( 184 ) 
respectively solid alcohol, solid anthraquinone, liquid and vapour. 
Towards higher temperatures the limitation is formed by the line dd' 
which is a perfectly straight one and of which each point represents 
the triple point of anthraquinone. 
What in a binary system constitute^ a line is a plane in a ternary 
system and consequently there extends between the plaitpoint curves 
ab and a x b x a plaitpoint surface which is limited towards lower 
temperatures by the plaitpoint line aa x which relates to ether-alcohol 
mixtures without anthraquinone, and towards a higher temperatures 
by the line bb x of which each point simply represents the critical 
point of anthraquinone. 
From the fact that in the system ether-anthraquinone the plait¬ 
point curve comes into contact with the three-phase line, whereas 
this is not the case in the system alcohol-anthraquinone it follows 
at once that the plaitpoint surface in the ternary system starting from 
the plaitpoint curve of alcohol-anthraquinone will approach the two- 
sheet three-phase surface more and more until a junction takes place 
where the solid-vapour sheet passes continuously into the solid-liquid 
sheet so that there is formed a plaitpoint line for saturated solutions 
which runs over the plaitpoint surface and renders a part of it 
between p p x q x q metastable. 
This circumstance now causes very peculiar phenomena which 
may be readily deduced from the accompanying figure in Space. 
For a small alcohol-concentration a p,t section of the three-phase 
surface has been indicated in the figure in space, it being assumed 
that for this mixture there exist also two critical terminal points 
p x and q x which represent the points of contact of the three-phase 
loops e'p l and cl'q with the plaitpoint surface, therefore also wi 
the plaitpoint curve. 
Here it should be observed that, as shown plainly from the drawing, 
the points p x and q x do not form the extreme limitation ofthethree- 
phase hiatus, for these three-phase equilibria may still exist in t ® 
supposed mixture above the temperature of p x and below t a o 
q x so that the temperature-distance of the three-phase loops w * 
is indicated by the vertical tangents is smaller than that o 
points p x and q x . , 
It is plain that when we take larger quantities of alcoho ^ 
points p x and q x and in consequence also the points r x an r t 
approach each other so that the latter will finally coincide, at 
moment the liquid branch of the right loop passes continuous y ^ 
the vapour branch of the left loop, the situation thus becomm 
indicated in fig. 2, 
