160 Dr. Henry on the aeriform compounds 
as a distinct species, requiring for the perfect combustion of 
each volume two volumes of oxygen, and affording one vo- 
lume of carbonic acid ; and that if olefiant gas be considered 
as constituted of one atom of charcoal united with one atom 
of hydrogen, carburetted hydrogen must consist of one atom 
of charcoal in combination with two atoms of hydrogen. 
2. That there is a marked distinction between the action 
of chlorine on olefiant gas, (which, in certain proportions, is 
entirely independent of the presence of light, and is attended 
with the speedy condensation of the two gases into chloric 
ether), and its relation to hydrogen, carburetted hydrogen, 
and carbonic oxide gases, on all which it is inefficient, pro- 
vided light be perfectly excluded from the mixture, 
3. That since chlorine, under these circumstances, con- 
denses olefiant gas without acting on the other three gases, 
it may be employed in the correct separation of the former 
from one or more of the three latter. 
4. That the gases evolved by heat from coal and from oil, 
though extremely uncertain as to the proportions of their in- 
gredients, consist essentially of carburetted hydrogen, with 
variable proportions of hydrogen and carbonic oxide ; and 
that they owe, moreover, much of their illuminating power 
to an elastic fluid, which resembles olefiant gas in the pro- 
perty of being speedily condensed by chlorine. 
5. That the portion of oil gas and coal gas, which chlorine 
thus converts into a liquid form, does not precisely agree 
with olefiant gas in its other properties ; but requires, for the 
combustion of each volume, nearly two volumes of oxygen 
more than are sufficient for saturating one volume of olefiant 
gas, and affords one additional volume of carbonic acid. It is 
