264 



rhodium-tri-oxalic acid, for which the possibility of a fission into 

 the optically-active components had been proved experimentally ^). 

 Moreover, a detailed investigation of these salts appeared also desi- 

 rable from another point of view, because in Werner's original 

 paper some facts are mentioned concerning the crj'stallisation-phe- 

 nomena of the optically-active components, which a priori must be 

 considered very improbable, and therefore worth controlling again 

 by means of new experiments. 



For instance, the fact was there brought to the fore, that from 

 solutions of the racemic compound under favourable conditions crystals 

 of both the enantiomorphous modifications would be deposited spon- 

 taneously, which hemihedral crystals of the optically active compo- 

 nents, if brought at room-temperature into a concentrated solution 

 of the racemoid, would increase slowly and grow to big individuals 

 within a few weeks. But, as we found during our investigations, 

 that the optically active forms are much more soluble under the 

 same circumstances than the racemic substance is, it seemed higiily 

 probable that an error was made here, because, moreover, the facts 

 mentioned cannot be right from a theoretical standpoint. The draw- 

 ings in Werner's paper, intended to give an impression of the 

 crystal-forms obtained, rather point to distorted, and accidentally 

 non-superposable tricUnic crystals of the racemoid being present here, 

 than to enantiomorphous crystals of true hemihedral symmetry. 

 Moreover, Werner himself mentions the triclinic symmetry of these 

 crystals, and therefore the validity of Pasteur's principle in his 

 case cannot yet be considered as proved by the data given in this 

 paper. Repeatedly we have made attempts in the way indicated by 

 Werner, to perform a spontaneous fission of the racemic salt; but 

 the solution of it saturated just above 100° C, first being rapidly 

 cooled down to OO'' C, and subsequently cooled down to room- 

 temperature, never deposited other crystals than the capriciously 

 distorted individuals of the triclinic racemoid. The microscopically 

 small crystals often obtained by very rapid cooling of the hot 

 solution, appeared to be no crystals of the active forms either; they 

 were rhombic individuals exhibiting prismatic, domatic and basal 

 facets, of a new hydrate of the racemic compound, probably at higher 

 temperatures stable, and containing less water of crystallisation. 

 These experiments, if varied in several ways, gave unexceptionally 

 bigger or smaller crystals of the racemic compound. The appreciably 

 greater solubility of the active forms in comparison with that of 



1) A. Werner, Ber. d. d. Ghem. Ges. 47. 1954. (1914). 



