38(1 PHILOSOPHY OF ZOOLOGY. 



of ice V The quantity of heat evolved during the in- 

 flammation of any particular part, is probably much greater 

 than is generally supposed. .Dr THOMSON found that a 

 small inflamed spot in his right groin, gave out, in the 

 course of four days, a quantity of heat sufficient to have 

 heated seven wine pints of water, from 40 to 212. Yet 

 the temperature was not sensibly less than that of the rest 

 of the body at the end of the experiment, when the inflam- 

 mation had ceased f . 



Two hypotheses have been devised to account for the 

 origin of animal heat. The first is that of the justly ce- 

 lebrated Dr BLACK. He supposed that the specific heat 

 of oxygen gas was greater than that of carbonic acid gas, 

 and consequently, when the former was converted into the 

 latter in the lungs, a quantity of latent caloric would be 

 disengaged, sufficient to heat the parts in contact, more 

 especially the blood, which, by its circulation, would 

 likewise communicate its high temperature to the distant 

 parts of the body. As the lungs, however, are not warmer 

 than the neighbouring viscera, it was supposed that they 

 were kept cool by the evaporation of the pulmonary va- 

 pour. When the quantity of oxygen consumed in respira- 

 tion is compared with the whole of the azote, and the 

 remaining unchanged portion of the oxygen of the air, 

 which have their temperature raised forty or fifty de- 

 grees, when the quantity of heated vapour given off by 

 the lungs and the skin is considered, when we like- 

 wise estimate the portion of heat abstracted from the 

 body by contact and radiation ; we clearly perceive, that 

 all the heat which the oxygen consumed can impart, (sup- 

 posing the inference respecting its specific heat to be just,) 



Phil. Trans. 1792, p. 218, f Annals of Phil. vol. ii. p, 27. 



