CHEMICAL ANALYSES OF LOGAN BLACKBERRY JUICES. 5 
TOTAL P.O; IN ASH. 
This determination was made by the optional volumetric method! 
TOTAL ACIDITY. 
Ten cubic centimeters of juice was diluted with 50 cubic centi- 
meters of boiled distilled water, and titrated with N/10 alkali, using 
neutral litmus paper outside the flask as an indicator. The mixture 
of dry phenolphthalem and sodium sulphate? was not satisfactory 
as an outside indicator, because of the deep color of the samples. 
The total acidity of the samples analyzed in Seattle was determined 
by using azolitmin as an indicator, and the volatile acidity was taken 
as the difference between the total and fixed acidity. 
ADDED SUGAR. 
Because of the presence of large amounts of added sugar in the 
commercial beverages and sirups, weight dilutions of these materials 
were made, and the analyses carried out on the dilute solutions. 
For sirups, the most convenient dilutions were from 50 to 100 grams, 
made up to 500 cubic centimeters. 
ORGANIC ACIDS. 
The organic acids in a number of samples were determined by the 
following method: After a preliminary precipitation of the pectins, etc., 
by alcohol, in a 25-cubic-centimeter portion of the juice, the filtered 
solution was neutralized with a strong barium hydroxid solution, 
and an excess of barium acetate added. Coagulation of the barium 
salts was effected by heating the material on a water bath for from 1 
to 2 hours. The barium salts were filtered off, and washed with 95 
per cent alcohol. 
For the determination of citric acid, the barium salts were de- 
composed with a slight excess of 1:4 sulphuric acid, and the Kinz 
method* applied. The values for citric acid thus obtained are practi- 
cally the same as those for the total acidity by titration, calculated 
to citric acid. 
For malic and tartaric acids separate portions of the barium salts, 
prepared as described, were decomposed by heating the material 
with an excess of sodium sulphate. A test for malic acid was made 
by the polariscope method.* No evidence of the presence of this 
acid was found. 
For tartaric acid the barium salts, prepared as already described, 
were decomposed with sodium sulphate, the solution concentrated to 
1U.8. Dept. Agr., Bur. Chem, Bul. 107, rev., 4. 2 Jour. A. O. A.C. (1915) 1, 3: 485. 
Jour. A. O. A.C. (1916) 2, 2: 182. 
