1820.] Mathematical Principles of Chemical Philosophy. 143 



phical Transactions for 1798, Part I. p. 86. Having noticed the 

 great degree of heat which is excited by turning or boring large 

 masses of metal, this philosopher was led to inquire, " Is the 

 heat furnished by the metallic chips which are separated by the 

 borer from the sohd mass of metal 1 If this be the case, then, 

 according to the modern doctrines of latent heat and of caloric, 

 the capacity for heat of the parts so reduced to chips ought not 

 only to be changed, but the change undergone by them should 

 be sufficient to account for all the heat produced ; but the 

 capacity is not changed. From hence it is evident that the heat 

 produced could not possibly have been furnished at the expense 

 of the latent heat of the chips." 



In order to try the experiment in the most satisfactory manner, 

 a cyUndrical hole, 3'7 inches in diameter and 7*2 in depth, was 

 bored in a cylinder of brass 7^- inches in diameter, and 9-jag.long; 

 this cyhnder was turned by means of powerful machinery upon 

 its axis ; while a solid blunt steel cylinder, having nearly the 

 same diameter as the hole, was pressed upon the bottom of it, 

 by means of a screw, with a force equal to about 10,0001b. 

 avoir. The cylinder soon became very hot, and the heat conti- 

 nued without diminution during the whole time of the experi- 

 ment. The cylinder was next enclosed in a wooden box filled 

 with water, the content of which was 2-^ wine gallons ; the 

 water was prevented entering the cylinder, by means of a tight 

 collar of leather ; in 2-i- hours the water was in a state of ebulli- 

 tion; and after the experiment was concluded, between 4000 

 and 5000 grs. of brass dust were worn off by the friction. He 

 now adds, " In reasoning upon this subject, we must not forget 

 to consider the most remarkable circumstance, that the source 

 of heat generated by friction in these experiments appears 

 evidently to be inexhaustible. It is hardly necessary to add, 

 that any thing which an insulated body or system of bodies can 

 continue to lumish without limitation, cannot possibly be a 

 material substance ; and it appears to me to be extremely diffi- 

 cult, if not impossible, to form any distinct idea of any thing 

 capable of being excited and communicated in the manner heat 

 was excited and communicated in these experiments, except it 

 be motion." In the commencement of this reasoning, an 

 assumption is made, which has been particularly unfortunate for 

 science ; viz. that if heat being an elastic fluid be evolved by the 

 compression of solid matter, the capacity of that solid for heat 

 must be diminished in proportion to the quantity which has been 

 separated. The whole quantity of heat contained in the solid is 

 doubtless diminished, but why is the capacity to be changed ? 

 Now the specific or latent heat of a body is the whob quantity 

 of caloric which it contains, at any given temperature, and the 

 capacity for heat is measured by the quantity that is absorbed or 

 evolved during the passage of the body from any one to any 

 other given temperature, very near to each other. It, therefore, 



