1679 
AV may be in (12) as well positive als negative; this depends 
on the direction, in which reaction (12) proceeds. When AV is 
positive in the one direction, then it is negative in the opposite 
direction. Now we assume that AV is the change of volume, when 
the reaction proceeds in such away that the phases, which have a 
negative sign in (12), are formed, and that consequently the quantities 
of the phases, which have a positive sign, diminish. We call this 
direction: the “direction belonging to AV”. When we let reaction 
(12) proceed in opposite direction, therefore in such a way that the 
quantities of the phases, which have a negative sign, diminish, then 
the change of volume is — AJ. 
In (13) we assume the same; consequently Ay is the increase of 
entropy, when reaction (13) proceeds in such direction, that the 
phases, which have a negative sign, are formed. 
For fixing the ideas now we shall assume that the series of signs 
of reactiOn-equation (12) is represented by: 
ARON MR Bal os C 
B | is 
LN gai Rod ae EN ee ah eae ft 
In each group we give to the phases from left to right the indices 
tree im proupy As Al. A, are IN PLOUP oO +. Og, Pete. 
When all ratios are positive in (14), then all phases have the 
same sign in (13) as in (12); when some of those ratios are negative, 
for instance beginning with u, then in (13) the phases FP, .../,-1 
have the same sign, but /,.../,+42 the opposite sign as in (12). 
Then we obtain the two series of signs: 
AH Rel Boet “By Al Gas" alee NE 
Rah tel fe cas ea | oy enim pee A OO) 
EE Sens PoE pee |p an EVA (20 
The upper one represents the series of signs of reaction (12), the 
lower that of (13). With this we have assumed that the phase #, 
is situated in group B; in the lower series of signs this group is 
divided then into two parts B, and 4, with opposite sign. 
We now let the isentropical reaction (12 between the phases 
of the invariant point occur in the direction belonging to AV. As 
with this reaction the quantities of the phases, which have a positive 
sign in (12) or (19) diminish, from the invariant equilibrium, a 
monovariant equilibrium is formed, which we shall call (X‚). Herein 
X represents, therefore, a phase with positive sign, consequently 
a phase from one of the groups A, B or C of (19). 
When we let the isentropical reaction go in opposite direction, then 
