126 CARBOHYDRATES. 



Dissolve some of the fawn-coloured powder in water (note 

 the smell). 



Test with iodine and Barfoed's reagent. 

 Saturate a small quantity of the solution or the iodide 

 with Am 2 SO 4 . 



Basic lead acetate gives no pp. 



Glycogen (animal starch). A sufficiently pure aqueous 

 solution is obtained by killing a rabbit which has been fed 

 three hours before on carrots. The liver is at once removed, 

 chopped fine, and thrown into actively boiling water, where 

 it remains ten minutes. Proteids are removed by acidulating 

 slightly with acetic acid and boiling two minutes longer. The 

 fluid is then strained through mull muslin, cooled, and neutral- 

 ised with sodium carbonate. It should not reduce Fehling. 

 Note how much if any reduction occurs. Examine the solution 

 provided for you as follows : 



1. The solution of glycogen is markedly opalescent. 



2. Add weak iodine to a portion red port colour. Effect of 



heating and cooling? 



3. Saturate some or the iodide with Am 2 SO 4 a flocculent pp 



results. 



4. Boil some in a tube with dilute H 2 SO 4 (0'25 p - c -). Test 



with Fehling. Reduction indicates the formation of a 

 reducing sugar (dextrose). 



5. Barfoed's reagent is not reduced. 



6. Basic lead acetate gives a pp. 



The lead acetate must be basic. To ensure this plumbic acetate is boiled with 

 litharge for ten minutes, the nitrate will be basic lead acetate. 



