14 An Inquiry concerning 



as the capacity of the body to receive and retain heat, 

 directly, and as its conducting power, inversely. 



The bottles were suspended to the balance by silver 

 wires about two inches long, with hooks at the ends of 

 them ; and, in removing and changing the bottles, I 

 took care not to touch the glass. I likewise avoided 

 upon all occasions, and particularly in the cold room, 

 coming near the balance with my breath, or touching it, 

 or any part of the apparatus, with my naked hands. 



Having determined that water does not acquire or lose 

 any weight upon being changed from a state of fluidity 

 to that of ice, and vice versa, I shall now take my final 

 leave of a subject which has long occupied me, and 

 which has cost me much pains and trouble ; being fully 

 convinced, from the results of the above-mentioned ex- 

 periments, that if heat be in fact a substance, or matter, 

 a fluid sui generis, as has been supposed, which, 

 passing from one body to another, and being accumu- 

 lated, is the immediate cause of the phenomena we ob- 

 serve in heated bodies, of which, however, I cannot 

 help entertaining doubts, it must be something so 

 infinitely rare, even in its most condensed state, as to 

 baffle all our attempts to discover its gravity. And if 

 the opinion which has been adopted by many of our 

 ablest philosophers, that heat is nothing more than an 

 intestine vibratory motion of the constituent parts of 

 heated bodies, should be well founded, it is clear that 

 the weights of bodies can in no wise be affected by such 

 motion. 



It is, no doubt, upon the supposition that heat is a 

 substance distinct from the heated body, and which is 

 accumulated in it, that all the experiments which have 

 been undertaken with a view to determine the weight 



