THE INFLUENCE OF SURFACES OF DISCONTI- 

 NUITY UPON THE EQUILIBRIUM OF HET- 

 EROGENEOUS MASSES. THEORY 

 OF CAPILLARITY 



[Gibbs, I, pp. 219-331; 331-337] 



JAMES RICE 



I. Introductory Remarks 



This part of Gibbs' work can be broadly divided into two por- 

 tions; the first of these, and much the longer of the two, deals 

 with surfaces of discontinuity between fluid masses, while the 

 second consists of a brief treatment of liquid films and surfaces 

 of discontinuity between solids and liquids. The first portion 

 itself falls broadly into three parts, one of which, after formulat- 

 ing the general conditions of equilibrium in a surface phase 

 between fluids, derives the famous "adsorption law" (a name 

 not actually employed by Gibbs) and treats briefly the thermal 

 and mechanical processes in such surface phases; another deals 

 with the stability of surfaces of discontinuity; and the third 

 part is concerned with the conditions relating to the formation 

 of new phases and new surfaces of discontinuity. In addition, a 

 few pages of the succeeding section on Electromotive Force are 

 devoted to electrocapillarity, a commentary on which naturally 

 belongs to this portion of the present volume. 



1 . The Surface of Discontinuity and the Dividing Surface 



As Gibbs points out in the first paragraph of this section, the 

 basic fact which necessitates a generalization of the results 

 obtained in the preceding parts is the difference between the 

 environment of a molecule situated well within a homogeneous 

 mass and that of a molecule in the non-homogeneous region 

 which separates two such homogeneous masses. In the sub- 



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