(b. Hořovice, Bohemia [now Czechoslovakia], 13 March 1878; d. Munich, Germany, 14 October 1945)
Hönigschmid was the son of Johann Hönigschmid, an Austrian officer who later went into financial administration. In the course of his sfather’s officials transfers, Hönigschmid lived in various places and finished his secondary schooling in Prague. He then studied chemistry at the German University in Prague and completed graduate work in 1901 with Guido Goldschmiedt, an organic chemistry. Thus his early publications are devoted to organic chemistry, although they show a tendency toward analytic chemistry as well.
Goldschmiedt encouraged Hönigschmid’s natural abilities, and from 1904 to 1906, on leave of absence from Prague, he continued his studies in Paris as assistant to Moissan. There he became familiar with high temperatures and the chemistry of silicide, carbide, and boride. In 1908 he made silicide the basis of his Habilitation and wrote a monograph, Carbide und Silicide. From scientific publications he became acquainted with the work of T. W. Richards of Harvard University, who had a worldwide reputation for his exact determinations of atomic weights. Enthusiastic about this area of study, Honigschmid in 1909 took a second leave of absence for a year in Cambridge, Massachusetts, where he made his first achievements as an atomic scientist.
As early as 1911 Hönigschmid was involved in the work of the Radium Institute that had just opened at Vienna. The precise calculation of the atomic weights of the elements of the radioactive disintegration series—radium, uranium, thorium, ionium, and lead—was then a critical problem, indispensable ofor the confirmation of the Rutherford disintegration theory and the displacement law of Soddy and Fajans. Hönigschmid’s lead determinations showed that lead, depending on its geological origin, exhibited variabgle atomic weights, a discovery which was the impetus for the isotope theory.
In 1911 Hönigschmid became extraordinary professor of inorganic and analytic chemistry at the German Technical University in Prague and, later, professor. He remained connected with the Vienna Institute. In 1918 he accepted a request to head the analytic chemistry department at the University of Munich and it was here that he established his famous atomic weight laboratory, his primary interest for the rest of his life.
Hönigschmid perfected preparative and analytic methods. With a large circle of students and colleagues he successfully determined the atomic weights of some fifty elements; among these were the first weight estimates for hafnium and rhenium. Special care was given to the so-called basic elements—including silver, the halogens, potassium, sodium, nitrogen, and sulfur—which served as foundations for determining the atomic weights of other elements.
Meanwhile, mass spectrographic investigations had showed that the natural elements are mixtures of isotopes of integral atomic weights. The Prout hypothesis of the unified building material in matter was revived, and Hevesy, Brønstedt, Clusius, and others accomplished the isotopic separation of ordinary elements through physical methods. Hönig schmid’s analytic atomic weight calculations were thus a welcome step toward decisiveness, confirmation, and completions.
As a result of the exclusion of Germany from the “Conseil International des Recherches,” Hönigschmid, Wilhelm Ostwald, Max Bodenstein, Otto Hahn, and R. J. Meyer joined together in 1920 to form their own atomic weight commission, with Ostwald as its head. After Ostwald retired Hönigschmid took charge and was largely responsible for the eleven annual reports of the commission. In 1930 an international commission on atomic weights was formed, with Germany as a participant, and Hönigschmid worked on its reports along with G. Baxter, M. Curie, Meyer, and P. LeBeau.
At the end of World War II Hönigschmid was seriouly ill. He and his wife killed themselves during the occupation when, after the destruction of the institute, they twice had to move and found the difficulties of their living conditions insurmountable.
I. Original Works. Honigschmid’s numerous publications appear chiefly in Sitzungsberichte der Akademie der Wissenschaften in Wien (1901–1916); Sitzungsberichte der Bayerischen Akademie der Wissenschaften zu Munchen (1920–1940); Bericht der Deutschen chemischen Gesellschaft (1921–1943); Zeitschrift für Elektrochemie und angewandte physikalische Chemie (1914–1937). The proceedings of the atomic weight commission are published in many different national journals. For a bibliography of Honigschmid’s work, see Poggendorff, V, 547–548; VI, 1137–1138; VIIa, 511.
II. Secondary Literature. See E. Zintl, “Otto Hönigschmid zum 60. Geburtstag,” in Zeitschrift für anorganische und allgemeine Chemie, 236 (1938), 3–11, with bibliography; and L. Birckenbach, “Otto Honigschmid,” in Chemische Berichte82 (1949), xi-lxv, with portrait and bibliography.
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