( 767 ) 
curve dm of the pseudo-binary system has the same direction as 
ep ; in this case the three curves of equilibrium S\ S\ , S\ and l t k 
might still have the same direction, and so the sign of Q need not 
be reversed. 
If we look upon the question of the reversal of the thermal sign 
from a general point of view, the following may already be remarked. 
When A and B are isomers , as for benzile-orthocarbonic acid, a 
reversal of the sign of Q seems possible, because Q r is probably 
small in this case 1 ). If, however, we have to do with the pheno¬ 
menon polymerism, we may expect with great probability that Q r 
will always predominate, and that the curves for the inner solid 
and liquid equilibria will always run in such a way that the 
equilibrium shifts towards the side of the less complex substance 
with rise of temperature. 
This leads us at the same time to the question what the 7>- 
figure will be for the case that the substance B is a polymer of A , 
and that a transition point exists. 
Fig. 2 shows that when the pseudo-binary system possesses a 
eutectic point, the curve for the inner liquid equilibria must meet 
the melting-point curve of the less complex substance, because only 
in these circumstances ail the curves for the inner equilibria can 
run to the ^4-side with rise of temperature. 
Yet this figure will not appear to be quite correct either, in 
my opinion, as a supposition is implied in it, which is highly 
improbable. 
When B is a polymer of A, and the pseudo-binary system pos¬ 
sesses a eutectic point, this means that there are liquids (ac) which 
contain more polymer than the coexisting solid phases (ad), and 
this is very improbable, so much so that we may disregard this 
figure altogether, in spite of Hollmann’s 2 ) assertion that he has found 
a eutectic point for the system acetaldehyde-paraldehyde. Probably 
this assertion of Hollmann’s rests on not quite reliable observations, 
for my assistant, Mr. de Lkeuw, who tested the said assertion at 
my request, has not found it confirmed. 
So for the case that B is a polymer of A and the two substances 
are not miscible in all proportions in the solid state, we must conclude 
to the existence of a Tx- figure as indicated by fig. 3, in which the 
x ) In consequence of the considerable displacement of the inner equilibrium at 
the transition temperature it is possible, that while Q r predominates below this 
temperature, above it the reverse takes place. 
Q,, too, can reverse its sign, but this seems less probable to me. 
a; Zeitschr. f. ph/s. Chem. 43, 129 (1903). 
