524 



Dr. Gr. Bakker on the 



In three points of the theoretical isotherm (fig. 4) the 

 thermodynamic potential has the same value i. e. 3 in the 

 points H, K, and F ; H and K are the points where 

 the physical isotherm (HK) cuts the theoretical, while we 

 have for the point F : 



surface NHGM = surface LFGM. 



Between H and F, fi>i>/* ; in the point F, fi=f^i ; and 

 between F and K, /jl>/jli. Now I have demonstrated that 



-TT * is always positive in the capillary layer ; -~~ 



has 



therefore in the equation (24) the same sign as p—pi. 

 If we therefore denote a point in the capillary layer by 

 the corresponding point f of the theoretical isotherm, 

 we have : 



between H and F, 



inF, 



dp2 n 



dk 



dp2 = 



dh 



dp 2 



0; 



between F and K, ^ >0. 

 ah 



The hydrostatic pressure p 2 parallel to the surface of the 

 capillary layer diminishes therefore between H and F, has a 



Fiar. 7. 



K-Axis 



minimum value in F, and increases between F and K. The 

 curve which presents p 2 as a function of h has therefore a 

 shape as in fig. 7. AB is the thickness of the capillary layer. 



* Zeitschr.f. Phys. Cfiem. xlii. p. 71 (1902). 



t That is to say, that this point corresponds with the same density as 

 the density in the considered point of the capillary layer. 



