Ramsay and ravers , ' Phil. Trans. , ' A , vol. 197 , 1901 , p. 58 . 1906 . ] Lighter Constituents of Air . Spectroscopic examination showed ( 5 ) and ( 6 ) to be chiefly neon and helium , with a little hydrogen\#151 ; no new lines were detected ; ( 7 ) was neon and nitrogen , while ( 8 ) and ( 11 ) consisted chiefly of nitrogen ; ( 5 ) , ( 6 ) , ( 7 ) were mixed and separated into the fractions ; ( 14 ) pumped off at -205 ' C. , ( 15 ) at -190 ' C. , ( 16 ) and ( 17 ) at 18 ' C. , and ( 18 ) at 236 ' C. ; ( 8 ) , ( 9 ) , ( 10 ) were mixed and similarly separated into fractions ( 19 ) , ( 20 ) , ( 21 ) ; ( 19 ) gave the nitrogen spectrum , ( 14 ) and ( 15 ) consisted of neon and helium ; ( 16 ) and ( 17 ) contained hydrogen in addition to neon and helium , while ( 18 ) contained more nitrogen than neon . Fractions ( 14 ) , ( 15 ) , ( 16 ) , ( 17 ) were therefore analysed for hydrogen , whilst the remaining fractions , as shown by the table , were worked up for neon and helium , of which 25 c.c. were obtained . The gases were measured separately , sparked with oxygen , the excess of which was subsequently withdrawn by means of phosphorus . The diminution in volume gave the amount of hydrogen present . The gases were measured by the method described by Ramsay.* c.c. Volume of ( 14 ) ... ... ... . 1*258 " after sparking 1*260 " of hydrogen ... nil c.c. Volume of ( 15 ) ... ... ... . 1*995 " after sparking 2 001 " of hydrogen ... nil N.B.\#151 ; The slight increase in volume represents a small error of measurement of the order about 1 in 400 . C.C. Volume of ( 16 ) ... ... ... . 11*615 " after sparking 11*420 " of hydrogen ... 0*195 Volume of ( 17 ) ... ... " after sparking " of hydrogen ... Total volume of hydrogen ... 0*778 c.c. C.C. 6*507 5*924 0*583 The spectra of ( 14 ) , ( 15 ) , ( 16 ) , ( 17 ) were very carefully compared with the spectrum of a neon and helium tube , and they agreed exactly throughout ; no new lines could be detected ; this also shows that the contractions could not have been due to the presence of carbon monoxide , possibly derived from the charcoal . Any hydrocarbons in the air would have been removed in the charcoal . As a test of this method of separating a small proportion of hydrogen from air , a parallel series of fractionations was performed on about 60 litres of air , to which 5*6 c.c. ( measured to 0*1 c.c. ) ol hydrogen had been added . Three fractions were finally obtained from charcoal : ( 1 ) at 205 C. , ( 2 ) and ( 3 ) at \#151 ; 190 ' C. Analysis , as before , gave the following results:\#151 ; * ' Eoy . Soc. Proc. , ' A , vol. 76 , 1905 , p. 113 . 482 An Examination of the Lighter Constituents of Air . ( 1 ) 4*602 c.c. gave 0*170 c.c. hydrogen ( 3*7 per cent. ) . ( 2 ) 13*005 " 0*702 " ( 5*4 " ) . ( 3 ) 29*259 " 1*585 " ( 5*4 " ) . Total volume of hydrogen ... . 2*457 c.c. Thus , only about half the added hydrogen was recovered . The most probable source of loss seems to be in the fractionation from the liquefied gas , when even the passage of air bubbles through the liquid appears insufficient to expel all the hydrogen . Dewar has also stated* that hydrogen is very soluble in liquid air ; it is thus possible that a little hydrogen might have been removed during the initial process with the liquefying machine . It is noteworthy that the fraction pumped from the charcoal at \#151 ; 205 ' C. contains less hydrogen than that which comes off at \#151 ; 190 ' C. ; the absorption of hydrogen seems to be of about the same order as that of neon . The total volume of hydrogen obtained from the air was 0*778 e.c. , and the total volume of mixed neon and helium was 46 c.c. Using the estimate of Ramsay , f agreeing with the previous one of Dewar , \#163 ; viz. , 60,000 volumes of air contain 1 volume of neon and helium together , it is found that 2,760,000 c.c. of air contain 46 c.c. of neon and helium and 0*778 c.c. of hydrogen , whence 3,550,000 c.c. of air contain 1 c.c. of hydrogen . This number can be corrected by assuming , as an approximate factor , the ratio 2*5/ 5*6 derived from the experiments on the air to which hydrogen had been introduced . The corrected estimate is 1 c.c. of hydrogen in 1,583,600 c.c. of air , or , approximately , one volume of hydrogen per million and a half volumes of air . On comparing the total volume of air originally dealt with , it is evident that the liquefying plant was of very little use in concentrating the lightest portions ; it is certainly better to calculate the hydrogen on the quantity of neon and helium actually obtained than on the original volume of air . It appears from these results that the proportion of free hydrogen in the atmosphere is exceedingly small\#151 ; so small , indeed , as to make its exact estimation a matter of extreme difficulty , and we must regard our results as indicating the order rather than the exact proportion in which the hydrogen is present . In conclusion , I wish to express my warmest thanks to Sir William Ramsay , who suggested and constantly superintended the work during its progress . * Loc . cit. f Loc . cit. J Loc . cit.

rspa_1907_0007

0950-1207

The photo-electric fatigue of Zinc

483

493

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

H. Stanley Allen, M. A., B. Sc.|Professor H. A. Wilson, F. R. S.

article

6.0.4

http://dx.doi.org/10.1098/rspa.1907.0007

en

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http://corpora.clarin-d.uni-saarland.de/surprisal/6.0.3/?id=rspa_1907_0007

