304 COMETS. 



constitute the purest and most active species of 

 matter which exists, or of which we have any 

 knowledge ; that as they proceed from the 

 sun, they are perpetually combining with the 

 opake and atmospheric matter with which they 

 come in contact, producing the various pheno- 

 mena of Comets and meteors, lightning, culi- 

 nary and atmospheric heat. That it is by the 

 chemical union of this matter of light with 

 atmospheric matter, that heat, or fire, is first ge- 

 nerated ; that this pure matter of light, or solar 

 rays, I conceive, constitute the caloric of the 

 present chemists ; that it is by the combination 

 of this light, or caloric, as they call it, not by the 

 decomposition of it, that sensible heat, or fire, is 

 produced, possessing properties in its com- 

 bined state, very different from what it did in 

 its simple one ; in its pure and uncombined 

 state it is analogous to what is absurdly 

 called latent heat ; in its compound, or com- 

 bined state, it is called sensible heat, or fire. 



