307 



employed for the absorption of carbonic acid, and then a solution of 

 green sulphate of iron, saturated with nitrous gas, to determine the 

 quantity of oxygen that remained. 



In the sixth experiment there were found 9 carbonic acid, and 9 

 oxygen; together 18. 



In the seventh experiment there were found 8 carbonic acid, 10^ 

 oxygen; together 18^. 



In the eighth experiment there were found 65 carbonic acid, and 

 12| oxygen; together 19. 



In the ninth experiment there were found 7 carbonic acid, and 1 1 

 oxygen; together 18. 



So that as one measure of carbonic acid contains just an equal 

 measure of oxygen, the apparent diminution of oxygen in these ex- 

 periments is 2| per cent. 



In the subsequent experiments two mercurial gasometers were em- 

 ployed, so that the hurry of measuring the gas, and inconvenience of 

 retaining the breath, were avoided, and the respiration was conse- 

 quently more natural throughout the whole of each experiment. 



Nevertheless, the result of the ten experiments still showed an ap- 

 parent diminution of 1 per cent. But the eleventh experiment showed 

 no diminution, and is considered by the authors as a standard ex- 

 periment. From this the quantity of oxygen consumed, and of car- 

 bonic acid formed in a minute, is calculated to be 26^ inches, and 

 hence the quantity of solid carbon given off by the lungs, in twenty- 

 four hours, is computed at 10|- ounces troy. 



The person who made these experiments breathes about nineteen 

 times in a minute, and takes about 16^ cubic inches of air at each 

 natural inspiration. 



In the twelfth experiment the same quantity of air was breathed 

 from one of the mercurial gasometers to the other repeatedly during 

 three minutes, and was then found to contain 9^ carbonic acid, 5^ 

 oxygen, and 85 azote per cent. ; so that six parts, in 100 of oxygen, 

 seemed to have disappeared, and some other gas, not absorbed by 

 water, was apparently given off from the lungs. 



The results of the fourteenth experiment were similar, and more 

 remarkable, as the respiration of the same air was continued for a 

 greater length of time : 100 parts contained 10 carbonic acid, 4 oxy- 

 gen, and 86 azote ; so that in this instance there appeared a loss 

 of 7 oxygen, and an equal increase of azote, or of some other gas 

 not absorbable by water. By careful examination, the authors 

 are satisfied that no other gas is present in the residuum but azote ; 

 that the azote itself, though apparently in greater proportion, is in 

 fact unaltered ; and that the difference arises solely from diminution 

 of oxygen when respiration is painfully protracted. 



By the respiration of another person, whose chest was of greater 

 capacity, the same quantity of air as by the former was taken in just 

 one half the time ; but nevertheless very nearly the same proportion 

 of it was found converted into carbonic acid. 



In the succeeding experiment nearly 10,000 cubic inches of air 

 x2 



