It was shown in 1927 that quinine, when combined with a diphenic acid derivative, gave a salt with an optical rotation in the opposite direction to that of the free alkaloid ("Kuhn's effect"). The present authors have prepared the salts of four of the cinchona alkaloids with 2-phenylpyridine-2′:3-dicarboxylic acid, and find similar results. In addition, a partial optical resolution of a derivative of this acid has been effected, the dextro-form of the methiodide of the dimethyl ester having been isolated.