RESPIRATION. 



were dead, and fome alive. ( Phyfico-Theol. p. 8.) Spal- 

 lanzani never found any animalcules produced in vegetable 

 infufions in vacuo. When infufions, containing animal- 

 cules, were placed under the exhaufled receiver, they lived 

 many days, but perifhed fooner than others of the fame kind 

 in the open air. (Trails, p. i, 2.) Hooke found that 

 the eels of vinegar died in a very fhort time, when the fluid 

 was put into a phial, and (topped clofe. (Microgr. p. 217.) 

 Scheele inclofed leeches in a phial, with a little air : they 

 IKed only two days, although they would have lived as 

 many years, if the water had communicated with the air. 

 Mr. Ray remarked, that fillies cannot live in water without 

 air : they will live in a veffel of water with a narrow mouth 

 for months or years ; but if the vcifel be Hopped, fo as 

 wholly to exclude the air, or interrupt its communication 

 with the water, they will be fuddenly fufl'ocatcd. (Wif- 

 dom of God in the Creation, p. 81.) Dr. Prieltley confined 

 feveral fmall fifties in a veffel, containing three pints of rain 

 water, that had been previoufly well boiled to deprive it of 

 its air, and they lived only between three and four hours. 

 (Oof. on Air, vol. v. p. 139.) Mr. Davy introduced a 

 large thornback into a jar, containing three cubic inches of 

 water, which had been deprived of its air by diilillation 

 through mercury : he was very quiet for four minutes and 

 a half, but then began to move about, and, in feven mi- 

 nutes, had fallen on his back, but itill continued to move 

 his gills. In eleven minutes, he was motionlefs, and when 

 taken out, after thirteen minutes, he did not recover. 

 (Refearches, p. 367.) Amphibious animals, likewife, can- 

 not live without air, but its deprivation is not immediately 

 fatal to them. Frogs and toads bear the pump for two or 

 three hours, and a frog recovered on expofure to the air, 

 after remaining in vacuo feemingly dead for eleven hours. 

 Hence we fee, that to all thefe animals, whether inhabiting 

 the air or the water, a conftant renewal of frelh air is re- 

 quired, while the aftions of life continue. What then are 

 the changes produced on atmofpheric air, by thefe feveral 

 clafles of animal beings, whereby it is rendered fo eilential 

 to the maintenance of vital action ? 



For the firft and moft accurate knowledge we poflefs 

 concerning the changes which the air fuffers by the refpira- 

 tion of iniefts, we are indebted to the labours of Scheele, 

 who placed bees and flies in phials with air, and found the 

 oxygen removed, and carbonic acid gas fubftituted in its 

 place. (On Air and Fire, p. 148 — 155.) M. Vauquelin 

 examined the fubjeft more accurately. The experimeats of 

 this excellent chemift were made on the grafshopper (gryllus 

 viridiffimus ) , which is defcribed as having 24 itigmata, or 

 breathing pores, ranged parallel with, but exterior to, two 

 white lines, extending longitudinally on the middle of the 

 belly. In this infecf they are of an oval form, but they 

 vary in fliape in different infefts ; and it is chiefly by their 

 mediation, that the changes on the air are effected. A fe- 

 male grafshopper was placed in eight cubic inches of atmo- 

 fpheric air: it breathed from 50 to 55 times in a minute, 

 and lived 36 hours. The air had not fenlibly diminifhed in 

 volume, but, when examined by the teft of lime-water, car- 

 bonic acid was detected ; and after this was removed, the 

 remaining air itill extinguifhed a taper. When many grafs- 

 hoppers were put at the fame time into a given bulk of air, 

 and left till they died, the oxygen gas was nearly, but not 

 entirely, confumed ; and phofphorus melted in the refidual 

 air, when heat was applied, but burned very little. A 

 male grafshopper lived 18 hours in fix cubic inches of oxy- 

 gen gas : its refpiration was opprellive, and it breathed from 

 60 to 65 times in a minute. The volume of air was not 

 fenfibly diminifhed, but it loft T £- ths of its bulk by being 



wafhed in an alkaline folution. (Ann. de Chimie, torn, xii.) 

