196 FRUIT-SUGAR. 



always be obtained from the latter when sodium chlo- 

 ride is added to it after a sufficient concentration has 

 been reached. 



Grape-sugar is resolved into alcohol and carbonic 

 anhydride by the process of fermentation (p. 42). 

 Nitric acid oxidizes it, forming saccharic, tartaric, and 

 oxalic acids. 



Diacetyl-grapesugar, C 5 H 6 .CHO. Is 



formed when 1 part of grape-sugar is heated with 2J 

 parts acetic anhydride to the boiling point of the latter. 

 Colorless, amorphous, bitter-tasting mass. Fuses 

 below 100. Easily soluble in water, alcohol, and ether. 

 "When heated with water to 160, it is resolved into 

 acetic acid and grape-sugar. 



Triacetyl-grapesugar, C^.CHO. Is 



formed when the preceding compound is heated at 

 140 with twice its weight of acetic anhydride. 

 Solid, white mass, but slightly soluble in pure water, 

 soluble in alcohol, ether, and dilute acetic acid. 



2. Fruit-Sugar. 

 C 6 H 12 6 . 



Occurrence and formation. Together with grape- 

 sugar in honey and the juices of ripe fruits. Cane- 

 sugar is decomposed, by heating with dilute acids, 

 into equal parts by weight of fruit-sugar and grape- 

 sugar. A similar process appears to go on in connec- 

 tion with the ripening of fruits, for in unripe fruits 

 cane-sugar is contained. 



Properties. Not crystallizable ; forms, when dried 

 at 100, a gummy, deliquescent mass. Easily soluble in 

 water and alcohol ; insoluble in absolute alcohol and 

 ether. Its solution rotates the plane of polarization 

 towards the left. Conducts itself towards an alkaline 

 copper solution, and, in connection with fermentation, 

 like grape-sugar. By oxidation with nitric acid there 

 result saccharic, racernic, and oxalic acids. 



