296 



optical antipodes of carvoxime in dextro gyratory limonene as a solvent, 

 and could not find any distinct differences. The partial separation 

 of an externally compensated mixture of the ammonium-sodium- 

 tartrates in solutions of dextrose, as described by Kipping and 

 Pope J ), seems, however, a fact in contradiction to this, so that a 

 new investigation of the solubilities under these circumstances 

 appears necessary. On diffusion-velocities of active substances in 

 optically active solvents no investigations have hitherto been made. 



The experiments on the solubilities of such antipodes in active 

 solvents just referred to, may give some insight into the causes 

 of the negative results hitherto obtained in all attempts to 

 find a difference in reaction- velocity for both antipodes, if optically 

 active liquids be used as solvents. 



The influence of the solvent on the reaction- velocity is still a 

 very obscure problem. It may be a pure "catalytic" one 2 ), in the 

 sense in which this expression is commonly used, when there is 

 no further explanation possible for the questions at hand. 



If so, the final equilibrium will not be influenced by the 

 presence of such a solvent, and there seems to be only a slight 

 chance that any positive result can be expected from the experi- 

 ments indicated above. 



Secondly, the solvent may really take an active part in the 

 reaction, for instance by means of the intermediate formation 

 of unstable compounds with the molecules of the reacting sub- 

 stances. In such cases also an influence upon the final state of 

 equilibrium will be present, or at least, may be present. If 

 B represents the solvent, such a case may occur when there is 

 an appreciable difference in solubility between the thus formed 

 compounds AB n and A'B n in the optically active medium. But 

 as we have seen in the preceding pages, this difference, if present 

 at all, seems in general not to be very great, and even in this 

 more favourable second case, therefore, no great expectations of 

 positive results in experiments of the above mentioned kind 

 should be entertained. 



Experiments to demonstrate the existence of such differences 

 in reaction-velocity, if the processes go on in a dissymmetrical 

 medium, have already been made from time to time. 



*) F. S. Kipping and W. J. Pope, Proceed. Chem. Soc. London, (1897). p. 113. 

 2 ) J. H. Van 't Hof f, Vorlesungen uber theoretische und physikalische Chemte, 

 I, (1898), p. 210, 216, 218. 