10.1098/rspa.1907.0007

Electricity

Tables

Electricity

]\gt ; The Photo-electric Fatigue of By H. STANLEY ALLEN , M.A. , B.Sc. , Senior Lecturer in Physics at 's College , London . ( Communicated by Professor H. A. Wilson , F.R.S. Received October \mdash ; Read November 15 , 1906 . ) Hertz 's observation*that ultra-violet light can facilitate the passage of an electric spark led to the discovery of other photo-electric actions . In the earliest experiments on the photo-electric effect of metals it was noticed that the action was diminished by exposure to . Thus vachsJ who founcl that a metal becomes positively electrified under the influence of ultra-violet light , states that " " old surfaces no show the phenomenon . The radiation itself lowers the potential to the plates can be electrified , so that with any succeeding experiment made with the same surface the potential obtained is lower , while tlJe rise to it takes place more rapidly , and the decrease is greater than when for the same of time the experiments the plate was not illuminated This diminution of the photo-electric action is spoken of as " " fatigue\ldquo ; of metals under the influence of . It has received attention from many physicists , of whom BuissonS and Ladenburg may be specially referred to . The present paper deals with the manner in which the photo-electric activity of zinc diminishes when the metal is exposed to DESCRIPTION 0F APPARATUS . 1 . Source of Light.\mdash ; Some preliminary experiments } made with the electric arc , limelight , and burning magnesium , but these proved too unsteady to give reliable results over long intervals of the Doeneral character of the fatigue curves was similar to that of the obtained later with a steady source . A Nernst lanJp was found to give actinic light for the observations , nd when the current was supplied from a battery of large storage cells this source reltained sufficiently steady for hours . When the lamp was run on the town mains the variations in 'Wied . Ann vol. 31 , p. 983 , 1887 . See J. J. Thomson , 'Recent esearches ' and tion of Electricity Gases . ' Phil. Mag Series 5 , vol. 2 p. 78 , 1888 . S 'Comptes Rendus , ' vol. 130 , p. , 1900 ; 'Ann . Chim . Phys vol. , pp. 320\mdash ; 398 , November , 1901 . 'Ann . . Physik , ' vol. 12 , pp. , 1903 . 484 Mr. H. S. Allen . lamp tntensity ohown borresponding irregularitiesof tupply caused considerable fluctuations iurrent through t : in the fatigue curve . 2 . Testing Vessel and pparatus was practically a rallel-plate air condenser enclosed in a metal box . The construction of the testing vessel employed is shown iu the diagram ( fig. 1 ) . The vessel was of brass , closed at top and bottom by brass covers screwed on . The top cover had a circular aperture closed by a quartz window , B. The central electrode , , was insulated from the base by an ebonite plug , E. Small iron cups containing mercury are shown at and * the latter being in metallic connection with the case of the apparatus , which was perwood lever served tmake oreak themanently earthed.upported connection between the mercury cups , whilst the observer relnained at a distance from the apparatus . is a thick lead plate with a circular hole , placed between the and the apparatus to shield the latter from ineffective radiation . In most of these experiments the upper plate of the condenser was formed by the lower face of the artz window , rendered conducting by phosphoric acid , as suggested by Strutt . In other experiments it consisted of a piece of wire gauze , ported by , but insulated from , the cover of the apparatus . This upper plate was connected to the positive terminal of a battery of small accumulators ( 200 elements ) , the other end of the battery being to earth . The lower plate of the condenser , formed by the piece of zinc to be tested , was connected to one set of quadrants of an electrometer , the other set being earthed . The rate of leak of electricity across the gap was measured by the time taken for the electrometer needle ( observed with telescope and scale ) to turn through aiven angle . A Kelvin electrometer , with replenisher and gauge , was used most frequently , but in some experiments an electrometer of the Dolezalek type wfts oyed . .3 . Method of ) erimenting.\mdash ; The zinc plates used in these experiments were 5 cm . in diameter . They were either polished or amalgamated . In the former case { he final polishing was done with rouge paper , either by hand or 1906 . ] The Photo-electric Fatigue of Zinc . in the lathe . Ladenburg*has pointed out that as the polish increases the discharge approaches a maximum , a result that was confirmed in these experiments . The surface of the amalgamated plate was renewed by rubbing a few globules of mercury over it with a cloth . The freshly polished or re-amalgamated plate placed in the vesse ] , on the central electrode , the cover put in position , the electrical connections made and the Nernst lamp lighted . Observations were usually commenced within two nlinutes of the preparation of the plate and were continued as as desired , readings of the rate of leak being generally taken at intervals of two minutes . 4 . Results ] with Zinc.\mdash ; The general course of the decay curves was similar for polished and amalgamated zinc . The fatigue was very rapid immediately after the ) etal to light , but after some time ( usually 20 or 30 utes from the commencement ) the rate of decay became much slower . Such a result would be expected in the case of a change following the compound interest law but the initial decay observed compared with that in the later stages was even more rapid than would be required by such a change . The results are most clearly exhibited by plotting them on semi-logarithmic paper , where the ordinate represents the arithm of the rate of leak , the abscissa the time from the first illumination of the piate . An exponential formula would be represented by a straight line . The curve the observed results consists of two parts , the first ( AB ) convex to the origin : the second ( BC ) a straight line inclined to the axes . That is to say , after about half hour 's exposure to light the decay of the activity may be expressed by a single exponential term . This was confirmed by continuing the oyer a lotJg period . The curve reproduced in fig. 2 shows that after the first rapid change the activity decays ill an exponential man ner for several hours . The place during the first 100 inutes of experiments are shown more clearly in and 4 . The vertical scale in . is ot the same as in the later ralns , for in these the of leak about 10 times those recorded in the former . If the straight portion is continued backwards in the manner shown in , and the difference between the rates of leak corresponding to and is plotted ainst the time on semi-logarithmic paper , another light line is obtained , steeply inclined to the horizontal axis . This shows the ) results can be represented by the sum of two exponential terms , so that the electric acCivity is given by the enlpirical formula 486 Mr. H. S. Allen . [ Oct. 26 , 486 Mr. H. S. Allen . [ Oct. 26 , For polished zinc this formula was found to apply under val'ied conditions , respecting the polish of the plate and the intensity of the illumination . The value of was than 10 times that of , and was of the same order of magnitude as 5 . In order to render more evident the reement between the results of observation and those obtained by calculation from the above formula , the Fro . 2 . Pboto-electric Fatigue of Zinc . Experiments made June 30 , 1905 . Nernst lamp taking ampore on 110-volt circuit . following table has been constructed for a selected case . This series of observations August was made with well polished zinc , illuminated by a 1-ampere Nernst lamp on a 110-volt circuit . The first reading was taken three minutes after the polishing of the ziuc plate was completed . The exact stant of lighting the Nernst lamp was not noted in this experiment , but it 906 . ] The Photo-electric of Zinc . is assumed to have taken place two minutes after polisbing . The first column of the table gives the time in minutes from the first illumination of the plate . The last column gives the observed value of the photo-electric current , expressed as the number of scale divisions that would be passed over in 100 seconds . * Experiments made ,1900 with by Lamp . Nernst Lan * The actual observation was the time taken to pass over 100 scale divisions . division per second corresponded to anlpore . 488 Mr. H. S. Allen . [ Oct. 26 , In the fourth column we have the calculated value of the current , the number being the sum of those in the two preceding columns . The first exponential term falls to half value in minutes , the second in 94 minutes , the constan ts of being and . The first term accordingly diminishes in value and becomes after Photo-electric Fatigue of Zinc . Experiment made August 7 , 1905 , with well-polished zinc . Experiment made July 24 , 1905 , with polished zinc . Nernst lamp taking 1 ampere on 110-volt circuit . 