ON PHYSICO-CHEMICAL METHODS AND PROBLEMS. 9 



that two processes influence each other in the way, for 

 example, that pressure affects the freezing-point of water 

 or the electric current a magnet, the degree of this action 

 upon each other can be directly deduced from the laws 

 of energy. 



If in the explanation of a phenomenon we build it 

 up out of the elements a,b t c,d..., then these elementary 

 processes correspond with a group of transformations in 

 energy which we will designate by a, /?, r, d . . . The 

 principle of energetics states that the sum of a+j3 + Y + 

 d . . . must be constant. The attempted analysis of the 

 phenomenon into a, &, c, d is possible only when it sat- 

 isfies at the same time, under the most varied circum- 

 stances, the above condition. The MAYER- JOULE law 

 contains no more than this. But while it itself therefore 

 gives no positive or complete insight into a phenomenon, 

 it nevertheless renders possible the exclusion of a whole 

 series of false interpretations of our observations. It 

 constitutes, therefore, an indispensable and excellent con- 

 trol of our suppositions. 



This control of our conceptions through the MAYER- 

 JOULE law may be of two kinds. In the one case it will 

 be able to prove that our assumption is wrong, in another 

 that it is incomplete. In so far as it points out in the 

 latter case an as yet undiscovered condition it seems 

 under these circumstances to lead directly to the dis- 

 covery of new facts. 



But even under these conditions we learn from the 

 law of energy only that something is to be sought or to 

 be discovered. What this really is, or what the nature 

 of the fact that is to be. discovered is, can never be learned 

 except through special investigation. We may say in 



