a test for acetone; the urine is rendered alkaline by a few drops of a solution of potassium hydroxide, and to this are added 2 or 3 drops of a freshly prepared 10% solution of sodium nitroprusside; it is colored red, then yellow; then a few drops of acetic acid are trickled down the side of the test tube and at the line of junction of the two fluids is formed a carmine or purple ring.
