le 
peratures for which the intersections in fig. 1 were studied, have 
been indicated in fig. 2 by the same letters. The three-phase line 
L, HL, HG retairs therefore the shape which it has when no 
solid substance occurs; one part has, however, become metastable 
here. Just as the line L,-+ L,-+G the three-phase line S + L, + L, 
possesses two plaitpoints, one of which is stable, and the other 
metastable or unstable. Besides the former possesses a ridge, which 
lies entirely in the non-stable region, the ends of which correspond 
with the points where the lines y and / of fig. 1 cut the spinodal 
curve. The two other three-phase lines S+-L,+G and 8+L,+G 
are continuously connected by means of such a ridge, the end-points 
of which correspond with the points A and £ of fig. 1. That really 
ridgelike figures occur here, with contact of every time two branches 
in the end-points is easy to see; this will always be the ease when 
two binodal lines touch in a point of the spinodal line (plaitpoints 
excepted). If we choose the temperature very little different from that at 
which contact takes place, then if the direction of the change of tempe- 
rature has been correctly chosen, an intersection will appear of the bino- 
dals; then in the J’, v-figure there are two three-phase-triangles present, 
the angular points of which draw near to each other on approach of the 
temperature of contact, and coincide when this temperature is reached. 
If e.g. we have the intersection of a line between =d and e with the 
transverse plait in fig. 1, then the two phases L,, the two phases 
G, and the two solid phases will coincide at a lower temperature. 
d 
Now the value for -= for both the two three-phase equilibria is 
given by the equation : 
vG == ff L 
GL NSL, 
d US Se L 
in DE EI 
0G — VSI 
in which all the quantities of the second member refer to the three 
coexisting phases. It is now clear that on approach of the tempe- 
rature of contact the two phases L,, the two phases G, and the 
two solid substances differ less and less in properties, and that at 
the temperature at which contact takes place, the quantities of the 
second member refer to identical phases. For the two three-phase 
‚dp 
branches the value of aT becomes exactly the same at the tempe- 
rature of contact, and so contact occurs. 
26° 