1906 . ] The Photo-electric of Zinc . 45 minutes . The values for the calculated current in the second part of the table are derived from the term 6 . These results are plotted on rithmic paper in fig. 3 . On the sanJe diagram is shown the fatigue curve for another experiment July 24 , 1905 in which the zinc plate was polished by hand instead of in the lathe , giving much smaller values for the photo-electric current . The constants of change in this case are and the time taken to fall to half value 5 minutes and 67 minutes respectively . 7 . The values found for and were of the same order as those just mentioned , in all the experiments carried out with polished zinc , the conditions as to polish and to intensity of illumination were varied within wide limits . The rate at which the character of the surface under the influence of is consequently not much affected by the conditions named . 8 . of Zinc.\mdash ; Fatigue curves of a similal character were obtained with malgamated zinc . Orle of the curves is shown in the lower half of fig. 4 . In the rapid change at the outset the activity falls to half value in minutes , the constant of chnnge . The second is much slower , the time taken for the activity to diminish one half minutes and the value of . In case is and K2 is 148 ( scale divisions per 100 seconds ) , so that is about six times 9 . The experiments I have carried out , using the Nernst lanll ) as a source of light , confirm in most particulars the results at ) ) with sunlight . The chief point of difference is the clear nitio of the fact that the rate of decay at the outset is too great to be represented ) the single exponential that is sufficient for the later . This is , in facf , , mentioned by Buisson , but is ibuted to experimental errors conse upon the use of a gold-leaf electroscope . have plotted some of his results , and find that they can bs represented with far greater accuracy by employing two exponential terms . 10 . th eory of jssive experiments already described show that the photo-electric activity of a zinc plate decays in a perfeotly definite manner when a freshly-polished plate is exposed to light . The activity at any time after the plate has been polished can be represented by an empirical formula the sum of two exponential terllS , . cit. Mr. H. S. Allen . [ Oct. 26 , . ' ' . FIG. 4 . Photo-electric Fatigue of Amalgamated Zinc . Experiment made July 28 , 1906 , without absorbing tion . Experiment made August 1 , 1906 , with absorbing solution . Nernst lamp taking 1 ampere on 110-volt circuit . To explain this esult we assume that freshly-polished zinc ( A ) gives out negative ions under the influence of ultra-violeb light , and changes to a form ( the change may be either a physical or a chemical one ) . also gives rise to a supply of negative ions , and to a third form , , which is supposed to be inactive . At present we do not consider the nature of the substances ( whether physical or chemical modifications of zino ) denoted by and C. 1906 . ] The Photo-electric ' Zinc . Suppose we start with a quantity of substance A. Let this change into in such a way that the rate of change at any instant is proportional to the quantity still unchanged . Let subsequently change into , in accordance with the same law . If denote the quantities of the several substances present at a time For the change from A to , so The quantity is the " " velocity coefficient\ldquo ; of the first change . The rate at which accumulates is equal to the quantity supplied by less the quantity that changes into , thus\mdash ; being the velocity coefiicient for the second change . This gives To solve this equation we assume Substituting this value , we find , or When ; so , giving . Thus , finally , we obtain as the values*of , and . We assume that the observed photo-electrical activity is due in part to the substance , in part to the substance , so that we write where A and are constants measuring the activity of the corresponding substances . * These results are given in Rutherford 's ' -ity ' ( Second Edition , S 10 Mr. H. S. Allen . [ Oct. 26 , 492 Mr. H. S. Allen . [ Oct. 26 , for and we obtain This expression is of the required form , provided the coefficients are both positive quantities , for the empirical results can be represented by the sum of two exponential terms . To satisfy this condition must be greater than , i.e. , the first must be the more rapid one . In the experiments already described was large in comparison with so that an approximate value of the activity by As is of the same order of magnitude as K2 for zinc , we should require to make A approximately twice as great as B. 11 . Recovery Due to the Longer Waves.\mdash ; In some of the experiments , more particularly with amalgamated zinc , the rapid at first observed was followed by a radual recovery of the activity to a maximum value , which was , however , far smaller than the initial value . After this maximum value was passed the ordinary slow decay set in . This effect is illustrated in the upper curve of fig. 4 , which shows the first part of the fatigue curve with the sudden fall in activity at the start followed by a rise . The subsequent slow decay is not shown here . The small recovery observed in these cases was traced to the action of the longer waves from the Nernst lamp . It very much diminished by filling the in the cover of the testing vessel with water and was completely eliminated when the water was replaced by a solution of alum . The fatigue curve obtained with amalgamated zinc when ) longer waves are absorbed is shown at the bottom of the same This action of the waves of greater wave length may be due simply to a temperature effect , for the photo-electric aclivity of metals is in general greater at a high temperature than at a low one ; or it may be analogous to the effect observed by Buisson , found that all radiations do not work in the same sense as regards the contact differeIlce of potential . 12 . Experiments on Zinc in has shown that many metals exhibit photo-electric in t ) vacuum . also maintains that the alteration in a metallic surface produced by sunlight is independent of the pressure . On the other hand , VarleyS states that zinc illuminated by the of an iron arc shows little or no sign of fatigue when the pressure . cit. . cit. . cit. S 'Phil . Traus pp. 439\mdash ; 458 , 1903 . $ 1906 . ] The of Zinc . is below , say , the tenth of an atmosphere . Smolochowski , in some unpublished experiments on the liquid alloy of sodium and potassium , found that the decay phenomena do not take place in a vacuum . I have carried out some experiments on zinc in a good vacuum obtained by Dewar 's method of absorbing the gas by charcoal cooled in liquid air , and found that the light of a Nernst lalnp produced unmistakable fatigue . The results , however , were not sufficiently accurate to allow satisfactory fatigue curves to be drawn . 13 . Summary \mdash ; The experiments described in this paper show that it is necessary to employ the sum of two exponential terms in order to obtain an adequate representation for the photo-electric curve of zinc . Just as Rutherford has explained the curves of decay for the excited activity of radium and thorium as a consequence of successive changes , so it is possible to explain the present results as to two consecutive changes . The nature of the modifications thus suggested is left an open question . It is also shown that the longer waves of light can bring about a in the opposite sense , that is to say , they can produce a certain amount of recovery of photo-electric activity . In conclusion , I must express my great indebtedness to Lord Blythswood , in whose at Renfrew some of these experiments were carried out , and also to Professor H. A. Wilson for advice and vgestions during the period of my work in the Wheatstone Laboratory of King 's College , London . [ Note added October \mdash ; In a paper published in the ' Philosophical azine ' for the present month ( pp. 414\mdash ; 418 ) , Sir Wm. Ramsay and Dr. Spencer discuss the " " tiring\ldquo ; of metals when exposed to ulra-yoet light . The curves they have obtained for nesium , zinc and tin show a number of breaks , the number to the number of valencies of the metal . In the case of aluminium at least five or six breaks were observed . The fatigue curves that I have obtained for zinc illuminated by the light of a Nornst lamp do not show these breaks , the point at which the first rapid becomes insensible is regarded as a break in the curve . If the results given above are interpreted in terms of the theory put forward by Sir Wm. Ramsay and Dr. Spencer , the modification that I have called zinc would presumably correspond to zinc which has lost the first of the " " metallic corpuscles * This may , perhaps , be due to the fact that the same zinc plate was used repeatedly , being repolished before an experiment . According to Sir William Ramsay and Dr. Spencer , the breaks in the curve are much less persistent in such a case . VOL. LXXVIII.\mdash ; A.

