6 BULLETIN- 335, U. S. DEPAETMENT OP AGEICULTUEE. 



nations were made as far as possible on the same day, or at least the 

 manipulation was carried to a point where any change in composition 

 would not affect the determination. All the determinations were 

 completed within 36 hours after crushing the fruit. 



Diluting the samples keeps the juice more nearly normal, pre- 

 venting precipitation of tartar, which may occur if the sample should 

 stand for some hours. The diluted sample can be filtered much 

 more readily than the undiluted juice, and in case of colored juices a 

 clearer end point is obtained when the sample is titrated for acidity. 



While the analyses made in 1912 were confined to three varieties, 

 the work was extended to include complete analyses of the fruit of 

 two varieties, as well as the analyses of the juice samples as hereto- 

 fore made. First, an analysis of the juice sample was made in the 

 manner detailed for 1911, and the results for 1912 are in all respects 

 comparable with the data for that year, save that the total tartaric 

 acid for 1912 was obtained by the method of half neutralization 

 proposed by Hartmann and Eoff .* 



It is evident that the analysis of a juice sample does not furnish 

 final data on the composition of the entire fruit, because it is impos- 

 sible to secure, by crushing and pressing a sample of the fruit, all of 

 the constituents of the berries. This method secures only such as 

 are in solution in the juice sample recovered. While the results for 

 many constituents when the juice and whole-fruit sample are com- 

 pared are somewhat similar, there are some important variations. 



For the sample for whole fruit analyses in 1912, taken at the same 

 time and from the same fruit selected for the juice sample, the berries 

 were carefully clipped with sharp scissors from the stems at the 

 junction of the fruit with the pedicels, care being taken not to break 

 the skin of the fruit. A sample of 800 to 1,000 grams was prepared 

 in this manner. The berries were held in a large piece of cheese- 

 cloth and rolled to and fro until they were thoroughly mixed, then 

 from different portions of the mass two samples of 100 grams each 

 were taken for duplicate determinations of the organic constituents, 

 and three samples of 100 berries each for triplicate weighings and 

 measurements of volume of the fruit. The several samples required 

 for burning direct to secure the ash samples were also taken at this 

 time. 



The samples for the organic determinations were exhausted in dis- 

 tilled water as follows: Each was placed in a cheese-cloth square and 

 tied firmly with twine, so that the fruit was confined in a ball. 

 These were suspended in 500 cc beakers containing about 200 cc of 

 distilled water, placed over a flame, and kept constantly at boiling 

 temperature. After 10 to 20 minutes the water containing the solu- 

 tion extracted from the fruit was removed to a large porcelain 



i U, S. Dept. Agr., Bur. Chem., Bui. 162, pp. 71-77. 



