qualitative purposes the solution may be prepared thus: Dissolve 35
gm. of recrystallized cupric sulphate and 200 c.c. of pure glycerin in
100 c.c. of distilled water. Dissolve separately 80 gm. of caustic
soda in 400 c.c. of water. Mix the solutions and boil for a quarter of
an hour. A small amount of reduction from impurity in the glycerin
takes place. Allow to stand till clear, decant, and dilute to 1,250
c.c. Ten cubic centimeters will then equal roughly 5 centigrammes of
glucose. For exact quantitative determination it is necessary to
standardize the solution with pure anhydrous dextrose.

To a practiced operator the indications yielded by the use of this
test are of great value; but beginners are exceedingly liable to
mistake its various reactions, and to report the urine as saccharine
when normal traces only of sugar are present. The bismuth test of
Bottger, as greatly improved by Nylander, is fairly delicate, and not
so easily misread as Fehling's. A large volume of reagent being used
with a comparatively small quantity of urine, the precipitate of
earthy phosphates does not interfere in the least with the reaction.
On boiling about 3 drachms of Nylander's solution and 20 minims of
urine for a minute or two, the liquid darkens with a trace of sugar,
and becomes opaque and black if the latter is present in quantity. The
reagent is prepared by dissolving 494 grains of caustic soda, 247
grains of Rochelle salt, and 154 grains of subnitrate of bismuth (free
from silver) in 13 fluid oz. of distilled water. It should be decanted
for use from any sediment.

[Illustration: DR. PAVY'S APPARATUS.]

In those cases where the amount of glucose present is required to be
determined, Dr. Pavy's ammonia cupric process distances all compeers