(518) 
Z = — Z(n,k) T (log T — 1) + Zln,le\) — T F(A (1,),) — 
— f pee + pu + RT X(n, log n‚), 
or ® 
Li == 2(n,C.)\— | [ree — RT Yn, . log Zn, =p | + RTS sz). 
e =n, 
Differentiating subsequently at constant 7’ and p with respect to 
n, and n,, we get: 
nF 0 
u, == ER log 
ane ny =n; 
OZ 0 
=z Sg, as | 
On, A 25 | 
where C, and C, are pure functions a the iN eee represented by 
n= — kT (log Lias Ta). 
C, = — kT (log T — 1) + (e)o — Ta) 
whereas the quantity @ is given by 
@ = (pdw — RT Zn, log Sn, — po. 2 2 2 2) 
e 
The meaning of the different quantities 7,, (e,),, (1,),, ete. ete. is 
supposed to be known. 
We will substitute now the variables n, and n, by w, so that 
n,=1—2, n, =x and 2n,=1. As w is, just as Z, a homogeneous 
function of the jirst degree with respect to 7, and ,, we may write: 
dw 
m=e,—(o- x oe) + RE log (1 — x) | 
av 5 
(2) 
nl Cen Di) ar log «x | 
Now, when there is a plait on the Z-surface, the spinodal-curve, 
that is to say its projection on the 7, 2-plane, will be given 
Petia MZ 
by the condition pee or also, p, being ae ‚ and 
Fi as wv 
k OZ du, Ô Ou, 0 
I= , by — =0 or == (0) 
f 2 ) Ow Ow 
We therefore find for the equation of this curve in the 7'v-plane: 
07a RT 
D= == (), 
Det l1—z 
or 
ir) 
RT = «(1 — ae) erect (3) 
