SEMI-TROPICAL FRUITS 205 



indicator. Fill other burette to zero mark with standard alkali solution, 

 and add solution to the 20 c.c. of orange juice, stirring constantly until 

 the color is permanently changed. 



One c.c. of the solution neutralizes approximately 10 m.g. of citric 

 acid. How many m.g. of citric acid are there in 20 c.c. of orange juice? 



Repeat using the juice of the lemon, calculating again the number 

 of m.g. of citric acid in 20 c.c. of lemon juice. How does the amount 

 of acid in a given quantity of lemon juice compare with that in the 

 same amount of orange juice? 



What connection is there between this fact and the taste of each of 

 the two fruits? 



EXERCISE III. Study of varieties. 



Procedure. Get in your neighborhood as many different types and 

 varieties of citrus fruits as you can find. Arrange these in the class-room, 

 being careful that each variety is named. Make a comparative study 

 of the different fruits, recording in the notebook the essential facts 

 regarding each one, such as size, color, shape, period of ripening, suscep- 

 tibility to frost, commercial importance, and any other facts which may 

 be ascertained. 



EXERCISE IV. Advertising citrus fruits. 



Materials. The leading national magazines. 



Procedure. Clip from magazines all the advertisements you can 

 find dealing with citrus fruits. Make a study of these advertisements, 

 noting especially their general appearance and their timeliness, from 

 the standpoint of household use and of crop production. 



It is said that the citrus interests of the country are among the 

 heaviest magazine advertisers. Notice how many advertising pages 

 there are in the periodicals you are examining and calculate the per- 

 centage of the whole contributed by the citrus advertisers. 



EXERCISE V. Citrus projects. 



Procedure. All students having citrus projects should at this time 

 prepare a detailed statement regarding the care of the project and its 

 financial condition. This should be presented to the class in the form 

 of a written and oral report. 



