For alkaloids; to the suspected solution is added a mixture of bismuth subnitrate, potassium iodide, and hydrochloric acid in water; a positive reaction is indicated by the appearance of a red colour; for acetanilid in the urine; the suspected fluid is extracted with chloroform and heated with yellow nitrate of mercury; if acetanilid is present, the fluid will be green.
(05 Mar 2000)