grams
of anhydrous salt) 200 grams
Sodium or potassium citrate 200 grams
Potassium sulphocyanide 125 grams
5% solution of potassium ferrocyanide 5 c.c.
Distilled water to make total volume of 1000 c.c.

Dissolve the carbonate, citrate, and sulphocyanide with the aid of
heat and enough water to make 800 c.c. of mixture. (Filter, if
necessary.) Weigh exactly the copper sulphate crystals and dissolve in
100 c.c. of water, now add it to the first solution; stirring
constantly. Add the ferrocyanide solution; cool and dilute to exactly
1 liter.

50 mg. (0.050 gm.) of sugar will reduce 25 c.c. of the above solution.

~Gerhardt's Ferric Chloride Reaction for Diacetic Acid.~--To 10 c.c.
of fresh urine, add carefully a few drops at a time of undiluted
aqueous solution of ferric chloride U.S.P. A precipitate of ferric
phosphates first forms, but upon the addition of a few more drops of
the same solution it is dissolved. A Burgundy red (red wine) color is
obtained in the presence of diacetic acid. The depth of this color is
indicative of the quantity of acid present. Joslin[112] records the
intensity of the reaction as follows, +, ++, +++, or ++++.

According to Joslin, it must be remembered that similar reaction is
obtained in the urine of individuals taking salicylates, antipyrin,
cyanates, or acetates, but it is a simple process to differentiate
between the color produced as a result of diacetic acid and that
produced by the above-mentioned drugs. If the solution is boiled for
two minutes, the color from diacetic acid will disappear, owing to the
unstableness of that substance, while that from the drugs will remain
unchanged.

~Test for Acetone.~--Pour 5 c.c. of urine to be tested into a test
tube, add a crystal of sodium nitroprusside, acidify with glacial
acetic acid, shake well, and then make alkaline with ammonium hydrate.
The presence of acetone is indicated by a purple color.

TESTS FOR ALBUMEN

The heat test[113] is the simplest. This consists of first filtering
the urine through filter paper, then pouring some of the clear urine
into a test tube, holding the test tube in a flame so that only the
upper layer boils, then adding a few drops of 2% solution of acetic
acid and boiling again. If there is albumen present, a very faint, or
a heavy cloudiness (precipitate of coagulated albumen) forms on
boiling an