b are the same points in fig. 3 as in fig. 1. In general viz. each 
saturation-curve under its own vapour-pressure from fig. 1 is represented 
in the P,7-diagram (figs 2 and 3) by a line parallel to the P-axis. 
Now we take a temperature 75 between 7’, and 7, = 1. The 
saturation-curve under its own vapour-pressure of Z, is situated at 
this temperature 7, in fig. 1 between point L and curve dim. When 
we follow this curve, starting from a point on LA, then the pressure 
increases, as is apparent from fig. 1. This is in accordance with 
fig. 3, in which curve dl is situated above curve vn. Hence it follows 
that each point of the region Ldm of fig. 1, must be situated in 
fie. 3 within the region idm. Region Ldm of fig. 1 is, therefore, 
represented in fig. 3 by region idm. 
Let us now take a temperature 7, higher than 7, for instance 
= ea T,—T;, (fig. 1). On curve ayb the pressure increases 
as well if we start from a as from 0, it reaches its maximum in g. 
In fig. 3 the point g must be situated, therefore, not only above 
point 4, but also above point a. The region Z,LG covers in fig. 3, 
therefore, not only the line a/, but also the line ag: consequently 
it extends over the point a. It appears from fig. 1 that a similar 
extension occurs for each temperature 7’, higher than 7. 
Starting from curve mb (fig. 3) the region Z,LG finishes, there- 
fore, not at once in eurve da; it extends viz. first over this curve 
da. up to a curve dg, then it turns to curve da, in order to finish 
in this curve. We call dy the turning-line of the region Z,LG. 
We may imagine, therefore, the region 7,LG' between the parts of 
the curves mb and dg, as consisting of two leaves, the one of which 
starts from mbh and the other from da, they pass into one another 
in the turning-line dy. Between the curves da and dy those leaves 
cover one another. In order to represent this reversion of the region 
in fig. 3 some lines have been drawn which unite a point of da 
with a point of mb and which touch the turning-line. 
The region Z,LG starts, therefore, from 4d towards the right, from 
da however towards the left, after having reached the turning-line, 
it goes, however, again towards the right. 
The turning-line dy from fig. 3 corresponds of course with the 
line dy from fig. 1. In the communications on equilibria in ternary 
systems several of these lines have been discussed in detail under 
the general name of M-eurve. I only mention here, that it touches 
curve ia in d and continues further, but then in metastable condition. 
When we consider the equilibrium Z,LG in its whole extension, 
viz. without taking into consideration which parts are stable or 
metastable, then each leaf of this region extends itself over the 
