521 
Let us assume that the series of signs of reaction (1) is represented by: 
A R B S C Ti D 
LEE aes Re eed AL args een Heels 0 LO) 
Consequently the P,7-diagram consists of seven bundles, in fig. 3 
(V) we find a similar diagram, in which, however, the bundles 5, 
C, D, T, and S are drawn onecurvical. As the indifferent phases 
Ff, and #41 have the same sign, they belong to a same group of 
series of signs (10) and the curves (/’,) and (/,41) belong to the same 
bundle of curves of the P,7-diagram [Fig. 3 (V)|. The curves (/;,) 
and (£41), therefore, coincide in the same direction, as in fig. 1. 
In order to define the direction of the curve (J/) we take the 
isovolumetrical or isentropical reaction {Communication LX] in which 
F, and # have, therefore, also the same sign. Let us take the 
isovolumetrical reaction and let us assume that /, and #4, have 
herein the positive sign. Now we cause the reaction to proceed in 
such direction, that the quantities of the phases, which have a 
positive sign, diminish. Then, besides perhaps also other monovariant 
equilibria, the singular ones (#), (+1) and M/ may be formed. 
The stable parts of the singular curves (/,), (4,41) and (M) go, 
therefore, starting from the invariant point in the same direction of 
temperature. [This is defined by the sign of 47 in the isovolume- 
trical reaction). When we take the isentropical reaction, then it 
‘ appears that the three singular curves go in the same direction of 
pressure, starting from the invariant point. 
The curves (Jf), (#,), and (#41) are situated, therefore, with 
respect to one another as in fig. 1. 
In the case 2 the two indifferent phases have opposite sign ; con- 
sequently they belong in the series of signs (10) to two succeeding 
groups. When e.g. /, is the last one of group A, then #4, is the 
first of group &; when ¥#, is the last of group A, then Wu is 
the first of group B etc. 
The two indifferent phases have, therefore, in all reactions, opposite 
sign, hence, also in the isentropical and in the isovolumetrical 
reaction. When the equilibrium (/’,) arises at a reaction in the one 
direction, then (4/41) may arise, when the reaction proceeds in the 
other direction. Hence it follows: the stable parts of the curves (4) 
and (#44) go in opposite direction, starting from the invariant point. 
The equilibrium Jf is not transformable, it may, therefore, not ” 
be converted into the invariant one, or be formed from the invariant 
one; the direction of the curve (J/) starting from the invariant point 
may not be deduced, therefore, from this reaction. This follows at 
once, however, in the following way. When we take away, while 
