i7? 



^ 3. Geometrical-physical interpretation of the capillary-constant f ot* 

 a special molecular scheme ; the surface energy appears then as continuous 

 function of the orientation, and yet produces a polyhedron as equili- 

 brium jiijure. The function of the "vicinal planes" . 



To throw tliis point into strong relief, the point which is our only 

 purpose here, we make use of an exceedingly simplified molecular 

 scheme : 



1. a two-dimensional scheme instead of a three dimensional one ; 



2. we leave the thermal motion 'out Of account and accordingly 

 we simply seek the molecular groupings with the smallest potential 

 energy ; 



3. the molecules may be scpiares, which tend to adjust their sides 

 close against each other. (We might as well use circular molecules 

 with four points of valency). 



Let an enormously large number of such square molecules be 

 given. We seek that grouping at which the maximum "saturation" 

 of the molecules has set \n. Complete saturation, at which all the 

 molecule sides are occupied, is of course impossible — at least the 



Fig. 1. 



extreme edge of the "crystal" consists of unsaturate molecule sides. 

 Let in tig. 1 the line ABODE .. . be a porlioii of the "real" edge, 

 the line ACE... a portion of the "apparent" edge. Let us [)ut : 



ABC = L<J and AC — Ls 

 then : 



Art = {cos n -\- sin (f) Lis. 



The maximum saturation has evidently been reached for that 



grouping of the molecules, for which the length of the real edge, i.e.: 



VA<j = :EkLs (2) 



