510 



Dr. G. Bakker on the 



to the walls of the vessel, are twofold the surface-tension H o£ 

 the theory of Laplace. (Fig. 2 presents a part of the liquid 

 film of fig. 1 on an enlarged scale.) 



Vapour. 



Fig. 2. 

 B, 



Jjionid 



Vapour 



If the film is thick enough we have between the capillary 

 layers AB and A^ liquid, while we have between A and B 

 as well between A 1 and B x a gradual transition of the 

 density. Above E>! as well below B we have saturated 

 vapour. If we gradually draw out the film it becomes 

 thinner and thinner. If there is still sufficient liquid between 

 A and A 1? we have thus, in supposing a gradual variation of 

 the density between A and B as well as between A, and B l5 

 all the densities of the theoretical isotherms of James Thomson 

 between A and B as well between A 1 and Bj of fig. 3, and 



Fig. 3. 



thus likewise the densities of the phases, which would be 

 unstable if they were isolated. The liquid layers CD and 

 C^ (fig. 2) are thus in equilibrium with the aid of the 

 matter between C x and C, the matter above D x and the matter 

 below D. If we continue to thin the film (fig. 2) the 

 densities G and C x , which correspond with the unstable phases 

 and C a (fig. 3) of the theoretical isotherm, will finally 



