233 



Pope, Kipping and their collaborators were able to proof the 

 validity of these views also in the case of the asymmetric tetravalent 

 snlf>/iur-B.tom 1 ), of the asymmetric selenium-atom 2 ), of the asymmetric 

 tin-atom*), while the work of Kipping 4 ) on the asymmetric silicium- 

 atom has splendidly confirmed the truth of this doctrine in these cases 

 too. Moreover, for the pentavalent phosphorus-atom, if asymmetric, 

 the analogous fact was proved by Meisenheimer and Lichten- 

 stadt 6 ), and by Kipping 8 ); so there can be no doubt whatever 

 as to the general correctness of the view that all higher-valent (t>3) 

 atoms may eventually reveal the said phenomenon. 



As the subject of the application of Van 't Hoff-Le Bel's- 

 theory to organic chemistry, and to the numerous particulars and 

 special cases of isomerism in this field, e. g. with unsaturated com- 

 pounds and the derivatives of trivalent nitrogen, etc., is too 

 large to be dealt with in detail in this book, the reader must for 

 that purpose be referred to the many text-books on stereochemistry 

 now in use. It need only be remarked that a final result as to the 

 arrangement of the radicals round the asymmetric pentavalent 

 nitrogen-atom, could up till now not be obtained from the study 

 of the possible isomerides in the case of such compounds as: 

 N v (abode), N y (a 2 bcd), and N v (a 3 bc).' 1 ) Much work in this field 

 remains yet to be done. 



16. The foregoing leaves the impression that the truth of 

 Pasteur's first postulation, namely: the general and constant 



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. 

 Ges. 38. 1838. 3438. (1905); M. Scholtz, Ber. d. d. Chem. Ges. 37. 3627. (1904); 

 38. 1289. (1905); F. S. Kipping, Journ. Chem. Soc. London 83. 873, 918. (1903); 

 O. Aschan, Zeits. f. phys. Chemie, 46. 293. (1903); A. W. Harvey, Joum. 

 Chem. Soc. 87. 1481. (1905), W. J. Pope and J. Read, Journ. Chem. Soc. London 

 101. 519. (1912). 



i) W. J. Pope and S. J. Peachy, Journ. Chem. Soc. 77. 1072. (1900); S. 

 Smiles, ibid. 77. 1174. (1900). 



'!) W. J. Pope and A. Neville, Journ. Chem. Sor. 81. 1079. 1552. (1902). 



3) W. J. Pope and S. J. Peachy, Proceed. Chem. Soc. 16. 42, 116. (1900); 

 Cf. : A. Werner, Lehrbuch der Stereochemie, p. 316. 



<) F. S. Kipping, Journ. Chem. Soc. 91. 209, 717. (1907); 93. 457. (1908); 

 95. 69, 408. (1909). 



6) J. Meisenheimer and L.Lichtenstadt, Ber. d.d. Chem. Ges. 44. 356.(1911). 



6) F. S. Kipping and F. Challenger, Journ. Chem. Soc. London, 99. 626. (1911). 



7) F. S. Kipping, Journ. Chem. Soc. London, 88. 873, 918. (1903). 



