504 
Solutions in benzene prepared in a similar way showed at —10° 
a transformation only in exceptional cases. In these cases the 68°- 
acid was obtained. At —16° after twenty four hours the 68°-acid was 
always formed. 
Further experiments were made by adding a few drops of the 
solvent to erystals of the 42°-, 58°-, and the 68°-acid contained in 
the flasks with the cotton wool plugs, in such a way that crystals 
still remained in the solution. The solvent was introduced into the 
flasks through the glass tube with the cotton wool plug, the part 
of the tube projecting beyond the cork having been previously heated 
in order to prevent infection. It was found that the 58°- and the 
68°-acid were unchanged. The 42°-acid was, however, transformed, 
the same changes being observed as with the solutions. 
STOBBE and ScHöNBURG*) assert that the 42°-acid and also the 
58°-acid in the solid state are transformed into the 68°-acid 
on cooling in ice and salt. As the results obtained by me 
would seem to cast doubt on the correctness of this assertion, the 
solid substances, after having been carefully dried, were cooled for 
six days in ice and salt in the flasks with the cotton wool plugs. 
In the case of the 42°-acid the drying was effected by heating the 
flask to 80°—90°. It was observed that none of the three acid forms 
was altered by cooling. As Sroppe and ScHönBurG always worked 
with capillary tubes, a small quantity of the dry acid was introduced 
into a capillary from the flask. After six days cooling this also 
showed no change in the melting point. The solid substances are 
thus unchanged by cooling in this way. If, however, the 42°-acid 
is moist, transformation can take place. To this fact the changes of 
this acid observed by the above investigators are probably due. 
It is difficult to understand the transformation of 58°-acid into 
68°-acid on cooling, as observed by Srospe and ScHönBurG, unless 
one assumes that they used only ten capillaries for the cooling of 
the acid, in which after determined intervals of time the melting- 
point was taken. In that case the possibility is always present that 
42°-acid is formed by the melting, as this takes place more easily 
in capillaries than would appear from the results of these investiga- 
tors (p. 239). From the 42°-acid in a moist state the 68°-acid would 
then be formed. 
As a further result of the investigation may be deduced, that there 
is a great difference between double molecules and nuclei. The 
transformations which have been described take place only in solu- 
1) loc. cit, p. 218, 236. 
