Improvements in Gas Detecting and Recording Apparatus.
Year: 1890

page_text: Date of Application, 16th July, 1890
Complete Specification Left, 16th Apr., 1891-Accepted, 30th May, 1891 .
PROVISIONAL SPECIFICATION.
Improvements in Gas Detecting and Recording Apparatus.
We JAMES PITKIN of 56 Red Lion Street, Clerkenwell, Philosophical Instru-
ment Maker, and JOB THOMAS NIBLETT of 20 Devonshire Road, Greenwich,
Electrician, do hereby declare the nature of this invention to be as follows:-
This invention relates to that class of apparatus in connection with which Letters
Patent have been granted to us dated March 16th 1889, No. 4629, and wherein
the peculiar property of certain metallic substances, notably platinum black, in
occluding and facilitating the combination of certain gases, and thereby causing
an abnormal temperature in the neighbourhood of such metallic substances, is
employed in connection with metallic or other thermometers for giving indication
of existence of a vitiated atmosphere, or of a mixture of various gases.
The present improvements consist in adapting to such indicating thermometers,
means for making a continuous record of the variations in the readings of the
thermometer treated with the platinum black or similar material, which, by a
comparison with the recorded readings of an ordinary thermometer, under the
same circumstances, will give data for determining the percentage of any given
gas in a gaseous mixture at any particular moment, and for giving an alarm
when the instrument is taken into the presence of such a mixture.
According to the first heading of our invention, we arrange a pair of pencils
or syphon pens in contact with a paper covered drum, which is continuously
rotated in one direction by any suitable means. These pencils are carried near
the extremities of rods formed of unequally expanding metals, such as brass and
steel, and constituting metallic thermometers. One thermometer is treated with
platinum or similar material, as described in the Specification of our Patent
before mentioned, and the other is plain.
The thermometers are so arranged as, by the unequal expansion of the metals
of which they are composed, to give to the pencils sideway movement as the
temperature varies, which movement will cause a wavy line or lines to be made
on the paper as the drum rotates.
In atmospheric air at all temperatures, the readings of both thermometers
will be similarly normal, as indicated by parallel lines on the paper, if the
thermometer bars are placed parallel, or by a single line if the thermometer
bars are arranged in line. In the presence of gas, however, the coated thermo-
meter will be immediately affected, and will therefore cause the reading of an
abnormal temperature to appear on the paper, by means of a line more or less
at variance with the normal readings, thereby giving a reliable record of the
amount of gas mixed with the atmospheric air, or, in the case of a mixture of
two or more gases, of the relative quantity of the gas under examination, which
record, when compared with the normal reading, will give data for determining the
percentage of gas present.
According to the second part of our invention, the variations of the coated
thermometer may be utilized for making contact either with the uncoated thermo-
meter or a fixed point, and thereby completing an electric circuit and ringing a
bell, lighting an incandescent lamp, or making other indication. The coated
thermometer may also be arranged, if desired, in connection with a series of
electrical resistances, so as to cut out one resistance after another, and thereby give
indication of the presence of gas in increasing quantities, and of the percentage
likely to be present, as shown by the energy of the thermometer, in cutting out
more or less of the resistances.

