APPENDIX K 

 DETERMINATION OF REDUCING SUGARS 



REAGENTS. REQUIRED 



1. Copper sulphate solution. Dissolve 34.639 g. of crystallized cop- 

 per sulphate in water and dilute to 600 cc. 



2. Alkaline tartrate solution. Dissolve 173 g. of Eochelle salts and 

 126 g. of potassium hydroxide in water and dilute to 600 cc. 



GRAVIMETRIC METHOD FOR THE DETERMINATION OF 

 DEXTROSE (ALLIHN) 



Place 30 cc. of the copper solution, 30 cc. of the alkaline tartrate 

 solution, and 60 cc. of water in a beaker and heat to boiling. Add 

 25 cc. of the solution of the material to be examined (which must be 

 so prepared as not to contain more than 0.250 g. of dextrose) and boil 

 for two minutes. 



Prepare an asbestos felt at least half a centimeter thick in the 

 bottom of a Gooch crucible. Wash the asbestos thoroughly with 

 water to remove small particles, then with 10 cc. of alcohol and 10 cc. 

 of ether. Dry the crucible and contents thirty minutes in a water 

 oven at the temperature of boiling water ; cool and weigh. 



Filter the precipitated cuprous oxide through the asbestos felt and 

 wash thoroughly with hot water, then with 10 cc. of alcohol and 

 finally with 10 cc. of ether. Dry the crucible and contents thirty 

 minutes in a water oven at the temperature of boiling water ; cool 

 and weigh. 



The weight of cuprous oxide multiplied by 0.8883 gives the weight 

 of metallic copper. From either figure the corresponding weight of 

 dextrose is found from the following table : 



154 



