154 Dr. Henry on the aeriform compounds 
As an illustration of the method of investigating the pro- 
portions of mixtures of the three last gases, we may take the 
instance of a mixed gas, free from olefiant gas, of specific 
gravity *534, of which 100 volumes consume 110 of oxygen, 
and afford 70 of carbonic acid, the diminution of the whole 
210 after firing being 14,0 volumes. Now it must be ob- 
vious from inspection of the Table, that the 70 parts of 
carbonic acid cannot all have resulted from the combustion 
of carburetted hydrogen, since, for the saturation of 70 mea- 
sures of that gas, 140 of oxygen would have been required, 
whereas only 110 have been expended. We may therefore 
safely infer the presence of carbonic oxide, a gas which, by 
combustion, gives its own volume of carbonic acid, with the 
expenditure of only half its volume of oxygen. The spe- 
cific gravity of the specimen being lower than that of carbu- 
retted hydrogen, indicates also an admixture of simple hy- 
drogen gas ; and of this the proportion must necessarily be 
considerable, to countervail the weight of the heavy carbonic 
oxide. The following proportions of the three gases will 
be found to coincide with the properties of the mixture. 
40 vols 
. of carb. hydrogen 
Consume Ox. 
80 
Give Carb. Ac. 
4° 
Dimin.by 
80 
3° 
— — carb. oxide 
15 
So 
15 
30 
hydrogen gas 
15 
0 
45 
100 
HO 
70 
14° 
No reliance, however, can be placed on the accuracy of 
such estimates, unless the specific gravity of the specimen 
agrees with that of the hypothetical mixture, as deduced 
from the proportion of its ingredients. But when this coin- 
cidence takes place, we have all the evidence, which the 
