A QUALITATIVE TEST FOR ARSENIC OR ANTIMONY JACOB CORNOG, UNIVERSITY on IOWA, IOWA CITY,IOWA Somewhat by accident, we recently observed that if a test tube, containing water a t any temperature up to boiling, is dipped into a solution containing either arsenic or antimony, and then held in the non-luminous flame of a Bunsen burner until the adhering solution is evaporated and the residue adhering to the outside of the test tube is slightly baked, a black mirror is formed. This mirror is similar in appearance to the mirror formed in the Marsh Test for arsenic. The mirror formed by arsenic may be distinguished from the one formed by antimony by the familiar hypobromite test. That is, the arsenic mirror is dissolved by a sodium hypobFomite solution while the antimony mirror is not affected in this solution. Continued heating of the mirror in the flame will cause its disappearance. This test is applicable to solutions in which the concentration of arsenic or antimony is two hundredths molar or greater. Unfortunately, the use of this test is restricted to solutions in which arsenic or antimony are the only metals present. When the ions of metals such as iron or copper are present the test gives indeterminate results. With a little practice, the test is quickly and easily made and where applicable much time may be saved.