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The effect of temperature on the activity of radium and transformation products.

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500

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Howard L. Bronson, Ph. D.|Professor E. Rutherford, F. R. S.

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Thermodynamics

Atomic Physics

Thermodynamics

494 The Effect of Temperature on the Activity of Radium and Transformation Products . By Howard L. Bronson , Ph. I ) . ( Communicated by Professor E. Rutherford , F.R.S. Received November 3 , \#151 ; Read November 15 , 1906 . ) Introduction . A large number of investigators have attempted to alter the activity of various radio-active substances by subjecting them to very high and also to very low temperatures . Among all these attempts only two , as far as the writer is aware , have apparently given positive results . Curie and Danne* found that the rate of transformation of the active deposit from radium was apparently permanently increased after it had been subjected to temperatures above 800 ' C. The writerf repeated these experiments , and showed that this apparent increase was due to the volatilisation of radium B. By having the active deposit sealed in a glass tube when heated , it was shown conclusively that the rate of transformation had not been permanently altered by temperature up to 1100 ' C. In both the above experiments the rate of transformation was determined in the cold after the active matter had been removed from the furnace , and no attempt was made to detect any change in the activity of the active deposit while it was actually at a high temperature . Results Obtained by Makower . Makowerf'has more recently made some further investigations on the same subject . He concludes : " The results show clearly that the activity , as measured by the / 3 and \lt ; y rays , can be changed by high temperatures , the observed effects being consistent with the explanation offered by Curie and Danne , that the rate of decay of radium C is increased by high temperatures . " The method employed by Makower differed from that employed in the previous experiments , in that he subjected radium emanation ( which was in a state of radio-active equilibrium ) to the high temperature , instead of merely the active deposit . The emanation was sealed in a quartz tube so that no volatile product could escape . This method had this advantage , that although the measurements were also taken when the tube was cold , * 'Comptes Rendus , ' vol. 138 , p. 748 , 1904 . t ' Amer . Journ. Sci. , ' July , 1905 , and ' Phil. Mag. , ' Jan. , 1906 . $ ' Roy , Soc , Prop , / March , 1906 . The Effect of Temperature on the Activity of Radium , etc. 495 yet it was possible to detect changes in the activity which had occurred during the time of heating . The activity of the quartz tube was always found to be diminished after it had been heated to 1000 ' C. or over . The amount of decrease varied from 3 to 15 per cent. , depending on the temperature and length of time of heating . On account of the presence of the emanation , the activity recovered its normal value again after about one hour , apparently showing that , after heating , the rate of production of the active deposit was greater than the rate of decay . No light , however , was thrown on the question , investigated by Curie and Danne and the writer , as to whether the rate of decay of the active deposit had been permanently altered or not . The arrangement of the apparatus employed by Makower is shown in fig. 1 . The ionisation in the testing vessel was produced by both / 3 and 7 Fig. 1 . rays , and it is easily seen that the distribution of the active deposit in the quartz tube might have considerable effect on the observed activity . It is also to be noticed that no change in the activity took place until a temperature of about 1000 ' C. was reached , which is about the temperature at which radium C begins to volatilise . As all the results obtained by Makower can be satisfactorily explained on the ' assumption that radium C volatilised and deposited itself near the ends of the tube , it seemed desirable to further test the effect of high temperatures on the activity of radium and its transformation products under quite different experimental conditions . Apparatus and Method . The arrangement of the apparatus , as used in the following experiment , is shown in fig. 2 . A few tenths of a milligramme of pure radium bromide Dr. H. L. Bronson . Effect of [ Nov. 3 , Electroscope Rheostat Fig. 2 . was sealed in a quartz tube , under diminished pressure , and placed in a small electric furnace directly below the electroscope , as shown in the figure . In order to protect the electroscope from convection currents of air , it was entirely surrounded by another vessel and separated from the furnace by two layers of asbestos and one of lead , with air spaces between them . In addition to this , the air between the furnace and the electroscope was continuously removed by an electric fan , not shown in the figure . Even with these precautions the gold leaf did not move with perfect regularity , but the errors due to this fact were very small , as can be seen from the observations plotted in fig. 3 ( see p. 499 ) . After several unsuccessful attempts , a satisfactory platinum resistance furnace was constructed , with which a temperature above 1600 ' C. was obtained . The construction of the furnace is shown in the figure . The inside cylinder was a platinum tube , which was surrounded by a layer of magnesium oxide in which the platinum wire was embedded . Surrounding the magnesium oxide was a porcelain tube , which in turn was covered with a thick layer of asbestos . The temperature was measured by a platinum-rhodium thermo-couple , and 1906 . ] Temperature on the Activity of Radium , etc. 497 a potentiometer specially designed for such measurements by Professor H. M. Tory . The couple was calibrated up to 1100 ' by comparison with one of Dr. Barnes ' platinum resistance thermometers , which had been carefully standardised . The calibration curve was extended beyond 1100 ' by means of an equation given by Le Chatelier . This equation is of the form log e \#151 ; a log t + b , where e is expressed in micro-volts . This equation with suitable constants fitted the calibration curve almost perfectly below 1100 ' . In order to make certain that it held true for higher temperatures , the melting point of platinum was directly determined , and was found to differ from the calculated value by less than 10 ' . The relative position of the quartz tube and thermo-couple in the furnace is shown in the figure . It is easily seen that the temperature of the couple is certainly not higher than that of the quartz tube . It is therefore evident that the values given for the temperatures in this paper are certainly not too high . The arrangement of the apparatus as described above furnishes certain favourable experimental conditions to which attention should be called . Errors due to change in the distribution of radium C were largely avoided by making the quartz tube short ( about 4 cm . ) , in comparison with the diameter of the electroscope ( about 12 cm . ) , and by measuring the activity entirely by the \lt ; y rays . Any possible error introduced by the decay of the emanation was avoided by the use of