GLYKOSE. 125 



separate the potassium sulphate, which will crystallise 

 out ; evaporate the clear liquid to dryness. Exhaust 

 the residue with hot alcohol ; allow to cool ; the gly- 

 kokoll will crystallise out. 



2. Boil hippuric acid for half an hour with strong 

 hydrochloric acid, dilute the liquid with water, and 

 allow to cool. The benzoic acid will separate in crys- 

 tals ; decant the clear liquid, treat with ammonia, and 

 evaporate on a water bath; wash the dried residue 

 with alcohol; the glykokoll is left in a crystalline 

 powder. 



3. Glykokoll crystallises in hard granular crystals ; 

 it has a sweet taste. 



4. It dissolves with difficulty in water ; it is inso- 

 luble in absolute alcohol. 



5. Pass nitrous acid into a solution of glykokoll. 

 The whole of the nitrogen is evolved, and glykollic 

 acid (C 2 H 4 3 ) is formed soluble in ether. Shake the 

 liquid with some ether ; allow to stand ; draw off the 

 ethereal layer with a syphon; evaporate, when the 

 crystallised glykollic acid is left. 



6. Boil an aqueous solution of glykokoll with copper 

 oxyde ; a copper salt is obtained, which crystallises out 

 in blue crystals, turning green when dried at 100C. 



GlyJcose or Glucose, C 12 H 34 13 . 1. Boil twenty 

 grammes of starch with eighty c.c. of water, add one to 

 two grammes of concentrated sulphuric acid, and boil for 

 twenty-four hours, adding water as the solution eva- 

 porates. Add calcium carbonate to neutralise the free 

 acid, allow to stand, decant, and evaporate the 



