t 4 
Mr. Brande on the composition and analysis 
1. One hundred volumes of coal gas were detonated by the 
electric spark over mercury, with 200 of oxygen ; the car- 
bonic acid was absorbed by liquid potassa, and 3 6 volumes 
of pure oxygen remained in the tube. Whence it appears 
that 100 volumes of the coal gas under examination required 
for its perfect combustion 164 parts of oxygen ; consequently, 
as 100 parts of olefiant gas require 300 of oxygen, and 100 of 
hydrogen 50, for their respective combustion, it might be 
concluded from the above experiments, supposing no foreign 
gases present, that the 100 of coal gas consisted of about 55 
parts of hydrogen and 48 of olefiant gas ; a mixture, of which 
100 cubical inches would weigh nearly 15 grains, and which 
closely corresponds with the specific gravity of the coal gaj. 
2. One hundred measures of coal gas were introduced into a 
small bent glass tube containing a little sulphur, and inverted in 
mercury ; a red heat was applied until the inclosed gas under- 
went no further dilatation ; and on examining its volume when 
cold, it was found to occupy 140 measures. If we consider the 
increase of bulk as resulting from the decomposition of ole- 
fiant gas, this experiment gives the composition of coal gas 
60 hydrogen and 40 olefiant by volume. 
3. One hundred measures of coal gas were introduced into 
a mercurial gasometer, connected with a second gasometer 
by means of a platinum tube, in the manner described by 
Messrs. Allen and Pepys, in their Essay on the Combustion 
of Carbon.* Some small quartz crystals previously heated 
red hot were introduced into the platinum tube, which was 
heated bright red ; the gas was then passed through it from 
* Phil. Trans. 1807. 
