or 
1 il 
ze 5 Bro! 
ty 1 1 r Wy acd < À ) 
EN PAER Wed je en: 
For always increasing values of 7, the left hand member tends 
to zero and the coefficient of B becomes infinite. Therefore (sym- 
bolically) : 
—0< BX oo 
So B cannot be negative. 
The former condition furnishes: 
ADS 
dr < 
—2fe~>*+2Ber fe x+ Ber fe Ben —fe »*+Bea 
ba im Mamail <0 
re Ar? Aa? op 
or 
BYE Ayer ef Atlet 
(A is replaced by — f). 
If r is always more increased, the left hand member becomes 
infinite, whereas the right hand member decreases infinitely. 
Therefore symbolically 
BX +o <fX+0. 
So B cannot be positive. 
As therefore B can be neither negative nor positive, B must be 0. 
The function of Van DER WAALS is the most general function 
which fulfils the conditions of the theory of capillarity and possesses 
the above mentioned property. 
In answer to a letter on the subject discussed here, Prof. 
VAN DER Waats and Prof. KoRTEWEG were so kind to draw my 
attention to the work of Dr. C. Neumann: ,Allgemeine Unter- 
suchungen über das Newron’sche Princip der Fernwirkungen mit 
besonderer Rücksicht auf die elektrischen Wirkungen” Leipzig 
B. G. TeuBNeR, 1896. 
