dE) 
Eriks 
in which D and C have another value than in (14). 
Equation (16) is, of course, also satisfied =x, and y= gy, 
hence by a singular point of the system liquid + gas. In this case, 
an eit) 
dP 
D and C and consequently —— obtain the same value as in (14). 
| yr 
( 
We now imagine also the P,7-eurve of the singular point drawn in 
> 
N ( 
fig. 4; we may then easily demonstrate that a is determined for 
: 
this curve by (14). 
If now, on one of the straight lines ZFZ, of fig. 1 a singular 
point oecurs, so that in the equilibrium of solid /’ + liquid + vapour the 
two latter ones have the same composition, its P,7-curve must meet 
the P,7-curve of the singular point in fig. 4. 
Such a case occurs when at a definite P and 7 a singular point 
appears or disappears on the saturation line of /’, so that the satu- 
ration line and the correlated vapour line meet each other in that point. 
With the aid of the previous formulae we might be able to inves- 
tigate more accurately the course of the P,7-lines if we expressed 
the quantities 7, s, ¢ ete. by means of the equation of state of 
Van per Waars, in which « and / must then be considered as 
functions of z and y. 
(To he continued). 
Chemistry. — “Aguilibria in ternary systems.” V. By Prof. F. A. H. 
SCHREINEMAKERS. 
(Communicated in the meeting of February 22, 1913). 
In the previous communication we have disregarded the case 
when the straight line Z/’Z, of fig. | (LV) coincides with the line 
NEY of this figure. If a liquid moves from the point # of this 
figure towards A or towards } then, as follows from (11%) (IV) 
both the numerator and denominator of A are = 0. 
) 
in) de 2 he 
The value of ao from (11) (LV) then becomes indefinite so that 
we will consider this case separately. In order to simplify the cal- 
culations we again limit ourselves to the case when the vapour 
contains one component only so that we may put «, and y, = 0. 
Our conditions of equilibrium are given in this case by (18) (ID 
(19) (II). We now write these: 
