54 CARBOHYDRATES [ch. 



{d) Osazone test. Take 10 c.c. of the solution and treat as for glucosazone. The 

 crystals of maltosazone will be found to be much broader than those of glucos- 

 azone. 



(e) Hydrolysis. Take 20 c.c. of the sugar solution and add 2 c.c. of concentrated 

 hydrochloric acid. Heat in a boiling water-bath for half an hour. Neutralize and test 

 for the osazone. Glucosazone will be formed. 



Sucrose. Sucrose or cane-sugar is very widely distributed in plants, 

 in leaves, stems, roots, fruits, etc. It is a white substance which crystal- 

 lizes well, and is soluble in water and alcohol. As previously stated it is 

 hydrolyzed by dilute acids and by invertase into one molecule of glucose 

 and one molecule of laevulose. It is formed by the condensation of glucose 

 and laevulose with the elimination of water. Its constitution is in all 

 probability as follows : 



CH2OH • C • (CH0H)2 • CH • CH2OH 



O 



/ 

 CH • (CH0H)2 • CH • CHOH • CH.2OH 



O 



SO that both the ketone and aldehyde groups are rendered inactive. It 

 does not reduce Fehling's solution and does not form an osazone. It is 

 dextro-rotatory. 



Expt. 46. Tests for cane-sugar. The following tests should be made with a 1 % 

 solution of pure crystalline cane-sugar (see also glucose, p. 50). 



(a) Moore's test. A negative result is obtained. 



(6) Fehling's test. No reduction talies place. 



(c) a-Naphthol test. A positive result is given since sucrose yields laevulose. 



{d) Hydrolysis. To a few c.c. of the solution add a drop of strong sulphuric acid 

 and boil for two minutes. Then neutralize with caustic soda using litmus as 

 indicator. Boil again and add Fehling's solution drop by drop. A reduction takes 

 place owing to the inversion of the cane-sugar by sulphuric acid. 



(e) Seliwanoff^s test. A positive result is obtained owing to the liberation of 

 laevulose. 



Tri- and Tetrasacch abides. 

 Several trisaccharides, condensed from various hexoses or pentoses 

 are known. Raffinose (fructose, glucose and galactose) has been isolated 

 from the seed of the Cotton Plant (Gossypium), from the Beet (Beta) 

 and other plants. Rhamninose (galactose and two molecules of rham- 

 nose) occurs in the fruit of Rhamnus infectoria, Gentianose (fructose 



