211 



little probability of it. According to Kruyt and Van der Linden l ), 

 they seem to occur only to an unappreciable amount in the cases 

 studied up till now, if present in the liquid state. 



Moreover, Shibata 2 ) proved that the absorption of light of the 

 racemic complex cobalti-salts in aqueous solutions and that of their 

 optical antipodes under the same conditions, is exactly the same. 

 This fact seems also to indicate that no such racemic compounds 

 really exist in solutions to any appreciable degree. 



We have seen that as long as the racemoid is stable, the concen- 

 tration of the metastable solution x which may possibly be in tempo- 

 rary equilibrium with a mixture of both components, will be greater 

 than that of the stable solution in equilibrium with the racemic 

 compound at the same temperature. As a complement of this, it may 

 be remarked that the reverse must be the case if the racemoid is no 

 longer the stabler solid phase, as is easily seen from the figures jj-p 

 and 160, when the inactive solution m is compared with /, which is a 

 metastable optically inactive solution, eventually in equilibrium with 

 the racemic substance at the same temperature. Here again the less 

 stable phase has always the greater solubility, as is observed in all 

 such cases. 



Of course it would have also been possible to deduce all 

 these relations from sections through the tridimensional model 

 parallel to the coordinate-planes XOT or YOT respectively, i. e. by 

 means of temperature-concentration-diagrams. This is the method 

 principally followed by Van 't Hoff in his work on the formation 

 and decomposition of double-salts 3 ). 



4. The solution of the problem: why a number of racemoids 

 can be spontaneously resolved by crystallisation and separating 

 both kinds of enantiomorphous crystals separated from each other 

 by selection, while others cannot be separated in this way, must 

 evidently depend on the situation of the transition-temperature. If 

 this lies in the neighbourhood of the temperature of crystallisation 

 and within the range of temperatures where the substances can exist 



!) T. Van der Linden, Ber. d. d. Chem. Ges., 44, 963, (1911); H. R. Kruyt, 

 ibid., 44, 995, (1911); A. Ladenburg, ibid., 44, 1677, (1911). 



2 ) Y. Shibata, Journal of the College of Science Imp. Univ. Tokyo, 37, Art. 2, 

 p. 28. (1915); Y. Shibata and T. Maruki, Journ. of Coll. of Sc. Imp. Univ. 

 Tokyo, 41, (2), (1917). 



3 ) J. H. Van 't Hoff, Vorlesungen iiber Bildung und Spaltung von Doppel- 

 salzen, loco cit. 



