Messrs. Allen and Pepys on Respiration. 413 
poured into the trough E, so as to rise to a level with the top 
of the mahogany stand, we placed a Guinea pig upon it, with 
the bell-glass over him, and as its edges were immersed in 
quicksilver, the animal was completely confined in atmos- 
pheric air : we found that his body occupied the space of 39 
cubic inches, which deducted from the cubic contents of the 
glass A, left 55 cubic inches for the air confined with the 
pig, to which must be added 5 more for that contained in the 
tube C. 
First Experiment with Atmospheric Air. 
The pig was placed upon the stand, and the apparatus 
arranged as represented in the plate: 250 cubic inches of 
atmospheric air were admitted into the mercurial gasometer 
communicating with B : the gasometer communicating with 
C was quite empty, the apparatus being tried was found per- 
fectly air tight, and the whole quantity of air 310 cubic inches. 
The cocks H and I being opened, gentle pressure was 
made upon the glass of gasometer B, so as to cause the air to 
pass through A, which consequently drove an equal portion 
through the tube C into the empty gasometer ; a quarter of an 
hour was employed in passing the gas, which measured ex- 
actly 250 cubic inches in C, so that there was no alteration of 
volume ; the cocks H and I were now closed, and the respired 
air being examined by the usual methods, 100 parts were 
found to contain 
5 carbonic acid 
16 oxygen 
79 azote 
100 
MDCCCIX. 3 H 
