Ut YY f 
From this follows for the boundary curve: 
dP (vw, — 2) B—(w--a)D 
dT (x, ~~ ayA— (w—a)C 
so that this boundary curve must come into contact with the subli- 
mation line of the compound in the maximum sublimation point X 
and with the melting line in the minimum melting point £. Further 
it is evident that the three-phase line K/ of the compound F is a 
part of the boundary curve. 
Hence, all the P,7-curves in fig. 4 are situated in the region 
encompassed by the boundary curve; through each point of this 
region pass two P,7-curves and through each point of the boundary 
line passes a P,7-curve which meets this boundary line in that point. 
The boundary curve itself is, therefore, no P,7-curve in that sense 
that it corresponds with a straight line passing through #’; this, 
however, is the case if only one of the three components of / 
occurs in the vapour. 
The double point 5 passes in fig. 4 through a curve terminating in the 
point #. When the saturation curves under their own vapour pressure 
possess, in the vicinity of the minimum melting point 7’, a form 
as in fig. 12 (1) no double point of a P,7-curve appears above 
Tp. The double point curve in fig. 4 then proceeds from / towards 
lower temperatures. 
If, however, the saturation line at 7'p under its own vapour 
pressure has a form such as the curve afb in fig. 2 (II) the double 
points are still possible above 7'p and at each temperature more 
than one may appear. 
From (11a) it appears that # can become nil only fore = a and 
y = g, therefore, in the point /’. A, however, may become infinitely 
great and change its sign in other points of the component triangle. 
This will be the case when the denominator becomes 0, hence: 
lere) 1» + (y,—y) 8} e087 Hera) + (y,—y) tf sing = 0 « (16) 
Let us call the solution for which this is the case, the solution q; 
(16) then means that the line #g comes into contact in q with the 
liquidum line passing through the point q, of the heterogeneous 
region L + G. We may express this also as follows: / becomes 
infinitely great when the conjugation lines liquid-solid and liquid-gas 
are conjugated diagonals of the indicatrix in the liquidum point, 
As R=o, (11) is converted: into: 
