Theory of Surface Forces. 137 



The pressures in the homogeneous phases we call resp. 

 pi and p v or p 1 and p 2 . The specific volume of these phases 

 we represent by v Y and v 2 . 



Upon the whole we have the following significations : 



f 



f = Thickness of the capillary layer ; dh = differential of f, or 

 > 



dA=f. 



1 

 S = Surface of the plane capillary layer per unit of mass. 



R x and R 2 = Radii of the two spheres which limit the spherical 

 capillary layer ; R 2 > Ji x . 



R = l 2 ; S = Collective surface of the spheres with 



radius R, the total mass of the spherical capillary 

 layers being unity. We call S the surface of the 

 spherical capillary layer per unit of mass. 

 v = Specific volume of the capillary layer or total volume of 

 the capillary lay ers of equal curvature per unit of mass. 



= p = Mean value of the density of the capillary layer. 



p 1 or pi =■■ Hydrostatic pressure of the homogeneous liquid 



phase. 

 p 2 or p v — Hydrostatic pressure of the homogeneous vapour 



phase. 

 v l = Spec, volume of the liquid phase ; p { = its density. 

 v 2 = Spec, volume of the vapour phase ; /o 2 = its density. 



i> 2 — vi = u ; p = P 1 ~TP* ; y= pressure of the theoretical 



isotherm. 



1 f 2 pi P2 V 2 — Pl V l 



p — - I p'dv = Mean value of the pressure =- — — — ^ — ; 



u Ji < # V2 1 



r = latent heat of vaporization. 



n= r—pu. 



e, and e 2 = resp. the energy of the liquid and vapour phase. 



Thus : ri=€ 2 — e v 

 Vl and t/o= resp. the entropy of the liquid and vapour phase. 



Thus: r=T(rj 2 - Vl ). 

 fM X and /x 2 = resp. the thermodynamic potentials, 

 e and 7)= resp. the energy and entropy of the capillary layer 



per unit of mass. 



■ . _2H 



R K = Radius o£ the equation of Kelvin: />i — pi— -jr • 



