Ls easieentame 
Dr. Hare’s Improved Barometer Gage Eudiometer. 283 
Method of Operating. 
In the engraving, a leaden tube is represented as making a com- 
munication between the gage tube and the cavity of the iron bottle, 
through one of the valve cocks. Let it be supposed that, by means 
of other valve cocks and tubes, like communications with an air, 
pump, and one or more reservoirs of gas, are under the control of 
the operator. 
In order to analyze the atmosphere, he should have at his com- 
mand a communication with a bell glass containing, over water, a 
mixture of five parts of air and three of hydrogen; also with a reser- 
voir of hydrogen.* 
These arrangements being made, ax banat the bottles ; and admit- 
ting two or three volumes of hydrogen, exhaust again. By repeat- 
ing this part of the process, nothing but hydrogen will remain in the 
vessel. let the zero of the descending scale be situated on a level 
with the surface of the mercury in the gage tube, and then admit 
eight volumes of the mixture, which will be known to have entered 
when the surface of the mercurial column has fallen to eight on that 
scale. All the cocks being closed, ignite the platina wire. The 
explosion will be known to take place, both by the flash and sharp 
noise which it produces. As soon as these indications are perceived, 
the cock communicating with the gage may be re-opened. Nearly 
three volumes of the mixture will be found to have disappeared, and 
by the time that the thermometer indicates the temperature to be in 
statu quo, it will be found that the deficit arising from the combustion 
will a little exceed that quantity. 
In analysing gaseous compounds of carbon with hydrogen, this 
apparatus may be advantageously employed ; due proportions of the 
carburet and of oxygen gas being previously mingled in an appro- 
priate vessel over water. Suppose, for instance, olefiant gas were 
in question; one volume of it being mixed with four of oxygen: 
after the explosion two volumes will be found wanting; because, in 
one volume of the carburet, there are two of hydrogen and two of 
carbon vapor. Each volume of the latter, will unite with one of 
oxygen, without altering its volume. The two volumes of hydrogen 
will take one of SES: and be condensed with it into water. “Or 
* The necessary mixtures are Pelfected either by means of the volumeters or 
the sliding rod gas measure, of which I published engravings and dese riptions in 
this Journal, vol. 12, page 36, 1827; and in the London Philosophical Magazine 
for 1828, vol. 32, page 126. 
