S60 ON THE CONSEHTATION OF FORCE. 



capable of work. The connections between the various 

 natural forces which modern physics has revealed, are so 

 extraordinarily numerous that several entirely different 

 methods may be discovered for each of these problems. 



I have stated how we are accustomed to measure 

 mechanical work, and how the equivalent in work of heat 

 may be found. The equivalent in work of chemical 

 processes is again measured by the heat which they pro- 

 duce. By similar relations, the equivalent in work of the 

 other natural forces may be expressed in terms of mechani- 

 cal work. 



If, now, a certain quantity of mechanical work is lost, 

 there is obtained, as experiments made with the object of 

 determining this point show, an equivalent quantity of 

 heat, or, instead of this, of chemical force ; and, conversely, 

 when heat is lost, we gain an equivalent quantity of 

 chemical or mechanical force ; and, again, when chemical 

 force disappears, an equivalent of heat or work ; so that 

 in all these interchanges between various inorganic natural 

 forces working force may indeed disappear in one form, 

 but then it reappears in exactly equivalent quantity in 

 some other form ; it is thus neither increased nor dimi- 

 nished, but always remains in exactly the same quantity. 

 We shall subsequently see that the same law holds good 

 also for processes in organic nature, so far as the facts 

 have been tested. 



It follows thence that the total quantity of all the forces 

 capable of work m the whole universe remains eternal 

 and unchanged throughout all their changes. All change 

 in nature amounts to this, that force can change its form 

 and locality without its quantity being changed. The 

 universe possesses, once for all, a store of force which is 

 not altered by any change of phenomena, can neither be 

 increased nor diminished, and which maintains any change 

 which takes place on it. 



