1000 
ponding pressure, then /, and F, do not get the composition £;’ 
and /,’, but another composition Fr’ and F,”. 
When we take away at 7, the phase F4, from (F,) = (//) 
+ F,41, then we do not obtain the equilibrium (M), but, as F’," 
and F," have another composition than /,' and #,/, an equilibrium 
different from (M). Consequently curves (J/) and (4) do not coin- 
cide. The same is true for (M) and (/7,4;) and for (/,) and (F4); 
“the singular curves do not coincide, therefore. They form, as is 
drawn in the figs. 1—5, three separate curves. Now we can show: 
1. the three singular curves touch one another in the point 4. 
2. (fF) and (/,41) are situated on the same side of the (J/)-curve. 
The first follows immediately from the relation 
gn Ss AW 
dr Ar 
In the point ¢ viz. the reaction, which occurs in the three singular 
equilibria, is the same, so that in the point i is the same also 
for the three curves. 
In order to show the second, we consider the bivariant equilibrinm : 
(BoB) = FH... +h HH H-1+ Pipe... Fite (1) 
This region has a turning-line (M), which is defined by the fact 
that in (1) the variable phases #,/,,... have such a composition 
that a phases-reaction is possible between those 7 phases. The 
singular curve (J/) is, therefore, the same as the turning-line of the 
region (/", F4): consequently we have here the special case, which 
we have already mentioned in (VIII) viz. that the point z in fig. 5 
(VIII) is situated on the turning-line zyzu of the region (/, F+). 
As (f,) and (/,41) must be situated within the turning-line of this 
region, they are situated, therefore, on the same side of the (J/)-curve. 
In order to deduce the P,7-diagrams, we are able to apply again 
the rules of the isovolumetrical and isentropical reaction to the 
curves (M), (HF) and (E41). In this application with respect to the 
(M)-curve we have, however, to bear in mind the following. 
When we have a constant singular curve (M), then we are able 
to realise always a whole series of equilibria (for instance: between 
the temperatures 7, and 7) of the (M)-curve with the aid of one 
single complex A’ of definite composition. When (M) is however 
variable singular, then this not always remains possible. Then we 
may have the case, that we can obtain only one single equilibrium 
of the (J/)-curve (e.g. that of a temperature 7’) with each definite 
