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reaction; the quantities À,...2 of the phases participating in this 
reaction are defined by (10). The change in entropy occurring with 
this reaction 2(/H) is defined by (11), the change in volume 2(4 V) 
is defined by (16). 
Some of the coefficients 2,...4n are positive, other ones are 
negative. As long as we do not assume for this a definite rule, we 
may arbitrarily interchange positive and negative. We assume the 
following: The coefficients of the phases, which occur with a reaction, 
are taken positive; the coefficients of the phases which disappear 
with the reaction, are taken negative. 
Now (4) is the algebraical sum of the quantities of the phases 
which participate in the reaction, of course this is zero. 
X(4y) is the algebraical sum of the quantity of the component Y 
which participates in the reaction; this is also zero. The same is 
true for the other components. 
As the component X does not occur in the invariant (P or 7) 
equilibrium, (A«) has, therefore, another meaning. When we add, 
however, a little of the component X to this equilibrium, then it is 
divided between the » phases; this division is defined by (7), so 
that z,...z» and consequently also 2 (Ar) are defined. 
Now we imagine a reaction in the invariant (Por 7’) equilibrium; 
2,...4, represent, therefore, the quantities of the phases participating 
in the reaction. When those phases would contain the quantities 
E‚--- An Of the new component, then 2(2r) would be the algebraical 
sum of the quantity of the component X, which participates in this 
reaction. For this reason we shall call 2 (Ac) “the fictitious quantity 
of reaction of the component X”. 
Now we take a point on the limit-curve of a region, e.g. point 
h on the limit-eurve ab in fig. 1. (XVI). This limit-curve represents 
an equilibrium of »—1 components (viz. the components Y, Z, U.) 
in 7 phases, consequently a monovariant equilibrium. In the point 
h itself PT y,y,..2,2,..ete. have definite values; the same is true 
for the ratios of 4,...4n which are defined by (10) Now we adda 
little of the component X, this is divided over the n phases; this 
division is defined by (7). For a delinite value of e.g. a, the ratios 
Ear): LAH) and Er): (AV) are also defined. In accordance with 
(12) and (15) we know consequently also (/T)p and (dP) 7. 
When (/T)p is positive, then the region Mis situated at the right 
of the point h; we enter then the region, just as in fig. 1 (XVI) starting 
from A in the direction Al. 
When (dr is negative, then the region M-is situated below 
