RES Pill ATlOtf. 



duced upon the blood by common refpiration may be in fome 

 meafure llltiitrated, by obferving the effects which follow the 

 ufe of the other gafcous bodies. 



Soon after the difcovery of the power which the oxy- 

 genous part of the atmofphere poffefles, of fupporting 

 animal life, feveral trials were made of the effects which 

 would refult from breathing it in an unmixed ftate. The 

 accounts given by thofe who were the fifty efts of thefe trials 

 were various ; Dr. Prieftley, who firft made the experiment, 

 conceived that he felt an agreeable light nefs in the cheft 

 (Obf. on Air, v. ii. p. 162.) ; fome perfons fuppofed that 

 it produced exhilarating effects upon the iyftem, while others 

 imagined that the employment of this gas was followed by 

 urieafinefs and pain about the region of the thorax. Thefe 

 different fehfations muft be attributed, in a great degree, to 

 the effects of imagination ; in part, however, they may be 

 afcribed to the gas which was employed in the earlier period 

 of the pneumatic experiments having been often in an im- 

 pure ftate, mixed with acid, acrid, or metallic particles. A 

 difference in the effects produced by the refpiration of the 

 "as, ought perhaps, in fome degree alfo, to be imputed to 

 the manner in which it was received into the lungs, whether 

 only in fmall quantities, or by deep and laborious infpira- 

 tions, and whether it was employed in a condenled or a 

 rarefied ftate. 



As Dr. Prieftley was the firil perfon who, himfelf, refpired 

 oxygenous gas, fo he was likewiie the firft who obferved 

 the effects which it produced upon animals altogether im- 

 merfed in it. His experiments were performed upon mice ; 

 they decidedlv proved the power which this gas poflefles of 

 fupporting animal life, but no other certain concluiions can 

 be deduced from them. M. Lavoifier afterwards turned his 

 attention to this fubject, and in the experiments upon guinea 

 pigs, to which we have already referred, he noticed with 

 more accuracy the effects refulting from the relpiration of 

 oxygen. He examined the ilate of the internal organs of 

 animals which had been for fome time confined 111 this gas, 

 and he conceived that a degree of rednefs and turgelcence 

 of the veflels was produced, and other effect* which indi- 

 cated that the fanguiferous fyltem had been in a ftate of in- 

 creafed action. (Soc. Roy. de Medicine, 1782, 17S3, 

 p. 576.I There i-, however, reafon to infer, that in this 

 cafe, either the gas cmpljyed was in an impure ftate, or 

 that there were fome circumftances attending the fit nation 

 of the animals, or the manner in which the experiment was 

 conducted, which affected the refults, for the fame philo- 

 fopher, in the fubfequent memoir of 1789, where there ap- 

 pears to have been the greateit attention to accuracy, and 

 where the moft perfect apparatus was employed, forms en- 

 tirely oppofite conclufions. In this paper, we are in- 

 formed, that he confined guinea pigs in pure oxygen, and 

 in mixtures of oxygen and azote, in different proportions, 

 until the former conftituted only one-fifteenth part of the 

 compound. In all thefe cafes, he found that the fame 

 quantity of oxygen was confumed, a circumflance, he ob- 

 ferves, in which refpiration differs remarkably from com- 

 buftion, though, in many refpects, thefe operations are 

 fimilar to each other. The effects produced upon the 

 animals were precifely the fame, whether they were confined 

 in pure oxygen, or in any of the mixtures of it, except 

 that when the proportion of azote was very large, they ex- 

 hibited marks of drowiinefs. The author exprefsly informs 

 us, that neither the temperature nor the circulation were in 

 any refpects affected by the infpiration of pure oxygen for 

 the fpace of feveral days. (Acad, des Sciences, 1789, 

 p. 573-) Thefe experiments muft be confidered as very 



valuable ; there it no reafon to doubt their accuracy, and 

 they may be relied on with more confidence, as the author 

 feems to have had no peculiar theory in view when he per- 

 formed them ; indeed the refults are different from what we 

 might previoufly have expected, and are unfavourable to the 

 analogy which Lavoifier had always endeavoured to eftablilh 

 between refpiration and combuftion. 



We have an account by Dr. Higgins of the refpiration 

 of pure oxygen by the human fubject ; in one experiment, 

 thirty-eight pints of this gas were refpired without inter- 

 ruption. No inconvenience was experienced, a fenfe of 

 warmth was, however, produced in the cheft, and the pulfe 

 was confiderably quickened, (Minutes of a Society, &c. 

 p. 144 - 6. ) Dr. Higgins, in a fecond experiment, breathed 

 a quantity of oxygen under an additional preffure, and by- 

 very full infpirations. He conceived that by thefe means its 

 conlumption was much promoted (ibid. 152.) ; but more 

 numerous and accurate experiments will be required before 

 this inference can be fairly eftablifiied. EfTay on Refpi- 

 ration, p. 139 — 144. 



In the year 1794, Dr. Beddoes publifhcd his experiments 

 upon this fubject. (On Factitious Air, pt. i. p. 13.) 

 They were performed upon rabbits, and the attention wa 

 principally directed to an examination of the ftate of the in- 

 ternal organs of the animal, after it had been fubjected for 

 fome time to the influence of pure oxygen. In detailing 

 the refults, we fee fuch obvious marks of the influence of 

 the author's prc-conceived notions, that our confidence in 

 them is much diminifhed ; and this unfavourable impreffion 

 is ftrengthened by finding that they do not coincide with the 

 reports of other very accurate obfervers. See Bollock on 

 Refpiration, p. 144, et feq. 



Mr. Davy has alfo recorded fome trials, which he made 

 with oxygen gas ; the refults of which, fo far as thev re- 

 gard the chemical changes of the air itfelf, we have noticed 

 in a previous part of this article. Refearches, p. 444. 



Mcflrs. Allen and Pepys made fome experiments on the 

 refpiration of oxygen. The pulfe was raifed about 15 beats 

 in a minute, a gentle glow and perfpiration were produced 

 over the whole body, and nothing elfe remarkable occurred. 

 The refpiration of the gas was continued about ten minutes 

 in thefe trials ; and the effects foon fubfided. We have de- 

 tailed the refults of their obfervations concerning the changes 

 of the air, in that divifion of this article in which the 

 quantity of carbonic acid, produced by breathing, is men- 

 tioned. 



It thus appears that we have no direct proof that the 

 refpiration of oxygen, for a fliort period, is injurious to the 

 animal economy. Whether a much longer ufe of the gas 

 would be hurtful, and what peculiar morbid action or con- 

 dition of parts would be induced, we have no means of de- 

 termining. 



Among the remaining refpirable gafes, that which appears 

 to be the leaft injurious to the living body is the oxyd of 

 azote. This aeriform fluid was firlt discovered by Dr. 

 Prieftley, and was by him fuppofed to be " in the liigheft 

 degree noxious to animals." (Obf. on Air, v. ii. p. jr.) 

 The fociety of Dutch chemifts, who afterwards examined 

 its properties with more accuracy, coincided with Dr. 

 Prieftley, as to its effects upon animal life. (Journal de 

 Phyfique, t. xliii. p. 329.) The experiment was, how- 

 ever, repeated by Mr. Davy, and he difcovered not only 

 that this gas may be refpired for a ihort tune without incon- 

 venience, (four or five minutes,) but that the employment 

 of it is fucceeded by a lingular excitement of the nervous 

 fyftem, which differs from that produced by alcohol and 

 8 opium, 



