281 
pheric air were, in the space of three minutes, passed 
eight or ten times through the lungs, until respira- 
tion became extremely laborious, and the operator 
was compelled to desist. On analysing the respired 
air, it was found to contain, in 100 parts, only 5.5 
oxygen, 9.5 carbonic acid, and 85 parts of nitrogen 
gas. In the fifteenth experiment, which occupied, 
also, about three minutes, until the operator became 
quite insensible, the same quantity of air was employ- 
ed, and afforded, by analysis, nearly the same results ; 
for it contained, in 100 parts, four of oxygen, ten of 
carbonic acid, and 86 of nitrogen. In the former 
experiment, we observe, therefore, an increase of six 
parts of nitrogen, and a loss of six parts of oxygen ; 
and in the latter, the oxygen had lost 7 from 21, 
and the nitrogen had gained 7 upon 29 * ; and 
hence it is inferred, that " when," as in these experi- 
ments, " respiration is attended with distressing cir- 
cumstances, there is reason to conclude, that a por- 
tion of oxygen is absorbed f," 
573. To this inference, as far as it regards what 
is here called an absorption of oxygen, we must beg 
leave to object. That the united volumes of oxygen 
and carbonic acid expired, were less than the total 
volume of oxygen inspired, we readily grant ; but 
we deny that this fact affords any adequate proof of 
an absorption of this latter gas. To the chemist, in- 
deed, the mere fact of the disappearance of a portion 
of oxygen may supply sufficient evidence of its ab- 
sorption, in the sense in which he may choose to em- 
* Phil. Trans, USDS, p. CtfO. i Ibid. j). 260. 
