294 



in solutions are at any rate dissociated to a large extent, in some 

 cases totally, into their optical antipodes, and as inactive mixtures 

 will of course only act, therefore, as if their right- and left-handed 

 components were completely free, - - the action of such inactive, 

 resolvable substances upon optically active ones thus belongs here, 

 and not among the cases dealt with in the preceding paragraphs. 



In the first place we may remark that in general the affinity- 

 constants of two antipodes A and A' with respect to another 

 substance B, appear to be the same in all cases, even if B itself 

 is an optically active compound. In the last case, however, there 

 will be a certain difference of reaction- velocities, because the products 

 formed are no longer mirror-images of each other. The speed with 

 which AB is formed, need not be the same as when AB' is 

 produced. l ) 



Therefore, if an optically active compound B acts upon a 

 racemic or externally compensated substance A A' (or A + A'), 

 and if the reaction, be stopped at a well-chosen moment before 

 completion, it will turn out, that wwequal quantities of AB andA'B 

 will have been produced during that lapse of time, and thus, if the 

 mixture AB + A'B be isolated and B removed from it, the sub- 

 stance A A' obtained will no longer be optically inactive, but will 

 show a positive or negative rotation, because there is now some 

 excess of one of the antipodes A or A'. Of course, if the original 

 compound A A' which has not yet combined with B, be examined 

 now, it will also show an optical activity which is opposite to that 

 found with the portion of A A' attacked, because there is now an 

 excess of the other antipode A' or A in the mixture. 



l ) L. Mam lock, Stereochemie, page 33, (1907); A. Werner, Neuere An- 

 schauungen auf dem Gebiete dev anoYganischen Chemie, 3e Aufl., page 313, 

 (1913); A. F. Ho 11 em an, Receuil des Trad. d. Pays-Bas, 32, 175, (1913); 

 J. Stark, Jahrb. fiir Electr. und Radioact., 11, 206, (1914). Of course, the 

 fact .that the affinities are the same between A and B, and between A' and B, 

 need not exclude the possibility of unequal reaction-velocities in both cases. In 

 the reactions: 



A + B ~^LAB, and: A' + B~j*~ A'B. 



the velocities are characterised by he velocity-constans Aj and k^, and k 2 and 

 k' 2 . The affinities, however, are expressed by a relation of the form: RTlnK, 

 in which the equilibrium-constant K is the same for both reactions and equal to 



*i * 2 



_JL or to JL. 



k'l k' 2 



Now (j k\] and (k z k' 9 ) can very well be different from each other, while 

 the quotients are in both cases the same. 