radium itself as the active substance . The relative position of the quartz tube and the electroscope remained absolutely unchanged throughout the entire experiment . The great advantage , however , of the above arrangement lay in the fact that measurements of activity and temperature could be taken simultaneously . This made it possible instantly to detect any change in the activity of radium C , as its temperature was raised . The importance of this point becomes evident , when we consider the complexity of the problem under investigation . This complexity arises from the fact that there were five radio-active substances in equilibrium , sealed together in the quartz tube . Since the writer has shown that the rate of transformation of the active deposit is not permanently altered by subjecting it to temperatures up to 1100 ' C. , the only explanation of the decrease of activity observed by Makower is that the equilibrium quantity of radium C at high temperatures is less than normal . A number of special cases will perhaps make this point more evident . For simplicity we will assume that in any particular case only one of the active substances is affected by the temperature . For example , suppose that at a certain definite temperature the rate of transformation of radium C is Dr. H. L. Bronson . The Effect of [ Nov. 3 , suddenly increased , the electroscope will show a sudden increase in the activity . This increase in activity will not be permanent , but will gradually diminish and practically disappear after three hours . This follows from the fact that , when equilibrium is reached , the number of atoms of radium C which break up per second must be the same as the number supplied , and this number , according to our assumption , has not been changed . If now after equilibrium is reached at this temperature the active matter is removed from the furnace and its activity measured again at ordinary temperature , it will be found to be less than normal , since the number of atoms of radium C present is less than the normal number . As a second example , suppose that the rate of transformation of radium B is suddenly increased . At once the activity of radium C begins to rise , reaches a maximum in about 35 minutes , and decays to its normal value again in about three hours . An increase in the rate of transformation of the emanation would produce similar results , except that it would take about three hours for the activity of radium C. to reach a maximum , and as much as three or four weeks to decay to its normal value again . With radium A the case is quite different . Its rate of transformation is so rapid that it would regain its equilibrium value very quickly . Therefore , unless a very large change in its rate of transformation took place , the effect on the activity of radium C would be very small and difficult to detect . On the other hand , the rate of transformation of the emanation is so slow , that any change in the activity of radium would not appreciably affect the activity of radium C for several hours , and could not possibly be detected in the present experiment . The above discussion is all based on the assumption that the activity is being measured by the penetrating 7 rays , which come entirely from radium C. It is thus clearly seen not only that it should be possible to determine the effect of high temperatures on the activity of the emanation and the active deposit , but that the particular substances affected ought also to be determined by the way in which the activity , as measured by the 7 rays , changes . Observations . When the apparatus was once arranged , as explained above , it was a very short , simple operation to perform the experiment . Simultaneous observations of activity and temperature were taken at intervals of two or three minutes . The temperature of the furnace was raised gradually up to about 1300 ' C. It was allowed to remain between this temperature and 1350 ' for over an hour , and then gradually raised again to 1500 ' . After keeping it at about this temperature for nearly another hour , it was raised again to over 1600 . 1906 . ] Temperature on t Activity of , etc. At about this temperature two difficulties were encountered , the insulation of the furnace failed , and the emanation began to escape from the quartz tube . The slightly increased activity shown by the last observation ( fig. 3 ) was due to this escape of the emanation and its presence around the electroscope . The furnace was then allowed to cool . Its activity measured several hours later was found to be less than half its original value . That this decrease in activity was actually due to the escape of the emanation was shown by the fact that the quartz tube regained about half its lost activity during the next four days . Time m Minutes \lt ; ? .v -C 0 to 20 30 40 6 \lt ; o as / os / \gt ; 30 135 250 o U \#166 ; \#169 ; - VQ o ' 0 ' o ' 0 ' c -\#169 ; \#151 ; OCO Ocr~ ... 2.00 900 1000 Temperature Fig. 3 . IZQO 1600 I\amp ; 00 Fig. 3 shows the results of the series of observations above described . The approximate times at which the measurements were taken are given at the top of the figure . Below 1200 ' each point in general represents a single observation , while above this temperature most of them represent a mean of several , which accounts for their greater regularity . There is no evidence of any change in the activity as measured by the penetrating y rays . If any change at all took place , it was certainly less than 1 per cent. The length of time during which the temperature of the furnace was above 500 The Effect of Temperature on the Activity of Radium , etc. 1500 ' was sufficient to have made it possible to detect a 1-per-cent , variation in the rate of transformation of either the emanation or radium B , but there was no evidence of any such change . A similar set of observations taken with decreasing temperatures also failed to reveal any change in the activity . Effect of Low Temperature . A number of investigators have tried the effect of subjecting radium to low temperatures , and have obtained negative results in every case . Nevertheless , it seemed worth while to supplement the above experiment by trying the effect of low temperature on the same radium that had been previously heated . Only one temperature was tried , namely , that of liquid air . The quartz tube was hung in a Dewar bulb beside the electroscope and its activity measured . The bulb was then filled with liquid air and measurements taken continuously for an hour , but there was no evidence of any change in the activity . Conclusions . The above experiments show no evidence whatever of any change in the activity of the transformation products of radium , when they are subjected to temperatures between \#151 ; 180 ' and 1600 ' C. If any change does take place , it is very small , and cannot be over 1 per cent , in the case of radium C for temperatures between \#151 ; 180 ' and 1600 ' , nor more than 1 per cent , in the case of the emanation of radium B for temperatures between \#151 ; 180 ' and 1500 ' . There is thus removed the only known exception to the general ruler that the activity of radio-active substances is not affected by temperature . In conclusion , I take pleasure in expressing my thanks to Professor Kutherford , who suggested the subject , and furnished all the necessary material for the investigation .

