Put some of the suspected urine into a large test-tube, and add a few drops of solution of sulphate of copper, then sufficient solution of potash to render it strongly alkaline. If sugar be present the precipitated oxide redissolves into a blue liquid, and on boiling, red oxide of copper is precipitated.

"Fehling found that one equivalent of grape-sugar, or 180 parts, decomposed exactly ten equivalents, or 1246.8 parts, of sulphate of copper. Accordingly he prepared a solution of copper of standard strength, and applied it to fluids containing grape-sugar; and the quantity of these required to decompose a fixed volume of the standard solution furnished an exact measure of the sugar they contained.

"Fehling's standard solution is prepared according to the following prescription: - Sulphate of copper 90 1/2 grs., neutral tartrate of potash 364 grs., solution of caustic soda (sp. gr. 1.12) 4 fl. oz., add water to make up 6 fl. oz. 200 grs. of this solution are exactly decomposed by 1 gr. of sugar." - Dr. Roberts.* For methods of performing the analysis, etc, consult Dr. Roberts' work,' Urinary and Renal Dseases.' Dr. Roberts gives the following directions for the quantitative examination of urine for sugar: - "Pour some of the prepared test-liquor (" Fehling's," as above) into a narrow test-tube to the depth of 3/4 of an inch; heat until it begins to boil, then add 2 or 3 drops of the suspected urine. If the sugar be abundant a thick yellowish opacity and deposit of yellow suboxide are produced (and this changes to a brick-red at once if the blue colour of the test remain dominant). If no such reaction ensue, go on adding the urine until a bulk nearly equal to the test employed has been poured in; heat again to ebullition, and, no change occurring, set aside without further boiling. If no milkiness is produced as the mixture cools, the urine may confidently be pronounced free from sugar."