bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Magnetic Losses at Low Flux Densities in 35 Permalloy Sheet
Authors: Ellwood W. B. , Legg V. E.
Published: January 2005

Energy losses in ferromagnetic materials subject to alternating fields have long been considered as due solely to hysteresis and eddy currents. However, at the low flux densities encountered in certain communication apparatus, a further loss is observed which has been variously termed ``residual,'' ``magnetic viscosity,'' or ``square law hysteresis.'' The search for an explanation of this loss has led to precise measurements of hysteresis loops with a vacuum ballistic galvanometer, and of a.c. losses with inductance bridges. From these results, it appears that that part of the a.c. effective resistance of a coil on a ferromagnetic core which is proportional to the coil current is strictly identified with the hysteresis loop area as measured by a ballistic galvanometer, or as indicated by harmonic generation in the coil. The hysteresis loop can now be constructed in detail as to size and skewness on the basis of a.c. bridge measurements. This conclusion was reached previously on a compressed iron powder core, and is now confirmed on an annealed laminated 35 permalloy core. Observed eddy current losses for this core exceed those calculated from classical theory by 20 percent. This excess is ascribed to the presence of low permeability surface layers on the sheet magnetic material. The a.c. residual loss per cycle (nominally independent of frequency, like hysteresis) is not observed by ballistic galvanometer measurements, although it indicates an energy loss some eight times the hysteresis loss for the smallest loop measured (Bm = 1.3 gauss). Analysis of the residual loss shows that it increases with frequency up to about 500 cycles, and remains constant at higher frequencies (to 10,000 cycles per second). Concurrently with the increase of residual loss, the permeability of the alloy is observed to decline with increasing frequency about 1 percent below the value predicted from eddy current shielding. This effect is most noticeable at frequencies below 1000 cycles.
Heat Effects in Capillary Flow at High Rates of Shear
Authors: Hersey M. D. , Zimmer J. C.
Published: January 2005

This paper describes a theoretical and experimental study of heat effects in viscous liquids up to rates of shear of the order of a million reciprocal seconds, corresponding to the rates experienced in lubrication practice. Even at much lower rates the effect of heat generated by viscous resistance in a capillary tube is sufficient to produce an appreciable drop in the apparent viscosity. This drop cannot be fully corrected for by laboratory observations of the mean efflux temperature, since the temperature rise will not be uniform over the cross section. Detailed calculations are necessary in order to distinguish between heat effects and non-Newtonian behavior. The theory is illustrated by experimental data on lubricating oils.
On the Creep of Solids at Elevated Temperature
Authors: Nadai A.
Published: January 2005

In this paper equations are set up which describe the behavior of a solid under the action of combined stresses when a steady state of creep is assumed to exist. A material is said to be in a steady state of creep if it yields with a constant speed under a given constant stress. In an ordinary creep test the steady state exists when the deformation has reached the point where the ``creep curve'' becomes a straight line. In mathematical language this can be expressed by saying that the stress is a function of the rate of strain and is independent of the amount of strain. Cases are worked out in which this stress vs. strain rate relation is a simple power function. Various types of flow including purely plastic flow and viscous flow can be discussed by changing the value of the exponent in the power function relation. Several specific examples which include the case of the thick walled cylinder with closed ends loaded by internal pressure and the case of a disk having a circular hole and loaded in its plane are worked out. Equations are developed which show the steady state stresses in such cases. Expressions for the stress concentration factors in creep are also obtained.
Heat Flow in an Infinite Solid Bounded Internally by a Cylinder
Authors: Smith Lloyd P.
Published: January 2005

The problem of the flow of heat through a long tunnel wall in an infinite solid has been treated and the results for the rate of flow and total heat flow have been expressed in a convenient form for numerical computations. This general problem has become of interest in connection with the cooling of deep mines.
The Effects of Elastic Stretch on the Infrared Spectrum of Rubber
Authors: Williams Dudley , Taschek Richard
Published: January 2005

The absorption spectrum of stretched rubber has been studied in the region between 2μ and 8μ. In the case of unilateral stretch transmission measurements indicate that the absorption bands near 3.3μ and 7μ become broader with increasing stretch while the general background absorption becomes more pronounced. Radial stretch was found to produce similar effects in the 3.3μ and 7μ regions while the bands near 6μ became less intense for both unilateral and radial stretch. In the spectrum of rubber stretched radially to approximately twelve times its original area a band was observed near 4.8μ in a region where there is no intense absorption in the unstretched material. Since both absorption and reflection are involved in transmission measurements, it was necessary to determine reflection and extinction coefficients. The results indicate that the reflection coefficient diminishes and the extinction coefficient increases with increasing stretch. The observed variations in the extinction coefficients are of greater magnitude than those to be expected from the known density changes which accompany stretching.
Note on the Indexing of Powder Photographs
Authors: Frevel Ludo K.
Published: January 2005

