422 Messrs. Allen and Pepys on Respiration. 
some circumstances occurred to prevent us- from discovering 
what change the azote had experienced : this point was, how- 
ever, decided by the following experiment. 
Experiment 7, Hydrogen and Oxygen. 
Having mixed hydrogen and oxygen gases in such propor- 
tion as that the oxygen should rather exceed the quantity 
contained in atmospheric air, we placed the same animal in 
the glass A with 66 cubic inches of atmospheric air, 250 cubic 
inches of the mixture were admitted into gasometer B, from 
the large water gasometer, and gradually passed through the 
glass A into gasometer C, during fifteen minutes. The pig 
did not appear uneasy, and the respired gas measured 250 in 
C : a portion of this was preserved for examination, which we 
shall call No. 1 . 
250 cubic inches more of the mixture were admitted into B, 
and gradually passed, as before, during thirteen minutes ; it 
measured 250 in C ; and a portion No. 2 was preserved for 
examination. 
The animal did not seem to suffer any inconvenience. 250 
cubic inches more of the mixture were admitted into B, and 
gradually passed, as before, through A into C during seven- 
teen minutes. The animal now become quite sleepy, but did 
not appear to suffer any thing. He was taken out at the end 
of forty-minutes. 
At the close of the experiment, the remains of the mixture, 
which had stood about an hour in the large water gasometer, 
being examined was found to contain 22 per cent, of oxygen and 
no carbonic acid ; of the residual 78 parts, 20 were mixed with 
10 of oxygen, which had been previously found to contain 
