OF COMMON MATTER. 165 



to its power, it would have remained as un- 

 known to us, at this time, as it vyas to Sir Isaac 

 Newton, a century ago. 



Is it not reasonable to suppose, that it is this 

 actual and individual ray, which penetrating 

 bodies the most diaphonous and solid, remains 

 in them in a latent^ invisible, insensible, and 

 uncombined state; and afterwards radiates 

 and issues out of them in a state of combina- 

 tion, manifesting* the phenomena of color and 

 of temperature; and, that it is this ray, which 

 has been so long known under the appellation 

 of latent heat ? 



On an attentive review of the attributes 

 which seem essentially to belong to light, 

 I am led to conclude, that in its nature, it is to- 

 tally and absolutely different from every other 

 species of matter, of which we have any know- 

 ledge. The phenomena which it describes de- 

 cidedly prove, that it is of a quality sui generis. 

 Instead of supposing light to be solid, massy, 

 and impenetrable, I contend, on the contrary, 

 that every phenomenon which it describes, 

 shows that it. is the most fluid, the most subtile, 

 and the most penetrable that can be conceived ; 

 that, instead of being inert and heavy, it is 

 essentially active and imponderable. Instead of 

 moving like the matter belonging to our world, 

 by a power from without, the solar rays tra- 

 verse, with the most incredible velocity, the 



