293 



quence; and every thing evidently depends on the relative effect 

 of this distortion in comparison with that necessary to cause a 

 real interchange of place leading to a consequent inversion of the 

 stereometrical arrangement round the asymmetric carbon-atom. 



The important recent researches of Senter 1 ) demonstrate con- 

 vincingly that the difficulty is yet much greater than has been 

 hitherto realised, and that the phenomenon itself is also much more 

 complicated than was at first thought. This author found that, if 

 in optically active ammonium-phenvl-chloro-acetate the chlorine-atom 

 is sustbituted by an amino-group, optically active products will 

 result, whose rotation is positive or negative, according to the special 

 nature of the solvent taken as reaction-medium. He stated, for 

 instance, that if water were used as a solvent, the product had the 

 opposite direction of rotation to that of the original substance ; 

 whereas if aceto-nitrile were the solvent, the resulting amino-derivative 

 showed a rotation of the same kind as before. 



Later a dozen optically active solvents were investigated in 

 this way, and the fact referred to above was clearly confirmed. 

 Senter concludes that it is becoming more and more evident, 

 that a satisfactory explanation of the Wai den-in version is not 

 likely to be reached at present, and that it must be considered 

 premature to enter now upon a full discussion of the significance 

 of the results obtained with respect to this highly interesting 

 phenomenon which, beyond all doubt, also plays an important 

 role in the chemical synthesis of the living organisms. 



5. Now we have to consider the two remaining cases: when 

 an optically active molecule acts upon an inactive one so as to 

 produce a new asymmetric carbon-atom in the already active 

 molecule, and the other case, when an optically active molecule 

 acts upon another optically active substance, or upon a substance 

 which is either externally compensated or racemic. 



Indeed, among these reactions we can safely include those, 

 where an optically active substance also acts upon a racemic or 

 an externally compensated substance. For as racemic compounds 



1) G. Senter, Journ. Chem. Soc. London, 107, 638, (1915); G. Senter and H. D. 

 K. Drew, 109, 1091, (1916); G. Senter and S. H. Tucker, Journ. Chem. Soc. 

 London, 109, 690, (1916); G. Senter and G. H. Martin, ibidem, 111, 447, (1917); 

 113, 140, (1918); G. Senter, H. D. K. Drew, and G. H. Martin, ibid., 113, 

 151, (1918).; G. Senter and S. H. Tucker, Journ. Chem. Soc. London, 

 .113, 140, (1918). 



