CONTENTS vii 



SECTION D 



PAOK 



(1) The gradual development of the idea that entropy depends on proba- 



bility or number of complexions 37 



Why it is difficult to conceive of entropy. Origin and first definition 

 due to CLAUSIUS; some formulas for it available from the start. Its 

 statistical character early appreciated; lack of precise physical mean- 

 ing; its dependence on probability; number of complexions a synonym 

 for probablity 37 



(2) PLANCK'S formula for the relation between entropy and the number 



of complexions 40 



Certain features of entropy 41 



SECTION E 



Equivalents of change of entropy in more or less general physical terms 



or aspects 41 



Not surprising that its many forms should have been a reproach to the 



second law 41 



General principles for comparing these aspects. Various aspects of 

 growth of entropy from the experiential and from the atomic point 

 of view 42 



SECTION F 



More precise and specific statements of the second law 44 



General arrangement and the principles for comparison 44 



Ten different statements of the law and comments thereon 44 



PART II 



ANALYTICAL EXPRESSIONS FOR A FEW PRIMARY RELATIONS 



Procedure followed 48 



SECTION A 



MaxwelVs law of distribution of molecular velocities 48 



Outline of proof, illustration, and consequences of this law 48 



