(5) 
d-oxime; we owe the /-oxime to the kindness of Prof. BECKMANN 
of Leipzig. 
1. The melting points of the pure oximes and of mixtures of 
them were first determined. Both melt at 118°.8; the inactive 
mixture, containing 50/, d- and 50%, /-oxime melts at exactly 
the same temperature as aiso a number of mixtures containing 
excess of d- or /-oxime. No difference could be discovered within 
the limits of attainable accuracy. The accuracy here is not more 
than 0°.1, because it is very difficult to determine the melting- 
point exactly, owing to the small difference in the refractive indices 
of the solid and liquid. Very satisfactory results were obtained finally 
by using very thin walled tubes in which a thin cylindrical ring 
of the solid mass was placed just above the lower end. The solid 
mass is, in all proportions, microscopically homogeneous and regular. 
Forster and Pore's view (Journ. Chem. Soc. 71.1049) that we are 
here concerned with mixed crystals is confirmed by the discovery 
of one melting-point line alone. 
At the same time the existence of mixed crystals of optical iso- 
mers, the probability of which was pointed out by Krppina and 
Pope, is confirmed. 
1200 In the figure, the horizontal 
line AB represents the melting 
115° _ point line. The view that the 
melting points of all the mixtures 
110° ~=would be the same is thus con- 
firmed in this case. I have 
105° already pointed out that this 
is possible in no other series 
100° of mixed erystals than those 
containing optical isomers. 
95° A consequence of the hori- 
zontal melting-point line is that 
9ge each mixture solidifies to a 
homogeneous mass. The melting 
gs0 point line therefore represents 
the compositions both of the 
liquid and of the solid phase. 
2. According to Pope the 
two isomers, as well as mixed crystals containing them, undergo a 
change from regular to monosymmetrie erystals shortly after they 
have solidified, 
