TO TEST FOODS FOR NITROGENOUS SUBSTANCES. 23 



the color of the Fehling's solution 

 when it was boiled with grape- 

 sugar? 



3. How can you determine, therefore, whether 

 or not grape-sugar is present in a given 

 food? 

 B. Application of Fehling's test to various foods. 



1 . Test as many different kinds of foods as you 



can, first treating them with water, boil- 

 ing in a test-tube and then boiling with 

 Fehling's solution (e.g., onions, grapes, 

 both ripe and unripe, pears, granulated 

 sugar, honey, molasses, meat, egg). 



2. Tabulate your results in columns under the 



following heads: 



ii. TO TEST FOODS FOR NITROGENOUS 

 SUBSTANCES. 



(Nitrogenous substances are also known as proteids and albumins. ) 



Materials: White of egg, corn-starch, grape-sugar, mutton tallow ; 

 piece of meat, milk, peas; concentrated nitric acid and ammonia; 

 test-tubes, beaker-glass, thermometer, alcohol-lamp. 



A. Effect of heat. 



i . Pour a small amount of the white of an egg 

 into a test-tube. (White of egg is com- 



