Balard, Antoine Jérome

Updated About encyclopedia.com content Print Article Share Article
views updated

Balard, Antoine Jérome

(b. Montpellier, France, 30 September 1802; d. Paris, France, 30 March 1876)

chemistry.

Balard was born into a family of modest circumstances; his parents were wine-growers. His godmother noticed his intelligence, however, and enabled him to attend the lycée in Montpellier. In 1819, upon his graduation, he began to train for a career in pharmacy. While training in Montpellier, he served as préparateur in chemistry to Joseph Anglada of the Faculté des Sciences and préparateur at the École de Pharmacie. At the latter he studied chemistry and physics under Jacques Étienne Bérard, who permitted Balard to do research at the chemical factory of which Bérard was the director. Balard received his degree in pharmacy in 1826, having written a thesis on cyanogen and its compounds.

It was in this period, about 1825 (the date is uncertain but was before 28 November), that Balard made his discovery of the element bromine. The discovery of a new chemical element by a young and obscure provincial pharmacist caused a sensation in Parisian, and subsequently in foreign, scientific circles. Balard’s achievement was recognized by the Académie des Sciences and he was awarded a medal by the Royal Society of London. Professionally he advanced steadily, first in Montpellier, where he succeeded Anglada in 1834, and later in Paris, where he assumed Louis Jacques Thénard’s chair at the Sorbonne in 1842 and that of Théophile Jules Pelouze at the Collége de France in 1851. For this last position, Balard’s chief competitor was Auguste Laurent. In 1844 Balard was elected to the Académie des Sciences.

Balard’s mode of life was modest, even in his successful years in Paris. Moreover, his abstemiousness influenced the style of his scientific research; both Jean Baptiste Dumas and Charles Adolphe Wurtz testified to Balard’s preference for simple apparatus and homemade reagents over elaborate techniques and materials. He was amiable and generous both to his colleagues and to his students.

Balard was principally an experimental chemist, although his experimentation was guided by a keen awareness of the analogies between the substances he was investigating and others of which the chemistry was better known. He did not publish a great deal, but what did appear was of high quality and great interest.

The discovery of bromine, Balard’s first and greatest achievement, actually was a by-product of his more general chemical investigations of the sea and its life forms. In the course of his studies, Balard devised a reliable test for the presence of iodine, the content of which he was determining in plants taken from the Atlantic and the Mediterranean. Chlorine water was added to the test solution, to which starch and sulfuric acid had already been added. The iodine was manifested by its characteristic blue color at the interface of the test solution and the chlorine water. Then Balard noticed that, in some samples, above the blue layer there appeared a yellow-orange layer, which had its own characteristic odor. He isolated the substance causing the yellow color, which proved to be a red liquid. He first collected it by simple distillation, but soon he found a more effective method; shaking the chlorinated sample with ether and treating the resultant orange layer with caustic potash. The crystallized precipitate was then distilled with manganese dioxide and sulfuric acid to produce the red vapor of elemental bromine, which Balard dried with calcium chloride and condensed to a liquid.

At first he thought the substance might be a combination of chlorine and iodine, but he was unable to detect the presence of iodine and the liquid did not decompose under electrolysis. Balard concluded that he had discovered a new element, which, at the suggestion of Anglada, he named muride, subsequently changed to bromine. He proceeded to study its properties, which he found to be analogous to those of chlorine and iodine.

A number of German chemists, including Justus Liebig, had in fact isolated bromine before Balard without realizing its elemental nature. Carl Jacob Löwig, while still a student, isolated it almost simultaneously with Balard. The discovery of this element had a significance greater than that of the isolation of most other elements, for it made manifest the most striking “family” of elements—the halogens—in which bromine possessed an atomic weight that was approximately the arithmetic mean between those of chlorine and iodine.

In 1834 Balard published the results of his study of the bleaching agent Javelle water. In the course of working out the chemistry of this chlorine bleach, he succeeded in preparing hypochlorous acid and chlorine monoxide.

The project to which Balard devoted the most time was the inexpensive extraction of salts from the sea. Beginning in 1824, he spent many years developing techniques for precipitating sodium sulfate and potassium salts, publishing his method in 1844. Unfortunately for Balard, cheaper techniques for producing sodium sulfate were developed and huge deposits of potassium sulfate were discovered at Stassfurt.

Two other chemical studies by Balard deserve mention: the discovery of oxamic acid from the decomposition by heat of ammonium hydrogen oxalate (ammonium bioxalate) and the study and naming of amyl alcobol.

Of perhaps greater importance than his chemical researches was the interest Balard took in his students’ careers, particularly those of Louis Pasteur and Marcelin Berthelot. Balard petitioned to have Pasteur assigned to him as an assistant in 1846, and in 1851 he secured a similar position for Berthelot at the Collége de France. He maintained close friendships with both these pupils, coming to Pasteur’s defense in the spontaneous–generation controversy and securing the creation of the chair in organic chemistry at the Collége de France for Berthelot.

BIBLIOGRAPHY

I. Original Works. For a listing of Balard’s scientific papers, see the Royal Society of London’s Catalogue of Scientific Papers, I, 166-167, and VII, 76. His most important papers are “Note pour servir à l’histoire naturelle de l’iode,” in Annales de chimie, 2nd ser., 28 (1825), 178-181; “Mémoire sur une substance particuliére contenue dans l’eau de la mer (le brôme),” ibid., 32 (1826), 337-384; “Recherches sur la nature des combinaisons décolorantes de chlore,” ibid., 57 (1834), 225-304; “Note sur la décomposition du bioxalate d’ammoniaque par la chaleur et les produits qui en résultent,” ibid., 3rd ser., 4 (1842), 93-103; “Mémoire sur l’alcool amylique,” ibdi., 12 (1844), 294-330; and “Sur l’extraction des sulfates de soude et de potasse des eaux de la mer,” in Comptes-rendus de l’Académie des Sciences,19 (1844), 699-715.

II. Secondary Literature. Works on Balard are J. B. Dumas, “Éloge de M. Antoine-Jérome Balard,” in Mémoires de l’Académie des Sciences, 2nd ser., 41 (1879), 1v-1xxx; M. Massol, “Centenaire de la découverte du brôme par Balard,” in Bulletin de la Société Chimique de France, 4th ser., 41 (1927), 1-9; J. R. Partington, A History of Chemistry, IV (London, 1964), 96-97; M. E. Weeks, Discovery of the Elements, 4th ed. (Easton, Pa., 1939), 360-362; and C. A. Wurtz, “Discours qui M. Wurtz, membre de l’Académie des Sciences, se proposait de pronocer aux funérailles de M. Balard, le 3 Avril, 1876,” in Journal de pharmacie et chimie, 4th ser., 23 (1876), 375-379.

Seymour H. Mauskopf