isle, 
Let us now take the case generally occurring in which, on a 
change in pressure in the one direction /’+ G is converted into 
FHL’ HG’, and into F+G" on a change in pressure in the 
other direction. Hence, on a change of pressure in the one direction 
liquid is formed, but not when in the other direction. 
In the previous communication we have deduced: if “+ L is 
converted into #+ L’ + G’ with increase in volume, the conjuga- 
tion line solid-liquid will, on lowering the pressure turn towards 
the vapour point. If F4 L is converted into / + L’ + G’ with 
contraction of volume, the conjugation line solid-liquid turns in the 
opposite direction. 
In a similar manner we may now deduce: if / + G is converted 
into F+ L’+ G’ with increase in volume, the conjugation line 
solid-vapour, on lowering the pressure, turns away from the liqui- 
dum peint, and on increasing the pressure it turns towards the same. 
If F+ G is converted into F+L’+G"’ with contraction of volume 
the conjugation line solid-vapour will turn in the opposite direction. 
The conversion of #-+ L into #’+- ZL’ + G’, or as we may also 
call it the formation of vapour from / + Z generally takes place 
with increase in volume and only on certain conditions with a 
decrease in the same. The conversion of /+G into F+L’+G", or 
in other words the formation of vapour from F+ G takes place 
as a rule with decrease in volume and only in definite conditions 
with an increase of the same. 
In the previous communication (V) we have demonsirated that the 
rule for the rotation of the conjugation line solid-liquid is in con- 
formity with the saturation lines under their own vapour pressure 
as deduced in communication (1): in the same manner we may now 
also show that this is the case with the movement of the conjuga- 
tion line solid-vapour. 
Let us imagine in fig. 7 (I) a tangent to be drawn through F 
on the vapour saturation curve of / under its own vapour pressure, 
therefore, on curve J/, a, m,6,. As on a change in pressure in either 
direction the new conjugation line solid-vapour falls outside the first 
three-phase triangle, the system F+ G, in this particular case, is 
converted on a change in pressure in the one direction into £ + G’ 
and by a change in the other direction into F+ G". Hence, no 
liquid is formed either on an increase or a decrease in pressure. 
At an infinitesimal change in pressure nothing happens but evapo- 
ration of a little solid substance / in, or else a slight deposit of solid 
fF from the vapour G. 
On evaporation of /’, the volume will as a rule increase; as the 
