XViii INTRODUCTION . 



mind, in taking a view of the different theories 

 that have been advanced in order to account for 

 the generation of animal heat, is continually 

 confused by their variety and discrepancy. 



It would be a waste of time to enumerate the 

 various hypotheses that have been formed from 

 the age of HIPPOCRATES to our own. The first 

 rational view was that stated by BLACK, in 

 which he regards the respiratory function as 

 producing changes upon the inspired air analo- 

 gous to those attendant on combustion. This 

 idea was eagerly adopted by LAVOISIER, and 

 was subsequently modified by him. The objec- 

 tion to the original view of BLACK is, that if the 

 disengagement of caloric take place in the lungs, 

 these would be consumed, or would become 

 much warmer, from the nature of their office, 

 than any other part of the body. This conse- 

 quence has appeared so obvious, that no one, 

 since the time of BLACK, has dared to support 

 the same opinion. The experiments of CRAW- 

 FORD appeared to remove every difficulty which 

 the subject presented. They seemed to prove that 

 the capacity of arterial blood for caloric is su- 

 perior to that of the venous. This circumstance 



