PREFACE ix 



coincidence occurs, as is very frequently the case, the necessary 



double numbering is given, e.g. Equation (a) [g]. Here 



a is the author's number, g is Gibbs' number. The same 

 method is followed in the reference numbers of equations given 

 in the text. 



The notation employed by Gibbs for the principal thermo- 

 dynamic quantities has been retained in general, the few devia- 

 tions from this procedure being indicated at the appropriate 

 places in the text. In order to facilitate comparison with the 

 usage of a number of other writers on thermodynamics, a 

 comparison Table of Symbols is given (Article A). This 

 Article also contains a comparison Table of the names as- 

 signed to the principal thermodynamic quantities by Gibbs 

 and a number of other writers. 



Of the Articles contained in this Volume, all, with the excep- 

 tion of A and C, refer to Paper III of Volume I of the Collected 

 Works, i.e., the paper on The Equilibrium of Heterogeneous Sub- 

 stances, and Papers (Sections) V, VII, VIII, and IX. Article 

 D deals with the general thermodynamic system of Gibbs, as 

 expounded in Gibbs, I, pp. 55-144; 419^24. Special parts of 

 this section of Paper III are further discussed and illustrated in 

 Articles E, F, G, and H, whilst Articles I, J, K, L and M deal 

 with the remaining portions of Paper III (and Sections V, VII, 

 VIII and IX) of Volume I of the Collected Works. 



Readers of this Volume will find in Volume II of the Com- 

 mentary a general survey of Gibbs' thermodynamical methods 

 and results (by A. Haas), as well as an account of certain sub- 

 sequent work (by P. S. Epstein). 



In the present Volume we have not dealt with such later 

 developments as the Nernst Heat Theorem and related topics, 

 since a proper understanding of the present state of this subject 

 requires a considerable knowledge of Statistical Mechanics. 

 These matters are dealt with by P. S. Epstein in Volume II of 

 the Commentary. 



Besides the condensed survey of Gibbs' thermodynamical 

 methods and results contained in Volume II of the Commentary, 

 students will find an excellent account in the book of E. A. 

 Guggenheim, entitled Modern Thermodynamics by the Methods 

 of Willard Gibbs (Methuen & Co., London, 1933). 



