QN THE HEAT PRODUCED BY FRICTION. $\ 



tible of, and which consists principally in the extreme atte- 

 nuation of their constituent molecules. Philosophers then 

 were divided into two classes, they who made the calorific 

 phenomena to depend on the action of a substance of a pe- 

 culiar nature, and which has been called matter of tire, or 

 caloric ; and those who supposed them to depend on a cer- 

 tain mode of being of the particles of bodies. The former The ancient 

 opinion, which was most generally adopted, had become P mion P ren " 

 almost universal, since the phenomena of heat, having been 

 more thoroughly studied, had been presented as dependant 

 on a substance that might be transferred from one substance 

 to another, in the same way as a fluid is poured from vessel 

 to vessel ; that might be combined with substances, and the 

 combination of which produces remarkable changes; and 

 lastly that might be set free from its combinations, and 

 determined to others by the same means as are employed to 

 produce similar changes in all substances. There seemed 

 to remain no doubt of the substantiality of caloric, and phi- 

 losophers seemed emploj^ed only in making better known a 

 substance, the existence of which appeared to them suffici- 

 ently demonstrated, when count Rumford, dear to his till opposed bj 

 country by his beautiful discoveries, and not less dear to hu- count Rum- 

 manity by his philanthropic, labours, began to excite fresh 

 doubts of the existence of caloric, and again place the phe- 

 nomena ascribed to it among the modifications of which sub- 

 stances are susceptible. 



The property of friction to develope heat had long been Heat produced 

 known ; but this fact, so deserving of attention, had not b y friction, 

 yet been subjected to proper examination. Count Rum- 

 ford, having made a blunt borer turn in a brass cylinder 

 immersed in water, obtained from it a quantity of heat so 

 disproportionate to any thing the brass could have lost, that 

 he thought himself warranted to infer, that this heat could 

 not have arisen from any condensation of the metal, but 

 must have been produced by the agitation of the particles 

 communicated to the water in the manner of sound. This 

 conclusion however, which tends entirely to overthrow the 

 theory of caloric, has not appeared to be legitimately deduced 

 from the facts; and Mr. Berthollet has refuted it in a note 



to 



