Analysis of the compound inflammable Gases. sgt 
been produced, by the oxygenation of the whole of the com- 
bustible gas, and what quantity of oxygen it would have 
saturated . 
The most obvious objection to this method of analyzing 
the compound gases is, that the real proportion of the products, 
resulting from their combustion, may perhaps be disguised, in 
consequence of the absorption of a part of the carbonic acid by 
the water, over which the experiment is made. By frequent 
trials, however, I find that this is a source of error too 
trivial to be deserving of consideration ; and that the propor- 
tion of carbonic acid, thus generated, exceeds what is com- 
posed by the rapid combustion of the same gas over mercury. 
When the operator has acquired sufficient dexterity, the in- 
terval of time, between the completion of the combustion and 
the admeasurement of the residue, is too small to allow an 
absorption to any notable amount. It must be observed, also, 
that the carbonic acid constitutes only a small part of the 
residue ; and is, for that reason, very little acted on by water, 
conformable to a principle which I have explained in the Phi- 
losophical Transactions for 1803, p. 274. I believe, therefore, 
that with an attention to those observances, which are required 
in all delicate experiments on gases, and to the changing cir- 
cumstances of temperature and pressure, this apparatus is fully 
adequate to the purpose for which it is intended. It will be 
easy, however, for those who have the command of a sufficient 
quantity of mercury, to adapt the apparatus to that fluid. As 
an exemplification of the method of using it, in the simplest 
possible case, I shall state the results of the combustion of 
hydrogen gas, 
At the outset of the experiment, there was contained in the 
P p 2 
