104 LABOEATOEY MANUAL 



solution and boil. Do you obtain the same result? 

 Take a fresh solution of cane sugar, add a few drops 

 of hydrochloric acid, then Fehling's solution and boil. 

 How does this result compare with the two preceding? 

 Thus cane sugar is converted into grape sugar by the 

 acid. 



C. Tests for protein : Into a test tube half full of 

 water, place some rav/ egg-white. Heat this over the 

 Bunsen flame. What is the effect of heat on the egg- 

 white ? Pour off the water. Cover the egg-white with 

 dilute nitric acid and boil. What is the color of the 

 egg? Pour off the acid. Add enough ammonia to cover 

 the egg. What is the color produced? 



D. Tests for oil and fat : To four teaspoonfuls of 

 ground flax seed, add an equal volume of benzine or 

 ether. Thoroughly stir the mixture and let it stand 

 for about ten minutes. Filter and place the nitrate 

 aside in a strong draught of air until the benzine or 

 ether has entirely evaporated. What is the substance 

 left? What is the odor? Why are benzine and ether 

 used to remove grease spots from clothing? 



Rub some mutton tallow on the surface of a piece of 

 unglazed paper. Hold the paper over a Bunsen flame 

 to melt the fat. Then hold it to the light. What is 

 the effect of fat or oil on paper? Summarize the tests 

 you have learned for protein, starch, sugar, fat. 



Exercise 70. Foodstuffs in Common Foods. 



Object: To determine the foodstuffs found in some 

 foods. 



