190 HOW TO TEST CANE JUICE. 
other methods, the hydrometer can then be employed to 
advantage for determining the per cent. of cane sugar, and 
it should_generally be limited to this use. 
The hydrometer of Beaumé is the common form, but the 
scales of different instruments do not always correspond, 
and hence the continued liability to error. Every instru- 
ment before being used should be subjected to the following 
test: Place the hydrometer in pure water at a temperature 
of 60° F., and the point near the top of the stem to which 
it sinks is the 0 of the scale. Prepare a solution of 15 
parts of common salt in 85 parts of water by weight, and 
at the same temperature as the above, and the place to 
which it sinks should mark 15° of the scale. The value of 
each degree of this scale expressed in specific gravities, 
and correspondent per cent. of sugar are given in table II. 
A specific gravity bottle affords a convenient means of 
testing the accuracy of the hydrometer, and when an ex- 
treme degree of accuracy is required, it should be used in 
its place. It is a bottle containing just 1000 grains, or 
100 grammes of distilled water at 60° F., when the stop- 
per is inserted and the outside of the bottle is wiped 
dry. The stopper is of ground glass with a hole through 
its center, or a groove cut in its side with a file, to admit 
of the escape of any superfluous liquid in filling the bottle. 
When such a bottle cannot be had, a phial of any capacity 
with a similar stopper may be used, and the exact weight 
of water at 60° F. which it will hold, ascertained) The 
specific gravity of the liquid to be examined is obtained by 
filling the bottle with it and dividing its weight by the 
weight of the water. 
Thus if the weight of the bottle full of water at 60° F. 
is 1000 grains, and the weight of the solution of sugar at 
60° F. is 1083 grains, the specific gravity of the solution 
will be 1083 divided by 1000, or 1:083. Referring to table 
