On Elasticity » 145 



be driven out of the mass by the. operation ; and I belitve 

 in the present state of our knowledge that few will be in- 

 clined to dispute it. As it is, however, of some importance 

 to establish this point, I shall, before proceeding fuvther 

 with the main argument, briefly point out some of the cir- 

 cumstances which seem to prove the escape of caloric : Tlie 

 bar becomes heated by the operation, and where heat ma- 

 nifests itself, it nuist be either passing off from or into the 

 body. If the capacity of the body be diminished at the 

 same time, and the chemical properties of the body remain 

 unaltered, which in the instance under consideration is the 

 case, how can we mistake the direction in which the caloric 

 moves ? 



I am aware of what has been advanced respecting friction 

 by men whose names stand high in the philosophical world, 

 and that hammering is a species of friction ; but names and 

 opinions should never be substituted for facts j for, if it be 

 true, which I deny not, but maintain that hammering is a 

 species of friction, it would not be difficult to show that it 

 is equally true that friction is a species of hammering. But 

 if by hammering such a quantity of heat may be driven 

 from the interior to the surface of a bar as will produce 

 effects similar to those of a combustible body in a state of 

 ignition, the caloric in this as in every other case must be 

 something else than mere motion. It is subject to certain 

 laws of motion, like every other species of matter 5 and like 

 every other species of matter too, when moved from its 

 place by any force, puttiug other matter in the spa'e or 

 spaces before occupied by it, it must take up another resi- 

 dence. To produce an accumulation of heat by hammer- 

 ing, repeated and a long continued succession of strokes 

 are not necessary : proportion the mass 01 metal to the im- 

 pulse to be applied, and with one stroke you may produce 

 such a heat as will make the part of the metal vvhere it is 

 accunudated visdile in the dark — hot enough to set tire to 

 a combustible body. 



It may here be also observed that heat is propagated even 

 through what is usually called a vacuum, that is, thiougli 

 spaces absolutely void of every other species of matter, 

 ■which could not possibly take placv.; if caU;nc were not sub- 

 stantial ; tor motion is a non-cniitv when we attempt to con- 

 .ceive of it' as distinct I'rom matter — it is an accident ol mat- 

 ter, and when we speak of its existence the presence of 

 matter is always implied. 'I'his is an argument in proof of 

 the substantiality of caloric which no powers of argument 

 can overturn ; for, whatever semblance of truth may attach 



Vol. 22. No. 66. July 1S05. K tu 



