$6 ON THE HEAT PRODUCED BY FRICTION. 



the inner box was pretty regularly 3° [5*4°]. Though the 

 communication with surrounding- bodies was alternately in- 

 terrupted and restored, it is to be observed, on comparing 

 heated more this experiment with the first, that, if the quantity of heat 

 were equal, it was iu a third longer time; whence it follows, 

 that in the same time it was a third less. 

 F.xperiiT ent 9. JExp. 9« The electric fluid, as well as caloric, is developed 

 ted* USU a " ky friction, and generally progagated with more facility; and 

 as these two fluids have some analogy to each other, the for- 

 mer may be suspected, to have some influence on the de- 

 velopement of the heat, and to furnish the matter. To ap- 

 preciate this hypothesis, I repeated the preceding experi- 

 ment, insulating the apparatus by nonconductors, and alter- 

 nately establishing its communication with the ground. For 

 this purpose it was placed in a box of very dry deal coated 

 with resin, from every side of which it was kept at the dis- 

 tance of a decimetre [3*9 inches] by pieces of wood baked 

 in an oven, and immersed while hot into boiling gum lac. 

 The whole was placed on an insulating stool with glass feat. 

 Electricity ap- T ne experiment, which continued an hour, was divided into 

 no effect in f° ur e qtfal portions of time, in which, though the commu- 

 the production nication with the earth was alternately interrupted and re- 

 friction. y stored, the quantities of heat appeared equal. In the GO 

 min. the water acquired 6° [10'8°], whence it would appear, 

 that insulation, either by nonconductors of electricity, or by 

 bad conductors of heat, diminishes the quantity of the heat 

 produced by friction. 



Fxp. 10. Exp, 10. Of all the causes suspected to influence the 



An iron wire ^ ■ r % ■ 



compressed by production ot heat in our experiments, none appears more 



repeated powerful, than the condensation of the particles of bodies 



arising from the pressure necessary for the friction. It is to 



this cause too, that Mr. Berthollet has thought fit to ascribe 



it; but as its influence rests solely on theory, I attempted to 



confirm it by experiment. For this purpose I constructed 



a small oak box, capable of containing a cubic decim. [6l 



cub. inches] of water. The four sides were firmly united by 



iron screws. The bottom was closed by a block of oak 3 



dec. [11*8 inches] long, one end of which was rabetted to 



receive the sides, and these were fastened to it likewise by 



screws. The whole was covered with a cement impenetrable 



to 



blows. 