page_text: The electric alarm can be readily employed in connection with a mercurial
thermometer coated with platinum black.
A fine wire, forming an electrical terminal, is in, constant contact with the
mercury, which, when expanded by the "heat generated in the platinum in a
vitiated atmosphere, or in a mixture of gases, will rise or expand until it
reaches another terminal fixed at a point which would indicate the presence of gas
in any given percentage. The circuit thus completed can be utilized to actuate any
suitable alarm.
If it be thought objectionable to introduce terminals through the glass of a
mercurial thermometer tube or bulb, to get contact with the metal contained
therein, the instrument may, if preferred, be arranged to balance at a normal
temperature, and when, by the heating of the platinum placed at one end, the
mercury expands and upsets the equilibrium, contact points on the outside of the
instrument may complete the electrical circuit and ring the alarm.
Dated this 16th day of July 1890.
NEWTON & SON,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Gas Detecting and Recording Apparatus.
We JAMES PITKIN of 56 Red Lion Street, Clerkenwell, Philosophical
Instrument Maker, and JOB THOMAS NIBLETT of 20 Devonshire Road, Green-
wich, Electrician, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
This invention relates to that class of apparatus in connection with which
Letters Patent have been granted to us, dated March 16th 1889, No. 4629, and
wherein the peculiar property of certain metallic substances, notably platinum
black, in occluding and facilitating the combination of certain gases, and thereby
causing an abnormal temperature in the neighbourhood of such metallic substances,
is employed in connection with metallic or other thermometers for giving indication
of existence of a vitiated atmosphere or of a mixture of various gases.
The present improvements consist in adapting to such indicating thermometers,
means for making a record of the variations in the readings of the thermometer
treated with the platinum black or similar material, which, by a comparison with
the recorded readings of an ordinary thermometer under the same circumstances,
will give data for determining the percentage of any given gas in a gaseous
mixture at any particular moment, and for giving an alarm when the instrument
is taken into the presence of such a mixture.
According to the first, heading of our invention, we arrange a pair of pencils or
syphon pens in contact with a paper covered drum, which is continuously rotated
in one direction by any suitable means. These pencils are carried near the
extremities of rods formed of unequally expanding metals, such as brass and steel,
and constituting metallic thermometers. One thermometer is treated with platinum
or similar material, as described in the Specification of our Patent before men-
tioned, and the other is, plain. The thermometers are so arranged as, by the
unequal expansion of the metals of which they are composed, to give to the pencils
sideway, movement as the temperature varies, which movement will cause a wavy
line or lines to be made on the paper as the drum rotates. In atmospheric air at
all temperatures, the readings of both thermometers will be similarly normal, as
indicated by parallel lines on the paper, if the thermometers bars are placed
parallel, or by a single line, if the thermometer bars are arranged-in line. In the
presence of gas, however, the coated thermometer will be. immediately affected,
and will therefore cause the reading of an abnormal temperature to appear on the

page_text: paper by means of a line more or less at variance with the normal readings, thereby
giving a reliable record of the amount of gas mixed with the atmospheric air, or,
in the case of a mixture of two or more gases, of the relative quantity of the gas
under examination, which record, when compared with the normal reading, will
give data for determining the percentage of gas present.
According to the second part of our invention, the variations of the coated
thermometer may be utilized for making contact either with the uncoated thermo-
meter or a fixed point, and thereby completing an electric circuit and ringing
a bell, lighting an incandescent lamp, or making other indication. The coated
thermometer may also be arranged, if desired, in connection with a series of
electrical resistances, so as to cut out one resistance after another, and thereby
give indication of the presence of gas in increasing quantities, and of the
percentage likely to be present, as shown by the energy of the thermometer in
cutting out more or less of the resistances.
The electric alarm can be readily employed in connection with a mercurial
thermometer coated with platinum black.
A fine wire, forming an electrical terminal, is in constant contact with the
mercury, which, when driven up by the heat generated in the platinum in a
vitiated atmosphere, or in a mixture of gases, will rise or expand until it reaches
another terminal fixed at a point which would indicate the presence of gas in any
given percentage. The circuit thus completed can be utilized to actuate any
suitable alarm or electrical recording instrument.
If it be thought objectionable to introduce terminals through the glass of a
mercurial thermometer tube or bulb, to get contact with the metal contained therein,
the instrument may, if preferred, be arranged to balance at a normal temperature,
and when, by the heating of the platinum placed at one end, the mercury expands,
and upsets the equilibrium, contact points on the outside of the instrument may
complete the electrical circuit, and give an audible or visible alarin.
In the accompanying drawings we have illustrated diagrammatically various
appliances embodying our invention.
In Fig. 1, A and B are a pair of parallely arranged compound bars composed
of unequally expanding metals, such as brass and steel, and constituting metallic
thermometers.
C is a drum constantly rotated by suitable means, and carrying a record sheet,
in contact with which are pencils or markers carried at or near the extremities of
the metallic thermometers A and B.
The thermometer A is treated with active material such as platinum black, but
the thermometer B is not so treated.
In a normal temperature, the markers carried by the thermometer make upon
the record of the drum, as it rotates, a pair of parallel lines, but immediately the
atmosphere becomes contaminated, as, for instance, by fire damp in a coal mine, the
fact is at once apparent upon the record sheet, by the abnormal temperature
registered by the thermometer A, as compared with the thermometer B.
Fig. 2 shews an arrangement wherein the thermometers are placed in line, so
that, under ordinary conditions, they trace their mark in the same line upon the
record drum, but diverge when the treated thermometer registers an abnormal
temperature.
The rate of travel of the paper under the markers may be regulated to suit
requirements, and it may be divided off in terms of temperature and time, or time
only, or time and percentage gas.
Fig. 3 shews a pair of metallic thermometers A and B, so arranged that when
the treated thermometer A is influenced by the heat generated by the occlusion of
gas in its coating of active material, a contact will be effected between the ends of
the bars A and B, and an electric current from the battery D will be permitted to
pass through the galvanometer E.
Fig. 4 is an arrangement slightly differing from Fig. 3, but acting precisely
similarly.

