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Clark, William Mansfield

Clark, William Mansfield

(b. Meyersville, New York, 17 August 1884; d. Baltimore, Maryland, 19 January 1964),


Clark descended on both sides of his family from clergymen, became interested in chemistry while at Wiliams College. In his senior year he taught chemistry in the local high school. After graduation in 1907, he took a master’s degree at Williams and then went to Johns Hopkins University, where he received a Ph.D. in physical chemistry in 1910. During his summer vacations he worked at Woods Hole under Carl Alsberg and alter, D. D. Van Slyke. These men aroused his interest in biochemistry.

After receiving the Ph.D., Clark became chemistry in the Daily Divison of the U.S. Department of Agriculture. His work on the bacteriology of milk products led him to study problems involving acidity, and he became adept in the use of the hydrogen electrode. Struck by the variability of titration indicators then available, he developed, with Herbert Lubs, a set of thirteen indicators. These studies led him to write The Determination of Hydrogen Ions (1920), which became a classic in its fields.

In 1920 Clark became chief of the Division of Chemistry of the Hygiene Laboratory, Public Health Service, the forerunner of the National Institutes of Health. Here he began studies on oxidation-reduction potentials of dyes, a field that, together with studies of metalloporphyrins, occupied him for the rest of his life. In 1927 he became professor of physiological chemistry in the Johns Hopkins Medical School.

Clark was an excellent teacher, stressing especially the importance of physical chemistry for medical students. He was active in many government bureaus, particularly during World War II. After his retirement in 1952 he devoted himself to writing, especially to his monograph on oxidation-reduction system (1960).


There is a bibliography of Clark’s works in Biographical Memoirs. National Academy of Science, 39 (1967) 27–36. His chief Works are the Determination of Hydrogen Ions (Baltimore, 1920; 2nd ed., 1923; 3rd ed., 1928); and Oxidation-Reduction Potentials of Organic Systems (Baltimore, 1960). An autobiographical sketch by Clark is “Notes on a Half-Century of Research, Teaching and Administration,” in Annual Review of Biochemistry, 31 (1962) 1–24.

More detailed information may be found in Hubert Bradford Vickery, “William Mansfied Clark,” in Biographical Memoirs. Nationals Academy of Sciences, 39 (1967), 1–26.

Henry M. Leicester

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