ANIMAL HEAT. 237 



the loss of caloric which occurs from the inferior temperature of 

 the medium in which we live, is compensated. The fresh supply 

 is taken in at the lungs, and brought into use in the minute vessels. 



Dr. Crawford's theory afterwards fell into some discredit. 



All experiments upon the capacities of bodies for heat are 

 very delicate and liable to error; and the conclusions of Dr. 

 Crawford on this point have been denied by Drs. Delaroche and 

 Berard, with respect to gases, and by Dr. Davy, with respect 

 to arterial and venous blood. a 



The experiments of these chemists have led them to believe 

 the difference of capacity less than Crawford supposed, and in- 

 sufficient to account for animal temperature. With respect to 

 the gases, Dr. Bostock 5 justly remarks, that the objection does 

 not apply more to the doctrine of animal heat, than to the theory 

 of combustion in general. Whenever carbon unites with oxy- 

 gen, and carbonic acid is produced, caloric is liberated, whether 

 in fermentation, or combustion, &c. With respect to the blood, 

 he declares, and Dr. Bostock's reputation for accuracy and 

 soundness in chemical matters is not little, that, "after attentively 

 perusing the experiments of Crawford, and comparing them with 

 those that have been performed with a contrary result, he con- 

 fesses that the balance of evidence appears to him to be greatly in 

 favour of the former, though he acknowledges that they are of 

 so delicate a nature as not to be entitled to implicit confidence, 

 and that it would be extremely desirable to have them carefully 

 repeated." 



If, however, it were true that Dr. Crawford's statement of the 

 relative capacities is incorrect, still the fact of heat being 

 necessarily evolved on the disappearance of oxygen in the lungs, 

 and the appearance of carbonic acid, provided they unite there, 

 would stand unaffected, and we should only be obliged to adopt 

 the doctrine of Mayow, that the lungs are the focus of the heat 

 of the body. This was relinquished, on the objection that the 

 lungs should then be hotter than other parts. But, when we con- 

 sider that the blood is incessantly streaming to the lungs from all 

 parts and again leaving them, we may, I think, presume that the 

 blood will always convey away their heat, and prevent their tem- 

 perature from rising above that of other parts. The heat of all 

 parts is, caeteris paribus, commensurate with the quantity of blood 

 circulating through them, and this is equally explicable on the 



8 PhUos. Trans. 1814. b 1. C. vol. ii. p. 263. 



