i 



H. Hehnholtz on the Interaction of Natui^al Forces, 201 



mechanical work only eighteen per cent of the heat generated 

 h}^ the fuel. 



From a similar investigation of all the otlier known physical 

 and chemical processes, we arrive at the conclusion, that nature, 

 as a whole, possesses a store of force which cannot in any way 

 he either increased or diminished, and that therefore the quan- 

 tity of force in nature is just as eternal and unalterable as the 

 quantity of matter. Expressed in this form, I have named the 

 general law ''The Principle of the Conservation of Force." 



We cannot create mechanical force, but we may help ourselves 

 from the general storehouse of nature. The brook and the wind, 

 which drive our mills, the forest and the coal-bed, which supply 

 our steam-engines and warm our rooms, are to us the bearers of 

 a small portion of the great natural supply which we draw upon 

 for our purposes, and the actions of Avhich we can apply as we 

 think fit. The possessor of a mill claims the gravity of the de- 

 scending rivulet, or the living force of the moving wind, as his 

 possession. These portions of the store of nature are what give 

 his property its chief value. 



Further, from the fact that no portion of force can be abso- 

 lutely lost, it does not follow that a portion may not be inappli- 

 cable to human purposes. In this respect the inferences drawn 

 by William Tliomson from the law of Carnot are of importance. 

 This law, which was discovered by Carnot during his endeavors 

 to ascertain the relations between heat and mechanical force, 



which, however, by no means belongs to the necessary conse- 

 quences of the conservation of force, and which Clausius was 

 ihe first to modify in such a manner that it no longer contradicted 

 the above general law, — expresses a certain relation between 

 the compressibility, the capacity for heat, and the expansion by 

 ^eat, of all bodied. It is not yet considered as actually proved, 

 tut some remarkable deductions having been drawn from it and 

 afterwards proved to be facts by experiment, it has attained 

 therel)y a great degree of probability. Besides the mathematical 

 form in which the law was first expressed by Carnot, we can 

 gi^^e it the following more general expression:— *' Only when 

 teat passes from a warmer to a colder body, and even then only 

 partially, can it be converted into mechanical work." 



The heat of a body which we cannot cool farther, cannot be 

 changed into another form of force; into the electric or chemical 

 force, for example. Thus in our steam-engines we convert a 

 portion of the heat of the glowing coal into work, by permitting 

 It to pass to the less warui'water of the boiler. If, however, all 

 the bodies in nature had the same temperature, it would be im- 

 possible to convert any portion of their heat into mechanical 

 work. According to this we can divide the total force store of 

 the universe into "two parts, one of which is heat, and must con- 



SECOND SERIES, VOL. XXIV, NO. 71. SEPT., 1857. 



