101 



the vessels in which the animals were confined, 

 must, by repeated breathing, have become less and 

 less fit for respiration, and was therefore gradually 

 declining from that state in which it is usually in- 

 spired. We have seen, that several of the inferior 

 animals will live in a given quantity of air until its 

 oxygen gas is completely (54. et seq.) consumed : 

 but those of the superior orders do not bear this to- 

 tal privation. Birds die in air confined by lime-wa- 

 ter, before they have consumed two-thirds of its 

 oxygen gas : and a mouse and guinea pig expire 

 when about three-fourths of this gas have disappear- 

 ed, although the carbonic acid be withdrawn *, 

 Spallanzani observes likewise, that birds and quadru- 

 peds consume not more than ^~ of the oxygen gas 

 of the air, and sometimes only 17, 16, or ^, and 

 then die, even although the carbonic acid be remo- 

 ved t Lavoisier found, that by repeatedly with- 

 drawing the animal from the vessel when he be- 

 gan to sicken, and re-introducing him after he 

 had revived, he could be made to consume almost 

 the whole of the oxygenous portion of the air J. la 

 all the foregoing experiments, it may be doubted, 

 whether the same actual diminution in bulk takes 

 place, as would have occurred if the same volume 

 of air had been submitted to successive respirations 

 in the open atmosphere. It is only with the latter 



* Higgins's Minutes of a Society, p. 158? 

 f Memoirs on Respiration, p. 318. 

 J Mem, Acad. 1783. 



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