181 
if x indicates the part CO in het gaseous mixture of CO + CO,, 
hence 
oh EN 
ons 
The graphic representation of this relation is again a similar curve 
as line e and — as y will be usually small, therefore — large — 
UL 
of a very high degree. 
The limits, between which y can vary, is on the one side the value 
of the saturated solution v, on the other side 0. 
In this latter case the above relation passes into the equation; 
— =h;,, that is the relation for the reaction FeO + COZ Fe + CO, 
which in Fig. 5 is indicated by the straight c. 
The lines indicating the equilibria of the different solid solutions 
FeC,, each with FeO and the gaseous phase, thus form a collection 
of curves of increasing higher order the latter of which, for y— 0, 
passes into the straight line c. 
The first, relating to the solid solution saturated with carbon 
is indicated by the line A. The point of intersection of this line 
with the line d gives the monovariant equilibrium VI. 
The points of intersection of the other lines / with the line d, 
also the point of intersection of ec with d (IIL) are metastable equi- 
libria because they relate to solid solutions unsaturated with carbon. 
They are, therefore, situated at the right from VI, between VI and III. 
Below VI the successive curves cut each other and the envelope 
/ formed by these intersections now forms the equilibrium line of FeO 
with the different unsaturated solid solutions. It runs from VI (equi- 
librium of the saturated solution) to A’ (equilibrium with pure Fe). 
From VI, the monovariant equilibrium between C, FeCy, FeO 
and gas, thus run 3 lines of divariant equilibrium, namely 
d, between II and VI for the phases C, FeO and gas. 
d, ah Se le amd OP „ ©, solid solution and gas. 
L _ Wham te le … ,, FeO, solid solution and gas. 
They enclose in the planes 
F where are stable solid solutions + gas. 
Or. 5 „ FeO + gas. 
Are ios eN „ C+ solid solutions (pressure < py7). 
or C+ FeO (pressure >> py; and < py) 
whilst in both cases the gaseous phase is metastable. 
