386 PHILOSOPHY OF ZOOLOGY. 
of ice*.” The quantity of heat evolved during the m- 
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, im 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 +. 
Two hypotheses have been devised to account for the: 
origin of animal heat. The first is that of the justly ce- 
lebrated Dr Biacx. 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 m 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 eompared 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, + Annals of Phil. vol. ii. p. 27. 