By taking two successive Debye-Scherrer-Hull pictures of a powder specimen at two different temperatures, one obtains on a single film a direct temperature shift of the diffraction pattern of the substance. An interval of 150°C or greater will generally suffice to produce easily measurable temperature shifts that can be related to the anisotropy of a crystalline substance. A systematic treatment of the various crystal systems has shown that the first four systems (cubic, tetragonal, hexagonal, and orthorhombic) can be indexed in a straightforward manner. Two cases of the monoclinic system: (1) ∂β/∂T=0 and (2) αb/2=(1/b)(∂b/∂T)>αa>αc>cot β∂β/∂T can be solved without time-consuming mathematical calculations.
Ambrose Swasey Builder of Machines, Telescopes and Men
Authors: Nassau J. J.
Published: January 2005

``You know, it wasn't so long ago since Galileo was put into prison for saying that the world was round and that the sun was the center of the Universe,'' once said Ambrose Swasey. ``That was not so very much before my time, only one hundred and twenty-five years before the birth of my grandfather whom I remember well. People now do not know much more than they did then.'' And yet people do know more on account of Ambrose Swasey for he built giant telescopes that pierced the depths of space and devoted his talents to science and engineering, leaving a lasting influence upon his age. On June 15, 1937, he died, a great task completed, four score and ten years of noble living.
A Photographic Study of the Vacuum Spark Discharge
Authors: Chiles James A.
Published: January 2005

Vacuum spark discharges between electrodes of several different elements were investigated by means of a camera and high speed rotating mirror. It was found that, with very rare exceptions, the luminosity always appeared at the anode before it appeared at the cathode. Measurements were made of the time interval between the appearance of luminosity at the anode and its later appearance at the cathode, and of the velocity of the luminous vapor from the anode. Evidence is given to show that positive ions from the anode have sufficient time to cross the gap during the average observed time intervals. Hypotheses are advanced of the mechanism of the discharge and to account for the observed vapor velocities. Apparently most of the phenomena observed after the formation of vapor at the anode can be accounted for by relatively low gap potentials.
A Hydrodynamic Analogy for Shearing Stress Distribution in Bending
Authors: Biot M. A.
Published: January 2005

It is shown here that the shearing stress distribution in the combined shear and bending is represented with practical accuracy by the distribution of velocity in the flow of a perfect fluid over the area of the cross section. This flow is produced by a linear distribution of sources above the neutral axis and of sinks below the neutral axis, the intensity of these sources and sinks being proportional to the distance to the neutral axis. For hollow beams the additional condition must be added that the circulation of the velocities is zero around each hole of the cross section. The analogy which is rigorous for a material of zero Poisson ratio holds within a small correction for the general case.
Compressibility and Velocity of Pressure Waves in Petroleum Oils
Authors: Matteson Robert
Published: January 2005

Curves are presented from which it is possible to obtain the adiabatic compressibility of a petroleum oil in the range of 40°–200°F and up to 5000 pounds per square inch when only the specific gravity at 60°F and the kinematic viscosity at 100°F are known. A chart is given for obtaining the velocity of a pressure wave in an oil in which both the viscous drag and expansion of the containing tube are neglected. A table showing compressibilities and wave velocities for a number of Diesel fuel oils at 120°F and 1750 pounds per square inch pressure is given. The effects of viscosity and tube wall expansion on wave velocity are discussed and a chart is presented to aid in determining the wave velocity in steel tubes. The paper is concluded with a discussion of the effect of wave velocity on the point of injection of the fuel in the Diesel cycle.
The Time Lag in Gas-Filled Photoelectric Cells
Authors: Skellett A. M.
Published: January 2005

Time lag measurements are described which were made with a light chopper on a gas-filled cell of special design. The resulting response vs. frequency characteristic exhibits the resonance oscillations predicted from theory and calculation of the lag from the positive ion mobility agrees with that determined from this curve. The construction of the cell is such that secondary emission and disintegration of the cathode by ion bombardment are eliminated even at high values of gas amplification.
Currents to Conductors Induced by a Moving Point Charge
Authors: Shockley W.
Published: January 2005

General expressions are derived for the currents which flow in the external circuit connecting a system of conductors when a point charge is moving among the conductors. The results are applied to obtain explicit expressions for several cases of practical interest.
A Type of Electrical Resonator
Authors: Hansen W. W.
Published: January 2005

The theory of the use of certain shapes of ``hohlraums'' as electrical resonators is developed. In many respects they are equivalent to lumped constant circuits with properly chosen circuit constants. Suitable values for these circuit constants are found. The theory of coupling onto these hohlraum types of resonators is developed approximately.
Electrical Conduction in Quartz, Periclase, and Corundum at Low Field Strength
Authors: Rochow E. G.
Published: January 2005

