1. F. Feigl, Specific and Special Reactions. Elsevier Book Company, New York, N. Y., 1940, p. 95.
2. For supplying the reagents used in this work we are indebted to several companies, to be specific, to the Bersworth Chemical Company, Framingham, Mass, for the Versene; to the Ciba Company, Inc., New York 14, N. Y., for the Solvadine K; and to the Carbide and Carbon Corporation, New York 17, N. Y., for the Tergitol 7.
3. F. Feigl, Spot Tests, 3rd ed. Elsevier Book Company, New York, N. Y., 1946, p. 100.
4. F. Feigl, Specific, Selective, Sensitive Reactions. Academic Press, New York, N. Y., 1949, p. 659.
5. Foster Dee Snell &F. M. Biffen, Commercial Methods of Analysis. McGraw-Hill Book Company, New York, N. Y., 1944, p. 96.