Improvements in the Method of and Apparatus for Determining the Density of Gases.
Year: 1894

page_text: Date of Application (in United Kingdom), 1st Jan., 1894
Complete Specification Left, 1st Jan., 1894-Accepted, 3rd Mar.,
1894
COMPLETE SPECIFICATION.
Improvements in the Method of and Apparatus for Determining the
Density of Gases.
We, GEORGES FRERE, and MAURICE MESLANS, of 15 Rue des Halles, Paris,
in the Republic of France, 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 present application has for its object to guarantee to us the ownership
of novel methods and apparatus which we have designed for the determination of
the density of gases and the applications resulting therefrom.
It is known that according to the principle of Archimedes any body submerged
in a fluid loses a part of its weight equal to the weight of the fluid which it
displaces. If therefore a balloon of volume V be plunged into a gas, the loss of
weight p which it undergoes will be-1.2932 being the weight of a litre of air
at 760 mm. pressure and 0.625 or the relative density of aqueous vapour, t the
= 0.00367
temperature a the coefficient of expansion of the gas at constant pressure
for air, H the atmospheric pressure, F the maximum tension of aqueous vapour
att degrees temperature, E the degree of humidity that is the relative tension of
the aqueous vapour; thus E F is the tension of the aqueous vapour, and D the
density of the gas in question--
This method presents great difficulties in its application. It is necessary in
effect to operate with the gas and with air at the same temperature at the same
pressure, and with gases perfectly dry or presenting the same hygrometrical
degree.
To obviate these disadvantages we have conceived the idea of effecting these two
operations simultaneously by means not of the same single balloon but of two
balloons of exactly the same volume, which we submerge, one in air and one in the
rene to be tested

page_text: For this purpose each of these balloons is suspended at the extremity of a single
balance arm above a receptacle. These two receptacles are placed in a vat full of
cold water to insure an equality of temperature.
In one of these receptacles is air, and in the other the gas to be tested; the two
gases are in contact with the water contained in their receptacles; they are
therefore in the same hygrometrical condition.
If the two receptacles contain air the arm will rest in equilibrium and the needle
will point to 0 on the scale. If in one of the receptacles the air is replaced by a
gas of different density the equilibrium will be destroyed and the difference in
weight will be found either by adding a known weight or by displacing a rider on
a graduated scale on the arm, or by reading the deflection of the needle on the
scale.
If the preceding formule be annlied to each one
and obtains
0.9714 being the density of nitrogen and 1.529 the density of CO2, and it is the
proportion of this mixture contained in the gases which will give the extent of the
combustion.
A graduation could be made of which the zero corresponds to
mixture and to a normal combustion.
100
100
of this
The apparatus designed for the application of the methods which we have just
pointed out may be variously arranged. We give one form as an example on the
annexed drawings in which Fig. 1 is a vertical transverse section and Fig. 2. a
view in plan.
DESCRIPTION.
A A¹ are the two balloons. B the receptacle containing air, B₁ that to which
the gas is supplied in a continuous manner by the pipe C. D is the vat full of
cold water and enclosing the two receptacles. E is the pipe serving for the supply
of water to the lower part of the receptacles and for the maintenance of an equal
hygrometric degree of the gases. Fare pieces of woven material hanging down
into the water in the receptacles and which traversed by the gas or in contact with
the air saturate them with humidity.
The description above given joined to the explanations which precede it will
enable our apparatus to be thoroughly understood. It indicates to us as a result
the density and in consequence the composition of the gases, in a continuous manner
and at each moment of production.

page_text: This apparatus also permits, in the special case of combustion and by means of
the method which we have pointed out, of the regulation of this combustion
and the admission of air to the furnaces of steam boilers furnaces &c. either by
hand, or automatically by a suitable arrangement, comprising for example an
alarm, register &c.
It can also be easily arranged to act in a mine containing fiery gases.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
The improvements in the method of and apparatus for determining the density of
gases substantially as described with reference to the drawings.
Dated this 30th day of December 1893.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.