1300 
gas then draws nearer to the point #, the pressure along the vapour 
saturation curve, starting from the point of contact, will decrease 
towards /’ and increase in the other direction. This is in agreement 
with fig. 7 (1) and 12 (I) but not so with fig. 13 (I); from the deduction of 
this last figure, however, it is more to be expected that the curve J/, m, 
is either circumphased or exphased, but is then situated at the other 
side of F like curve Mm. 
Let us now consider the case when the vapour saturation curve 
of F under its own vapour pressure possesses a form like curve 
amb in fig. 4(V); the saturation line should then be supposed to 
lie more towards the right. We may then draw through /’ tangents 
to the vapour saturation line with the points of contact R, R’, 
ean 
In the point ACN) now also takes place the above considered 
conversion of A+ G into #-+ G’ and #’+ G". In the point A, 
however, the system /#’+ G is converted, on change in pressure, 
in the one direction, into “+ L’ + G’, and by a change in the 
other direction into #4 LL" + G". Hence, liquid is formed on increase 
as well as on decrease in pressure. At an infinitesimal change in 
pressure, only a little solid substance /’ evaporates into, or else a 
little of this is deposited from the vapour; hence, when starting 
from the point of contact, the pressure along the vapour-saturation 
curve will decrease towards /’, but inerease in the other direction. 
We have noticed above that the rotation-direction of the conjuga- 
gation line solid-liquid depends on the change in volume when vapour 
is formed from # + LL, whereas that of the conjugation line solid-vapour 
depends on the change in volume when liquid is formed from /'--G. 
In the three-phase equilibrium 4 + L + G we may now suppose 
four cases to occur. 
1. The formation of vapour from # + L takes place with 
increase, the formation of liquid from /’-+ G with decrease in volume. 
2. The formation of vapour from /# + L takes place with 
decrease, the formation of liquid from /’ + G with inerease in volume. 
3. The formation of vapour from /’-+ Z and that of liquid from 
F+G both take place with increase in volume. 
4. The formation of vapour from # + L and that of liquid from 
F4 G both take place with decrease in volume. 
Let us first take the case mentioned sub 1 which is also the one 
usually occurring; from what has already been communicated it 
follows that, on inerease in pressure, the conjugation line solid-liquid 
turns towards the vapour point and that the conjugation line solid- 
vapour turns away from that point. 
