CALORIFICATION. 349 



insensible. While the solar rays subsist in this 

 pure and elementary condition, they are as 

 different from what they are in a state of com- 

 bination, as the attributes of different com- 

 pounds are different from the elementary parts 

 out of which they were formed, as different as 

 the neutral salt is different from the acid and 

 the alkali, as ice is different from water, as 

 color from light, and as figure itself from ex- 

 tension simply: insomuch, - that the definition 

 that would apply to the accident, would be al- 

 together irrelevant and improper for the ele- 

 ment. It is in manifest contradiction of this 

 truth, that the doctrine of latent heat, as 

 invented by Dr. BLACK, and as it is handed 

 down to us at this day is founded. Accord- 

 ing to this hypothesis, fire, or the matter of 

 heat, as it is called, is supposed capable of 

 existing in two separate states ; in the one, it 

 excites the sensation of heat to animated beings 

 in general, and causes expansion to take place 

 in common matter in particular. In the othef 

 state, it neither excites sensation nor produces 

 expansion; in the former, it subsists simple 

 and elementary, in the latter, it is united and 

 neutralised (as it were) with th bodies in 

 which it is involved ; insomuch, that whenever 

 combustion, or the evolution of fire, takes 

 place, it is supposed to arise from the decom- 

 position which pure fire has undergone, that 



