206. SOBIN, INOSITE, ETC. 219 



According to the researches of Scheibler, 1 a freshly prepared 

 solution of araUnose possesses a rotatory power (a) D =+121, 

 diminishing, after heating, to +116. It crystallizes, far more 

 easily than dextrose, in rhombic crystals ; but is not directly fer- 

 mentable. Its action on Fehling's solution resembles that of 

 grape-sugar. As already observed Kiliani maintains that arabinose, 

 when treated with nitric acid, yields mucic acid, and is identical 

 with lactose. (This is contradicted by Clsesson.) 



For caragheen-sugar see Bente. 2 It is said to be optically 

 inactive, and to reduce Fehling. 



Galactose, regarded by Fudakowski 3 as a mixture of lactose and 

 another glucose, also belongs to this group. It differs from most 

 other glucoses in yielding mucic instead of oxalic acid when treated 

 with nitric acid. (See also 195,) 



206. Sorbin, Inosite, etc. Sorbin, inosite, and eucalyn differ 

 considerably in their properties from the foregoing sugars, but 

 correspond to the glucoses in formula. 



SorUn can be obtained in colourless crystals, which are freely 

 soluble in water, sparingly in cold spirit. It reduces Fehling, 

 possesses a rotatory power ()/= 46 '9; but is not ferment- 

 able. Sorbin must not be confounded with the sorbite belonging 

 to the mannite group (212). 



Inosite, or phaseomannite, forms colourless rhombic plates melting 

 at 210, soluble at 19 in 6 parts of water, insoluble in cold absolute 

 alcohol and ether. It is not fermentable, does not reduce Fehling, 

 and is optically inactive. 4 When warmed with nitric acid and 

 dried, inosite is said to leave a residue that is coloured purple or 

 blue by ammonia and chloride of calcium. 



Eucalyn has been obtained, up to the present time, only in the 

 form of an uncrystallizable, non-fermentable syrup. It possesses 

 for (a) r a dextro-rotatory power of 65. 5 



1 Ber. d. d. chem. Ges. vi. 612, 1873. 



2 Ibid. ix. 1157, 1876. 



3 Ibid. viii. 599, 1875 ; ix. 42, 1876. 



4 On the occurrence of inosite in the vegetable kingdon (grape- juice) see 

 Hilger, Annal. d. Chem. und Pharm. clx. 333, 1871 (Year-book Pharm. 156, 

 1872) ; also Neugebauer, Zeitschr. f. anal. Chem. xii. 39, 1873. Neugebauer 

 has found inosite in vine-leaves also, and at the same time discusses the detec- 

 tion of quercetin, quercitrin, etc. NucUe, which has been discovered in hazel- 

 leaves, appears to be very similar to inosite (Jahresb. f. Pharm. 167, 1877). 



5 For some other saccharine bodies that have been hitherto but little 

 investigated, such as dambose, etc., see Ber. d. d. chem. Ges. vi. 1314, 1873. 



