(194) 



treatment and discussion of the (7^, .iO-fig^i'es for constant value of 

 p was left. I have not given the third communication, in which these 

 last figures were to be discussed, first because tliey could be derived 

 directly from the other communications on the discussed equilibrium 

 and secondly because I w^ould not make it appear as if I attached 

 too much importance to the hidden equilibria, showing the continuity 

 between the equilibria which can be observed and wiiich seem 

 discontinuous without the hidden ones. However, some noteworthy 

 particularities would have presented themselves, and so, induced by 

 questions of Dr. Smits on subjects in which suchlike particularities 

 occur and at his request, I will briefly discuss at least the principal cases. 

 The differential equation (see the preceding communication) has 

 the following form for constant value of p : 



Let us think the (T,.x')^-curve of the fluid equilibria inter se construed. 

 If the second component is more volatile than the first, the two bran- 

 ches of this curve descend. In fig. 1 this (T,,r)-curve is closed on the 

 side of the second component, and it is therefore assumed that the 

 pressure chosen lies above the critical pressure of this component. 

 Further in fig. 1 the curve of the fluid phases has been drawn, which 

 coexist with the solid body. For so far as these phases lie within 

 the curve of the fluid equilibria, they are not to be realised or with 

 difficulty. In fig. 1 it has been assumed that the circumstances are 

 chosen in such a way that this curve passes the region of fluid equi- 

 librium twice, as is the rule for lower pressures and so also for 

 low^er temperatures. 



If the value of the pressure increases, and so also the value of T, 

 the curve of the fluid equilibria inter se ascends, while its form is 

 modified at the same time. The curve of the equilibria with the solid 

 phase ascends also with p, but in a smaller degree, at least on the 

 side of the liquid equilibria. Now in fig. 1 we have ascribed such 

 a value to the pressure, that there are still two different three phase 

 equibria, while in fig. 2 a value is ascribed to p, at which the solid 

 body coexists with a plaitpoint phase of the fluid equilibria — so 

 that above that pressure the curve of the equilibria with the solid 

 phase passes only once through the region of the equilibria inter se 

 of the fluid phases. In fig. 3 p has ascended so far that there is 

 again equilibrium betw^een the solid body and a plaitpoint phase. 



For still iiigher value of p there are no longer three phase equi- 

 libria and the curve for the equilibria of the solid body with a fluid 