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Section A. -Mathematical and physical sciences. - Address of the President, Lord Rayleigh, O. M., D. C. L., at the anniversary meeting on November 30, 1906.

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12

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character

Lord Rayleigh, O. M., D. C. L.

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10.1098/rspa.1907.0009

Biography

Thermodynamics

Biography

PROCEEDINGS OF THE EOYAL SOCIETY . Section A.\#151 ; Mathematical and Physical Sciences . Address of the President , Lord Rayleigh , O.M. , D.C.L. , at the Anniversary Meeting on November 30 , 1906 . Since the last Anniversary the Society has sustained the loss of twelve Fellows and two Foreign Members . The deceased Fellows are :\#151 ; Professor Lionel Smith Beale , died March 28 , 1906 . Sir Walter Lawry Buller , K.C.M.G. , died July 19 , 1906 . Charles Baron Clarke , died August 25 , 1906 . Bight Hon. Sir M. E. Grant Duff , G.C.S.I. , died January 11 , 1906 . Professor Charles Jasper Joly , died January 4,1906 . Colonel Sir Alexander Moncrieff , K.C.B. , died August 3 , 1906 . George James Snelus , died June 18 , 1906 . Professor Hermann Johann Philipp Sprengel , died January 14 , 1906 . General Sir Henry E. L. Thuillier , C.S.I. Bev . Canon H. B. Tristram , died March 8 , 1906 . Professor Harry Marshall Ward , died August 26 , 1906 . Professor Walter Frank Baphael Weldon , died April 13 , 1906 . The Foreign Members are :\#151 ; Professor Ludwig Boltzmann . Professor Samuel Pierpont Langley . On this list are to be found the names of veterans distinguished in .many branches of science and in public affairs . One name is a household word in 2 Anniversary Address by Lord Rayleigh . [ Nov. 30 , , every physical and chemical laboratory . It would be difficult , indeed , to\gt ; enumerate the investigations which have owed their success to the invention of the Sprengel mercury pump . In other cases , scientific careers still in full activity have , unhappily , been cut short . I allude especially to Joly , Marshall Ward , and Weldon . Even within my term of office our discussions have been enlivened by Weldon 's scientific enthusiasm and vigorous polemics . On the Foreign list are two distinguished names . Professor Ludwig Boltzmann , of Vienna , was perhaps the first Continental physicist to take up the ideas of Maxwell 's electric theory of light , of which he had early grasped the scope and became for many years one of its most emphatic supporters . One of his earliest series of experiments was a determination of the influence of the crystalline quality on the dielectric constant of sulphur , , with a view to comparison with its optical double refraction . In the theory of gases he is to be classed along with Clausius and Maxwell as one of the creators of the dynamical theory , on which he became the highest authority . By developing an idea originated by Bartoli he placed Stefan 's law of intensity of natural radiation on a theoretical basis , and thus became the pioneer in the modern thermodynamics of radiant energy . He contributed to the advance of physical science by many other investigations , and by his books on Gas Theory , on Electrodynamics , and on Mechanics . I may perhaps be allowed to add that at the time of his unhappy death , Boltzmann 's name was before the Council as proposed for one of our medals . Professor Langley 's work was more on the experimental side of physics. . In his bolometer he applied electric resistance thermometry to radiation , and was thereby enabled to penetrate further into the important and mysterious region of the ultra-red than had before that time been possible . For this work he received the Rfumford Medal in 1886 . During the later years of his life his attention was largely occupied with the mechanical problem of flight , and his models attained a considerable measure of success . As Secretary to the Smithsonian Institution at Washington he did much to ' forward , by his co-operation and advice , all kinds of scientific investigation . In the Report of the Council there has been laid before you an account of the work of the Council and of various Committees in a very wide field . The investigation of the terrible disease known as Sleeping Sickness has unhappily been marked by the tragic death of Lieutenant Tulloch , who has fallen a victim to his zeal in studying the disease in Uganda . Vigorous efforts are being undertaken to discover some therapeutic remedy for the malady . In the case of Malta Fever , too , the investigation of which was entrusted to the Royal Society by the Colonial Office , good progress has been 1906 . ] Anniversary Address by Lord Rayleigh . made . It has been ascertained by the Society 's Commission in Malta that the main source of propagation is the milk of infected goats . When this discovery was made the authorities of the island were at once warned of the danger in the milk supply , and the necessary precautions were taken . Since then the number of cases of fever in the hospitals has so greatly diminished as to afford good hope that this disease , which has been so great a scourge in Malta , may ere long be reduced to insignificant proportions or altogether exterminated . T observe that a movement has been been started in this country in aid of the Greek Anti-Malaria League . Professor Ronald Ross , than whom there is no higher authority , bears witness to the unexpected prevalence of the infection in most .of the localities examined , and he is confident that practical results of the highest value would follow expenditure in combating the disease on lines already laid down . Although I speak only from general knowledge , I cannot let this opportunity pass without emphasising my sense of the enormous importance of this class of work . If men knew where their real interests lie , \#171 ; ur efforts in this direction would be doubled or quadrupled . In this way discoveries , which the future will certainly bring , might be accelerated by decades , giving health and life to thousands or millions who now succumb . Willing and competent workers would soon offer themselves ; the principal obstacle is the want of means . The preparation of the ' Royal Society Catalogue of Scientific Papers ' for the remaining portion of the 19th century , which has proved a task so much more gigantic than can have been contemplated by the originators of the Catalogue nearly half a century ago , has been actively pushed forward . In consequence of the increased expenditure , now at the rate of nearly \#163 ; 2000 ' a year , the funds available are again approaching exhaustion . The difficulties of the President and Council and of the Catalogue Committee on this subject have once more been promptly resolved by the action of our Fellow , Dr. Ludwig Mond , who , after consultation with the Officers , has again made himself responsible for a further subsidy amounting to \#163 ; 2000 a year for three years . It is hoped that with the balance in hand and other sources of income , including ; the Handley Fund of the Royal Society , the income of which is devoted to this purpose , this subvention will suffice for the preparation of the work and for passing it through the press . Since the Royal Society took this-great national task in hand there has already been spent on it over \#163 ; 23,500 , . while on each occasion of financial stress Dr. Mond has come forward with the means of relief , his direct contributions , including that just promised , now amounting in the aggregate to \#163 ; 14,000 . This great work when published will thus be a tangible memorial of Dr. Mond 's practical insistence on 4 Anniversary Address by Lord . [ Nov. 30 , the importance of adequate indexes of the vastly increasing literature of science . Of the activities working under the Royal Society the one with which I have been especially connected is the National Physical Laboratory . In their Report for the past year the Executive Committee call attention to the loss they have sustained by the deaths of Sir Edward Carbutt and Sir Bernhard Samuelson , both members of the Committee and warm supporters of its work . The Report shows continued progress . As a result of a memorial to the Chancellor of the Exchequer , signed by about 150 Members of Parliament , the G-rant for building and equipment for the year was increased from \#163 ; 5000 to \#163 ; 10,000 , and this has enabled the Committee to take in hand some urgently needed extension . Buildings are now in course of erection for Metrology and for Metallurgical Chemistry , while the Engineering Laboratory is being doubled in area . The two last additions were called for in great measure in consequence of an arrangement with the India Office whereby the testing work required for the Indian Government , hitherto carried on at Coopers Hill , is to be transferred to the Laboratory . The Indian Government provide the testing machine and other appliances required for the work , and , in addition , have intimated their intention of placing in the charge of the Committee the very admirable electrical equipment now at Coopers Hill . Towards the equipment of the Metallurgical Laboratory the Goldsmiths ' Company have made a very generous donation of \#163 ; 1000 , while the Governments of New Zealand and Western Australia have contributed \#163 ; 100 each to the equipment of the Metrological Laboratory . The buildings of the Electrical Laboratory have been completed , and were formally opened by the Right Hon. R. B. Haldane in June last . On this occasion many representatives of electrical industry from various parts of the world , who were attending the special conferences of the Institution of Electrical Engineers , were present , and joined in the inspection of the Laboratory . After the meeting Sir John Brunner announced his intention of subscribing \#163 ; 5000 towards the equipment of the various buildings now in hand . A number of important researches , a list of which is given in the Report , have been published during the year , and others are in a forward state of preparation for publication . Dr. Carpenter and Mr. Edwards have completed the first part of their research into the properties of the copper-aluminium alloys for the Alloys Research Committee . Dr. Stanton and Mr. Bairstow have read a paper before the Institution of Civil Engineers on 1906 . ] Anniversary Address by Lord Rayleigh . the effect of alternating stresses on steels . The work on electrical standards with the Ampere Balance , which has a special interest for myself , is well advanced . In the hands of Mr. Smith the measurement of the electrolytic deposits of silver , which represent the whole passage of electricity through the apparatus , has