1214 
when Zr is a maximum; A7 >>0 when Tr is a minimum] two 
equilibria exist, viz. 
ESF, Rae and Se se ie 
No phase-reaction can occur between the phases of 4’; no more 
between those of /#’’. The invariable phases have of course the 
same composition in the three equilibria; the compositions of the 
variable phases differ only little from one another in the three 
equilibria. Now we shall show: 
a. The concentration-regions of Hp, K’ and F’’ are situated in 
the concentration-diagram outside one another. 
The three equilibria have, therefore, such compositions that none 
of them can be converted into one of the two other equilibria. 
b. The concentration-region of Ep is situated between those of 
E' and E£”’. 
c. The corresponding phases of the three equilibria (e.g. #, FP,’ 
and F,’; F, F,’ and F,’’; etc.) are situated on a straight line; 
this is divided into equal parts by the phase of the equilibrium Zr. 
Before showing this, we shall first elucidate the meaning by 
some examples. 
Fig: 1. Fig. 2. 
For this we choose the ternary equilibrium 
DER F. 
When we represent those phases in the concentration-diagram by 
the points 1, 2 and 3, then at 7'r those three points are situated 
on a straight line (line 123 in figs. 1 and 2). The concentration- 
region of Hp is, therefore, the line 123. 
At the temperature Tr AT’ exist the equilibria: 
E'=F)+F/+F! ond EN=F."+F,' + FS 
First we shall assume that each of the phases of the equilibrium 
E has a variable composition; the phases of £’ are then represented 
