344 Dr. G. Bakker on the 



H being the value of H at the melting-point, for 

 inula (10) gives : 



Hence we find for the constant of Laplace : 



h 



Ho 



_1 



Pl 2 - 



P2 2 



2 Ry 



~P2 



o 



Pl 





3 



Pk 



In this periodical * I have given for the difference of 

 the hydrostatic pressure pi, perpendicular to the surface of 

 the capillary layer, and the average value p of the pres- 

 sure p 2 parallel to the surface of the capillary layer : 



_ 25tt/T H \ 2 , m 



62 a- Lp 1 —p 2 J 

 where / denotes the constant of the used potential function 



r 



-ft", 



while a is the coefficient of the expression ap 2 of Laplace 

 for the so-called molecular pressure or the function a in the 

 equation of state of van der Waals. Although a is a func- 

 tion of the temperature, I have, as a first approximation, con- 

 sidered a and /' as constants ; k being a new constant, wejhad 



Pi—p = K 



P1 — P2J 



IT 



or, the expression being proportional to 1 — 3, 



p 1 -p= K {l-$Y (12) 



If the pressure is expressed in atmospheres, I have found for 

 ether, k = 238. When h denotes the thickness of I he plane 

 capillary layer, we have, further j*, 



*=— (13) 



Pi— V 



Substituting respectively the formula (9) for H and the 

 formula (12) for ^,— p in "(13), we find : 



h = JL. - £, 



where a and j3 are constants. 



* Phil. Mao-. Oct. 1907, p. 521. 

 T Ibid. p. 522. 



