1100 
Fig. 3 
was already used before in this laboratory.*) Fig. 4 shows the P7- 
projection of the space figure, whilst table I gives a survey of the 
observations. 
The three-phase line BSQ, on which solid naphtalene coexists 
with a solution of ethane in liquid naphtalene and vapour, was 
determined by slowly heating at a definite pressure till the mass 
began to fuse. As the equilibria established themselves extraordinarily 
slowly, the experiments required much time, and it was very difficult 
to fix the moment that the liquid appeared and increased. 
The second critical end-point g could not directly be observed. 
lt was almost impossible to determine the point, where two phases 
became identical in the presence of the third, because the tem- 
perature varies only extremely slightly at considerable changes of 
3) SCHEFFER, Proc. Royal Acad, Amsterdam 1912. 
