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and at last coincide and disappear, which means that the longitudinal 
plait does not cross the binodal curve of the transverse plait but 
remains entirely hidden inside it (e. g. at negative pressures) Then 
non-miscibility could only be observed in consequence of retardation 
phenomena; we have then what in a former paper Timmermans has 
called a negative saturation curve. ... ,, , 
But theory has taught and experiment has con la med that 
there exists a second, more complicated type, that of the splitting 
„p of a plait, which is represented in fig. 2. On the par t BE of the 
plaitpoint line two homogeneous double plaitpoints have arisen in 
H and /, so that the plaitpoint line, after having descended in tem¬ 
perature from D to H, rises again to /, after which it descends 
again through E to C. In this case two possibilities may present 
themselves. Either the three-phase pressure line will run from a 
point between C and E to a point between / and H, or the upper 
end-point of the three-phase pressure will lie between H and D. 
In the former (more probable) case we shall get into the heterogeneous 
region, if the pressure is raised in the upper end-point, in the second 
case in the homogeneous region, and increasing the pressure still 
more at constant temperature, we shall either get into the heteroge¬ 
neous region or not, according as G lies at higher or lower tempe¬ 
rature than I. Whether we pay attention to the bmodal or the spi- 
nodal line, in any case we shall have to speak here of a separate 
longitudinal plait. For the further elucidation of the difference between 
2n and 26, we give also the i;,^-projection of the binodal and the 
spinodal curve for this case in fig. 6a and 6* at the temperature 
of the homogeneous double plaitpoint. 
Let us then consider the case for which the region of non-misci- 
bility extends into the critical region proper. The plaitpoint lines of 
longitudinal plait and transverse plait, which were separate m the 
preceding figures, will now unite to the plaitpoint line of one p ait, 
which we may now more appropriately call a “complex’ plait. As 
we said before, we shall not discuss here all the possibilities of a 
complex plait, but only those which are important for our investi¬ 
gation. The simplest case now of a complex plait is again that only 
two heterogeneous double plaitpoints occur. Then we shall get fig. d. 
The realizable part of the plaitpoint line begins in A, the critical 
point of the first component, and runs to the critical end-point G in 
the presence of a second liquid phase. The real non-miscibihty of 
two liquids begins in the lower end-point F, which may, of course, 
lie considerably below A, but the coexistence between two liquids, 
as it would in the beginning undoubtedly be called in this case, 
