WHAT BECOMES OF LIGHT. 103 



caloric from one to the other, attended in most 

 cases, with a change of temperature. 



But if the ultimate atoms of ponderable matter 

 be identical with those of light, and the latter 

 consist of seven primitive rays, as supposed by 

 Newton, it follows that the fifty-four elements 

 enumerated by chemists are not simple bodies^ 

 but compounds of two or more primitive elements, 

 as before suggested ; or, that if light consist of 

 only three primitive rays, united with caloric^ 

 everything in nature must be composed of four 

 elements. Nor is it possible to admit with New- 

 ton, that the blue and indigo are distinct primitive 

 rays ; while it is certain that all the known varie- 

 ties of colour may be produced by combinations 

 of red, yellow, and Hue ; which, as Brewster has 

 shewn, overlap each other, and extend quite 

 across the spectrum. 



What then becomes of the enormous quan- 

 tities of light perpetually radiated throughout 

 the solar system ? This is doubtless one of the 

 most curious, important, and comprehensive pro- 

 blems in the whole range of physics, and deserves 

 the profoundest attention of philosophers. Thus 

 much is certain, that if light be matter, it cannot 

 be annihilated, any more than the great fountains 

 from which it emanates ; that whatever falls upon 

 the earth, and is not reflected or radiated from it 

 into surrounding space, must combine with, and 

 become a constituent portion of, its surface ; that 

 certain rays produce specific chemical and vital 



