42 THE PHYSICAL SIGNIFICANCE OF ENTROPY 



different forms, 1 but now that we know precisely that it stands 

 for the growth in the number of complexions we can more easily 

 trace the connection between any of these rather vague state- 

 ments and the present precise definition. As we have in the 

 main reserved physical interpretations to a later section we 

 need here only bear in mind certain general principles of com- 

 parison : 



Any complete summary of the premises necessary for estab- 

 lishing the inevitable growth of the number of complexions of 

 a system is a valid statement of the second law. 



Any general corollary from said growth is a valid statement 

 of the second law. 



When instituting any comparison we must keep in mind also 

 the two principal points of view of regarding any physical problem, 

 namely, the view of it in the aggregate and that which sees it in 

 its constituent parts. 



While we cannot here sharply separate these two points of 

 view, we have on the whole sought to present first those statements 

 which are based on experience and next those based on the atomic 

 theory. 



(1) Growth of entropy is a passage from more to less avail- 

 able energy. By available is here meant energy which 

 we can direct into any required channel. With the growth 

 in the number of complexions we can readily see there 

 is greater inability, on the part of the molecules, for that 

 concerted and co-operative action which is necessary for 

 the putting forth of the energy of a system. 



(2) Growth of entropy is a passage from a concentrated to a 

 distributed condition of energy. Energy originally con- 

 centrated variously in the system is finally scattered uni- 



1 This need cause no surprise, for it is only very recently that the conviction 

 is gaining ground that the Second Law has no independent significance, but that 

 its full content will only he grasped when its roots are sought in the Theorems of 

 the Calculus of Probabilities. 



