RESPIRATION, AKD ANIMALIZATIOIS:. 



• the course of these experiments is carbonic acid ; a very minute propor- 

 . tion of which appears also to be almost always contained in the atmos- 

 pheric air, though altogether a foreign material, probably eliminated from 

 the decomposition of animal and vegetable bodies that is perpetually 

 taking place, and certainly unnecessary to healthful respirationo 



The general result of these experiments was as follows ; the natural in^^ 

 spirations were about twenty-six or twenty-seven in a minute ; thirteen 

 cubic inches of air were in every instance taken in, and about twelve and 

 three-quarters thrown out by the expiration that succeeded. 



The atmospheric or inspired air contained in the thirteen cubic inches, 

 -^nine and a half of nitrogene, three and four-tenths of oxygene, and one- 

 tenth of an inch of carbonic acid. The twelve inches and three-quarters 

 of returned air contained nine and three-tenths of nitrogene, two and two- 

 tenths of oxygene, and one and two-tenths of carbonic acid. 



This inhalation, however, varies in persons of different sized chests 

 from 26 to 32 cubic inches, at a temperature of 65° ; but these, by the 

 heat of the lungs, and saturated with moisture, become forty or forty-one 

 cubic inches. 



Taking, therefore, forty cubic inches as the quantity of air equally in- 

 haled and exhaled about twenty times in a minute, it will follow that a 

 full-grown person respires 48,000 cubic inches in an hour, or 1,152,000 

 cubic inches in the course of a day ; a quantity equal to about 79 hogs* 

 heads. 



A similar train of experiments has more lately been pursued by Messrs^ 

 Allen and Pepys, and will be found fully detailed in the Transactions of 

 the Royal Society for 1808. They confirm the preceding proportions, 

 excepting in the retention of nitrogene ; this substance having been found 

 by Messrs. Allen and Pepys to have been returned, in every respiration, 

 in the precise proportion in which it was received. It is highly probable, 

 however, that the diet of these two sets of ingenious experimenters had 

 not previously consisted of the same proportion of animal and vegeta- 

 ble materials ; and that the blood in the former instance was less charged 

 with nitrogene than in the latter ; which would at once account for the 

 difference. 



Upon Sir Humphry Davy's experiments, however, the quantity of nitro- 

 gene received by the lungs is very inconsiderable, not amounting to more 

 than two-tenths of a cubic inch in an inspiration. And omitting the con- 

 sideration of this gas, as also that of caloric, on account of the unsettled 

 state of the question, respiration, from this view of the subject, consists 

 merely in the act of receiving oxygene, and throwing out carbonic acid 

 gas ; the lungs imbibing and communicating to the system not less than 

 32.4 cubic inches of the former, and parting with not less than 26.5 of 

 the latter, every minute. So that, taking the gravity of carbonic acid gas, 

 as calculated by Lavoisier, eleven oimces of solid carbon or charcoal are 

 emitted from the lungs every twenty-four hours.* 



The whole of the theory and some of the supposed facts here advanced 5 

 however, have of late been very considerably disputed by Mr. Elhs, in his 

 Inquiry into the Changes induced on Atmospheric Air by the Germina^ 

 tion of Seeds. He concurs with Messrs. Allen and Pepys, in ascertain- 

 ing that precisely the same quantity of nitrogene is expired as is inspired ; 

 but he objects to their conclusion, that the whole of any constituent eh- 



Phil, Trans. 1808. part ii, §49; 



