Improvements in Instruments for Indicating the Presence of Hydrogen Gases or Fire-damp in Mines and other Places.
Year: 1889

page_text: Date of Application, 16th Mar., 1889
Complete Specification Left, 16th Jan., 1890-Accepted, 22nd Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in Instruments for Indicating the Presence of
Hydrogen Gases or Fire-damp in Mines and other Places.
We JAMES PITKIN of 56 Red Lion Street, Clerkenwell Philosophical Instrument
Maker, and JOB THOMAS NIBLETT of 20 Devonshire Road, Greenwich, Electrician,
do hereby declare the nature of this invention to be as follows:-
The chief object of this invention is to provide a simple instrument which will
give prompt and unmistakeable indication of the presence of fire damp in mines,
but it is also intended to provide a detector for escapes of ordinary lighting gas in
gas mains.
In carrying out this invention, the peculiar property of certain metallic substances,
among which are those known as spongy platinum or platinum black, of evolving heat
when in the presence of hydrogen gas or its gaseous compounds, is made available.
The instrument consists essentially of a thermometer, metallic or otherwise, to
which the platinum black is applied in such a way that on the instrument being
taken into the presence of fire damp or hydrogen gas, the increased temperature of
the platinum black will at once be indicated. by the thermometer on a suitable dial
or scale.
In this way, if two thermometers are placed side by side in a suitable case, one
being coated with platinum black and the other not so coated, in a normal atmo-
sphere, their register will be about alike, but on coming into the presence of
atmosphere vitiated by hydrogen gas, the heat generated in the platinum will give
rise to an upward movement of the thermometer to which it is applied, while the
other thermometer remains the same.
Thus, a comparison of the thermometers will not only give indication of the
existence of fire damp in the mine, but also will give data for the calculation of
the actual per centage present.
1000
1 1000
NEWTON & SON,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Instruments for Indicating the Presence of
Hydrogen Gases or Fire-damp in Mines and other Places.
We, JAMES PITKIN of 56 Red Lion Street, Clerkenwell, Philosophical Instrument
Maker, and JOB THOMAS NIBLETT of 20 Devonshire Road, Greenwich, 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 :-
The object of this invention is to provide an instrument that will not only detect,
without risk to the operator, the presence of hydrogen gas or its gaseous compounds,
but will also give data for calculating the percentage of gas present in the atmosphere,
whether of a mine or of a tunnel containing gas mains.
In carrying out this invention, the peculiar property of certain metallic substances,
among which are those known as spongy platinum or platinum black, of evolving heat
when in the presence of hydrogen gas or its gaseous compounds, is made available.
In this way, if two thermometers are placed side by side in a case with perforations
covered in with wire gauze, one being coated with platinum black, and the other
not so coated, in a normal atmosphere, their register will be about alike, but on
coming into the presence of atmosphere vitiated by hydrogen gas, the heat generated

page_text: in the platinum will give rise to an upward movement of the thermometer to which it
is applied, while the other thermometer indicates merely the temperature of the
atmosphere.
1 -
Thus a, comparison of the thermometers will, not only give. indication of the
existence of fire damp in the mine, but will also give data for the calculation of the
actual percentage present. .
According to our invention, the coating of platinum is overlaid with a covering
of silk or similar material, to maintain its adhesion to the thermometer, and to
prevent particles from becoming detached under the influence of heat and firing
the explosive mixture which passes through the gauze. The silk covering is however
not sufficient to obstruct the full access of the surrounding atmosphere to the
platinum black, and does not influence the deterioration of the platinum black under
repeated use, as is the case when the said platinum is mixed with cementing
materials to cause its adhesion, which materials generally have the effect of destroying
the porosity of the platinum.
In the accompanying drawings we have shown a fire damp indicator or detector
embodying our invention, in several forms.
Figs. 1 and 2 shew a pair of ordinary bulb thermometers placed side by side in a
< wooden block, their bulbs being let into the wood, and enclosed by fine wire, gauze
secured by a metal plate. In Fig. 2 the gauze and securing plate is removed to shew
the bulbs, one of which a' is without coating, the other a is coated with metallic
substance having the property, as before mentioned, of becoming heated in the presence
of hydrogen gas or its gaseous compounds. This substance, preferably platinum black,
is first applied to the bulb in a pasty state, and afterwards enveloped with a ribbon of
silk, or some such material, to maintain its adherence, without obstructing the access
of the gas thereto.
:
:
Figs. 2 are illustrative of this; A shows the bulb merely coated with metallic
substance; B shews. a ribbon of silk laid over; and c a silken thread as an
alternative.
In a normal atmosphere; both thermometers indicate a like temperature upon the
scale; which, in the present case, is Fahrenheit, but in the presence of hydrogen gas
or its gaseous compounds, the platinum becomes heated, and sends up the reading of
the thermometer to which it is applied, while the uncoated thermometer indicates a
normal temperature:
Fig. 3 shews a thermometer of another type. It is a differential air thermometer,
consisting of two bulbs, and a single tube connecting them, and containing a
mercurial thread. One of the bulbs a is coated with platinum black, as before
described with reference to the previous example. The ends of the mercurial thread
are normally equidistant from their respective bulbs, but on the rise of temperature
of the platinum, by reason of the presence of fire-damp, the expansion of air within
the bulb a causes the the advance of the mercury, and the compression of the air in
the bulb a². A sliding scale marked with suitable degrees according to any
approved table of percentages, may in this case be adopted, so that o may be adjusted
at will to the real temperature, while the difference between that and the reading
on the scale will give data for ascertaining the percentage of fire damp present.
Figs. 4, 5, 6 and 7 shew a mercurial and metallic thermometer used in combination,
'enclosed in a suitable metallic case.
Fig. 4 is a face view of a dial shewing the indicating hand b of a metallic
thermometer a, and the tube of a mercurial thermometer a¹. Fig. 5 is a back view,
and Fig. 6 is a horizontal section on line a, a of Fig. 5.
Fig. 7 is a back view of the case, shewing perforations, and wire gauze, which admit
of access to the thermometers by the atmosphere. a is the metallic thermometer,
composed of two strips of dissimilar metals, preferably steel and brass, after the
manner of a chronometer balance. One end of this compound bar is secured at
while the other end is connected by a chain to the arbor of the indicating hand c.
The compound bar is coated with platinum black, and lapped around with ribbon, as
before explained with reference to the bulbs.
C,

page_text: C,
In the example shewn, the compound bar is curved, and is so arranged that it will
straighten, under the influence of heated platinum acting upon the unequally
expanding metals, steel and brass, and thus rotate the arbor of the pointer hand
thereby indicating a different temperature from that given by the mercurial
thermometer. In this way, the presence of hydrogen gas is readily detected, and its
quantity estimated.
Having now particularly described and ascertained the nature of our said inven-
tion & in what manner the same is to be performed, we declare that what we
claim is :-
1. The treatment of thermometers as above described with metallic substances,
having the property of evolving heat in the presence of hydrogen gas or its gaseous
compounds, overlaid with a covering of fibrous material, such as silk, for the purpose
set forth.
2. The construction and arrangement of instruments for indicating the presence of
hydrogen gas or its gaseous compounds, as described and illustrated in the
accompanying drawings.
NEWTON & SON,
Agents for the Applicants.