512 Dr. Davy's observations and experiments 
on the right side, and the fluctuation of a fluid in the left 
cavity of the chest is very distinct on any sudden motion of 
the body, I indulge the hope, if his lung be not tuberculated, 
that he will eventually recover completely. 
The air collected in the bladder amounted to 25 cubic 
inches. Examined by means of lime-water and phosphorus, 
it was found to consist of 93 azotic gas and 7 carbonic acid 
gas : thus, in composition, proving almost exactly the same 
as the air found in the fatal case described in the preceding 
part of this Paper ; and, as in that instance, it had not the least 
offensive smell. 
Whether the origin of the air in this instance was the same 
as in the former, it is not easy at present to decide ; most 
probably it was, considering the nature of the preceding dis- 
ease, and the sudden supervention of the symptoms of pneu- 
mato-thorax after a violent fit of coughing ; when it is likely 
the pleura was ruptured, and a kind of valvular communica- 
tion established between its cavity and the aspera arteria, 
permitting air to enter, and preventing its return. 
Relative to the secretion of air in the human body, and 
its effusion into closed cavities, I have ventured in this 
Paper to make some remarks, and to express an opinion in 
favour of such an occurrence. Very recently I have met 
with two fatal cases, in which shortly after death, and before 
there was the least indication of putrefaction having com- 
menced, I detected air, apparently secreted and accumulated 
in sufficient quantity to admit of its being collected and exa- 
mined. As the subject is quite novel, I trust a brief notice 
of these two instances may prove not unacceptable to the 
Royal Society. 
