564 
In the system of the carvoxims it is sure to be the same case 
and then the equation of the three-phase line becomes 
pee _ Qas— Qs _ QGL 
BE WEE TEN aie 
The three-phase line simply coincides with the vapour tension 
line for liquid carvoxim (whether d, 1, r or a mixture) between the 
melting temperature of the components and that of the pseudo-race- 
mic mixed crystal. This curve is then a double line and ina certain 
sense we might then say that it has one maximum which of course, 
is plainly noticed in the /x-projection. 
But as to the decision between racemic compounds and 
pseudo-racemie mixed crystals this course of the three-phase line 
yields no eriterion. Only, van Laar *) has pleaded for the conception 
that the form of the melting line of the carvoxims solely points to 
a compound, whereas TamMANNn*) on account of caloric values 
exactly arrives at the opposite result. 
Utrecht, August 1916. van “T Horr- Laboratory. 
Chemistry. — “On Nitro-derivatives of Alkyltoluidines and the 
relation between their molecular refractions and those of 
similar compounds”. By Dr. J. D. Jansen. (Communicated by 
Prof. P. van ROMBURGH). 
(Communicated in the meeting of June 24, 1916). 
Some years ago appeared a communication from HaNtzscH *) on 
chromoisomerism and homochromoisomerism of nitroanilines. In the 
conclusion of this remarkable publication, Hantzscu says that yellow 
and orange di- and tri-nitroanilines, when their molecular refractions 
are abnormal, probably contain chromophores of different constitution. 
The yellow 3.4. dinitro-dimethyl-aniline and the orange 3.4. dinitro- 
diethyl-aniline, according to his opinion, are not real-, but pseudo- 
homologues, which manifested itself in the molecular refractions, 
LG EL 
mRTL ——— = mRT|— 
1— #G 1 
wv I J 
or 
EE == di 
The fact that a. =d) certainly points out that in the liquid and vapour occur 
no (or at least very few) racemic molecules. 
1) Zeitschr. f. physik. Chem. 64, 289 (1908). 
2) Göttinger Nachrichten 1913. 
3) B 48, 1662, (1910). 
