CALORIFICATION. 363 



meates and penetrates the pores of which the 

 most solid substance is composed, expanding 

 and devellating the whole into parts, and like 

 the baseless fabric of a vision leaves not a 

 wreck behind. It is, I may say, owing to the 

 warfare of opposite elements, uniting and fight- 

 ing together, that the different materials of 

 which fire is constituted, lose the identity, 

 which each separately possessed. So far, 

 therefore, from lire being a simple, elementary 

 body, it is far more reasonable to suppose, that 

 it is one which is compounded and factitious 

 and that it bears the same relation to light and 

 opakc matter, as the prismatic colors to atmos- 

 phere and light ; the opake matter, becoming 

 the pabulum to light; and light the pabu- 

 lum to opake matter, the result of which is the 

 generation of fire ; fire, therefore, neither in- 

 heres in any part of the materials of which the 

 world is composed ; nor in the pure solar 

 rays, the immediate and proximate cause, ap- 

 pears to consist in the chemical union and com- 



from the bottom to the top ; when the air, however, which the re- 

 ceiver contains, becomes exhausted, the column of smoke is sus- 

 pended, and as it becomes heavier than the medium which it has 

 displaced, (at the same time that it has lost its elastic power, 

 from the fire which it contained,) it becomes heavy and sinks 

 to the bottom. Fire may, therefore, be considered heavy 

 with relation to the matter of light, but light with relation to 

 all other bodies. 



