394 -Experiments on the Gas from Coal. 
2. CARBURETTED HYDROGEN has been 
shewn to constitute the gas of marshes, and 
the fire-damp of .coal mines. .. In these natu- 
ral. forms, ‘it 1s contaminated with a small 
proportion of carbonic acid, and a larger 
one of azotic gas, but appears to be free from 
all other impurities. It is proved to be a 
definite compound of hydrogen and charcoal 
without any oxygen. It is lighter than com- 
mon air, in the proportion of about 600 to 
1000; it has very little odour; and burns 
with a flame greatly surpassing that of hy- 
arBeD, in density and illuminating power. 
Products, 
oz. dr.* > ‘oz. dr. 
A cubic foot x 7. 
weighs... 0.12 Leunbicfootof - 
carb. acid... 1.13 ° 
Consumes 2 ; =e 
cubic feet of 
oxygen eoeso 2 . 10 : Water... eeece 1 ° 9 
3.6 3.6 
3. CARBONIC OXIDE is rather lighter. 
than common air—It contains no hydrogen, 
and is purely a compound of charcoal and: 
oxygen, the latter being in just half the pro- 
portion which is required to constitute car- 
bonic acid. It burns with a feeble bluelight. 
* The avoirdupois ounce of 437% grains, or 16 drams, 
is to be understood. 
