PART II 

 THE INCOME OF ENERGY 



I FERMENTATION 

 HYDROLYSIS OF STARCH BY DIASTASE 



Conversion of Starch to Sugar by Germinating 

 Barley. To 5 grams crushed, germinating barley 

 add 10 grams potato starch, and 20 c.c. of cold 

 water. Then add gradually 70 c.c. of hot water 

 with constant stirring. Keep the mixture in a 

 temperature of about 60 C. for one hour. 



The insoluble starch will be converted to a 

 sweet liquid. 1 



Boil 10 c.c. of Fehling's solution, 2 dilute the 

 syrup with water and add it drop by drop to the 

 boiling Fehling's solution. 



1 Kirchoff : Schweigger's Journal fur Chemie und Physik, 

 1815, xiv, p. 389. There is a small amount of sugar and starch 

 in the barley itself. 



2 Fehling's solution. In a large watch glass weigh 34.639 

 gms. pure cupric sulphate (clean crystals). Dissolve the crystals 

 by warming them with about 150 c.c. water in an evaporating 

 dish. Place the solution in a 500-c.c. measuring flask. Wash the 

 remnant from the dish into the flask. Allow the liquid to cool 

 completely. Add water to the mark on the neck of the flask. 



Warm about 173 gms. potassium sodium tartrate in a little 

 water until dissolved. Place the solution in a 500-c.c. measur- 

 ing flask, add 100 c.c. sodium hydroxide, sp. gr. 1.34 (about 

 31 per cent), and, after the mixture has completely cooled, fill 

 the flask to the mark on the neck. 



In use, mix equal volumes of each solution in a dry glass. 



One molecule grape sugar reduces five molecules cupric oxide 

 to cuprous oxide ; 10 c.c. of Fehling's copper sulphate solution 

 equals 0.05 gm. grape sugar. 



