Hence we deduce the type of the P,7 diagram in the way indi- 
cated above. Although there are in series (18) eight groups of signs, 
yet in the diagram not 8, but only 7 bundles are found. We obtain 
viz. again fig. 3 (V), in which we have, however, still to draw the 
curves U,U,... and in such a way that they form with A,A,... 
one single bundle only, in which the order of succession from left 
to right is U,U,...A,A,.... Consequently we find a diagram, 
satisfying also the series : 
U A Rass S GEN Wee) 
NE ay reac Ee 
Hence it is apparent: when the last group of a series is negative 
| ay 
(series 18) then we may place this last group, after reversing its 
sign, before the first group and unite them to one single group 
(series 19). : 
[Below we shall indicate in another way that a similar removal 
is possible and in what way we can carry it out. | 
From the previous considerations follow at once the rules: 
in each P,7' diagram the number of bundles of curves is always 
odd and three at least ; 
in a P,7 diagram always a same number of bundles of curves 
is situated at the right and at the left of each bundle of curves. 
We can also find in this way the types of the P,7 diagram, 
which may occur. in a- system of m components. We have viz. to 
examine in how many and in what ways the 7+ 2 signs of a 
series can be divided into an odd number of groups. This is perfectly 
the same as the way followed in communication V viz. examining 
in how many and in what ways*2 + 2 curves can be divided into 
an odd number of bundles. 
The following is apparent for the relation between the type of 
the concentration- and the P,7-diagram. 
1. We know 2 reactions between the phases, which occur in 
the invariant point and we seek the corresponding type of the 
P,T-diagram. We write then those two reactions just as the equations 
(1) and (2) viz. in such a way that condition (3) is satisfied. Now 
we take the series of the signs of reaction (1); when the last group 
is negative, then we combine it with the first in the way indicated 
above (compare series 18 and 19). We may use the following pro- 
perties for drawing the type of the P,7-diagram. 
With each group of the series a bundle of curves corresponds, 
which contains as many curves as the group contains signs. 
These bundles succeed one another in the same order as the 
groups in the series, on condition that we follow it from left to right 
