WIEDEMANN, GUSTAV HEINRICH

(b. Berlin, Germany, 2 October 1826; d. Leipzig, Germany, 23 March 1899)

physics, physical chemistry.

Wiedemann was one of the outstanding members of the group of physicists trained in Berlin by H. G. Magnus. He held the first professorship of physical chemistry created in Germany (at Leipzig); and he became famous through his works on electromagnetism, especially his textbook on the theory of electricity, and through his long editorship of Annalen der physik und Chemie, known as Wiedemanns Annalen.

Wiedemann came from a merchant family. His father died when the boy was two and his mother when he was fifteen, and subsequently he lived with his grandparents. From 1838 to 1844 he studied at the Köllnische Realgymnasium in Berlin. At that time the school’s director was the physicist E. F. August, and its teachers included Louis Seebeck. Wiedemann also received much encouragement and help in his studies from an uncle in Berlin, the mechanic C. A. Gruel.

From 1844 to 1847 Wiedemann studied natural sciences at the University of Berlin. His professors included the mathematicians Dirichlet and Joachimsthal; the chemists Heinrich Rose, F. L. Sonnenschein, and E.Mitscherlich; and the physicists Magnus and Dove. Magnus allowed students to use his private laboratory: and it was there that Wiedemann met Helmholtz, who became a lifelong friend. Since Magnus, in conscious rejection of the nineteenth-century Naturphilosophie, concerned himself exclusively with experimental physics and neglected all theoretical questions, Helmholtz and Wiedemann decided to work through Poisson’s work on the theory of elasticity. In 1847 Wiedemann received the doctorate from Berlin for a dissertation on the urea derivative biuret. In 1850 he qualified as a lecturer with a work on the turning of the polarization plane of light discovered by Faraday. He lectured at the university on selected topics in theoretical physics.

In 1851 Wiedemann married Mitscherlich’s daughter Clara; they had a daughter and two sons: Eilhard, who became a physicist and historian of science, and Alfred, who became an Egyptologist. In 1854 Wiedemann was appointed professor of physics at the University of Basel, where he worked closely with the chemist C.F. Schönbein. He returned to Germany in 1863 to accept a post at the Polytechnische Schule in Brunswick. In 1866 he moved to the Polytechnische Schule in Karlsruhe, where, in addition to his duties as professor of physics, he organized meteorological observations for the state of Baden. His works on physical chemistry brought him an offer from Leipzig in 1871 to occupy Germany’s first chair of physical chemistry. Upon the retirement of Wilhelm Hankel in 1887. Wiedemann succeeded him as professor of physics at Leipzig, and Wilhelm Ostwald was given the chair of physical chemistry.

In 1877, following Poggendorff’s death, Wiedemann became editor of the Annalen der Physik und chemie, a position he held for the rest of his life. During his editorship the Annalen became one of the most distinguished German physics periodicals. He was able to increase its usefulness by publishing the Beiblä zu den Annalen der Physik, of which his son Eilhard became editor.

At Berlin, Wiedemann devoted his first studies to electrical conductivity on the surfaces of various metals, to the rotation of the plane of polarization of light under the influence of electric current, and to the thermal conductivity of metals. In 1853, collaborating with Rudolph Franz, he discovered the physical law named for them. It states that at a constant, not very low temperature T, the electrical conductivity k of metals is approximately proportional to their thermal conductivity λ : that is,

At Basel, Wiedemann continued the studies he had begun at Berlin on endosmosis, in which he established the dependence of the osmotic pressure on the current intensity and composition of the solutions. He also performed experiments on torsion and on the magnetization of steel and iron, and examined the influence of temperature on both phenomena. In later years he returned to the problem of the relations between magnetic and mechanical phenomena. This research also constituted the work. Die Lehre vom Galvanismus (1861–1863), a systematic presentation of everything known about the subject. This textbook was quickly recognized as the standard work on galvanism and was widely read.

