PRESENT FUNDAMENTAL CONCEPTIONS OF PIIYSICS. 491 



of the tube and shavings could not with propriety be attributed to the 

 diminution of the heat capacity; the less so, as Rumford, by his own 

 tests in drilling-, succeeded in bringing nearly 10 pounds of water to the 

 boiling-point after a continuous friction of two and a half hours. To 

 what extent would the heat capacity of the metal subjected to the fric- 

 tional test have had to be diminished to explain this heating of the water! 

 At the same time it had been demonstrated, as previously mentioned, 

 that the heat capacity of the substances subjected to the friction had not 

 perceptibly diminished. Whence then came these enormous quantities 

 of heat? How is it that they show themselves incessantly as long as 

 friction continues? Can it be that bodies contain caloric, accumulations 

 in inexhaustible quantities, or could these be called forth by friction 

 simply? Could a substance be created by friction, or rather by the 

 cause of it, that is, by a moving force"? That would mean that the im- 

 material effect of force was transformed into caloric! Is this conceiv- 

 able? Because it is inconceivable, Rumford supposed that heat was in 

 essence a motion of the constituent particles of bodies, which had been 

 increased by friction in such a manner that the visible motion of the 

 body subjected to friction had been transformed into the invisible motion 

 of their ultimate particles — that is, of their molecules, and thus mani- 

 fested itself as an increased temperature. It is very clear from this, 

 that as long as friction, i. e. the visible motion of the body subjected 

 to it, continues, so long there can and must appear free heat, which 

 means increased molecular motion in the bodies iu question. 



Only one year later (1799) Davy took sides with Rumford. Davy, by 

 means of a clockwork, had two pieces of ice rubbed on each other ; they 

 were placed under a nearly air-tight glass globe which was constantly 

 kept at a temperature below zero; they melted at the frictional planes. 

 As they melted only at these, and since any influx of heat to the 

 ice was carefully guarded against, the cause of the melting could only 

 be the heat called forth by the friction. It was known even at that 

 time that the specific heat of water was double that of ice, so it 

 could not be presumed that this was a case of diminution of the heat 

 capacity by friction. There was, on the contrary, the proof of its being 

 doubled. In addition, it was known from previous calori metrical re- 

 searches, which had also originated with Black (1700-17G5), that in 

 order to melt one kilogram of ice, greater quantities of heat would be 

 required (79 heat-units). The question then arose, whence originated the 

 quantities of heat required to melt those frictional surfaces of ice? 

 "Caloric" could not introduce itself either from within or without, 

 owing to the excellent arrangement, and yet there was heat present. 

 It could only originate in the transformation of the visible exterior 

 frictional motion of the muss, into the invisible, interior molecular one. 

 After these experiments of Davy the idea of the existence of an inde- 

 pendent caloric could no longer be entertained. 



