CHEMICAL ANALYSES OF LOGAN BLACKBERRY JUICES. 3 
mass. This material is then pressed like fresh pulp. The second- 
pressing juices thus obtained have a high color, and are used with 
first-pressing juice for further blending. Often the juice from the 
presses is passed through a continuous sterilizer and placed in cans 
for storage. 
Because of variations in the flavor and character of the juice at 
different periods of the season, all juices are blended before being 
bottled. This is done by racking off the cans, filtering the juice 
through a mechanical filter, and then sending it to the blending and 
mixing tanks, whence it goes to the bottling machine. After bottling 
the juice is pasteurized by heating it to from 165° to 180° F., for 
periods varying with the size of the bottles. It is then labeled for 
the market. 
Some of the sweetened but undiluted juices have been described 
as " concentrated " on the commercial labels. This description is 
entirely unwarranted, as there is no evidence that any of them have 
been concentrated or evaporated, and they should properly be 
described as Logan blackberry sirup. 
PURPOSE OF THE INVESTIGATION. 
The object of the investigation herein reported was to establish 
methods for the detection of dilution common in commercial products 
made from the Logan blackberry, and to set analytical standards for 
such products. Before the inauguration of this work the only analyses 
of Logan blackberry juice appear to be those by Lewis and Brown, 1 
giving merely specific gravity, acidity, and total sugar. Since then, 
two articles by Daughters, 2 giving analyses of the berries, the 
exhausted marc, and several samples of the juice, have appeared. 
PREPARATION OF THE ANALYTICAL SAMPLES. 
In the workconducted during the season of 1916 berries grown in 
Washington and Oregon were examined; during 1917 the California 
berries were analyzed. In 1916 the juice of fresh berries from various 
places, bought on the open market in Seattle, was expressed in the 
Seattle laboratory of the Bureau of Chemistry, filtered through cot- 
ton plugs, and immediately analyzed. These samples are repre- 
sented by the numbers 76 to 87, inclusive. 
The samples analyzed in the San Francisco laboratory in 1916 were 
of two classes— the pure expressed juices and the commercial prod- 
ucts. The samples represented by numbers 101, 102, 112, and 114 
were pressed in the presence of a Government inspector, and are, there- 
fore, known to be pure juices; Nos. 107, 108, 111, 116, 119, and 120, 
although not pressed in the presence of an inspector, are believed to be 
» Lewis, C. I., and Brown, F. R., Oregon Agr. Expt. Sta. Bui. 117. 
2 Daughters, M. R., J. Ind. Eng. Chem. (1917), 5:1043; (1918) 10:30. 
