( 261 ) 
IV. One critical end-point lies on SM, the second on BM. (points 
p t and 7, of fig. 1). In this case, which is given by fig. 4, the melting- 
point S still occurs on the three-phase line on the side of the first 
component, while the maximum sublimation point has disappeared. 
In connection with this is the fact that the plane of the compound 
is only intersected by a liquid branch; the plaitpoint k lies between 
p and q. In S the melting-point line touches, in the other point, where 
the solid compound exists by the side of liquid of equal concentration, 
a second line for solid-fluid, which proceeds towards lower temperature 
touching the three-phase line in the P-P-projection. This latter line 
has been omitted for the sake of clearness. 
V. Both the critical end-points lie on BM (points p s and q t , fig. 
1) so for concentrations which lie between those of the compound 
and of the second component. The equilibrium liquid-gas in the 
middle plane, which gave rise to a metastable critical phenomenon 
in the preceding case, yields here a stable critical point (fig. 5). The 
lines that indicate the behaviour of the mixture of the concentration 
of the compound, have been inserted in the figure. 
Proceedings Royal Acad. Amsterdam. Vol. XU. 