page_text: +
Fig. 5 shews the metallic bars connected together, but electrically insulated
the one from the other. The increased deflection of the bar A, under the
influence of abnormal heat, is relied on to overcome the mechanical resistance of
the bar B, and effect the completion of the electric circuit through the post F.
Fig. 6 exemplifies two somewhat different contrivances in connection with a
differential air thermometer. Gis a differential air thermometer, with two bulbs a
and a being treated with active material, as before explained. In the bend of
the thermometer tube is a column of mercury, the position of which in both limbs
of the thermometer tube will be the same, except in the presence of gas, when the
coated bulb will exert its influence, and drive over the mercury towards the uncoated
bulb. is a permanent electrical contact midway between the bulbs. i is a wire
or carbon filament, or other high resistance conductor, inserted through the uncoated
bulb into the thermometer tube. The filament i forms the opposite pole of an
electric circuit containing a galvanometer, upon which is recorded the passage of
an electric current, as soon as the mercury column reaches the filament and com-
pletes the circuit. As the mercury rises under the increased temperature generated
in active material, by degrees, the resistance of the filament to the passage of the
current decreases, thereby shewing, by the increased deflection of the needle of
the galvanometer E, or other electrical recording instrument, the growing percentage
of gas in the gaseous mixture. On the other side of the instrument (Fig. 6),
resistances R, RI, R", R, and RIV, are shewn, which may be cut out one by one
as the mercury recedes from the bulb a, which fact is immediately registered by
the increased deflection of the needle of the galvanometer E. Instead of the
galvanometer E, a contrivance similar to an electric recording volt, or ampere
meter, may be used, by which a permanent record may be obtained.
Figs. 7 and 8 show how a mechanical balance in a differential thermometer may
be utilized to operate an electric alarm.
In Fig. 7, this effected through a pendent rod j, dipping into a mercurial
contact J, when the balance is upset by the deviation of the mercury within the
thermometer tube. Balance nuts n " are arranged to facilitate the accurate
adjustment of the instrument.
In Fig. 8, the tipping of the balanced tube is utilized to bear down a spring
contact k, and so complete an electric circuit.
In Fig. 9, A is an ordinary mercurial thermometer treated with active material.
h is a scaled-in contact wire or filament at the bottom of the bulb, and i is an
adjustable contact filament at the top of the tube. When the circuit is completed,
through the mercury reaching the filament i, the instrument E is put in action, or
the electric current may work a relay Z, and bring into action the lamp 1, or bell 1,
or both.
The conductor i may be of platinum or other suitable metal, or it may be a carbon
filament. If it be of high resistance, the rise of the mercury cuts out or decreases
the resistance, as before explained with reference to Fig. 6.
Fig. 10 shews a differential electric arrangement for recording or transmitting
indications of the presence of mixtures of gas and air.
A and B are coils of wire of equal electrical resistance when at the same tem-
perature. E is a differential galvanometer or recording instrument. D is a
battery. The coil A is treated with active material, but the coil B is not so
treated.
Under ordinary circumstances, and at all temperatures, an equal current passes
through each coil, and there is therefore no deflection of the galvanometer. As
soon, however, as heat is developed in the coil A, the balance of the current is
upset, owing to the increased resistance in the coil Á, and a deflection of the needle
is at once visible.
Fig. 11 shows a Wheatstone's bridge arrangement. If the resistance of the
coils A and B are equal, no difference of potential is obtained at the points and e
and no current passes through E, but if the electrical balance is broken by the
heating of one of the coils, a difference of potential is obtained, and a current

page_text: flows through E, such current being proportional to the difference in the relative
resistances of A and B. An electrical recording instrument may be used instead of
a galvanometer E.
The amplitude of the deflection, according to the calibration of the instrument,
bears a direct proportion to the amount of gas in the mixture under test.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :-
The gas detecting and recording apparatus substantially as herein described with
reference to the accompanying drawings.
NEWTON & SON,
Agents for the Applicants.