252 



cessive binary axes; moreover there is a symmetry-centre, and the 

 whole symmetry is that of class D^. In a molecule of the formula // 

 there is a heteropolar senary axis perpendicular to the plane of 

 the ring, and six vertical planes of symmetry passing through it, 

 but there is no symmetry-centre, and the whole configuration has 

 the symmetry of the Class C V 6 . As both configurations have symme- 

 try-elements of the second order, there is of course no possibility 

 of resolving the optically inactive substance into active antipodes, 

 the arrangements being both congruent with their mirror-images. 

 The same would be true for inosites with configurations as: 



and 



HE. 



where /// has the symmetry of class C^, and IV that of the class S, 

 both belonging to those figures which are superposable with their 

 mirror-images. Inosites of this kind should therefore not be resolvable. 

 Such is the inactive, non-resolvable inosite: phaseomannite 1 ) which, 

 according to Villiers' and Von Zepharovitsch' investigations, 

 crystallises in the holohedral class of the monoclinic system; further 

 quercine (mtpt: 301 C.), and cocosite (mpt: 350 C.), which show 

 the same crystallographical symmetry. Somewhat similar is the 

 case of quercite : C 6 H 7 (OH) 5 (mpt. : 225 C.) which crystallises in the 

 domatic class of the monoclinic system 2 ). 



The case of the optically active inosites is very well suited for 



1) G. Tanret, Compt. rend, de 1'Acad. d. Sc. Paris 84. 393. (1877); 86. 486. 

 (1878); Ann. de Chim. et Phys. (-5). 23. 391. (1881); V. Von Zepharovitsch, 

 Sitz. Ber. d. Akad. d. Wiss. Wien, 58. (//). 121. (1868); A. Villiers, Compt. rend. 

 84. 393. (1877) ; G. Wyrouboff, Bull, de la Soc. Min. 25. 169. (1902). J. V. Lewis, 

 Proceed. Cryst. Soc. London, 2. 49. (1882); Ref. Zeits. f. Kryst. 1. 406. (1877); 2. 

 190. (1878); 3. 105. (1878)); 6. 276. (1881); 39. 316. (1904); G. Friedel, Compt. 

 rend, de 1'Acad. d. Sc. Paris, 105. 95. (1887); G. V. Barker, Journ. Chem. Soc. 

 London 91. 1789. (1907). 



2) G. Prunier, Ann. de Chim. et Phys. (5). 15. 1. (1878) ; Compt. rend. 85. 808. 

 (1878). There are agreeing measurements made by J. V. Lewis, H. de Senarmont, 

 W. G. Hankel, C. Bodewig, and R. de Neufville; cf. also: R. Bohm, Archiv 

 der Pharmac. 235. 662. (1897). 



