a. Reflux 1 g of the sample, in No.150 powder,with 20 ml of chloroform in a water-bath for 15 minute, and filter(solution A) . Evaporate 2 ml of solution A to dryness add 2 ml of acetic anhydride, shake well, and add carefully 1 ml of sulfuric acid to make two layer: abrownish red colour develops at the zone of contaction