ABSTRACT
About a decade ago, Kralchevsky [18] showed that a surface shear term should be added to the Laplace equation due to Boruvka and Neumann to attain the same degree of generality by means of the thermodynamic approach as by the mechanical approach. Evidently, choosing the thermodynamic route, all Laplace equations, including Eq. (4) above and the even more general one derived by Kralchevsky [18] (see also Ref. [19]), result from optimizing the free energy of an interface plus portions of the adjacent bulk phases. Hence, a Laplace equation is the very condition which makes the first variation of the overall free energy vanish upon varying the position of the interface in the direction of its normal.
