1545 
It appears from a comparison of figs. 3 (//) and 4(//) [we have 
to bear in mind that the figs. 4 (ID) and 6 (//) have to be inter- 
changed) that (Z,) and (Z,) and also (Z,) and (G) must form a 
bundle. 
Now we draw in the P,7-diagram only the regions which contain 
liquid and vapour. The region Z, L G is situated between its 
limiting-curves (Z,) and (Z); the region Z, L G between (Z,) and 
(Z,); the region Z, L G between (Z,) and (Z,). 
Now we draw a vertical line in the /,7-diagram; this is dotted 
in fig. 2. As far as this line is situated in the region 4, L G, it 
represents the equilibrium 7, Z G at constant temperature, conse- 
quently all the solutions which are saturated with solid 7, at that 
temperature under their own vapourpressure. In the concentration- 
diagram (fig. 1) these solutions* are represented by a curve, “the 
saturationcurve of Z, under its own vapourpressure”. [For a 
fuller examination of these curves confer the communications [—- 
XVIII over “ternary equilibria” }. 
In fig. 1 curve fa represents the solutions, which are saturated 
at the temperature 7, curve d/ the solutions which are saturated 
at 7), curve Lp the solutions saturated at 7), with solid Z, under 
their own vapourpressure ete. All dotted curves, which proceed in 
fig. 1 starting from cL and La towards the left, are, therefore, saturation- 
curves of Z, under their own vapourpressure. All dotted curves 
between Za and Zh are saturationcurves of Z,, under their own 
vapourpressure for instance the curves agh and dm. All dotted 
curves, going to the right starting from cL and Lé are saturation- 
curves of Z, under its own vapour-pressure. In fig. 1 the bivariant 
region 7, LG is situated, therefore, at the left of the curves cL and 
La, the bivariant region Z,LG, therefore, between the curves 
La and Lb; the bivariant region Z,LG at the right of the curves 
cL and Lb. 
The regions 7,LG and Z,LG exist, therefore, in stable condition, 
as well above as below the temperature 7’; of the invariant point; 
the region Z,LG, however, only above this temperature. This is 
also in accordance with the P,7-diagram; herein a line parallel to 
tbe P-axis, intersects at temperatures below 7; only the regions 
Z,LG and Z,LG; at temperatures above 7; besides those also the 
region Z,LG. 
Previously we have deduced that a saturationcurve under its own 
vapour-pressure shows a point of maximum- and a point of minimum- 
pressure; these points are situated on the: conjugation-line solid- 
vapour. On the parts of these curves, drawn in fig. 1 only points 