1. A method has been devised for measuring the electrical conductivity of single crystals at elevated temperatures and at field strengths below 3 volts per mm. 2. The conductivities of single crystals of quartz, periclase, and corundum have been measured by this method over a temperature range of 600° to 1400°C, in equilibrium with air. 3. The increase of conductivity with temperature follows a single exponential relation in all cases, throughout the temperature range covered. Experimental curves and a table of interpolated values are given.
The Effect of Pressure on the Viscosity of Boric Anhydride Glass
Authors: Dane Ernest B. , Birch Francis
Published: January 2005

The effect of pressure on the viscosity of B2O3 glass has been determined by a high pressure capillary flow method up to about 2000 kg/cm2, at two temperatures, 516° and 359°C. The results are satisfactorily represented by the expression η = η0eαp, with α = 4.6·10−4 cm2/kg at 516°, α = 15·10−4 cm2/kg at 359°. The ratio of the viscosity at 1000 kg/cm2 to the viscosity at 1 atmosphere is therefore 1.58 at 516°, 4.48 at 359°. The results are briefly compared with those for organic liquids.
On the Starting of Hg Vapor Discharge Tubes
Authors: Kenty Carl
Published: January 2005

In a commercial method of starting the Cooper Hewitt Hg vapor lamp, a current of about 0.7 amp. is first made to flow in a circuit containing an inductance and a Hg vacuum switch or ``shifter.'' This shifter is then opened magnetically and the resulting arc therein is unstable and begins to go out. But the inductance acts to keep the current flowing and develops a high voltage which is impressed as a negative kick of about 1000 volts, in the average case of starting, on the Hg pool cathode of the main tube. This kick, as a result of the action of a strip of tinfoil on the outside of the cathode bulb surrounding the Hg pool edge and connected to the main anode, starts the arc. The whole process results in the transfer of nearly the entire current from the shifter arc to the main arc in a time of the order of a few microseconds. The initiation of the cathode spot is attributed to the action of a high electric field at the Hg pool edge existing between this edge and the tinfoil on the outside of the glass. In accord with this theory is the fact that anything which can be done to cause the Hg to wet the glass at the pool edge at a number of points (thereby increasing the field) such as by baking a little carborundum powder on the glass at the edge, helps starting enormously.

If the anode of the tube is disconnected, simple electroscopes show that the walls of the tube everywhere become charged to a negative potential of the order of 10,000 volts as a result of the kicks. High speed electrons are thus evidently shot up the tube. Ionization produced by these probably forms the beginning of the positive column. After initiation, the current in the tube rises to a maximum at a rate limited by the inductance in the circuit and then decreases to a low value sometimes going out altogether. This decrease is shown to be due to an extreme deficiency of Hg vapor in the tube caused by the electrical clean-up of Hg on the walls. Violent voltage surges set in across the tube at this time and a hissing noise is heard. The region of aggravated low pressure can be seen as glowing weak and reddish compared to the blue white of the rest of the tube. This appearance vanishes when, as a result of the rising vapor pressure due to heating, the hiss and surges stop. The surge period may endure many seconds in cold weather before the arc is able to pick up.
The Role of Solid Friction in Synthetic Dielectrics
Authors: Gemant Andrew
Published: January 2005

New synthetic dielectric materials, both of the ceramic and resinous type, exhibit, among other features, a high grade of homogeneity. This will not only affect the mechanical properties, the electrical breakdown strength and the dielectric losses due to layer mechanism favorably, but will reduce also losses due to dipole rotation. In case, namely, dipolar constituents rotate at all in the solid state, dissipation of energy will be caused by the solid friction, which has to be overcome. This latter, on the other hand, can be shown to be related directly to the imperfections of the material, thus indicating the beneficial effect on the dielectric loss angle of a homogeneous structure.
On the Symmetry of the Benzene Ring
Authors: Simons Lennart
Published: January 2005

The values of the pulsation frequencies of C6H6 and C6D6 are calculated for trigonal and hexagonal symmetry, corresponding with the Kekulé and the centric formula, respectively. In the calculations it is assumed that the elastic forces for C–C, C=C linkages in the benzene ring equal these in open chains. In the centric model it is, moreover, assumed that the elastic forces between the C-atoms are equal to the average of the elastic force of the single and double bonds. The comparison of the experimentally observed Raman frequencies with the calculated shows that for the plane regular hexagonal structure we get a good agreement with the experimental values, while the Kekulé model gives much too low values. The frequency calculations decide also for the centric model.
Studies in Lubrication. I. The Theory of the Thick Film Lubrication of a Complete Journal Bearing of Finite Length
Authors: Muskat M. , Morgan F.
Published: January 2005

