264 



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 # 7 (0#) 5 (mpt. : 225 C.), which crystallises in the 

 domatic class of the monoclinic system J ) . 



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

 the purpose of giving full evidence, that not the presence or absence 

 of an asymmetric carbon-atom in the chemical molecules, but 

 only the special circumstance, according to which the atomistic 

 configuration of the molecule as a whole has only axial symmetry or 

 not, is a decisive one for answering the question, whether the 

 molecule may be considered as resolvable into optically active 

 components or not. As a full proof, that even the existence oino 

 carbon-atom whatsoever is necessary for this, we will mention here 

 Werner's dodecamine-hexol-teira-cobalti-bromide: 2 ) 



n 'pro 



Co\ HQ CoiNH^ 



in which the complex: Co 



(HO), 



evidently plays the same role 



as the triethylenediamine-complex does in the luteo-salts mentioned 

 previously. The molecular rotatory power of the active components 

 of this substance amounts to a value of about 47600; its rotation- 

 dispersion is, moreover, remarkably abnormal. 



25. In this respect some other examples are of interest, which 

 are related to cases, where double bonds between carbon-atoms form 

 part of the peculiarities of the molecules, or where a single carbon- 

 atom is common to two different rings (see p. 260). 



A case of the first kind was already mentioned by Van 't Hoff, 

 namely in carbon-derivatives of the following structure: 



A\ /A 



B B 



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). 



1 ) 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. deSetiarmont, 

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

 der Pharmac., 235, 662, (1897). 



2 ) A. Werner, Ber. d. d. Chem. Ges., 47, 3087, (1914). 



