To 100 c.c. of urine of known specific gravity, add one-fourth of fresh yeast cake thoroughly broken up. Mix thoroughly and set aside at a temperature between 85 deg. and 95 deg. F. for twenty-four hours, after which time test with Benedict's or Fehling's solutions. If reduction is obtained, it will be necessary to allow the fermentation to continue until it is complete. When no further reduction is obtained, the specific gravity is taken after the urine has reached a temperature of 76 deg.. The difference in the specific gravity at the beginning and end of the test multiplied by 0.23 gives the percentage of sugar in the urine. The following formulas represent the various solutions used in the above test: BENEDICT'S QUALITATIVE SOLUTION _Gm. or c.c._ Copper sulphate (pure crystals) 17.3 Sodium or potassium citrate 173.0 Sodium carbonate (anhydrous) 100.0 Distilled water to make 1000.0 FEHLING'S SOLUTION (1) Copper Sulphate Solution: 34.65 grams copper sulphate dissolved in water and sufficient water added to make 500 c.c. (2) Alkaline Solution: 125 grams potassium hydroxide. 173 grams Rochelle salts dissolved in water q.s. to make 500 c.c. Keep solution in separate bottles and mix in equal quantities when ready to use. HAINES'S SOLUTION Copper sulphate (pure) 30 grams (dissolved in 1/2 oz. (15 c.c.) distilled water) Add 1/2 oz. pure glycerin, mix thoroughly, and add 5 oz. liquor potassae. BENEDICT'S (QUANTITATIVE) SOLUTION Copper sulphate (pure crystals) 18 grams Sodium carbonate (crystallized) (or 100 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 ++++.