A successive approximation theory is developed for the hydrodynamics of journal bearing systems of finite length, the expansion parameter being the journal eccentricity. This is applied through the second approximation to full journal bearings of lengths exceeding the bearing perimeter. The existence of the lubricant source and associated end leakage is explicitly taken into account, it being assumed in the actual analysis that the source is set 90° in advance of the maximum film thickness. It is found that contrary to prevailing opinion, based on the infinitely long bearing theory, the friction coefficients and eccentricities for the systems are not uniquely determined by the ``Sommerfeld variable''—(r2/c2)(μN/P), where r=journal radius, c=radial clearance, μ=lubricant viscosity, N=journal speed in r.p.s., P=bearing load per unit projected bearing area. It depends also on the leakage flux or source strength. For the position of source assumed in the analysis the friction coefficients and eccentricities increase with increasing source strengths. Further, the load carrying capacities of the finite length bearings are shown to be considerably less than for the infinitely long bearings, and decrease with increasing source strength if the source is placed in the low pressure part of the film. Finally, the theory shows how the consideration of the source of the lubricant permits a resolution of the difficulties with respect to the negative film pressures predicted by the infinitely long bearing theory. The numerical calculations show that the third and higher approximations may be neglected for eccentricity ratios not exceeding 0.4. General formulas are also developed for the asymptotic behavior of the friction coefficients on both the journal and bearing at very low eccentricities or large values of the Sommerfeld variable. These apply to bearings of all lengths and to partial as well as full journal bearings.
Film Lubrication of Finite Curved Surfaces
Authors: Skinner Selby M.
Published: January 2005

In treating film lubrication, Reynolds and Sommerfeld confined themselves to surfaces of infinite width, for mathematical reasons. Michell obtained the solution for a plane surface of finite width; the importance of this lies in the fact that leakage of lubricant through the lateral edges of a finite bearing reduces considerably the load supportable by the bearing. Solutions are obtained here for general cases of rectangular bearings with surfaces curved in both directions; for the Michell sector type of thrust bearing plate, in a case which allows consideration of the effect of the variation of film thickness with the radial distance from the center of rotation; and for the fitted finite journal bearing. General methods are exhibited suitable for handling other cases. In particular, the equations for the finite journal bearing in the general case are partially developed. Solutions for the journal bearing are shown to require laborious computation, so that an approximation to the film thickness is preferable; such an approximation, which can be handled relatively easily, is treated, and the solution obtained.
Dynamic Characteristics of Glow Discharge Tubes
Authors: Reich Herbert J. , Depp Wallace A.
Published: January 2005

This paper describes a method for determining the dynamic current voltage characteristic curves of glow discharge tubes. The technique differs from that previously used for the oscillographic study of glow tubes in that the manner in which the current varies with time is under control. This is accomplished by the use of a vacuum tube to limit the current passed by the glow tube. The rate at which the current rises and falls, the current amplitude, the frequency of repetition of the current cycle, and the interval between cycles can be varied at will by changing the wave form of the voltage applied to the grid of the control tube, and the grid bias of the control tube. A number of oscillograms obtained by this method are shown, and the form of the characteristics is explained on the basis of time taken for ionization and deionization of the gas.
The Operating Characteristics of Power Tubes
Authors: Chaffee E. L.
Published: January 2005

This paper describes a new method of precalculating the performance of a power tube from its static characteristic curves. The 60-cycle test method is also briefly outlined and the results of the two methods compared and discussed. An appendix discusses the effect of secondary emission from the plate and grid and primary emission from the grid on the performance of the tube.
Method of Measuring Luminescent Screen Potential
Authors: Nelson Herbert
Published: January 2005

A method has been devised for the determination of potentials of areas on the interior surface of the glass envelopes of vacuum tubes. Measurements by this method may be made on almost any type of finished tubes. Results obtained have been checked by a second method. Determinations of luminescent–screen potential as a function of second–anode voltage have been made for kinescope tubes under different conditions as to type of screen material, manner of bombarding the screen, beam–current density and previous electron bombardment. It was found as a general feature that as the second anode is made increasingly positive, the screen follows and remains a few volts negative with respect to the second anode until it starts to approach an upper limit of potential with respect to the cathode. When this occurs, the screen rapidly becomes more negative with respect to the second anode. Calcium–tungstate screens and clean Nonex glass surfaces have been found to reach upper limits of potentials between 2500 and 5000 volts, while willemite screens have been carried to potentials as high as 20,000 volts. The upper limit of potential for a particular type of screen varies from tube to tube. Values as different as 4000 and 20,000 volts have been obtained for willemite. In general, the upper limit of potential is found to be lowered as an effect of increased current density in the bombarding beam. Aging of a screen has been found to lower permanently its upper limit of potential. Accumulation of negative charges on the glass base of a screen and on depressed surfaces in the screen layer appears to be important in determining the upper limit of screen potential.
FLOW OF GAS THROUGH POROUS MATERIALS
Authors: Muskat M. , Botset H. G.
Published: January 2005

