RESPIRATION. 



though, in the latter cafe, the quantity confumed appeared 

 to be lefs. Chemical Rcfearches, p. 434. 



This abforption of nitrogen in refpiration appeared to 

 be confirmed by other experiments. It was obferved by 

 Dr. Henderfon, in breathing a portion of air repeatedly 

 from and into a gafometer. (Nicholfon's Journal, vol. viii. 

 p. 40.) And it feemed likewife to be eltablifhed by 

 the experiments of Pfaff. Nicholfon's Journal, vol. xii. 



p. 249. 



Thefe experiments, however, are not free from fallacy, 

 particularly thofe where the fame quantity of air was re- 

 peatedly breathed ; for, as Mr. Ellis has juftly obferved, 

 (Inquiry on Vegetation, Refpiration, &c. p. 114.) the 

 refpiration, as it proceeds, becomes more difficult and la- 

 borious, and is at length terminated by a feeble expiration, 

 in confequence of which the due proportion of air is not 

 thrown from the lungs. There appears, therefore, a dimi- 

 nution ; and accordingly it is ftated by Pfaff, that the di- 

 minution and the lofs of nitrogen is always the greater, the 

 longer the air is refpired. There can be little doubt that 

 the apparent diminution arifes from this caufe ; and accord- 

 ingly, in the experiments of Allen and Pepys, in which this 

 fource of error is avoided, there is no apparent confumption 

 of nitrogen. The fame refult is itated to h3ve been ob- 

 tained in the laft experiments of Lavoifier and Seguin, 

 " there being neither any difengagement nor abforption of 

 nitrogen gas during the refpiration." (Mem. de l'Acad. 

 des Sciences, 1789, p. 374-) F rom . the experiments of 

 Vauquelin, Spallanzani, and Ellis (Inquiry, &c. p. 87, 88.), 

 it alfo appears that there is no fenfible confumption of ni- 

 trogen, by the refpiration of the lower orders of animals, 

 while there is the ufual confumption of oxygen, and forma- 

 tien of carbonic acid. 



Meflrs. Allen and Pepys, from fome experiments (Phil. 

 Tranf. 1809), inferred, that there is even an evolution of 

 nitrogen in refpiration. They obferved this, liril, in the 

 refpiration of oxygen gas ; in one experiment, where 3000 

 cubic inches of oxygen had palled through the lungs, 62 

 cubic inches of nitrogen being found in the full 260 cubic 

 inches expired, though the gas originally contained only 

 fix cubic inches in this quantity ; and in the next 562 cubic 

 inches, 56 cubic inches were found, though this quantity, 

 before it was refpired, contained only 14 ; and a fimilar evo- 



lution of nitrogen was obferved in the repeated refpiration 

 of the fame quantity of oxygen, an equivalent quantity of 

 oxygen difappearing. Much ot this lofs of nitrogen may, 

 as they obferve, be afcribed to the intermixture of the 

 refidual air in the lungs ; but from comparing the capacity 

 of the lungs with the quantity of nitrogen evolved, they 

 found more of it to be evolved than could be derived from 

 this fource ; and were therefore led to the concluiion, that 

 where oxygen gas is refpired, a portion of nitrogen is given 

 otf from the blood. This conclufion appeared to be con- 

 firmed by the refults of experiments on a guinea pig, con- 

 fined in a quantity of atmoipheric air. In one experiment, 

 at the end of an hour and twelve minutes, the inereafe of 

 nitrogen in the air was more than equal to the cubic con- 

 tents of the body of the animal. In the refpiration of a 

 mixture of oxygen and nitrogen gafes, a fimilar evolution 

 of nitrogen, and difappearance of an equivalent portion of 

 oxygen, was obferved ; but not in the refpiration ef atmo- 

 fpheric air. 



Three thoufand four hundred and twenty cubic inches of 

 air, confuting of 2.5 azote, and 97.5 oxygen in 100 parts, 

 were breathed for 7' 25" : the expired air meafured 3362, 

 therefore the deficiency was 58. The expired air was 

 received in 13 fucceffive portions ; of which N° I. con- 

 tained, in 100 parts, 9 carbonic acid, 25 azote, 66 oxygen. 

 N 3 13. coniiiled of 12.5 carbonic acid, 5.5 azote, and 

 82 oxygen, in 100 parts. When all the thirteen were mixed, 

 the compoiition was 12.0 carbonic acid, 6.5 azote, 81.5 

 oxygen. The whole quantity of carbonic acid formed 

 in this experiment was 396.78 cubic inches. The quantity 

 of azote taken into the lungs was 85.50 ; the quantity ex- 

 pired, 263.10: the inereafe is, therefore, 177.60. (Phil. 

 Tranf. 180S.) In another experiment of a fimilar nature, 

 2668 of gas were breathed backwards and forwards for 13 

 minutes : it contained 4 per cent, of azote. There was a 

 deficiency of 1 24 cubic inches in the expired air, the largeft 

 ever obferved by thefe gentlemen. In this experiment there 

 was an inereafe of 105.08 of azote. If the azote emitted 

 from the lungs in thefe experiments be fuppofed to have 

 been contained in thofe organs before the experiments 

 began, it will make their contents more confiderable than 

 we had before calculated. The following is a fummary of 

 four experiments on this fubje£t : 



Barom. 



N°i. 

 2. 



3- 

 4- 



3°-3 



3°-'5 



29.4 



Therm. 



53° 

 70 

 70 

 5 1 



gas, 81c. 

 infpired 



3260 



3420 



3 '3° 

 2668 



Gas 



expired. 



3 l 93 

 33 fi2 

 3060 



2544 



Deficiency. Time. 



The particulars of two analogous experiments on the guinea pig 



Barom. Therm. 



N° 



29.05 



57° 

 56 



Oxygen, &c. 



iniprerl. 



1060 



8l6 



Gas after 



the Ex|>. 



1056 



814 



4 

 2 



67 



58 



70 

 124 



follow : 



Carii. acid 

 tunned. 

 106. 

 78.91 



9' 20" 



7 25 



8 45 

 13 o 



Quantity re- 



ipired in a 



Minute. 



348 

 461 



357 

 205 



Azote 



1 M ihred. 



I 10 



177 

 187 

 105 



arb. aci'I pc 



Minute. 



I.4S 



I. II 



Time. 



Oxygen 

 milling. 



54.07 

 36.20 



Inferred n*- 



parity nf 



Lunps. 



141 

 225 

 236 



!33 



AzOCe 



.-.dried. 

 50.12 

 34.20 



Philof. Tranf. 1808 and 1809. 



The conclufion that the nitrogen, found in thefe cafes, 

 is derived from the refidual air of the lungs, is fo probable, 

 that it would at once be admitted, were it not that tin- 

 quantity evolved is fo large, as apparently 10 preclude its 

 admiffion. Mr. Ellis, however, in fome very ingenious 

 observations on this quellion, has pointed out a fource of 

 fallacy to which there is every probability that the reiult 

 is to be afcribed. It is, that the air in the lungs may be 



in a condenfed Hate, or occupy lefs volume than it would 

 do when it is expired ; and hence, in the refpiration of oxygen, 

 a larger portion of nitrogen derived from the refidual air in 

 the lungs may be given out than could lie interred from their 

 known capacity. The ttructure of the lungs is cellular, 

 and the air is diiTulcd in cells of an immenfe number, and 

 at the fame time of diameters extremely fmall. If their 

 cells have any degree of contractile power, this may pro- 

 H 2 duce 



