279 
loss whatever would have appeared in that which 
yielded the most. In experiments, where so many 
causes concur to render the apparent bulk of acid 
less than it ought to be, and less than that of the 
oxygen lost, it is surely more reasonable to give 
greater credit to those results which indicate an 
equality of volume between these gases, than to 
those which declare a difference ; since the former 
not only go with the latter to the fullest extent, but, 
pursuing the same track, have actually gone beyond 
them, and thereby reached a point, which the 
others have been unable to gain. In fact, to prefer 
those experiments, which indicate a difference, to 
those which prove an equality of volume, would 
be not only to halt in our progress, but to make a 
retrograde movement, and thus to suffer a negative 
inference to outweigh a positive proof. 
570. Even Messrs Allen and Pepys, however, 
whose experiments so clearly demonstrate the equa- 
lity of bulk in these two gases, in every case of natu- 
ral respiration, have been led, by the results of other 
experiments, to suppose, that, " when respiration 
is attended with distressing circumstances, there is 
reason to conclude that a portion of oxygen is ab- 
sorbed *. In the deduction of such an inference, re- 
gard seems to have been paid to mechanical and che- 
mical considerations alone, and little or no attention 
given to the structure and properties of the living in- 
struments by which respiration is performed. We 
before endeavoured to impress the necessity of at- 
* Phil. Trans. 1808, p. 280. 
