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of the pseudo-binary system. In the first place we see that the 
stable unary liquid line meets the melting-point line of the pseudo- 
system in ZL, so that there a total solidification will take place, at 
least if phenomena of retardation fail to appear. 
The solid states, which are in internal equilibrium below this 
temperature, and so belong likewise to -the unary system, lie on 
the line SS,. It is further noteworthy that one of the two meta- 
stable parts of the melting-point line of the. pseudo-component B, 
intersects the metastable liquid line of the unary system in L’. 
At the temperature of this point of intersection an intersection 
must also take place of the metastable produced parts of the mixed 
crystal line mf and of the line for the solid internal equilibrium S,S, 
which intersection is denoted by the point S’. 
It follows from this that when the metastable unary liquid is 
cooled down, and no retardation takes place, at L’ total solidifica- 
tion to the metastable unary solid phase S’ will set in, which, 
however, becomes stable at S. So what is remarkable about this, 
is that the metastable point of sodification lies /igher than the stable 
one, and this is due to this that here there is no monotropy in the 
solid state but monotropy in the liquid state, in consequence of 
which we get the reverse of what we are accustomed to, as is 
immediately clear, when we draw the P, 7-fig. Our 7, X-fig. 5, 
however, reveals more. We see namely from it that when the 
metastable part of the region of incomplete miscibility extends far 
enough below the eutectic point of the pseudo-system, the metastable 
unary liquid line can also be cut by the metastable prolongation 
of the melting-point line of the pseudo-component A, so that the 
possibility also exists that in LZ" total solidification of the metastable 
unary liquid to the metastable unary solid substance S” sets in, 
which solid phase will then follow the line S'S," at lower tempe- 
ratures. So one of the peculiarities of this case consists in this that 
the metastable unary liquid possesses fwo metastable points of solidi- 
fication, and that when this liquid is not converted to a stable one, 
it can solidify to a solid substance which is at first metastable and 
at lower temperatures stable when it is first heated above a definite 
temperature, and then cooled down. If the temperature is not raised 
so high, the metastable unary liquid solidifies to another solid 
substance, which remains metastable, at least when no transition 
equilibrium occurs in the solid state. 
Now it should, however, be pointed out that the two mentioned 
points of solidification of the metastable unary liquid need not neces- 
sarily exist. The upper point of solidification may be absent, in con- 
