MATTER, LIVING FORCE AND HEAT. 9 



cannot be heated if it be rendered hard and elastic, so as to 

 transfer the living force of the hammer to the anvil. 



" The general rule, then, is, that wherever living force is 

 apparently destroyed, whether by percussion, friction, or 

 any similar means, an exact equivalent of heat is restored. 

 The converse of this proposition is also true, namely, that 

 heat cannot be lessened or absorbed without the production 

 of living force, or its equivalent attraction through space. 

 Thus, for instance, in the steam-engine it will be found that 

 the power gained is at the expense of the heat of the fire, — 

 that is, that the heat occasioned by the combustion of the 

 coal would have been greater had a part of it not been 

 absorbed in producing and maintaining the living force of 

 the machinery. It is right, however, to observe that this 

 has not as yet been demonstrated by experiment. But 

 there is no room to doubt that experiment would prove the 

 correctness of what I have said ; for I have myself proved 

 that a conversion of heat into living force takes place in the 

 expansion of air, which is analogous to the expansion of 

 steam in the cylinder of the steam-engine. But the most 

 convincing proof of the conversion of heat into living force 

 has been derived from my experiments with the electro- 

 magnetic engine, a machine composed of magnets and bars 

 of iron set in motion by an electrical battery. I have proved 

 by actual experiment that, in exact proportion to the 

 force with which this machine works, heat is abstracted 

 from the electrical battery. You see, therefore, that living 

 force may be converted into heat, and that heat may be 

 converted into living force, or its equivalent attraction 

 through space. All three, therefore — namely, heat, living 

 force, and attraction through space (to which I might also 

 add light, were it consistent with the scope of the present 



