72 



then also be situated inrtlier from the anglepoint C and closer to 

 the side AB, so that also the vaj)onr region is large. At a siitricient 

 decrease of pressure or increase of temperature, the vapour-region 

 shall even cover the whole components-triangle. Consequently it is 

 absolutely necessar}- that we must distinguish the three regions, of 

 which the movement, occurrence, and disappearance were already 

 formerly treated. 



When the equilibrium F -\- L -{- G occurs, we may now deduce 

 this in the same way as it was done formerly for a ternary vapour. 



a) The solid substance is a ternary compound or a binary com- 

 pound, which contains the volatile component 6'. 



For tixing the ideas we shall assume I hat in the triangle ABC 

 of fig. 1 which is partly drawn, the point C repi'esents water, if an 

 aqueous doublesalt, F' and F" binary hydrates. In accordance with 

 our previous general deductions we now find the following. 



The saturationcurves under their own va[)Our-pressure arecircum- 

 or exphased at temperatures below 7], (7's = minimum meltingpoint 

 of the solid substance uiuier consideration). The corresponding vapour- 

 curves are reduced to the point 6'. When these substances melt with 



Fig. 1. 

 increase of volume, the points H, H' and H" are situated with 

 i-espect to F, F' and F" as in fig. 1 ; when they melt with decrease 

 of volume, these points are situated on the other side. 