At Brunswick, Wiedemann discovered the additive law for the magnetism of chemical compounds. He also investigated the vapor pressures of salts containing water of crystallization and demonstrated that they depend solely on temperature. At Karlsruhe he worked with R. Rühlmann on an exhaustive study of the processes involved in gas discharge and thereby became a pioneer in that field as well.

Pursuing his early research on magnetism while at Leipzig. Wiedemann posited the existence of “magnetic molecules,” His new, reliable determinations of the unit of electrical resistance, the ohm, won the admiration of his colleagues. In making these measurements Wiedemann used the large induction coil designed by Wilhelm Weber. In addition he improved the existing techniques for measuring temperature and devised a new galvanometer that bears his name.

Through both his teaching and his research, Wiedemann made important contributions to physics and chemistry, especially in electromagnetism. In addition as an editor and as an organizer, he possessed a virtually universal knowledge of physical science and performed many valuable services for his fellow physicists.

BIBLIOGRAPHY

I. Original Works. A bibliography of Wiedemann’s numerous scientific papers is in Poggendorff, II, 1319; III, 1441; IV, 1631; and A. von Harnack, Geschichte der Königlichen Preussischen Akademie der Wissenschaften zu Berlin, III (Berlin, 1900), 288 (Wiedemann’s academic writings only).

His papers include his dissertation, “De nova quodam corpore ex urea producto” (Berlin, 1874); “Ueber die Wärmeleitungsfähigkeit der Metalle,” in Annalen der physik und Chemie, 89 (1853), 457–531, written with R. Franz; “Ueber den Einfluss der Temperaturänderungen auf den Magnetismus des Eisens und Stahls,” ibid., 122 (1864), 346–358; “Magnetische Untersuchungen über den Magnetismus der Salze der magnetischen Metalle,” ibid.,126 (1865), 1–38; “Ueber den Magnetismus der chemischen vervindungen,” ibid., 135 (1868), 177–237; “Uever den Durchgang der Elektricitä durch Gase,” ibid., 145 (1872). 235–259, 364–399; and 158 (1876). 71–87, 252–287, written with R. Rühlmann; “Ueber die Dissociation der gelösten Eisenozydsalze,” ibid., n.s. 5 (1878), 45–83; “Ueber die Torsion,” ibid., 6 (1876), 71–87, 252–287, written with Rühlmann; “Ueber die Dissociation der gelösten Eisenoxydsalze,” 452–461; and 37 (1889), 610–628; and “Ueber die Bestimmung des Ohm.” ibid., 42 (1891), 227–256, 425–449, first published as Abhandlungen der preussischen Akademie der Wissenschaften, phys. Kl. (1884) no. 3.

His book is Die Leher vom Galvanismus and Elektomagnetismus nebst technischen Anwendungen, 2 vols. (Brunswick, 1861–1863; 2nd ed., 1872–1873; 3rd ed., Die Lehre von der Elektrucität, 4 vols., 1882–1885; 4th ed., 1893–1898).

II. Secondary Literature. see H. von Helmholtz. “Gustav Wiedimann beim Beginn des 50. Bandes seiner Annalen der physik und Chemie gewidmet.” in Annalen der physik, n.s.50 (1893), iii–xi; F. Kohrausch, “Gustav Wiedemann.” in Verhandlungen der Deutchen physikalischen Gesellschaft, 1 (1899), 155–167; W. Ostwald. “Zur Erinnerung an Gustav Wiedemann,” in Berichte der kgl. Sächsischen Gesellschaft der Wissenschaften. math.-phys. Kl., 51 (1899), lxxvii-lxxviii; M. panck. “Gustav Wiedemann, dem Herausgeber der Annalen zum Füfzigjährigen Doctorjubiläum gewidmet,” in Annalen der physik und Chemie, n.s. 63 (1897), vii-xi: and H. Reiger, “Wiedemann, Gustav Heinrich,” in Allgemeine deutsche Biographie, LV (1910), 67–70.

Hans-GÜnther KÖrber