Boisbauran, Paul Émile Lecoq De

(called Francois )

(b. Cognac, France, 18 April 1838; d. Paris, France, 28 May 1912)

chemistry.

Boisbaudran’s family belonged to the ancient Protestant nobility of Poitou and Angoumois, and had been wealthy prior to the religious persecutions of the seventeenth and eighteenth centuries. When Boisbaudran was born, however, his father and uncle were corproprietors of a wine business at Cognac. His mother, daughter of an army officer, was a learned woman who taught her son classics, history, and foreign languages. Although he had no formal schooling, Boisbaudran worked through the course books of the École Polytechnique, Performing experiments in a home laboratory equipped by his uncle.

At the age of twenty, Boisbaudran began to work for the family company, traveling through the Continent and England on business. He continued to study chemistry and physics in his spare time; as business prospered, he was allowed to spend more time on scientific work. His early research concerned supersaturation of salt solutions, conditions of crystallization, and crystalline shapes.

Boisbaudran is best known for his work on spectroscopic methods of elementary analysis. In a volume entitled Spectres lumineux (1874), he reported the results of extensive and refined spectral examinations of thirty-five elements. This work was undertaken to test several generalizations relating spectral wave-lenght to atomic weight. In this work, Boisbaudran held that the various kinds of spectra for the elements were related to the various motions (rotation, vibration, and translation) of the molecules. He believed, however, that the displacement of the lines in related elements did not correspond to the magnitude of the molecular forces (as some chemists held) but to the mass of the molecules.

In 1875 Boisbaudran spectroscopically discovered a new element, gallium, which he found in zinc blende from a mine in Hautes-Pyrénées. Continuing his work in Wurtz’s laboratory in Paris, he wasa able to obtain the free metal by electrolysis of a solution of the hydroxide in potassium hydroxide. Gallium, Boisbaudran realized, was the “eka-aluminum” predicted by Mendeleev, and was the first of Mendeleev’s predicted elements to be isolated. Boisbaudran’s finding thus provided valuable evidence for the validity of Mendeleev’s periodic classification of the elements.

In 1879 Boisbaudran began spectroscopic experimentation with the rare earth elements, research that he pursued for several decades. Collaborating with John Lawrence Smith, he showed that didymium from cerite differed from that coming from samarskite. This discrepancy led to the discovery of samarium. In 1885 the elements that have since been named dysprosium, terbium, and europium were identified from their Phosphorescent spectra. Such Phosphorescent bands were produced by making the liquid under consideration the positive pole, instead of the negative pole, when a line spectrum is formed. In 1886 a new element, later called gadolinium, was detected in earths yielding samarium. In 1904 Boisbaudran used “Z” to denote an element contained in earth separated from impure terbium and subsequently identified as pure terbium.

After 1895 Boisbaudran’s scientific work decreased considerably because of failing health and family and business concerns. He married late in life, but no further information about his family can be found. Boisbaudran was a winner of the Cross of the Legion of Honor, the 1879 Davy Medal (for his discovery of gallium), and the Prix Lacaze. He was a corresponding member of the chemistry section of the French Academy of Sciences, and a foreign member Off the Chemical Society of London.

BIBLIOGRAPHY

I. Original Works. Among Boisbaudran’s writings are Spectres lumineux: Spectres prismatiques et enlonguers d’ondes destinés aux recherches de chimie minérale, 2 vols. (Paris, 1874), and an article on gallium, in E. Fremy, ed., Encyclopédie chimique, XVI (Paris, 1884), 201–222. The discovery of gallium is reported in Comptes rendus de I’Académie des sciences, 81 (1875), 493–495; Philosophical Magazine, 5th ser., 2 (1876), 398–400; and Annales de chimie et de physique, 10 (1877), 100–141. A crucial work is Analyse spectrale appliquée aux recherches de chimie minérale2 vols. (Paris, 1923), written with A. Gramont, which contains a biographical sketch of Boisbaudran and a Complete bibliography, pp. xi-liv; most of his publications are also listed in Poggendorff.

II. Secondary Literature. Works on Boisbaudran are M. A. Gramont, “Lecoq de Boisbaudran: Son oeuvre et ses idées,” in Revue scientifique, 51 , pt. I (25 Jan. 1913), 97–109: W. Ramsay, obituary, in Journal of the Chemical Society, 103 (1913), 742–746; Urbain, obituary, in Chemische Zeitung, 36 (1912), 923–933; and Mary Elvira Weeks, Discovery of the Elements, 6th ed. (Easton, Pa., 1956). Esp. chs. 25, 26.

Susan G. Schacher