on air found in the pleura , &c. 503 
The results of these experiments seem to warrant the con- 
clusion, that in the preceding case the carbonic acid gas found, 
was not derived from the surface of the pleura by secretion 
or exhalation, but from the respired air through the ulcerated 
opening. And with this remark I shall dismiss the case of 
Pneumato-thorax, the consideration of which, as a medical 
subject, would not be appropriate to this place. 
The power exhibited by the pleura in the preceding in- 
stances of absorbing gases, and the manner in which it exer- 
cised that power, in a greater degree, on one air than on 
another, and that in no ratio to their solubility in water, 
appeared to me so interesting and novel, that I was induced 
to prosecute the subject a little farther. With the same 
apparatus, I made similar experiments on the admission of 
three other gases into the pleura of dogs, viz. hydrogene, 
nitrous oxide, and nitrous gas, the results of which I shall 
briefly describe. 
About 20 cubic inches of a mixture, consisting of 57.5 parts 
carbonic acid gas, and 42.3 hydrogene were admitted into the 
left pleura of a dog, in the manner, and with the precaution 
already noticed. The health of the animal was not appa- 
rently affected. At the end of two days, about 30 cubic 
inches of a mixture, consisting of 44.5 azote, and 55.5 nitrous 
gas, were passed into the right pleura. Immediately the 
dog’s breathing became quick and short, but not laborious. 
It refused to eat, and expired in the evening, at the end of 
five hours from the time that the air was introduced. The 
next morning the body was examined. About six cubic inches 
of air were collected from the left pleura, consisting, appa- 
rently, of 12 carbonic acid gas and 88 azote. After the 
