Atmospheric Air and Oxygen Gas by Respiration . 257 
gasometers as they were filled, which being mixed together, 
for the average gave the following results : 
100 parts of the mixture contained 
8.5 carbonic acid 
12.5 oxygen. 
79 azote. 
100 
Calculation for Carbonic Acid . 
100 : 8.5 : : 3311 : 281.43. 
Consequently 281,43 cubic inches of carbonic acid gas were 
given off in minutes. 
In this experiment we meet with a remarkable fact, viz. that 
as much carbonic acid gas was given off in minutes, as in 
the former experiment in eleven minutes ; so that it appears, 
whenever atmospheric air is taken into the lungs, it returns 
charged with about 8 per cent, carbonic acid. The faster re- 
spiration is performed, the more carbonic acid is given off, and 
consequently the more oxygen consumed : in this instance it 
was given off at the rate of fifty-one cubic inches per minute. 
Thirteenth Experiment. 
We now proceeded to carry on the respiration of common 
air for a much longer period than usual, and of course on a 
much larger quantity. The experiment was made by the 
same operator who had performed all the others, except the 
12th. Eleven mercurial gasometers having been filled, taken 
off, and registered, the operator continued to breathe in the 
12th until a mark was made by his colleague upon the scale 
LI 
MDCCCVIII. 
