Theory of Surface Forces. 523 



parallel to the surface of the capillary layer) I have found*, 

 the potential function of the forces of cohesion being 



p ' 



J r 



and 



&1_ ~ '$TTf\\dh) \*f 



s _. 1 r/ rfV v+ V2 i 



The hydrostatic pressure being, in every direction, the 

 difference between the thermic pressure 6 and the cohesion, 

 we have 



*>.--»-{^ + 6V/(S)'}- ' • M 



and therefore 



1 /dV\ 2 /o \ 



^-P^^rfKdh)- •■:■•; (22) 



Now the pressures p± and ^> 2 are respectively the maximal 

 and minimal value of the hydrostatic pressure in any direc- 

 tion in the considered point and the equation (22) shows 

 therefore that : — 



The departure from the law of Pascal in a point of the 

 capillary layer is proportional to the square of the intensity of 

 the force of cohesion. 



Differentiating the equation (22), p x being a constant, 

 we find : 



__dp2_J_dVd 2 V . 



dh ~ 2tt/ dh dli 2 ^ - 



Now we have found [see above, equation (6)] 



X 7U?=^-> X > • • • ( 6 ) 



where /ju is the thermodynamic potential for the considered 

 point in the capillary layer and fi ± its value in the liquid- 

 and vapour-phase. We have therefore 



dp 2 1 dY , . 



-M^&^dh^-ti (24) 



* Phil. Mag. for Dec. 1906, p. 564. 



