Prepare a paste of 2.0 g of the sample with a little cold water & add to it with stirring 100 mL of boiling water. The solution should be no more than opalescent, and on cooling it should remain liquid and not increase in opalescence.
Test for sensitivity : To a mixture of 1 ml Starch solution and 20 ml of water, add about 50 mg of potassium iodide & 0.05 ml of iodine solution. The solution is blue.