501 
of the 58°-acid, beautiful needle crystals of this acid are formed 
on standing. 
Experiment gave the following result: 
Solutions of the 58°-acid and the 68°-acid in petroleum ether, 
saturated at 25° (about 0.26 erm. and 0.17 grm. in 5 c.c. respectively) 
were allowed to stand for eight days in the dark at 25° to 30°. 
Without the previous presence of crystals the solutions gave, on 
evaporation of the solvent at the ordinary temperature by means ot 
a current of air, a residue which in ice was transformed into 
the 42°-acid. 
After having stood for eight days in the dark, less concentrated 
solutions of the two acids gave always the 42°-acid. This 42°-acid 
remained unchanged during the whole period of observation, about 
one month. 
If, however, the solvent was distilled off immediately after the 
preparation of the solution, it was found impossible to effect the 
transformation even of a solution containing only 0.05 grm. of either 
of the two acid forms in 5 ee, into the 42°-acid. Solutions in 
petroleum ether which were kept for eight days before distillation 
in contact with crystals of one or other of the two higher melting 
forms, gave, either during or immediately after the distillation of 
the solvent, crystals of the acid from which the solution was made. 
LieBERMANN and TrucksAss *) succeeded frequently in excluding nuclei 
of the higher melting acids by filtering the petroleum ether solution 
and afterwards heating it on a water bath at 35°. In six out of ten 
experiments with 68°-acid the transformation into the 42°-acid was 
effected. The same result was obtained with the 58°-acid in two 
out of four cases. 
Experiments were carried out to ascertain if it were not perhaps 
possible to remove the nuclei more quickly than by a complete 
dissociation at ordinary temperature. The same procedure was 
adopted as before to exclude atmospheric nuclei. Heating at 35° was 
however, omitted. It was found that when solutions, almost satu 
rated at the ordinary temperature and prepared immediately before- 
hand, were filtered through cotton-wool, ordinary filterpaper, or 
even through quantitative filterpaper, they yielded the original 
acids. If the solutions, even those containing crystals, were filtered 
after standing for twenty four hours, a residue was frequently, 
though not always, obtained, which yielded crystals of the 42°-acid. 
The reason for this may be ascribed to an alteration in the size 
ij Ber. 43, 411 (1910). 
