4 BULLETIN 773, U. S. DEPARTMENT OF AGRICULTURE. 
pure juices. The samples analyzed in the San Francisco laboratory in 
1917 were prepared as follows: 
The Logan blackberries, bought in various California wholesale mar- 
kets, were pressed as soon as they were received at the laboratory, the 
expressed juice filtered through cotton plugs, and pasteurized in 
glass bottles by being heated to about 80° C. and held at that tem- 
perature for an hour. The juices kept very well and at the time of 
analysis showed no signs of fermentation. 
METHODS OF ANALYSIS. 
SOLIDS.. 
Ten cubic centimeters of juice or diluted sample was evaporated 
with about 10 grams of sand, on a water bath, to apparent dryness, 
and then dried in vacuum for from 10 to 14 hours at 70° C., at about 
70 millimeters pressure. This gave approximately 1 gram of dried 
material to be weighed. For comparison, the total solids by the 
indirect method, calculated from the specific gravity of the juices, 
using the wine extract tables,' are given. In the case of the samples 
analyzed in the Seattle laboratory, the solids were determined by 
the indirect method, from the specific gravity, using the tables for 
the extract in wine.t’ The solids also were determined by direct 
drying at the temperature of boiling water, but the figures thus 
obtained varied so much from the figures obtained by the other 
methods that they are not included in the tables. 
NONSUGAR SOLIDS. 
The nonsugar solids were calculated as the difference between the 
total solids in vacuum and the total sugars. The nonsugar solids 
of the samples analyzed in Seattle were obtained by subtracting the 
total sugars from the total solids determined by the indirect method. 
SUGARS. 
The sugars were determined on suitable dilutions of the sample 
before and after inversion, by copper reduction methods, using 
Munson and Walker’s tables.? 
ASH. 
Twenty-five cubic centimeters of juice, or 25 grams of sweetened 
product, was ashed directly in platinum. In 1916, the ash was 
separated into water-soluble and water-insoluble ash, and the re- 
spective amounts of each and their alkalinites determined. As this 
seemed to supply little information, no such separation was made 
in 1917. 
1U.S. Dept. Agr., Bur. Chem, Bul. 107, rev., 218, 2 Tdem, 234, 
