75 
solution, and almost certainly in the molten mass. But only, if such 
differences be really stated in the liquid phases to a measurable 
Fig. 1. 
degree, it appears rational to speak of two kinds of chemical molecules. 
However, disregarding for a moment their chemical isomerism, 
from a crystallographical point of view, the red and yellow 
modifications of the base mentioned, seem, in our opinion, to be 
related as true enantiotropic forms, as e.g. is the case with mono- 
elinie and rhombic sulphur. The zrreversibility observed by ANsELMINO 
is evidently only an apparent one, caused by intensive retardation 
phenomena: the transition-temperature: yellow = red, is 34° C., 
while the meltingpoint of the red modification is found to be 74° C. 
and that of the (metastable) yellow form 70° C. By this interpretation 
all relations existing between the red and yellow forms, as observed 
by ANSELMINO, may be explained in an unambiguous way. 
§ 2. With respect to the erystallographical properties of these 
compounds, in the first place the numbers relating to the derivatives 
already obtained by ANseLMINo, may be recorded in the following. 
They were already obtained by us in 1906, but by special circum- 
stances their publication has been postponed till now. 
The condensation-product of p-homosalicylaldehyde (from p-cresol) 
and aniline: 0o-oxy-m-methyl-benzylidene-aniline : 
occurs in two forms, of which the one is yellow, the other red, and 
which were studied already formerly by H. Trause and F. SCHMELING ') 
1) F. ScrweLinNg, Diss. Greiswald, (1905), p. 56, 58. 
