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point of /. The saturation- and the vapour-saturation curve of / under 
their own vapour pressure then have a formas in fig. 11(1), the isothermic- 
isobaric diagrams as in figs. 1(1), 2D, 3 (1), 4), 8), 1) and 101). 
As soon, as on distillation, the liquid M has disappeared and, 
consequently, only the solid substance /’ remains, the pressure con- 
forming with fig. 2 (I) will fall. [f now, however, the pressure Pade: 
which now conforms with fig. 3(1) has been attained, the solid 
matter /' will not be capable of splitting, as in the previous case. 
On further lowering of the pressure, fig. 10 is formed; hence, the 
substance / will only appear in the solid condition. On further 
decrease in pressure the vapour saturation curve of fig. 10 (1D under- 
goes contraction and finally, at a definite pressure, coincides with 
the point /. The solid substance /” can now be in equilibrium 
with vapour of the composition /’, or in other words: the substance 
fF sublimes. 
Hence, the liquid first traverses, at a pressure Pj/, a distillation 
curve terminating in the point J, where it is converted into the 
solid substance /’, which at a further lowering of the pressure 
sublimes at a definite pressure. The distillation of the liquid is, 
therefore, finally changed into a sublimation of the solid substance /’. 
We will now investigate what happens when we distill a liquid 
saturated with a solid substance /’. We take a liquid s (fig. 3) and 
the solid substance # in such proportion that the complex is repre- 
sented by point A’ of the line s/. We now withdraw from this 
complex A a little vapour s,, which can be in equilibrium with this 
complex; the complex now arrives in / and hence, is resolved into 
liquid a + solid F. The little straight line A/ is now an element of 
the curve which the complex A. will traverse on distillation; we 
will call this curve the complex distillation curve. From the deduction 
of this curve it now follows at once that the tangent drawn in the 
point K at the complex distillation curve which passes through this 
point, passes through the point s,. Further, it is evident that this 
applies to all complexes situated on the line /’s. From this follows: 
in order to find the direction of the tangent to a complex distillation 
curve in a point (4) we should take the three-phase triangle, whose 
conjugation line solid-liquid (s/’) passes through this point A. The 
line which connects this point (A) with the vapour point (s,) of 
the three-phase triangle is the looked for tangent. We may express 
this also as follows: in the point of intersection of a complex 
distillation curve with a conjugation line solid-liquid the tangent 
to this curve passes through the vapour point correlated to that 
conjugation line. 
