112 LABORATORY EXERCISES 



To another portion of a solution of granulated sugar add 1 

 drop (not more) of concentrated hydrochloric acid. Boil the 

 solution for a few minutes; then add Fehling's solution and boil 

 again. Has the granulated sugar been changed to grape sugar? 



d. Proteids. In a beaker boil half a teaspoonful of white of 

 egg with about a test tube full of water. Note how the pro- 

 teid is coagulated. Pour off the water, and heat the white of 

 egg with dilute nitric acid. How is its color changed? Now 

 put the white of egg into ammonia water. Is the color removed, 

 or made more intense? 



Boil a piece of white woolen yarn in the nitric acid in which 

 you heated the white of egg; then put the yarn into ammonia 

 water. Results? Do the same with a piece of white cheese, 

 or with the curd of sour milk. Results? 



e. Fats. Review the test for fats in Exercise 89, d. Try it 

 with some ground peanuts. 



EXERCISE 102 

 THE MOUTH AND THE THROAT 



Apparatus. A hand mirror, a rubber band. 



a. Read 359, 360, and 361 of the text, also 388. Go 

 through the process of chewing a rubber band, and make a 

 note of all the motions of your tongue, teeth, jaws, cheeks, and 

 the special organs of swallowing. Swallow the saliva and at 

 the same time feel of your throat. What rises in it in the act 

 of swallowing? You can understand these motions better if 

 you stand with your back to a well-lighted window and look 

 into a hand mirror. 



b. Open your mouth wide, and examine the inside by the 

 aid of the mirror. Can you move any part of the roof of your 

 mouth? This is the soft palate. Is it in the front, or the back, 

 of the mouth? 



