352 CALORIFICATION. 



were altogether insensible and invisible, while 

 they subsisted in their elementary and indivi- 

 dual state ;. it was not until they had united 

 with the muriate of silver, that it turned to a 

 black color, and temperature was produced. 



While the attributes of pure light, therefor^, 

 enable us to understand its actual existence, in 

 different bodies, without either exciting sensation 

 or expansion, they lead to an explanation of the 

 various changes which different bodies are found 

 to undergo, in consequence of their union and 

 combination with it, by means of which the 

 various phenomena of color and temperature 

 are produced. 



All the facts which we possess, go to prove, 

 that the solar rays not only remain in different 

 bodies in a latent state ; but that they pass 

 through particular bodies without uniting with 

 them ; they pass through snow, without melt- 

 ing it, they pass through glass, without any 

 sensible increase of temperature. It may, in- 

 deed, be observed in a general way, that the 

 solar rays pass through transparent bodies, 

 without being either arrested by them, or unit- 

 ing with them in any great degree. It, on. the 

 contrary, appears that the color of a body has 

 a considerable influence on them; insomuch, 

 that if bodies of different -colors, placed contir 

 guous to each other, are exposed to the solar 

 rays, the different changes which take place on 



