4 E. BERNER. M.-N. KI. 
In order to obtain measureable crystals of the inactive 122? acid, I pre- 
pared a saturated watery solution (the acid is very easily soluble in water), 
dropped on the surface a few small grains of the same acid and evapor- 
ated the solution in a vacuumexsiccator above sulphuric acid. After a few 
days I obtained a number of crystals, consisting of needles and tables, which 
were removed from the mother liquor and dried between filter paper. 
This inactive acid presents a very interesting case, for it crystallises 
in the monoclinic-sphenoidal class and appears, according to the symmetry 
of this class, in two enantiomorphous forms, which are completely inac- 
tive in solution. Each of these forms has also the same meltingpoint as a 
mixture containing 50 °/, of either. 
This phenomenon seems to be a merely crystallographic one with- 
out any connection with the acid, as a true racemic compound, but only 
a result of the hemihedral symmetry of the class to which it belongs. 
Such a case has till now been known only in compounds not con- 
taining asymmetric carbon-atoms, for example, in Quartz and Sodium 
chlorate. 
As the case may possibly be of another nature, caused by the con- 
tents of two asymmetric carbon-atoms in the molecule, it will be subjected 
to a thorough investigation, as soon as I have worked out a new quantity 
of the acid. 
In my attempts to crystallise the two optically active components of 
the 122? acid, I have hitherto only succeeded in preparing measureable 
crystals of one of them, the dextro-acid. 
As this acid is too soluble in water, this solvent could not be used. 
However, by preparing a dilute solution of the dextro-acid in chemically 
pure methylal, adding to this an equal volume of benzene and evaporating 
this solution slowly above vaseline oil, a mumber of fairly well deve- 
loped crystals were formed. 
The racemic Phenylglycerinic acid. 
Melting-point 122° C. 
Specific gravity (by the Retgers suspension method) r,370. 
The crystals are obtained from a watery solution by 15—17° C. 
Class of symmetry: Monoclinic-sphenoidal. 
Axial angle f = 101° 27‘. 
Ratio of axes: a:b:c= 2,5605: 1: 1,7251. 
Appears in two enantiomorphous forms, which in solution show no 
optical activity. 
