264 Dr. Davy on 
to be so large, post mortem. On what this depended, it is not 
easy to say ; it is matter for conjecture, and seems to require 
farther investigation. Messrs. Allen and Pepys, after a 
forced expiration, found air from the lungs to contain as 
much as 9.5 per cent, carbonic acid gas ;* and, in different 
instances that I have examined the air contained in the lungs 
a few hours after death, I have found the proportion of car- 
bonic acid gas to vary from 8 to 12 per cent. ; thus, in a 
fatal case of empyema, the air procured from one lung that 
was sound, consisted of 
8.3 carbonic acid gas, 
5.0 oxygene, 
86.7 azote : 
that from the other lung, which was condensed, and as it 
were hepatized, of 
12.5 carbonic acid gas, 
2.0 oxygene, 
8 5.5 azote : 
whilst in another case, in which one lung was sound, and 
the other abounded in minute cavities full of pus, air from 
the sound lung consisted of 
12.2 carbonic acid gas, 
3.0 oxygene, 
84.8 azote. 
Had the proportion of carbonic acid gas, in the instance 
under consideration, been within these limits, the expla- 
nation would have been attended with little difficulty ; 
Philosophical Transactions, 1808. 
