URBAIN, GEORGES

(b. Paris, France, 12 April 1872; d xParis, 5 November 1938)

Chemistry, mineralogy.

The son of a professor of chemistry and assistant to Edmond Frémy, Urbain entered the École de Physique et de Chimie in Paris at his father’s request and graduated first in his class in 1894. While serving as assistant in the mineral laboratory, he came under the influence of Pierre Curie, who introduced him to scientific research. From 1895 until 1898 he was the private assistant of Charles Friedel and was awarded his doctorate in 1899 from the University of Paris of his thesis on the rare earths. In 1906 Urbain was named assistant professor of analytical chemistry at the Sorbonne and was rapidly promoted to professor of mineral chemistry in 1908. In 1928 he was appointed professor of general chemistry, director of the Institut de Chimie de Paris, and codirector of the Institut de Biologie Physicvo-chimique. During his term as professor at the Institut he created a mecca for good chemistry students. His lectures were well-delivered and extremely popular.

Urbain’s name is linked with his important studies of the rare earths, which occupied him mainly from 1895 until 1912. More than 200,000 fractional crystallizations enabled him to separate rigorously samarium, europium, gadolinium, terbium, dysprosium, and holmium. He found that the ethyl sulfates of the rare earths were the easiest derivatives to separate. The most important single study was his separation of ytterbium (considered an element by Jean Marignac) into ytterbium and the previously unknown lutetium, named after Lutetia, the ancient name of Paris. Urbain’s determinations of the atomic weights of these elements were accepted by the authorities and led to his later election as president of the International Committee on Atomic Weights.

In 1911 Urbain observed another element, not of the rare earth family, which he named celtium. Henry Moseley felt that it was the missing element 72, although X-ray evidence was inconclusive. After World War I, Urbain continued his investigations and, in 1922, confirmed the presence of element 72 in his samples. But Havesy and Coster isolated larger concentrations of the element that same year and are credited with the discovery of hafnium. For a short period of time the committee accepted both the symbols Ct and Hf for the element.

After 1912 Urbain’s interests turned increasingly toward theoretical complex chemistry. He critically evaluated and extended Alfred Werner’s coordination theory and proposed his own theory of homeomerism (equal properties). This concept extended the idea of isomorphism beyond the limits of the crystalline state by dropping the condition of equality of interfacial angles. Two sub stances, then, in order to be homeomeric must have equal molecular coefficients of energy-properties that are generally easy to measure. Thus he defined isotopes as elements that are nearly rigorously homeomeric.

Among Urbain’s other deep interests were music and the history and philosophy of science. A fine piano player, he read most of the didactic works on music and composed several brilliant pieces as well as a book on the subject. He keenly analyzed the development of chemistry in a work that has been compared to those of Jean-Baptiste-André Dumas. He firmly believed in the essential unity of inorganic and organic chemistry and felt that by modifying Werner’s theory he could achieve this unification for theoretical chemistry.

BIBLIOGRAPHY

I. Original Works. A complete listing of Urbain’s papers is found in Paul Job, “Notice sur la vie et les travaux de Georges Urbain,” in Bulletin de la Société chimique de France, 6 (1939), 745–766.

Urbain wrote seven books on chemistry. They are, in chronological order, Introduction àl’étude de la spectrochemie (Paris, 1911), which is not an advanced trestise on spectrochemistry but is rather an introduction for the beginner on methods of special analysis, inculding a lengthy historical survey of the subject: Introduction à la chimie des complexes minéraux (Paris, 1914), with A. Sénéchal, which is based on Urabain’s course at the Sorbonne and, despite its title, is a general text on physical and inorganic chemistry; Les disciplines d’ une science. La chimie (paris, 1921), which discusses his attempt to unify inorganic and organic chemistry: L’énergétique des ré chimiques (paris, 1925), which is a theoretical introduction to chemical thermodynamics based on a course given at the Sorbonne; Les notions fondatmentales d’ éléments chimiques et d’ atomes (Paris, 1925); and La coordination des atomes dans la molecule et la symbolique chimique, 2 vols. (Paris, 1933), which are two purely theoretical treatises; and Traité de chimie générale, notions et principes fondamentaux (Paris, 1939), with P.Job, G. Allard, and G. Champetier but mostly the work of Urbain.

Urnain places his rare earth studies in their historical perspective in his review article, “Research on Yttirum Earths,” in Chemical Reviews, 1 (1924), 143–185.

Worthly of note is his book Le Tombeau d’ Aritoxè. Essai sur la musique (Paris, 1924), in which he proposed that music is more intellectual than sensuous and consequently, can be the object of a methodical (if not truly scientific) study.

II. Secondary Literature. The most detailed biographical sketch of Urbain is Paul Job’s obituary notice cited above. An interesting English article written by two of Urbain’s former students is Georges Champetier and Charlotte H. Boatner, “Georges Urbain,” in Journal of Chemical Education, 17 (1940), 103–109.

Sheldon J. Kopperl