on air found in the pleura , &c. 513 
On the 23rd of May, on examining the body of a soldier, 
aged 27, who had died of chronic dysentery, complicated 
with an ulcer of the larynx, the cellular membrane in both 
mediastina was found vesicular, and distended with air. The 
vesicles were burst under water, and a half cubic inch of air 
collected, which w 7 as found to consist of 
7 oxygene, 
4, carbonic acid gas, 
89 azote. 
The surrounding parts were carefully examined, particularly 
the trachea, lungs, and oesophagus; but no passage could be 
detected through which air could have entered the medias- 
tina ; nor could any air be forced into them by distending the 
lungs by means of a double bellows. Probably the oxygene 
found was extraneous, and was derived partly from common 
air adhering to the surface of the cellular membrane, and 
partly by penetrating through the delicate vesicles during the 
preparatory dissection, when they were exposed to the at- 
mosphere for half an hour at least. 
On the 2nd of June, on examining the body of a soldier, 
aged 3 6, who had died of tubercular consumption, I found 
air vesicles on the surface of the lungs, similar to those de- 
scribed by Dr. Baillie in his Morbid Anatomy,* and consi- 
dered by him as formed by the secretion of air, and not by 
the extravasation of air under the pleura, agreeably to the 
opinion lately advanced by Dr. Laennec.-J- The air con- 
tained in the vesicles, in this instance, consisted of 5 parts 
azote and 1 part carbonic acid. The quantity of air collected 
* Fifth edit. p. 80. 
f A Treatise on the Diseases of the Chest, &c. p. 89. 
3 U 
MDCCCXXIII. 
