Synthetic Drugs—IV**Contribution from the Chemical Laboratory of the American Medical Association.The previous articles were: “Examination of American-Made Acetylsalicylic Acid,” J. Ind. and Eng. Chem., April, 1918, p. 228 (see also editorial, Ibid., April 1918, p. 225); “American-Made Synthetic Drugs—II. Examination of Procaine (Novocain), Barbital (Veronal), Phenetidyl-acetphenetidin (Holocain), Cinchopen (Atophan), Manufactured under Federal TradeLicenses” (with Wm. Rabak and A. H. Clark), J. A. M. A., 73, 754 (Sept. 6), 1919; “Synthetic Drugs—III. The Digestion of Tannin Compounds Used as Intestinal Astringents by ArtificialDigestive Mixtures,” J. A. M. A,, 75, 1120 (Oct. 23), 1920.