144 Dr. G. Bakker on the 



We can easily prove the identity : 



Consequently, if v 2 —t'i is replaced by u : 



By substitution in (21) : 



,= ,- F( =<T;i|-,) + ^(H-Tf). . («0 



If a is the coefficient of the Laplace expression for the 

 molecular pressure ap 2 and the thermic pressure of the form 

 T/», I have found: 



*-(a-TJ|) <*-*)•. 



In the case when the equation of state is of the form : 



y> = T/X.-)-" 2 , 

 where a represents a temperature function, we have thus : 



The identity : _ 0, + r 2 pi—p 2 



^ P~~ v 2 — Vi 2 



gives by differentiation with respect to T, with second para- 

 meter constant : 



d ($-p) v i + v * d (P\-P*\,P\-P* i M + i?A /M v 

 ■ |dT ~ r 2 -n M 2 y + 2 dT\ v 2 -vj K } 



(23) and (18) consequently give in general : 



^- T *=l T i<S) — <*> 



These relations we shall use in § 4. 



§ 4. The equation of energy of the capillary layer. 



If x and 1 — x are resp. the quantities of the liquid and 

 vapour, which have formed the capillary layer without 



* Zeitschrift f. phys. Chemie, xii. p. 283 (1893). 



