2*24 QENERAL CONCLUSIONS. 



finely comminuted sand. But the same degree 

 of heat acting upon an equal weight of oil, wood, 

 or bituminous coal, would produce one hundred 

 times the quantity of light, though of much less 

 intensity. 



That modification of light termed phosphores- 

 cence, is generally the result of a slow combustion. 

 Being produced at very low temperatures, it is 

 both small in quantity, and of low intensity. 



From all the preceding facts and observations 

 it would appear, 



1. That the heat of combustion results from 

 the disengagement of that principle which holds 

 the particles of bodies together. 



2. That the attraction of ponderable matter 

 for caloric is modified by every chemical change 

 which it undergoes, whether of combination or 

 decomposition, contraction or expansion. (See 

 Chapter III.) 



3. That the light of combustion, or flame, results 

 from the ultimate division of ponderable matter 

 by caloric, which is diffused in all directions by 

 radiation with extreme velocity ; and that with- 

 out the volatilization of combustible matter, there 

 could be no artificial light. 