attained a remarkable precision and , what is perhaps more important , some anomalies met with at first seem to be on the road to elucidation . Mr. Campbell has made progress with his research on hysteresis in steel sheets , and Dr. Harker is engaged with interesting investigations in high-temperature thermometry . Changes in the staff have taken place . Dr. Caspari resigned his position in order to take up private practice , while Dr. Carpenter has been appointed the first Professor of Metallurgy in the Victoria University of Manchester . The arrangements with the Indian Government have necessitated an alteration in the metallurgical division , and the Committee have thought it right to constitute a Department of Metallurgy and Metallurgical Chemistry , with a Superintendent in charge of the work . They have been fortunate in securing the services of Mr. W. Eosenhain as the first occupant of the post . A question of importance has arisen as to the performance at the Laboratory of tests , partaking of a routine character , on the physical and mechanical properties of specimens of material . To this objection has been taken on the ground of competition with the work of private establishments . In one of its aspects the question is financial . But the Executive Committee are of opinion that , even if the pecuniary loss were recouped , the efficiency of the Laboratory would suffer from the abandonment of this work . While anything like unfair competition with private establishments should be avoided , the execution of tests is good practice for the staff , and tends to keep them in touch with the manufacturers and with the practical problems which may demand examination . In view of the difference of opinion that has manifested itself , the Treasury has decided to appoint a small committee to inquire into the working of the Laboratory , with a special reference to this question . On a former occasion , my distinguished predecessor , Sir William Huggins , called attention to some of the more important matters on which the Society in the past had initiated , supported , or given advice about scientific questions in connection with the State , and in other ways had made its influence felt strongly for the#good of the country . It would hardly become me , with my short experience of the working of the Society , at least in recent years , to pursue this theme . The function of the Society which lies most open to the observation of an incoming President is that exercised at the ordinary meetings . I am impressed with the difficulty , arising out of the ever6 Anniversary Address by Lord Rayleigh . [ Nov. 30 , increasing specialisation of science , in rendering really useful the reading of papers and discussions thereupon . It is , of course , felt more severely in a Society like our own , which embraces within its scope the whole scientific field . It not infrequently happens that a paper is addressed to an audience among whom there is no one competent to follow the detailed observations and reasonings of the author . I am sometimes reminded of a saying of Dalton 's on similar occasions at Manchester , quoted by Sir Henry Iioscoe in his genial and entertaining ' Reminiscences ' : " Well , this is a very interesting paper for those that take any interest in it . " A little more discretion on the part of readers of papers in having regard to the composition of their actual audience would be helpful here . In some cases experimental illustration would bring home to a larger number what is followed with difficulty from a merely verbal statement . But I am afraid that no complete remedy is within reach . Increase of specialisation , however inconvenient in some of its aspects , is , I suppose , a necessary condition of progress . Sometimes a big discovery , or the opening up of a new point of view , may supersede detail and bring unity where before there was diversity , but this does not suffice to compensate the general tendency . Even in mathematics , where an outsider would probably expect a considerable degree of homogeneity , the movement towards diversity is very manifest . Those who , like myself , are interested principally in certain departments , and can look back over some 40 years , view the present situation with feelings not unmixed . It is disagreeable to be left too far behind . Much of the activity now displayed has , indeed , taken a channel somewhat remote from the special interests of a physicist , being rather philosophical in its character than scientific in the ordinary sense . Much effort is directed towards strengthening the foundations upon which mathematical reasoning rests . No one can deny that this is a laudable endeavour ; but it tends to lead us into fields which have little more relation to natural science than has general metaphysics . One may suspect that when all is done fundamental difficulties will still remain to trouble the souls of our successors . Closely connected is the demand for greater rigour of demonstration . Here I touch upon a rather delicate question , as to which pure mathematicians and physicists are likely to differ . However desirable it may be in itself , the pursuit of rigour appears sometimes to the physicist to lead us away from the high road of progress . He is apt to be impatient of criticism , whose object seems to be rather to pick holes than to illuminate . Is there really any standard of rigour independent of the innate faculties and habitudes of the particular mind ? May not an argument be rigorous enough to convince legitimately one thoroughly 1906 . ] Anniversary Address by Lord Rayleigh . 7 imbued with certain images clearly formed , and yet appear hazardous or even irrelevant to another exercised in a different order of ideas ? Merely as an example , there are theorems known as " existence-theorems " having physical interpretations , the object of which is to prove formally what to many minds can be no clearer afterwards than it was before . The pure mathematician will reply that even if this be so , the introduction of electrical or thermal ideas into an analytical question is illogical , and from his own point of view he is , of course , quite right . What is rather surprising is that the analytical argument should so often take forms which seem to have little relation to the intuition of the physicist . Possibly a better approach to a reconciliation may come in the future . In the meantime we must be content to allow the two methods to stand side by side , and it will be well if each party can admit that there is something of value to be learned from the point of view of the other . In other branches , at any rate , the physicist has drawn immense advantage from the labours of the pure analyst . I may refer especially to the general theory of the complex variable and to the special methods which have been invented for applying it to particular problems . The rigorous solution by Sommerfeld of a famous problem in diffraction , approximately treated by Fresnel , is a case in point . We have moved a long way from the time when it was possible for the highest authority in theoretical optics to protest that he saw no validity in Fresnel 's interpretation of the imaginary which presents itself in the expression for ' the amplitude of reflected light when the angle of incidence exceeds the critical value . In this connection it is interesting to remember that , in his correspondence with Young , Laplace expressed the opinion that the theoretical treatment of reflexion was beyond the powers of analysis . The obvious moral is that we are not to despair of the eventual solution of difficulties that may be too much for ourselves . As more impartially situated than some , I may , perhaps , venture to say that in my opinion many who work entirely upon the experimental side of science underrate their obligations to the theorist and the mathematician . Without the critical and co-ordinating labours of the latter we should probably be floundering in a bog of imperfectly formulated and often contradictory opinions . Even as it is , some branches can hardly escape reproaches of the kind suggested . I shall not be supposed , I hope , to undervalue the labours of the experimenter . The courage and perseverance demanded by much work of this nature is beyond all praise . And success often depends upon what seems like a natural instinct for the truth\#151 ; one of the rarest of gifts . Anniversary Address by Lord Rayleigh . [ Nov. 30 , Medallists , 1906 . i The Copley Medal is awarded to Professor Elias Metchnikoff , For . Mem. E.S. , on the ground of his distinguished services to zoology and to pathology , particularly for his observations on the development of Invertebrates and on phagocytosis and immunity . From 1866 to 1882 Professor Metchnikoff s work was exclusively zoological , and mainly during that period he produced a series of brilliant memoirs dealing with the early development and metamorphoses of Invertebrates . Although his name stands in the first rank of investigators of these subjects , the most celebrated of his discoveries are those relating to the important part played by wandering mesoderm cells and white blood-corpuscles in the atrophy of larval organs , and in the defence of the organism against infection by Bacteria and Protozoa . It was on these researches that he based his well-known ' Phagocyte Theory . ' Metchnikoffs fundamental observations were made in Messina in 1882 , and were published in the following year . In these he showed that the absorption and disappearance of the embryonic organs of Echinoderms were effected by wandering mesoderm cells , which devoured and digested the structures which had served their purpose and become effete . The observation that white blood-cells accumulate in an inflamed area after infection by Bacteria suggested that these cells might also devour and thus destroy the invading microbes , and that the process of inflammation was really a physiological and protective reaction of the organism against infection . The study of the infection of Daphnia by Monospora entirely justified this prediction . The account of the phenomena of infection as seen in this transparent Crustacean was published in \#163 ; Virchow 's Archiv ' ( vol. 96 ) in 1884 , while , later in the samb year , Metchnikoff published another paper extending these observations to Vertebrates , and showing the universal applicability of his generalisation as to the essential character of the inflammatory process . During the twenty years which have elapsed since the publication of the * Phagocyte Theory , ' Metchnikoff , with the assistance of a host of pupils and disciples from all parts of the world , has been continuously engaged in the study of the reaction of the organism against infection , and in investigating the essential features of immunity in the light of the illuminating generalisation laid down in 1884 . Though of limited range , and therefore inferior in scientific importance to the more fundamental researches carried out by him previously , 1906.J Anniversary Address by Lord Rayleigh . 