. 278 
by an animal subsisting wholly upon vegetables, no 
other change takes place in it than the substitution 
of a certain portion of carbonic acid gas for an 
equal volume of oxygen *." 
569. It is, we conceive, impossible to refuse entire 
credit to the accuracy of these experiments, or to the 
legitimacy of the conclusions drawn from them, so 
far as relates to the chemical changes actually indu- 
ced on the air ; and these conclusions we have seen, 
also, to be supported by the experiments of many 
other able chemists, and by the results afforded in 
the exercise of the respiratory function in almost 
every other class of animals. We grant, however, that 
other chemists, equally able, whose experiments we 
have already detailed (122.) have concluded, that, 
because the carbonic acid obtained did not quite 
equal in bulk the oxygen lost, a portion of this lat- 
ter gas was absorbed in the lungs. In some late ex- 
periments on the respiration of rabbits, and of Guinea 
pigs, M. Berthollet adopts this opinion. In these 
experiments, the bulk of acid gas produced did not 
quite equal that of oxygen which disappeared,- so 
that the loss of oxygen appeared to vary from 1.07 to 
4.09 per cent f. These two results, therefore, differ 
more from each other, than the former does from 
that of Allen and Pepys ; and as this difference may 
be conceived to indicate error in that experiment 
which afforded the least acid, it may reasonably be in- 
ferred, that, had greater correctness been attained, no 
* Phil. Trans. 1809, P- 427- 
t Mem. d'Arcueil, t. ii. p. 46 1. 
