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agreement with tigs. 8(I) and 9(I). On lowering the pressure, the 
first figure is converted into the second and we notice that in 
this conversion both three-phase triangles turn in such a manner 
that the conjugation line solid-liquid gets in front. 
In the case now considered when the reaction # + LZ G takes 
place from the left to the right with increase in volume, the pressure 
can also be a maximum; I will elucidate this with a single example. 
We take a saturation line of the solid substance /’at the pressure 
P; this is represented in fig. 1 by the curve fy); within this satu- 
ration line is situated a vapour region encompassed by a heterogeneous 
region, of which the liquidum line is drawn and the vapour line 
dotted. 
On lowering the pressure the vapour region expands and at a 
certain pressure ?, the saturation line of /’ and the liquidum line of the 
heterogeneous region meet each other in M. There is now formed 
the three-phase equilibrium solid F+ liquid M+ vapour M, represented 
by three points of a straight line, whereas the vapour phase M, 
lies between the points F and M. Hence, the reaction is F+ LSG 
namely from the left to the right with increase of volume, whilst 
the pressure Py is a maximum. 
At a pressure somewhat lower than Pj, is now formed a diagram 
as in fig. 2 in which, however, we must imagine the only partially 
drawn saturation line af and lg of F to be closed. The vapour 
