1323 
rule situated at a lower temperature and pressure than the minimum 
melting point of each of the substances /’ and /” separately. 
For in fig. 1 we have assumed that curve S/’ corresponds with 
branch ZF of fig. 4 (IV) and that S is situated on the rising part 
of this branch and is removed far from the point with the maximum 
pressure. If, however, S lies on this branch somewhere between the 
point with the maximum pressure and that with the maximum tem- 
perature the curve Sf in fig. 1 no longer exhibits a pressure maxi- 
mum but only a temperature maximum; the pressure in the minimum 
melting point of F+ #” is then higher than that in the minimum 
melting point of //. 
If S is situated on branch ZF’ somewhere between the point with 
maximum temperature and the point /, curve SF in fig. 1 proceeds 
from ‚$ towards lower temperatures and pressures. In that case not 
only the pressure but also the temperature of the minimum melting 
point F+F” is situated higher than that of F. 
From our previous considerations as to curve ZZ, of fig. 4 (IV) 
it follows that the latter case can occur only then when the liquid 
formed at the minimum melting point of # + /” differs but little in 
composition from the substance //. 
From these considerations follows: at a constant pressure the melt- 
ing point of the complex /’+ #” is always lower than that of each 
of the substances /#’and /” separately. As a rule the minimum melt- 
ing point of “+ fF” is also lower than that of each of the com- 
pounds individually. By way of exception, the minimum melting 
point of + /” may, however, be somewhat higher than that of 
one or even of both of the substances /#’ and #7. 
We shall see Jater that in this case at the temperature of the mini- 
mum melting point of “+ #”, the saturation curve of # or F” 
under its Own vapour pressure is exphased. 
A similar consideration applies to the maximum sublimation points 
of the complex #’+ #” and the compounds fand #7. 
Let us now bring a complex /'+./”. of a detinite composition c, 
to a temperature 7, and a pressure P,. In order to investigate in 
which of the 10 possible conditions this complex will now occur 
we take a pressure concentration diagram of the temperature 7, and 
place in this the concentration c, and the pressure P, of the complex. 
If now the figurating point lies for instance in region 7, /”+2-+-G 
is formed, if in region 3, /’'+ L is formed, if it lies in region G it 
is converted wholly into gas, in region £ wholly into liquid, ete. 
Besides the pressure concentration diagrams considered above we 
may also deduce from fig. 1, or its corresponding spacial represen- 
