simple. If you wish to give the percentage of sugar, multiply 0.005 by
100, and divide the product by the number of cubic centimeters of
dilute urine employed. The figure thus obtained, multiplied by the
extent of dilution--i.e., if there is 1 of urine in 10, multiply by
10--gives the required percentage. The number of grains per fluid
ounce can of course be obtained by multiplying the percentage by
4.375. To observe easily the exact end-reaction a piece of white paper
should be placed behind the flask. If the analyst objects to the
escape of the waste ammoniacal fumes, they may be conducted by a
suitable arrangement into water or dilute acid. In addition to glucose
there are small quantities of other copper-reducing bodies present in
all urine, which always render the reading higher than strict accuracy
would demand. Their aggregate proportion, however, is, comparatively
speaking, so minute that for most medical purposes their presence may
be disregarded. Greater care must be exercised, though, in those
instances where such a deoxidizer as chloral hydrate is accidentally
present. In case of doubt, a little washed and pressed yeast should be
allowed to stand with the urine for a day or two in a warm place.
Alcoholic fermentation with evolution of carbonic acid gas soon sets
in, and the specific gravity of the liquid is lowered considerably.
This reaction points conclusively to the presence of sugar.

Based upon Braun's potassic picrate test, Dr. G. Johnson has devised a
colorimetric process for the estimation of sugar. On boiling an
alkaline solution of that salt with glucose, the former is reduced to
deep red-brown picramate, the color of the liquid, of course, varying
in intensity according to the proportion of sugar present. This
solution is diluted till it corresponds in tint with a ferric acetate
standard, and the percentage of sugar is then readily calculated. For
those who prefer this process the convenient apparatus manufactured by