361 
Chemistry. — “Litension of the theory of allotropy. Monotropy 
and enantiotropy for liquids.” By Prof. A. Smits. (Commu- 
cated by Prof. A. F. HorLEMAN). 
The extension meant above concerns the case that the pseudo- 
binary system exhibits the phenomenon of unmixing in the liquid state. 
Pie TX 
Let the $,v-line be schematically represented 
by fig. 1 at the temperature and pressure at 
which the phenomenon of unmixing takes 
place. Then in the first place it is noteworthy 
that 7, and /, are the coexisting liquid phases 
of the psendo-binary system, and that more- 
over there exist two minimum points L, 
and L, representing the liquid phases which 
may be formed when the system gets in 
internal equilibrium, and consequently be- 
haves as a unary substance. 
The two liquid phases are not miscible, 
and when they are brought into contact 
the metastable liquid ZL, will pass into the 
stable liquid phase Z,, so that this operation means the same thing 
as seeding the metastable liquid. As fig. 1 shows the metastable 
unary liquid point ZL, lies inside, and the stable unary liquid point 
L, outside the region of incomplete mis- 
cibility, and now it is of importance to 
examine what 
happens when we move 
toward such a temperature that the critical 
phenomenon of mixing occurs in the pseudo- 
binary system. The coexisting phases /, and 
1, have drawn nearer and nearer to each other, 
and finally coincided in the critical mixing- 
point, and the §,z-line has then changed into a 
curve with only one minimum, as fig. 2 shows. 5 
It is now, however, of importance for 
our purpose to consider the way in which 
the $,2-line has changed its form from that Fig. 2 XZ. 
of fig. 1 to that of fig. 2. 
It is known that before the points /, and /, coincide, the maximum 
24 
Proceedings Royal Acad. Amsterdam. Vol. XV. 
