SO ON TIIE HEAT PRODUCED BY FRICTION. 



the surbase of the Society's Great Room ; where it is also 

 intended to place such other marbles, the produce of the 

 British Empire, as may be presented to them, with refer- 

 ences to each sample, that the public may know whence each 

 kind can be procured." 



VII. 



Inquiries concerning the Heat produced by Friction : by Dr» 

 Haldat, Secretary to the Academy of Nancy*. 



Heat an object k^O much has been done concerning heat in our days by 

 of difficult re- eminent natural philosophers, that the subject would be ex- 

 hausted, if it accommodated itself so easily to experimental 

 research as many others ; and if the fluid, which is pretty 

 generally admitted as the cause of calorific phenomena, 

 could be treated like those elastic fluids, the knowledge of 

 which is at present so far advanced : but, incoercible in the 

 highest degree, and incapable of having either its bulk mea- 

 sured or its weight ascertained, it eludes our research, and 

 this real Proteus escapes into the depths of nature, the mo- 

 ment we attempt to lay hold of it. These properties how- 

 and opinions ever, which seem calculated to render it the despair of phi- 

 on it divided. ] OSO p nerSj nave excited their emulation : but, as they exhi- 

 bit themselves in different points of view, each has adopted 

 for their explanation that hypothesis, which appears to him 

 the most natural, and their opinions are divided. 

 According to The ancients explained the calorific effects, with which 



the ancients an t ^ e y were acquainted, by means of a fluid of extreme sub- 

 element. ., , . , , A . . , . . . . 



tilty and incomparable activity, which gave it the power of 



attacking bodies, and resolving them into their first princi- 

 ples. They ranked this substance among the elements, of 

 Thiscontro- which they composed the universe. This opinion, variously 

 ▼erted by Des modified a t different times, was generally adopted till the 

 age of Descartes; when that great genius, sent to renovate 

 the sphere of science, represented these phenomena as a 

 simple modification of matter, which all bodies were suscep- 



♦ Journal de Physique, vol. LXV, p. 213, 



tible 