An experimental study has been made to establish quantitatively the characteristics of and laws governing the flow of gases through consolidated and unconsolidated porous materials of fine texture. Experiments were performed with columns of glass beads, homogeneous and heterogeneous unconsolidated sands, as well as with samples of actual sandstones. With the sandstones linear flows were made both perpendicular and parallel to the bedding plane. Radial flows through annular sections of the sandstone were also made. In all cases it was found that the gradient of the squares of the pressures is proportional to a power of the mass velocity. In the various cases the exponent was found to lie between the limits 1 and 2 corresponding respectively to completely viscous and completely turbulent flow in straight cylindrical tubes. For a given sand however it remains fairly constant over a considerable range in the mass velocity. On the basis of these results a theory was developed for the production from and pressure decline in a closed sand reservoir of uniform thickness producing into a well under conditions of radial two-dimensional flow. The theoretical predictions check qualitatively with the limited field data that are available.
AN ELECTROMAGNETICALLY CONTROLLED THREE-ELECTRODE VACUUM TUBE
Authors: Haynes F. B.
Published: January 2005

A three-electrode tube in which the electron current is controlled by means of a magnetic field instead of the customary electrostatic field. This is accomplished by means of a special type of ``grid'', the construction of which determines the static characteristic of the tube.
A STUDY OF LIGHT SIGNALS IN AVIATION AND NAVIGATION
Authors: Langmuir I. , Westendorp W. F.
Published: January 2005

Visibility of point sources.—Laboratory experiments have been devised to make measurements of the visibility of light signals under conditions essentially similar to those encountered by the aviator or the navigator. Data have been collected on the direct visibility of flashing point sources of light of different colors, flash lengths and intervals, against different backgrounds; the time it takes to locate a visible beacon was studied as a function of the beacon intensity and frequency of flashing. The threshold candle power C required for visibility of a point source at distance D (cm) against a background of brightness H (candles×cm−2) is given by the empirical equation C/D2=3.5×10−9 H1/2. Colored point sources were not found to be useful except in the case of red lights with background intensities above moonlight. For an airplane approaching a beacon it is advantageous to use frequencies of flashing as high as 12 to 30 per minute, although with exceptionally clear atmosphere, lower frequencies may be better.

Visibility of diffuse light.—In a study of the visibility of flashes of diffuse light superimposed on a steady white background, white light flashes gave the best results. The sensitivity of the eye to light from point sources is from 10,000 to 170,000 times as great as from diffuse sources, this range corresponding to an increase in background brightness from 0.1 starlight up to moonlight. A selective differential photoelectric receiver is described which detects signals of modulated diffuse light of an intensity of only 4×10−11 candles×cm−2. This sensitivity is independent of the steady background brightness up to 100 times moonlight, and is from 6 to 13,000 times as great as that of the eye in the range of background intensity from darkness up to moonlight.

Diffusion of light in fog.—The greatest difficulty in transmission of light signals through fog lies in the loss of advantages of the point source. Dense fog may increase the distances at which diffuse light signals may be detected. The range depends to a considerable extent on the reflectivity of the ground. A theoretical treatment of the diffusion of light through fog, based on the scattering of the light rays by fog particles, indicates that airplanes can be guided through fog at distances of several miles by means of diffuse modulated light acting on a differential photoelectric receiver.
THE TIME LAG OF THE ELECTRIC SPARK
Authors: Tiedeman John A.
Published: January 2005

The variation in the time lag of the electric spark has been investigated as a function of the applied field and the number of electrons liberated at the cathode by ultraviolet light, during the application of the field. The time intervals were measured by a Lichtenberg figure method with a precision of 5×10−10 sec. A biasing positive potential was applied to the zinc cathode in such a way that not only were the residual ions removed from between the electrodes before the application of the field but a known number of electrons could be liberated from the cathode by ultraviolet light while the field was applied. For the case of air, hydrogen, and nitrogen curves are given showing how the time lag decreases with an increase in the number of electrons liberated during the application of the field. It is shown that with comparatively high applied fields the time lag reduces to approximately the time required for an electron to be liberated in the gap.
CHARTS FOR TRANSMISSION LINE PROBLEMS
Authors: Hartig H. E.
Published: January 2005

Charts to a reduced scale are presented from which it is possible to determine with very little labor the vector voltage, current and impedance at any point of a transmission line with given terminations. Examples are given exhibiting the properties of the charts and the method of use, illustrating how without computation the variation of E, I and Z from one end of the line to the other may be visualized. The charts are chiefly useful for visualizing the electrical conditions on lines which are electrically long, that is, telephone or radio transmission lines.
THE THERMO-STROMUHR METHOD OF MEASURING BLOOD FLOW
Authors: Herrick J. F. , Baldes Edward J.
Published: January 2005

