388 



Wc now lake in Iv^. 1 a lemperature T^ between the melting 

 point Ts und the point of inaxininni temperature 7^- The saturation 

 and vapour saturation curve under their own vapour pressures, 

 corresponding to this temperature, are parti}' drawn and indicated 

 by 4. One of the liquid points of intersection is situated between 

 /.S and jV, the corresponding vapour point of intersection between 

 S^ and ^1- Fig, 4 indicates the complete diagram. The points ƒ and 

 g as well as the points /\ and <:/j are situated in conjunction as 

 regards the line FF\ When fig. 3 passes into fig. 4, the point c/ 

 falls on the line FF' ; this is the case at the minimum melting point 

 Ts- The points g and g^ of this transition figure agree with the 

 points S and S^ of fig. 1. 



At the maximum temperature Tjsi the two saturation curves touch 

 one another in the point N', the two vapour saturation curves in iVj. 

 We find the complete diagi-ani in fig. 5. At tliis temperature, thei'e- 

 fore, only one single solution JV exists, saturated under its own 

 vapour pressure with F -\- F' ; the corresponding vapour is repre- 

 sented bj iV^i- If we raise j< the temperature still more, the two 

 saturation- as well as the two vapour saturation-curves fall outside 

 each other, and finally disappear. The manner in which this takes 

 place has already been described in communication I. 



In deducing diagrams 2 — 5 we have based our arguments princip- 

 ally on fig. 1, in which the points F, F' , S and D^ are situated 

 as in type 1. As w^e have seen before, however, that 12 types can 

 be distinguished, we shall now consider from another point of view 

 the appearance of two saturation- and two vapour saturation cur\es 

 under their ow]i x^apour pressures. We shall namely distinguish 7 

 chief groups with respect to the temperature. We assume again in 

 the first instance that the volume of F -\- F' increases on melting 

 (congruent and incongruent). The points N', S, and F> are situated 



with respect to one another as in 

 fig. 4 (VQI) and 1. 



I. The temperature is lower than 

 the maximum point of sublimation 

 7/) . It is easy to see that not 

 only the two liquid points of 

 intersection but also the two 

 vapour-points of intersection are 

 situated in opposition as regards 

 the line FF. 



One of the many diagrams, satis- 

 fying these coi»ditions, is drawn in 



Fi2'. 2. 



