(b. New York, N.Y., 17 August 1865; d. Berlin, Germany, 21 March 1942)
Rosenheim was the son of Wilhelm Rosenheim and Maria Hallgarten. When he was eight years old the family returned to Germany and settled in Berlin. Later he claimed German citizenship. He was educated at the Wilhelm-Gymnasium in Berlin, from which he graduated in the autumn of 1884. He then entered the philosophy faculty of the University of Berlin. In 1886 he went for one semester to the University of Heidelberg and then, from 1887 to 1888, wrote his Ph.D. dissertation, “Über Vanadinwolfrämsaure,” at Berlin. His teachers at Heidelberg were Bunsen, Königsberger, and Rosenbusch; at Berlin they included Gabriel, Geiger, Helmholtz, Hofmann, Kundt, Liebermann, Rammelsberg, and Tiemann. Rosenheim received the Ph.D. cum laude on 24 November 1888. The following year he went to Munich but in 1891 returned to Berlin as assistant at the II. Chemical University Laboratory. In March 1896 Rosenheim qualified as Dozent with his thesis “Über die Einwirkung anorganischer Metallsäuren auf organische Säuren.”
From 1891 Rosenheim worked at the Wissenschaftlich Chemisches Laboratorium, which he shared with Friedheim and later with Richard Meyer. In 1903 he was named professor of chemistry at Berlin, where he lectured until 1920 and then, for three years, supervised practical exercises in inorganic chemistry. Later he taught graduate courses for advanced students. A Jew, Rosenheim’s teaching license was revoked by the Nazi minister in 1933. But he remained in Berlin until his death, possibly of apoplexy. He was buried in the Jewish cemetery in Berlin-Weissensee.
Except for a review article on heteropoly acids in Richard Abegg’s Handbuch (1905), all of Rosenheim’s chemical contributions appeared in journal articles published between 1870 and 1934. His findings were based on careful analyses and often rectified the errors of earlier chemists. Landolt and Emil Fischer remarked that his investigations chiefly repeated and extended the research of others and were scientifically reliable.
Rosenheim’s papers are not easily grouped by distinct periods: he usually worked on several projects simultaneously and often returned to previous ones years later. Certain of his publications contain carefully specified directions for conducting analyses, and these constitute penetrating explanations of the chemical processes involved. Noteworthy are his papers on methods of determining vanadic acid (1890–1892); the separation of nickel and cobalt, of nickel and zinc, and of zinc and cobalt from complex thiocyanates; the analyses of hypophosphoric, phosphorous, hypophosphorous, and phosphoric acids (1909); on the gravimetric determination of tellurium and the alkalimetric determination of telluric acid (1911); and the determination of thorium by means of sodium phosphate (1912). Using his own preparations and analyses, Rosenheim also explained the reactions between ferric ions and thiocyanate and corrected the erroneous views of earlier researchers (1901).
Rosenheim’s thoroughness is evident in a series of studies on the molecular weight of hypophosphoric acid. On the basis of conductivity measurements and ebullioscopic molar mass determinations (1906, 1908, 1910), he assigned to this acid the incorrect formula H2PO3. He then compared his results with those of other chemists, at first misinterpreting their findings. Later, in 1928, using kinetic measurements, he obtained the correct molecular weight, H4P2O6. In the same paper, he also formulated the correct structure with P—P bonding.
Generally Rosenheim’s arguments are supported by exhaustive experimental evidence and are so thoroughly conceived that they need only minor correction in view of current research. Although the application of physical methods has yielded considerable additional data about complex compounds, for example, heteropoly acids, Rosenheim’s achievements are in no way diminished.
Rosenheim’s publications dealt primarily with six areas of research:
1. The complex chemistry of nitrogenous, phosphorous, arsenical, and sulfurous ligands, including amines, cyanides, phosphites, hypophosphites, hypophosphates, phosphates, diphosphates, arsenates, diarsenates, thiocyanates, sulfates, and thiosulfates.
2. The complex compounds formed by halides and organic compounds, especially acids and ketones. In this connection he also investigated thio acids.
3. The salts of elements of adjacent groups and the coordination complexes to which they give rise. Notable are his studies on the halides of the elements of adjacent lower valence groups—his observations match the cluster structure that has since been established for these substances.
4. Internal complex borates and beryllates, as well as bismuth, antimony, and arsenic compounds.
5. Peroxy compounds of elements from adjacent groups.
6. Isopoly and heteropoly acids.
In all of these studies Rosenheim used Werner’s coordination theory and arrived at conclusions that are still valid. Current refinements concern primarily structural questions.
With Miolati, Rosenheim laid the foundations for later research on isopoly and heteropoly acids. His last publication (1934) was a comprehensive survey of contemporary knowledge of heteropoly compounds, and it offered a critical evaluation of the most important experimental findings. Rosenheim also wrote many works on the nomenclature of inorganic compounds and on bibliographic matters. With J. Koppel, he prepared the cumulative index of the first one hundred volumes of Zeitschrift für anorganische Chemie. He also wrote obituary notices on several scientists, including Carl Friedheim (1911), Leopold Spiegel (1927), and Fritz Raschig (1929). In 1925 a special volume of the Zeitschrift für anorganische und allgemeine Chemie (no. 147) was a Festschrift for Rosenheim on the occasion of his sixtieth birthday.
Rosenheim’s major works are “8 Seiten über Elektroreduktion der Wolframsäure nach experimentellen Untersuchungen von R. Bernhardi-Grisson,” in Proceedings of the International Congress of Applied Chemistry (1909); and “88 Seiten über Heteropolysäuren,” in R. Abegg and F. Auerbach, eds., Handbuch der anorganischen Chemie, IV (Leipzig, 1921). An extensive bibliography is given in Poggendorff, IV, 1271; V, 1066–1067; VI, 2220–2221; and VIIa, 813.
On Rosenheim and his work, see Kürschner’s Deutscher Gelehrtenkalender (1937).