44 LABORATORY EXERCISES. 



b. Examine a drop under the compound 



microscope as directed above. Do 

 you see any difference between this 

 mixture and that formed in B i 

 above? 



c. Taste of the mixture. What kind of 



substance has been formed? 

 2. What is meant by saponification? 



D. Effect of acids and alkalis on fats. 



1. Pour a little melted butter into each of two 



test-tubes. Add to test-tube No. i 

 some diluted hydrochloric acid; to test- 

 tube No. 2 some sodium carbonate solu- 

 tion. Shake both tubes well, and allow 

 them to stand for a few moments. 



2. Does the butter remain mixed better with 



an acid or with an alkali? Why, then, 

 dre fats not digested in the stomach? 



E. The digestive action of bile. 



1. Test with litmus paper the bile solution. Is 



it acid, alkaline, or neutral? 



2. Pour a little melted butter into a test-tube ; 



add some of the bile solution. Does the 

 mixture resemble that formed in B i or 

 B 3 above? 



3. Examine a drop of the mixture under the 



compound microscope. Does this ob- 

 servation agree with that made in 2 just 

 above? 



4. Pour a little thin starch paste into a test- 



tube ; add some bile, and after a time test 

 the mixture with Fehling's solution. 

 Does the bile act upon starch? 



