( 185 ) 



For greater concentrations of anthraqiiinone the plaitpoint lies on 

 the metastable branch of tlie border curve, so that not a single 

 critical phenomenon is to be observed in stable state. 



When we have arrived at that concentration for which contact 

 takes phice on the left, we have the case that at a certain temperature, 

 with compression of the three-phase system [S-\-L-\-G), tiie solid 

 substance and the vapour disappear simultaneously, while this was 

 the case at two difterent temperatures with smaller concentrations. 



It is of importance to point out here that this contact does not 

 take place in the point where iVgf=z 0, but where this quantity has 

 a positive value. (See the communiciitions on retrogressive melting 

 point lines ^)). 



If we take a greater concentration of anthraquinone, the line for 

 solid-fluid has got detached from the border line on the left, and 

 as we now proceed to still greater anthraquinone concentrations, the 

 plaitpoint K approaches the point G^, and finally coincides with it. 



If this takes place, the second critical end-point q has been reached, 

 which case is indicated by fig. 3. 



r.(() 



If now with our concentration we pass the point q, the plaitpoint 

 K will lie on the right of the line for solid-fluid, and again critical 

 phenomena are observed for unsaturate solutions. 



The following figure 4 shows what the investigation of the system 

 ether-anthraquinone has yielded on this point. 



In this fig. 4 we see the two parts of the three-phase line and 

 further the PT-sections of the surfaces solid-fluid for different 

 constant values of x, (mol. 7o anthraquinone), while for some very 

 slight anthraquinone concentrations also the section of the liquid- 

 vapour surface is indicated, which however is rather indistinct in 

 consequence of its being so small. 



If we begin with the PT-sections corresponding to the very slight 



1) These Proc. p. 170 and p. 189. 



