EFFECTS OF FREEZES ON CITRUS IN CALIFORNIA 301 



Definite points on which information was desired were: (1) Do 

 all frozen fruits have a lower specific gravity than any sound fruit? 

 (2) If so, is the difference great enough to make it possible to separate 

 the two classes absolutely? (3) How soon after the freeze is it possible 

 to detect any difference that may occur? (4) What changes occur in 

 the specific gravity of the fruit if it is picked from the tree and 

 stored? (5) What explanation can be given of these changes? 



The specific gravity of the individual fruits was found by dropping 

 them in alcohol of varying specific gravity until that of the fruit and 

 the alcohol was the same. Jars were prepared containing alcohol of 

 specific gravity from .82 to .97 varying from each other by .01. The 

 results obtained are summarized in table 5. For the sake of clearness 

 only the figures for the best and worst fruit are presented. The inter- 

 mediate classes of fruit which were only partially frozen, gave results 

 which were in complete agreement with those presented. 



TABLETS. Average Specific Gravity of Fruit. 



The first two columns in table 5 present the record of the oranges 

 picked on January 13 and kept in storage, the specific gravity of the 

 fruit being determined every four days. The average specific gravity 

 of the stored navel oranges which were unfrozen incerased from .876 

 on the date of picking, to .936 on February 27. The average specific 

 gravity of the badly frozen oranges in storage decreased from .850 

 on the date of picking to below .820 on February 3.* The third and 



* A specific gravity of .820 was the lowest determined with the jars of alcohol. 

 Where a lower specific gravity is shown in the tables it is of special fruits. 



