1539 
rapidly, on the other hand very slowly in glacial acetic acid or 
chloroform’); the reaction may, however be accelerated under the 
influence of daylight. 
Maleic acid behaves in quite an analogous manner; the velocity 
of absorption, however, (as might be expected from the constitution) 
is greatest with glutaconie acid. 
From the material communicated in this treatise I believe it may 
be safely concluded that the symmetric formula of THorPE is indeed 
a fairly proper interpretation of the properties of glutaconic acid. 
In the following communication, I hope to elucidate this formula 
with a model. 
Delft, February 15, 1916. 
Chemistry. — “/n-, mono- and divariant equilibria.’ VUI. By 
Prof. F. A. H. SCHREINEMAKERS. 
(Communicated in the meeting of March 25, 1916). 
12. Further consideration of the bivariant regions; the turning lines. 
The different properties of the curves and the regions, which we 
have deduced in the previous communications, are only true under 
some conditions, which we have up to now assumed silently. They 
are valid viz. not only in the immediate vicinity of the invariant 
point, but still also at some distance, viz. under the conditions: 
1. the points under consideration must not be situated in the 
P,T-diagran too far from the invariant point; consequently the P 
and 7’ of the equilibria under consideration must not differ too 
much from the P and J of the invariant point; 
2. the compositions of the occurring phases must not differ too 
much from the compositions, which they have in the invariant point. 
Further we shall indicate somewhat more exactly what is the 
meaning of “not too far’ and “not too much” in these conditions. 
As long as those conditions are satisfied, the deduced properties 
remain valid; when they are not satisfied, deviations may occur. 
When all phases have a constant composition, the latter condition 
is always satisfied; this should be the case in fig. 1 (II) for instance 
when one of the phases represents watervapour and the others 
1) The bromination in chloroform in sun-light is the best way of preparing the 
2G-dibromoglutaric acid. There are always formed, however, smalltquantities of by 
products (probably higher brominated ones). 
99 
Proceedings Royal Acad. Amsterdam. Vol. XVIII. 