 From thefe fails we learn, that infedts, by their refpiration, 

 confume the oxygenous portion of the air ; that carbonic 

 acid is, at the fame time, produced ; and that, when all 

 the oxygen gas has difappeared, the animal no longer fur- 

 vives. 



M. Huber found, that bees very fpeedily die, when put 

 into nitrogen gas ; but that they furvive in a clofe veflel of 

 atmofpheric air, until almoit the lall atom of its oxygen gas 

 is confumed. (Mem. fur la Germination, &c.) We 

 likewife confined, fays Mr. Ellis, a number of flies in a 

 flafk, containing nine cubic inches of air, and then inverted 

 it into a tall glafs of mercury. By the third day, the fifes 

 were all dead, and the mercury had rifen confiderably into 

 the neck of the flafk. The refidual air loft about -roV^s 

 by agitation with lime-water, and the remainder did not 

 fuffer the fmalleit diminution by being placed in contact 

 for two days with phofphorus. Thefe refults, therefore, 

 agree with thofe obtained by Vauquelin, and prove farther, 

 that, by the refpiration of flies, the whole of the oxygen 

 gas of the air difappears, and that a bulk of carbonic acid 

 nearly equal thereto is formed. The fmall diminution of 

 bulk, alio, which the air fuffcred, is to be regarded as a 

 neceflary confequence attending the converfion of oxygen 

 gas into carbonic acid, and which, as it accounts for the 

 whole lofs the air experienced, feems to authorize the con- 

 clnfion, that while the oxygen gas had, in this cafe, com- 

 pletely difappeared, the nitrogenous portion of the air con- 

 tinued undiminilhed, and probably unaltered. 



The refearches of Spallanzani and Reaumur further 

 fhewed, that the ova of infefts cannot be evolved without 

 air ; that the larvx cannot exift without it, nor undergo 

 their change to the pupa Hate ; and that it is equally ef- 

 fential to the transformation of the latter into the perfect: in- 

 fedt. Rapports de l'Air avec les etres Organifes, torn. i. 

 Memoires pour fervir a l'Hift. des Infedles, torn. ii. 



M. Vauquelin proceeded next to inveiligate the changes 

 produced on the air by the refpiration of the vermes clafs 

 of animals. He confined a red flug in twelve cubic inches 

 of atmofpheric air, and it lived 48 hours. The air was not 

 fenlibly diminifhed in volume, but it extinguifhed candles, 

 and copioufly precipitated lime from water. Phofphorus 

 was melted in this air, but did not fuffer any combuition or 

 change of colour. A fnail (helix pomatia) was next put 

 into twelve cubic inches of atmofpheric air, and lived four 

 days. The oxygen gas entirely difappeared ; for the refi- 

 dual nitrogen gas contained not an atom of vital air, and, 

 oonfequently, phofphorus did not burn in it at all : it con- 

 tained, however, carbonic acid. Slugs and fnails, there- 

 fore, require frefh air while in an adtive Hate, the oxygen 

 gas of which, by the fundi ion of their refpiratory organs, 

 is made completely to difappear, and a quantity of carbonic 

 acid is produced, while the nitrogenous portion of the air 

 remains unaltered : and when thefe changes are effected, 

 living action fpeedily comes to an end. So exactly do thefe 

 animals ieparate the oxygenous from the nitrogenous portion 

 of the atmofphere, that M. Vauquelin fuggefts the employ- 

 ment of them for eudiometrical purpofes. Ann. de Chimie, 

 loc. cit. 



The numerous experiments of Spallanzani on worms, 

 fnails, flugs, &c. confirm the ftatements of Vauquelin in all 

 eflential points. (Memoirs on Refpiration. Rapports de 

 l'Air.) He alfo made experiments on mufcles, and feveral ma- 

 rine teftacea : they confumed the air of water in which 

 they were confined, and the water then attracted more, fo 

 as to confume all the oxygen when a fmall quantity of air 

 was confined in contadt with it. 



We 



