84 Chemistry. [Lecture 26. 



say it is a fallacious way of judging of the loss 

 of heat by our senses. It is very clear, that 

 when bodies receive caloric in the usual manner, 

 they retain or part with it in a sensible manner, 

 except in the case of combination, or latent ca- 

 loric. We may cause a body not inflammable 

 to retain heat longer by surrounding it with 

 bodies of a looser texture ; but whatever pains 

 we take the body will cool in time, and the 

 caloric will communicate itself to the surround- 

 ing matter : but such is the nature of combus- 

 tible bodies, that, when heated to a certain de- 

 gree in the air, they not only become hot, but 

 by proper management they may be heated to 

 any degree, and the heat which is thus generated 

 may be communicated to other bodies without 

 any loss of heat to the combustible bodies : they 

 are in general also luminous ; hence their uses 

 in chemistry and the arts. While the stream of 

 heat and light flows from them, they are con- 

 sumed or changed into a different matter, which 

 cools or heats in the usual manner, and is no 

 longer combustible. 



Some combustible substances have been 

 thought exceptions to this, as spirit of wine 

 highly rectified. To a rude observer it seems 

 to be totally consumed during its inflammation, 

 and he is apt to conclude that the spirit of wine 

 is not converted into a matter no longer com- 

 bustible *. The reason of the phenomenon is, 

 * This was even Boerhaave's opinion. 



