( 265 ) 



strated, the mixed crystal lines fe and (i(\ corresponding to the 

 melting-point lines have been drawn. 



The existence of the latter mixed crystal line, which at e^ passes 

 into the line (\m with a break, involves the necessity of two mixed 

 crystal lines starting from the transition point 0, which run down- 

 ward, because as was found by me in collal)oration with Dr. dk Leeuw 

 and was also stated by Dr. van Klooster^), the transition point is lowered 

 on increase of the /SVconcentration. At the point where the lower, 

 the rliombic mixed crystal line oq, meets the other rhombic mixed 

 crystal line e^m, this latter line becomes stable. So the point q indi- 

 cates a stable rhombic mixed crystal phase, which coexists with the 

 monoclinic mixed crystal phase y, and at the same time with the 

 liquid h. 



So the monoclinic mixed crystal phase must also coexist with the 

 liquid h, and the point h being the point of intersection of the melting 

 point lines of the monoclinic and the rhombic sulphur, the said 

 monoclinic mixed crystal phase must lie on the line ep^ or in other 

 words the mixed crystal lines eu and ov meet in p. Below the 

 three-phase equilibrium byq the rhombic mixed crystals qm are in 

 equilibrium with the liquids along ha in the pseudo-binary system. 



It is not difficult to see now what must be the relation between 

 the pseudo-binary and unary equilibria, or in other words how the 

 lines for the internal equilibrium must be drawn in this figure. 



The line for the internal equilibrium in the monoclinic sulphur 

 starts from S.-,, and that for the internal equilibrium in the rhombic 

 modification from S^. 



Above 95.°4o, the unary point of transition, the monoclinic modi- 

 fication is stnble, below it the rhombic modification. At the tempe- 

 rature of 95.°45 the first line, which starts from 6\, must intersect 

 the monoclinic mixed crystal line op, and the second line, which 

 starts from S^, must intersect the rhombic mixed crystal line o q, 

 so that >S/ and S^' are two coexisting solid phases, which are in 

 internal equilibrium, one of which is monoclinic and the other rhombic. 



Below this unary point of transition the rhombic modification is 

 stable, its internal equilibria being indicated by the line S' S^. 



According to the new \iew, however, the 7\Y-figure given hei'e, 

 is illogical, for to account for the observed phenomena it had to be 

 assumed here that the pure pseudo-component Sy possesses a point 

 of transition, and the theory of allotropy says that the phenomenon 

 of transition implies non-miscibility in the solid state For the phos- 



1) See communication of Kruyt Chemisch Weekblad 34, G47 (1911) 



