Life of Count Rumford. 479 



and which of course would have been capable of melting 

 six and a half pounds of ice, or of causing near five 

 pounds of ice-cold water to boil) could have been fur- 

 nished by so inconsiderable a quantity of metallic dust, 

 and this merely in consequence of a change of its ca- 

 pacity for Heat ? " The weight of the metallic dust was 

 no more than ^{ part of that of the cylinder. The 

 dust, then, would need to have parted with 948 degrees 

 of heat to have raised the temperature of the cylinder 

 by a single degree. Consequently the dust must have 

 yielded 66,360 degrees of the virtue called latent heat, in 

 order to have produced the effects which were reached 

 by the experiment ! 



This experiment having been repeated with the ut- 

 most care several times, the Count satisfied himself that 

 the heat which, as he prefers to say, had been excited, 

 rather than generated, by them, was not furnished at the 

 expense of the latent heat or combined caloric of the metal. 



The Count's second experiment was for the purpose 

 of ascertaining whether the air, which had free access to 

 the inside and bottom of the bore in the cylinder, did or 

 did not contribute to the generation of the heat. He 

 therefore excluded the external air by means of a piston 

 fitted to the mouth of the bore. The test proved 

 that there was no diminution of the quantity of the heat 

 excited. 



A slight doubt suggesting itself whether some part 

 of the heat produced might not be occasioned by the 

 friction of the piston, fitted as it was, air tight, by 

 means of leather collars, the Count had recourse to 

 a third experiment. His apparatus was enclosed in a 

 strong deal box, which was filled with cold water, 

 and suspended between the muzzle of the cannon 



