799 



Now we will suppose that botli A and B are volatile, and that a 

 ternary compound 0, occuis, giving critical endpoints with A and 

 B, whereas C presents critical endpoints neither with .4 nor with 

 B. We then get fig. 5, wliich does not call for further elucidation. 



Case 11. The case we are going to consider now on'y differs 

 from the preceding one in this that in the binary .system A — C 

 critical endpoints occur. The critical endpoint curve for solid Z) and 

 solid C intersect, and give then rise to the origin of two double 

 critical endpoints 1\ and P^ . 



B 



Fig. 6. 

 D3 the least volatile ; B more volatile than C ; A very volatile. 



As it has been supposed that also B is volatile, critical endpoints 

 could also occur in the binary system BC, with this result that 

 also on this side double critical endpoints make their appearance. 



Case 12. We shall now proceed to the case that the three com- 

 ponents are volatile, but form a ternary compound melting at a high 

 temperature and much less volatile, which yields critical endpoints 

 with the three components. Here too, as in the preceding cases, 

 unmixing in the liquid phases is excluded. 



Fig. 7 represents the case supposed here in drawing, and shows 

 that the ternary comjiound />., with all the mixtures gives critical 

 endpoints, so that two closed critical endpoint curves are formed, 

 an inner (^-cnrve and an outer p-curve. 



