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sublimation-curves of + #”, F+ #" and #’+ 4”’. It is apparent 
from (8) that these three curves do not touch one another in 7, but 
they intersect one another. According to our previous considerations, 
these curves, except in the point 7, are always situated below the 
equilibrium-curve PH #” + #’’ HG. Further it appears that at 
the one side of the point 7 two of these curves represent stable 
conditions, on the other side one of these curves. 
Consequently we find: in the point 7 five curves come together, 
the conversion-curve (/° + #” +. F”’’)- and the equilibrium-curve 
(P+ fb’ + #’’ + G) of which coincide. This last curve ends in 7; 
the four other curves go through this point; the point 7 divides 
these curves into two parts, the one of which represents stable con- 
ditions and the other metastable conditions. 
We find these results also in the following way. We may consider 
the equilibrium /’-+ /” + FH G, when G is represented by a 
point of FFF’, consequently it is invariant and it can be represented 
in the P, 7-diagram by a point 7. Therefore, through r four triple- 
curves must go, viz. the conversion-curve (/’+ PF’ + F”’) and the 
sublimation-curves of /’-+ #”,F+ #" and FF’ + F’’. When we 
consider stable conditions only, we may say that these curves start 
all from 7 or that they end in #. The situation of these four curves 
with respect to one another is fixed by a definite rule.) We may 
determine the direction of these curves with the aid of the iso- 
volumetric and the isentropic reaction, which can occur between 
these 4 phases.*) Let the isentropical reaction be: 
ON LES) Jes We rad PUN Me er (AE) 
wherein one or two of the coefficients 7, m’ and n" can be negative; 
in the ordinary manner we must write the phases relating to that 
in the right part of the equation. As the volume of the vapour (@ 
is very large with respect to that of the solid substances, the reaction 
will take place from the right to the left with decrease of volume. 
The equilibria, which are formed at this reaction (from the right to 
the left) occur consequently under higher pressures. As we, in order 
to get tbe equilibrium /’+ /” + #”’, must cause the reaction to 
take place from the right to the left, the conversion-curve (AH 4” 4/7’) 
will go consequently always starting from * towards higher pressures. 
This is in accordance with our previous considerations, 
1) F. A. H. SCHREINEMAKERS, Z. f. Phys. Chem. 82 59 (1913). 
F. E. CG. ScHEFFER, These Procéedings 21 446 (1912). 
2) F. A. H. ScHREINEMAKERS, Die heterogenen Gleichg. von BAKHuis Roozr- 
Boom, lll’, 219—220. 
