li'i 



and SD will be situated in regard to each other as in fig. 1 (VII); 

 if series 7 or 9 appears K'F' meets the curve Z)>S; if 8 or 10 occurs 

 KF meets BS and if Jl or 12 appears K'F' as well as KF meeAs 

 that curve. 



As a rule tlie case drawn in fig. 1 (Vll) and corresponding with 

 series 1 — 6 is the one likely to occur. If, however, the minimum 

 melting or the maximum sublimation point of the complex F -\- F' 

 is situated but a xery little lower, or somewhat higher, than the 

 same points of one or of both compounds separately, KF or K'F' 

 or both will then lie in the vicinity of Z>6' and contact may take place. 



We now imagine drawn in the tigs. 1, 2, or 3 the sti-aight lines 

 ciF ajid aF' ; the first may be considered as being part of a recti- 

 linear solution path of F, the second as a part of such a path of 

 F' under its own vapour pressure. We have noticed previously 

 (communication IV) that the P, 7'-curves of these paths meet the 

 melting point line of the com|)Ound in the minimum melting point. 

 We now imagine drawn, as in tig. 1 (Vllj, the melting point lines 

 Fd and Fd' in fig. 4 also. 



We now^ take on the four-phase curve LSDU of tig. 4 a point 

 corresponding with point a of fig. 1 — 3 which we will also call a. 

 From this point a the two /*, 7-curves of the solution paths of F 

 and F' then proceed; the one meets the melting point line of F, 

 the other that of F' in the minimum melting point. 



It is now evident that from each arbitrary point X of the curve 

 LSDR in fig. 4 proceed two solution paths of which the one 

 meets the melting point line of F and the other the melting point 

 line of F' ; in fig. 1 (VIIj are drawn only the two paths proceeding 

 from the point S. 



The paths proceeding from an arbitrary point .Y of the four-phase 

 curve generally intersect this curve in A^ Contact takes place if in 

 the point A' occurs a reaction of group c or d ; in the first case 

 the solution path of F, in the second case that of F' meets the 

 four-phase curve in the point A. 



We have seen previously (communication IV) : if in a point X 

 of a solution path of i^ a reaction is possible between the three 

 phases it comes into contact in the point A^ with the boundary 

 curve of F. Previously we have deduced also: if in the point A' of a 

 four-phase curve occurs a reaction of group c it meets in the point 

 X the boundary curve of F. From this now follows: if in a point 

 A' of a four-phase curve occurs a reaction of group c, the four- 

 phase curve, the boundary curve of F and the solution path of F 

 come into contact with each other in the point A'. 



