a test for ketone bodies; 5 mL of fresh urine are saturated with solid ammonium sulfate and mixed with 10 drops of freshly prepared 2% sodium nitroprusside solution, which is then mixed with 10 drops of concentrated ammonia water and allowed to stand for 15 minutes; the presence of acetoacetic acid, or of larger concentrations of acetone, is indicated by the development of a blue-purple color.