The purpose of the following article is to bring to the attention of the physicist, who is interested in the application of physics to physiology, a typical problem in biophysics. Rein, a physicist at the University of Freiburg, was confronted with the necessity of knowing accurately the blood supply to a certain organ. Because the various standard methods proved inadequate he developed an ingenious method which he calls the thermo-stromuhr. This method of determining blood flow has been modified in two respects: in the method of measuring the heating energy applied to the blood vessel, and in the method of construction of the diathermy-thermoelements. A tuned circuit is used which permits the measurement of resistance by the method of substitution. The diathermy-thermoelements are made from transparent bakelite and the process of construction is fully described. The theory of the thermo-stromuhr as well as the experimental application is explained in detail.
ELECTROKINETIC POTENTIALS. XI. THE EFFECT OF SODIUM SOAPS ON THE ELECTRIC MOMENT OF THE DOUBLE LAYER AT AN AQUEOUS-CELLULOSE INTERFACE
Authors: Bull Henry B. , Gortner Ross Aiken
Published: January 2005

1. Electrokinetic studies of aqueous solutions of sodium formate, sodium acetate, sodium propionate, sodium butyrate, sodium caprylate, sodium oleate and sodium oxalate have been conducted at a cellulose interface with the streaming potential technique.

2. It is suggested that in interest of clearness and accuracy the attempt to express electrokinetic data in terms of ``potentials'' be abandoned and that the electric moment of the double layer, which does not require a knowledge of the magnitude of the dielectric constant, be substituted for ζ.

3. It is indicated that after the fourth carbon atom has been added the electric moment of the double layer is essentially a constant.

4. It is noted that there is no correspondence between the ionization constant of the fatty acid from which the soap is derived and its effect on the electrokinetic conditions at the interface. This indicates that hydrolysis and the resulting OH ion plays a minor role.

5. It is pointed out that the electric moment of the double layer in the case of the longer chained soaps is almost independent of the concentration whereas that of the short chained soaps are much more sensitive to increased concentration.

6. The maximum electric moment is found at about 2×10−4 normal. This is true also for a number of salts.
A THERMIONIC FREQUENCY DOUBLER
Authors: Stedman C. K.
Published: January 2005

The output voltage ep of a thermionic tube operated over a suitable restricted range of grid voltages eg may be represented by the parabola ep=b0+b1eg+b2eg2. By adding to this in opposite phase the output of another tube, operated on the straight line portion of its curve, we may balance out entirely the term b1eg, so that the characteristic of the combination of tubes is ec=b0+b2eg2. The system will then operate as a frequency doubler, for the output is proportional to eg2 alone. In the experimental set-up described, with a 201A tube, an output of 0.175 volts of frequency 2f is obtained from an input of 1.0 volts of frequency f. It is found that when the characteristic of the system is plotted, the curve is never a symmetrical parabola ec=b0+b2eg2 over a very wide range of grid voltages. This is because the coefficient of the cube term in the equation of the tube characteristic is not negligibly small, and the equation must be written ec=b0+b2eg2+b3eg3. It is shown how the coefficient b3 may be determined by measuring the dissymmetry of the curve.
ELECTRON DIFFRACTION FOR CLASSROOM DEMONSTRATION
Authors: Phillips C. J.
Published: January 2005

An apparatus is described for the class-room demonstration of electron diffraction photographs obtained from thin metallic films and using the range 2000 to 15000 volts. It is very simple to build and reasonably stable. The method of operation is explained.
THE EFFECTS OF HEAT TREATMENT ON FINE METALLIC SUSPENSIONS
Authors: Zirbel N. N.
Published: January 2005

When a suspended system is supported by a fine wire the equilibrium position usually changes slowly for a long time after the load is applied. The equilibrium position also changes with temperature. It is found that both of these disturbing factors can be eliminated by a suitable heat treatment of the wire. Observations have been made on tungsten and platinum-iridium wires of sizes suitable for use in the Eötvos torsion balance.
CATHODE SPUTTERING, A COMMERCIAL APPLICATION
Authors: Fruth H. F.
Published: January 2005

The theory of cathode sputtering with the advantages and limitations in the application of this process is discussed, followed by a description of the commercial equipment and methods for applying gold electrode surfaces to diaphragms of certain types of microphones. By proper design of the vacuum chamber and the inside parts, a fairly uniform discharge current density and a uniform deposit is obtained. A constant sputtering rate is produced by the use of a bleeder valve which maintains a proper residual pressure. Adherence and continuity are obtained by the use of a special cleaning process. An extensive bibliography on cathode sputtering is included.
Potential Distributions in Large Cylindrical Disks with Partially Penetrating Electrodes
Authors: Muskat Morris
Published: January 2005

Because of the equivalence of the pressure in a liquid bearing sand to a velocity potential, an analysis has been carried through of the potential theory of the electrical analogue of an artesian well partially penetrating a water bearing sand.

Part I. In Part I the method of analysis is illustrated by the solution of the problem of a hemispherical electrode imbedded in one of the faces of the disk. Two types of formulae are developed suitable for study of the potential distribution at small and large distances from the electrode respectively. The resistance of this system as a function of the disk thickness is computed and plotted.