9 Metchnikoffs recent work on infection by the micro-organism of syphilis and the attainment of protection and immunity against this disease may be mentioned on account of its important practical applications . It is not too much to say that the work of Metchnikoff has furnished the most fertile conception in modern pathology , and has determined the whole direction of this science during the last two decades . The Eumford Medal is awarded to Professor Hugh Longbourne Callendar , F.R.S. , for his experimental work on heat . Professor Callendar has devoted his attention chiefly to the improvement of accurate measurement in the science of heat by the application of electrical methods . His first paper " On the Practical Measurement of Temperature , " ' Phil. Trans. , ' 1887 . paved the way for the application of the electrical resistance thermometer to scientific investigation . In a later paper , written ** in conjunction with Griffiths , " On the Boiling Point of Sulphur , etc. , " ' Phil. Trans. , ' 1891 , the application of his method was further extended , and a simple method of standardisation was proposed . In continuation of this work Professor Callendar has written a number of subsidiary papers dealing with details of construction of instruments , and applications to special purposes . The results of this thermometric work have since been confirmed by Chappuis and Harker , 'Phil . Trans. , ' 1889 , at the Bureau International , Paris , and by other observers , and are now generally accepted . More recent developments in accurate electrical thermometry have been described by Professor Callendar in later papers . He has also devised a special type of " gas-resistance " thermometer , depending on the increase of viscosity of a gas with temperature , which is the exact analogue of the electrical resistance thermometer , and possesses peculiar advantages for high-temperature measurements . The application of electrical resistance thermometers and thermo-couples to the observation of rapid variations of temperature has been utilised by Professor Callendar in the study of the adiabatic expansion of gases and vapours , and in the observations of the cyclical changes of temperature of the steam and of the cylinder walls in a steam-engine . The latter research was undertaken in conjunction with Professor Nicholson , with a view to elucidate the theory of cylinder-condensation . The researches of Rowland and other experimentalists on the specific heat of water , and the mechanical equivalent of heat , had shown that grave uncertainties affected the value of this most fundamental physical constant , which could not be removed satisfactorily without a complete investigation of the variation of the specific heat of water between 0 ' and 100 ' C. Professor 10 Anniversary Address by Lord Rayleigh . [ Nov. 30 , Callendar devised a continuous electrical method of attacking this problem , possessing many important advantages as compared with older methods . He was assisted by Dr. Barnes in carrying out this work , the results of which form the subject of papers by Callendar and Barnes in the ' Phil. Trans. Roy \#166 ; Soc. , ' 1901 . As an illustration of the probable accuracy of their results it may be observed that , whereas by any of the older formulae accepted for the variation of the specific heat of water the values of Rowland and of Reynolds and Moorby for the mechanical equivalent are seriously discordant , they are brought into perfect agreement by the work of Callendar and Barnes . In the subject of conduction of heat Professor Callendar has contributed many original methods described in various minor papers , and , in addition to the thermal investigations with which his name is chiefly associated , has .carried out some purely electrical researches . One of the Royal Medals has been awarded , . with the approval of His Majesty , to Professor Alfred George Greenhill , a Pellow of the Society , on account of the number and importance of his mathematical investigations produced between the year 1876 and the present time . They embrace a variety of mechanical and physical subjects , including dynamics , hydromechanics , electricity , and gunnery . He is the author of two treatises on hydromechanics , both remarkable for originality of treatment . The subject , however , to which he has devoted most time and attention is the theory of elliptic functions . His work on this subject may be placed in two classes : ( 1 ) Investigations in which he has extended the subject into new fields , as in the series of memoirs on the " Transformation and Complex Multiplication of Elliptic Functions , " contributed to the ' Proceedings of the London Mathematical Society ' ( vols . 19 , 21 , 25 , 27 ) , and in the memoir on the " Third Elliptic Integral and the Ellipsotomic Problem , " in the * Phil. Trans. ' ( vol. 203 ) . ( 2 ) Applications to Mechanical Problems , mainly dynamical , for purposes of calculation or illustration . In this class may be jplaced his treatise on the Elliptic Functions , as well as numerous papers in journals and the proceedings of scientific societies . . All Professor Greenhill 's work is characterised by much originality , and by a rare power and skill in algebraic analysis . His Majesty has also approved the award of a Royal Medal to Dr. Dukinfield Henry Scott , also a Fellow of the Society , for his investigations and discoveries in connection with the structure and relationship of fossil plants . Dr. Scott began the very important work which he has accomplished in this subject by helping the late distinguished pakeo1906 . ] Anniversary Address by Lord Rayleigh . botanist , Professor W. C. Williamson . In this co-operation he greatly -enhanced the value of Williamson 's work . He not only added many new discoveries , hut , what was more important , demonstrated the value of the work in relation to ' phylogeny . Dr. Scott has since added much of first-rate importance . He has discovered and elucidated many important types , his work constituting a most valuable acquisition to botany from the evolutionary point of view . It is not only in the accurate investigation of difficult structures that Dr. Scott has been so successful ; not the least of his merits lies in the philosophical treatment of the problems suggested by his discoveries . His position as one of the leading paleeobotanists in the world is well recognised . He has , both by his personality and by his writings , exercised a well-marked and widespread influence on the work of other botanists . The fact that he has created in this country a vigorous school of palseobotanists may be regarded as an additional claim for the honour now conferred upon him . The Davy Medal is given to Professor Rudolf Fittig , Professor of Chemistry in the University of Strassbourg , who began to publish scientific work as early as 1858 , and in 1864 discovered the method for the synthesis of hydrocarbons homologous with benzene , which has ever since borne his name . Up to about 1880 he worked chiefly on benzene derivatives , but his attention was gradually attracted to the study of lactones and acids , both saturated and unsaturated , which has largely formed the subject of his numerous published papers down to the present day . Fittig has been a remarkably active worker . The Royal Society Catalogue contains under his name alone 96 papers , and , jointly with students and others , 71 more down to 1883 . Since that time a number about equally large lias been recorded in the indexes of the chemical journals . The work of Fittig and his students on lactones and acids , and particularly the inter-molecular changes which many unsaturated acids undergo , may be said to be classical , and it has had an important influence on the progress of theoretical chemistry . The Darwin Medal has been awarded to Professor Hugo de Vries , For . Mem. R.S. Professor de Vries has made a series of important discoveries in connection with the manner in which new races of organisms may originate , and he has materially extended and systematised our knowledge of the laws affecting the results of hybridisation . His work is the outcome of very extensive experiments that have been carried on for many years . He has stimulated numerous investigators , both in Europe and in America , Anniversary Address by Lord . to extend these enquiries ; and the results already obtained are of great importance , both from a theoretical and from a practical point of view . De Vries ' work has exercised considerable influence on other branches of biology , and has suggested new lines of investigation in many directions . Mrs. W. E. Ayrton is the recipient of the Hughes Medal , which is awarded for original discovery in Physical Sciences , particularly electricity and magnetism , or their applications . Her work on the Electric Arc has been described in a paper published in the ' Philosophical Transactions , ' and in various other publications . Mrs. Ayrton 's investigations cover a wide area . She discovered the laws connecting the potential difference between the carbons of an arc with the current and with the distance betw* even them , and proved these to apply not only to her own experimental results but to all the published results of previous observers . Dealing with the modifications introduced into the arc by the use of cores in the carbons , she found the causes of these modifications . The peculiar distribution of potential through the arc was traced , and its laws were discovered by her . Having found the conditions necessary for maintaining a steady arc , and for using the power supplied to it most efficiently , she was able to explain the cause of " hissing , " and the causes of certain anomalies in the lighting power of the arc . For the past four years Mrs. Ayrton has been engaged in investigating the causes of the formation of sand ripples on the seashore .

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ERRATA . ---- t Page 240 , line 25\#151 ; For T'/ T = O'/ p ) ? -1 read ( T'/ T)v = 07 Same page , line 28\#151 ; For286 ' C. read 286 ' Abs . Same page , line 30\#151 ; For 13^ read 39 . On Plate 2 omit the note at foot . Page 431 , fig. 2 , curves marked 5 = 15 , 5 = 20 should 5 = 10 , 5 = 15 . marked

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A comparison of values of the magnetic elements, deduced from the British magnetic survey of 1891, with recent observation.

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