(532) 
Attending to the condition (IV) in the usual way, we find that 
the numbers 7, in the system of maximal frequency must fulfil the 
condition 
te + Ny a ed Ap, hse as Aces ee 
on an; 7) 
whereas the second variation of log $, 0° log & given by the formula 
Ae B dns i d , dlog w, 
JN 
k 
mdz 
+ dn, w(vdz)(dn,— + dn) , . (VID) 
Ye 
must be essentially negative. 
The first conditions are equivalent to those given by van DER WAALS. 
It is easy to give the equation (VI) the form which is assigned to 
it by van DER Waars. We have only to introduce the hypothesis 
that n changes continually with the height and then to calculate the 
energy &. 
We obtain in this way *) 
oy, dlogw, Zan, 1 5 
l a le ~ = G 
ed Nn, ou dn, ca 0) 25 } ES 
Ì 
_d?sn, 
EE 
d 2,78 
== 2.7) or VA 
1) To calculate e/ we proceed as follows. On account of our hypothesis we 
can write 
En ante (vdz)? d° n, ne (vdz)?s d?sn, 
ey Nn, ty == aD, EPS ea en 
: oT a! de (2s)! dz? 
Introducing this into the formula for €, and putting 
0 
20 a 
= [+228 4p (2) de = SU 
(2s)! w ( ) Qs 3 
we find for &, 
ex d2sn, 
END En Mals er € (6) 
1 
I shall write for &, also 
5 UD en ae 
It is only in the capillary layer that the quantity ex differs from zero, 
2) We may mention as another advantage in the above deduction of (VI’) that 