Part II. In Part II is treated the more general problem of the potential distribution for a partially penetrating electrode, with a uniform flux density along the electrode surface. Separate formulae for the potential function are again derived that are convenient for discussion at small and large separations from the electrode. It is shown that they reduce in the limit of small penetrations to those of Part I and in the limit of complete penetration to well-known radial flow formulae. Expressions are also given for the stream functions corresponding to the derived potential functions. Finally it is shown that when the flux density along the electrode is assumed to be constant the potential over the electrode is far from uniform, falling sharply near the electrode extremity to a value slightly more than half of that at the top of the electrode.

Part III. The problem of physical interest in which the electrode is at uniform potential is attacked in Part III. After discussing the case of a flux density over the electrode surface increasing with distance from the top the direct method of superposing discontinuous flux density elements is finally used to obtain electrode surface potentials uniform to within 2 percent of the average surface value. The equivalence of this method to the direct solution of the integral equation for the problem is pointed out. The resistances of the disk for various electrode penetrations and disc thicknesses are then computed and plotted. From these a semi-empirical approximation is derived permitting the resistances for other cases to be derived from a single expression without the necessity of first adjusting the electrode flux distribution so that its potential be uniform.
Chemical Treatment of Rotary Drilling Fluids
Authors: Lawton H. C. , Ambrose H. A. , Loomis A. G.
Published: January 2005

The desirable properties of rotary drilling fluid in the technique of boring oil wells are considered. An analysis of the problem of elimination of cuttings by differential settling with reclamation of the colloidal content of clay dispersions shows that viscosity should be lowered as much as possible when the density is held constant. It is demonstrated that lowering of viscosity results in a small lowering of pump pressure, even though the velocity of the mud-fluid is increased to maintain constant carrying capacity for cuttings. Several chemicals have been found that cause remarkable lowering of the viscosity of clay drilling fluids. Suitable adjustment of the concentration of caustic soda in these chemical reagents imparts desirable thixotropic properties to the clay dispersion. The theoretical results of this study are applied to some of the practical problems of oil-well drilling.
Radon Content of Soil Gas
Authors: Botset Holbrook G. , Weaver Paul
Published: January 2005

An electroscope and technique for measuring the radon content of soil gas are described. Measurements were made to answer several questions regarding the radon content of soil gas. It was found that there is no systematic increase of radon content with depth of penetration into a soil, that soil formations appear to have more or less characteristic radon contents, that high radon content of a soil gas is not necessarily an indication of the presence of a fault, and vice versa; and finally it is found that there is great local variation of radon content of soil gases.
Speed, Speed Factor and Power Input of Different Designs of Diffusion Pumps, and Remarks on Measurements of Speed
Authors: Ho T. L.
Published: January 2005

The speed factor of a diffusion pump is defined as the ratio of its real speed to the ideal maximum speed. The fact that the speed factor is much less than unity is due to three causes, namely, the vapor dispersed through the slit, the nozzle chamber resistance and the diffuse reflection of gas molecules at the boundary of the vapor-stream and at the condensing wall. Some effects on the speed are considered as being independent of the configuration. The following general conclusions result from the measurement of the speeds of different configurations. (a) In order to reduce the amount of dispersed vapor by the slit, the vapor nozzle should be divergent instead of being parallel; (b) in order to reduce the chamber resistance the space surrounding the slit should be large and the nozzle chamber should be cold; (c) there exists for each design a certain slit area at which the speed is maximum, but there has been no general rule to predetermine it; (d) in designing a large pump either a narrow throat annular nozzle or multiple nozzles can be used. In measuring speeds some precautions should not be overlooked, unless the results will be falsified: Either the determined speed will be too small or too large (pseudospeed).
The Mechanics of Effervescence
Authors: Stuhlman Otto
Published: January 2005

Bubbles of gas when released in a liquid, at depths great compared to their diameters, on reaching the surface burst and eject droplets of the fluid into the air. Each bubble whose diameter is less than the critical value, on bursting simultaneously ejects many droplets. As many as seven droplets were observed for pure freshly-surfaced water at 21°C for bubbles less than 0.12 cm in diameter, for benzene as many as four at 22°C when bubble diameters were less than 0.15 cm. For the same diameters maximum heights of 14.0 cm and 9.0 cm were found for water and benzene. Bubbles having diameters less than 0.10 cm eject droplets to heights which are proportional to the three-halves power of the radius. Bubbles having greater diameters than those mentioned as critical, burst with less regularity, but always project larger droplets to lesser heights as the diameter increases. This irregularity is attributed to instability of the rising bubble. The height distribution h of the droplets at any single explosion is found to vary with the number n so that log h decreases proportionally as n increases. If a large number of droplets at a given height is examined for variation in distribution it is found that a sharp lower boundary exists but a more straggling distribution for the larger values of height. An analysis shows this to be approximately a Maxwellian distribution. The bursting bubble is accompanied by a gas vortex ring ejection, which assists in raising a liquid jet and stretching it beyond its stable configuration until it breaks into the exponentially distributed droplets mentioned above. After integrating this exponential drop distribution with respect to the integral number of drops observable it was found that the reconstructed jet had the form hx2=constant. Because of the microscopic form of the jet no quantitative measurements could be made so that the converse case was considered, namely the jet produced by the reaction of a falling drop on a liquid surface, as presented by the photographic results obtained by Worthington. His jets when analysed as to volume gave the same mathematical expression as the one found from the data cited above. This reconstructed picture is offered as the solution of the mechanics of effervescence.
Eötvös Torsion Balance
Authors: Barton Donald C.
Published: January 2005

