( 784 ) 
an outgomg molecule is: 
dar at 4 | 5 AN ; 
— 3 0 a dz == 3 Fi re) (P — Py) — N (Pi = Ps) 
So when a molecule penetrates into the capillary layer in the 
direction from the liquid to the gas, it can traverse it entirely 
only when the z-component (f) of the velocity is so great that: 
2a Za 25 
Ph a 2 Se A a ee ep, ey 
Ope > ta) 5 ) N Ei Ps ) 
Let us call the smallest value of « which satisfies this 4, we then 
find the number of particles which escapes from the liquid per second 
: N' 
as follows: Let ” be the number of particles per em*., son= — (v = 
5 
the volume of 1 gram molecule), then the number that has a velo- 
u? 
. . . . . nl 1 » u 
city component « in the z-direction is —e *d —, and the number 
Va « 
which passes through an area of 1 em? with that velocity : 
n - Uu 
ue ad — 
Va a 
So the number that passes from liquid to vapour is: 
u— £ u- 
u Mt 
na u TO u na — 5 
5? =e ze d — : e 4 
Vr @ a Ar 
Ait 
If we have to deal not with a simple substance, but with a 
mixture of (1—.) molecules Ist kind and « molecules 2"¢ kind, and 
if we want to ascertain the equilibrium for molecules 1** kind, we 
get, as is easy to see, the same expression, in which, however, 
N' (1—2) 
n= ———- 
1 
¥ % 2 §(1—2) a,+-«a,, } 2{§(1—a#)a,+2a,,} 
HMW m = 3 a ar at | ie GEUR 
N'v l Nv 1 
IRT b, (l—e) + Det b, (l1—«) Hb, 
are N' EEN m0 (5 v—b ’ q 
: (l—#)RT cn 
The expressions — and 
vu—D u—D 
(v = the volume of 1 gram molecule of the mixture 
and : 
here represent the partial pres- 
sures exerted resp. by molecules of the 1st and of the 2"¢ kind on the 
distance spheres round those of the 4s" kind. The available spaces 
