262 



in resolving the trans-hexa-hydrophtalic acid by means of its quinine- 

 salt, and measured the optical rotation of both antipodes. 



Here the fission of trimethylene-dicarboxylic acid by Buchner 

 and Von der Heide 1 ), and that of the corresponding tricarboxylic 

 acid, may again be mentioned, as being also in full accordance with 

 the theoretical predictions. 



24. Again another remarkable case is found in the inosites, 2 ) 

 which have the composition: C & H Q (OH}^, and which must be con- 

 sidered to be hexa-hydroxy-hexa-hydro-benzenes. Besides a racemic 

 substance which, according, to Wyrouboff 3 ), crystallises in the 

 holohedral class of the monoclinic system, two optical antipodes: 



OH' H 



^^Ji fi^Xj 



F : P^ H - 



are known, which crystallise (+ 2H 2 0) in the rhombic system, 

 although no hemihedral forms could hitherto be obtained. The 

 molecule of this cyclic compound does not possess, properly speaking, 

 an asymmetric carbon-atom at all, at least not in the sense of Van 

 't Hoff's and Le Bel's theory. The whole configuration, however, is 

 such, that there is only a single binary axis of the first order, the 

 direction of which is indicated in the formula by a dotted line. The 

 symmetry of both molecules is, therefore, that of the cyclic group C 2 ; 

 the atomistic arrangement, having thus only axial symmetry, must 

 be different from its mirror-image, and the occurrence of the dextro- 

 and laevogyratory forms of inosite is in this way easily explained, 

 notwithstanding the fact, mentioned above, that no true asymmetric 

 carbon-atoms are really present. 



Of course optically inactive, non-resolvable modifications will be 

 also possible in the case of the inosites. If the subsitutest be placed, 

 as follows for instance: 



!) E. Buchner and R. Von der Heide, Ber. d. d. Chem. Ges., 38, 31 12, (1905). 

 2) L. Maquenne, Ann. de Chim. et Phys., (6), 29, 271, (1893); G. Tanret, 

 Cojnpt. rend, de 1'Acad. des Sc. Paris, 109, 908, (1899). 



8 ) G. Wyrouboff, Bull, de la Soc. Miner., 25, 169, (1902). 