The presence of an extra-heavy (or light) body in the sub-surface warps the level surfaces up (down) over the body and the lines of the vertical toward or into (away from) itself. The Eötvös torsion balance consists of a calibrated platinum-iridium torsion wire which supports a beam of negligible weight; a weight is attached to one end of the beam and a second weight is suspended from the other end. Curvature of the level surfaces and curvature of the vertical each produce at the two weights horizontal components of gravity which are respectively equal and opposite in actual but the same in rotational direction. The torque produced by the curvature of the vertical is a function of the difference of the radii of curvature of the level surface in the directions of major and minor curvature. There has been only one slight important improvement of the torsion balance in the past twenty-five years. There is room for improvement in the avoidance of temperature effects and in speeding up in the time necessary for observation. The mathematics of the torsion balance and of the gravitational effects of simple geometrical bodies is simple and developed. The main field of research with the torsion balance lies mainly in the geological-geophysical field of interpretation, although there are still unsolved problems in the mathematics of interpretation.
Thickness Vibrations of Piezoelectric Oscillating Crystals
Authors: Koga Issac
Published: January 2005

For several years, it has been well known that, in the natural vibration of a piezoelectric oscillating crystal, there is a certain period proportional only to the thickness, but, so far as we are aware, there has been no concrete explanation for this vibration nor how its period is connected with the physical constants of the medium. The present paper shows that such a vibration, named thickness vibration for brevity, is due to the standing wave produced by interference of plane waves incident to and reflected from the plane boundary surfaces of the medium, and verifies the theoretical results by several examples. There are three normal modes in the thickness vibration, and the corresponding frequencies are given in first approximation by a representative formula: P/2π = (q/2a) (c/ρ)1/2, where q is any integer, a the thickness of the plate, ρ the density and c a certain adiabatic elastic constant depending upon the orientation of the plate with respect to the crystallographic axes of the medium. It is not always possible to excite all normal modes of vibration piezoelectrically. The electrically measured natural frequency of the thickness vibration is always a little higher than that calculated by the formula. Adiabatic elastic constants of piezoelectric crystals may be determined in first approximation by measurement of the frequencies of thickness vibrations of plates prepared from given crystals.
Reduced Scale Studies in Armor Penetration
Authors: Thompson L.
Published: January 2005

The attack of armor by competent projectiles involves a punching cycle of very short duration and extreme reactions. The characteristic results, with respect to the essential properties in the design of ship protection, have been investigated by means of simple dimensional forms, and a generalization has been made by reference to a penetration coefficient. The latter is a function of the penetration number (ratio of plate thickness to projectile diameter) and the obliquity of impact. A similar treatment of the absorption problem is outlined, and the special case of thin plate is of note in the implied linear velocity law of reaction. Conditions for extension in scale are stated and also certain convenient ratios for the estimation of the relative limits of nonsimilar systems.
X-Ray Study of the Plastic Working of Magnesium Alloys
Authors: Morell L. G. , Hanawalt J. D.
Published: January 2005

The inner structure of Dowmetal fabricated by various processes, such as forging, rolling, extruding and drawing, has been studied by means of x-ray diffraction. The x-ray diffraction patterns are identified by comparing them with computed fiber patterns for the close-packed hexagonal system, c/a=1.62. Three distinct structures are obtained—a [210] fiber structure at ordinary temperatures and a [110] fiber structure at temperatures higher than about 450°C with the fiber axis, in both cases, in the direction of extrusion or drawing, and a [001] fiber structure with the fiber axis in the direction of forging. The difference in the structure of metal extruded at low and high temperatures is discussed in terms of the glide systems of magnesium.
The Crystal Structure of Electrodeposits from Copper Acetate Solutions
Authors: Allen S. J. M. , Kersten H. , Maas Joseph
Published: January 2005

It is shown by x-ray diffraction methods that electrodeposits from copper acetate solutions consist principally of a mixture of crystals of copper and cuprous oxide and that the proportion of cuprous oxide deposited with the copper increases when the bath is made less acid. Rectification or photoelectric properties such as are exhibited by cuprous oxide prepared on the surface of copper were not observed for the electrodeposits.