124 GLYKOKOLL. 



and press. Precipitate the filtrate with four or five 

 times its volume of 90% alcohol. Yellowish white 

 flocks will be precipitated. These are well washed 

 with alcohol and then boiled for half an hour or an 

 hour with solution of caustic potash; dilute the 

 solution with a small quantity of water and add four 

 or five times its volume of 90% alcohol. The glykogen 

 is precipitated and, by washing with alcohol is obtained 

 tolerably pure. 



2. Mince a liver and boil, &c., as before, allow the 

 extract to cool, and add glacial acetic acid, when the 

 glykogen will be precipitated ; filter off and dry. Grly- 

 kogen is a white mealy powder ; it exhibits no definite 

 structure under the microscope. 



3. It is soluble in water, insoluble in alcohol. 



4. Boil glykogen with some dilute hydrochloric acid, 

 it will be transformed first into dextrine and finally into 

 grape sugar. This transformation can be detected by 

 the reducing action of sugar on alkaline copper solu- 

 tion. (See Dextrine, &c.) 



5. Boil an aqueous solution with a solution of 

 caustic potash to which a drop of dilute solution of 

 copper sulphate has been added. The copper salt will 

 not be reduced. 



6. Add to an aqueous solution a drop of dilute 

 tincture of iodine ; a violet-red colour is produced. 



Glykokoll, C 2 H 5 N0 3 . 1. Boil glue with caustic 

 potash. Ammonia is evolved in large quantity. Add 

 sulphuric acid till the liquid is neutral ; evaporate, 



