241 



the central carbon-atom is of course very improbable, although 

 it need not be considered as wholly impossible. 



15. According to the Van 't Hoff-Le Bel- theory therefore, 

 the possibility always exists of a chemical substance occurring in 

 two enantiomorphously related isomerides, as soon as a plurivalent 

 asymmetric atom of the kind just described is present in its molecules. 



As already pointed out, this doctrine has proved admirably far 

 reaching: for not only have hundreds of such carbon-compounds 

 been since resolved into their antipodes, but also in the case of other 

 plurivalent atoms than carbon, it has been proved to hold absolutely. 



J. H. Van 'tHoff. 

 18521911. 



J. A. Le Bel. 



Its truth was upheld in the case of the asymmetric pentavalent 

 nitrogen-atom, as Le Bel, Kipping, Pope, Wedekind, Aschan, 

 and many others, have demonstrated in a series of admirable 

 investigations ! ). 



l ) J. A. Le Bel, Compt. rend, de 1'Acad. d. Sc. Paris, 112, 725, (1891); E. 

 Wedekind, Zur Stereochemie des funfwerttgen Stickstoffs, Leipzig, (1899); 

 W. J. Pope and S. J. Peachy, Journ. Chem. Soc. London, 75, 1207, (1899); 

 79, 828, (1901); W. J. Pope and A. W. Harvey, Proceed. Chem. Soc. London, 

 17, 120, (1901); Proc. Cambr. Phil. Soc., 12, 466, (1904); H. O. Jones, Journ. 

 Chem. Soc., 83, 1400, (1903); E. Wedekind and E. Frohlich, Ber. d. d. Chem. 



16 



