Gay-Lussac, Joseph Louis

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Gay-Lussac, Joseph Louis

(zhôzĕf` lwē gā-lüsäk`), 1778–1850, French chemist and physicist. He was professor in Paris at the Sorbonne, at the Polytechnic School, and at the Jardin des Plantes. Gay-Lussac made two balloon ascensions in 1804, attaining on the second a height of about 7,016 m (23,000 ft), to test the variation of the earth's magnetic field and the composition of the atmosphere at varying altitudes. He made advances in industrial chemistry; in the field of analytical chemistry he improved the methods of analyzing gas mixtures, studied prussic acid and iodine, and isolated cyanogen. With L. J. Thénard he improved Davy's method of isolating alkali metals, showed chlorine to be an element, and isolated boron. In physics he is known especially for his work on gases. In 1802 he discovered independently that a gas at constant pressure expands, for each degree of temperature, by a constant fraction of its volume at 0°C;. This law, first discovered (1787) by J. A. C. Charles, is known as Charles's law or as Gay-Lussac's law (see gas lawsgas laws,
physical laws describing the behavior of a gas under various conditions of pressure, volume, and temperature. Experimental results indicate that all real gases behave in approximately the same manner, having their volume reduced by about the same proportion of the
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). However, Gay-Lussac's name is more commonly associated with another law of gases, the law of combining volumes, which Gay-Lussac was the first to formulate (c.1808). This law states that the volumes of gases that interact to give a gaseous product are in the ratio of small whole numbers to each other and that each bears a similar relation to the volume of the product.

Gay-Lussac, Joseph Louis


Born Dec. 6, 1778, in St. Léonard; died May 9, 1850, in Paris. French chemist and physicist; member of the Paris Academy of Sciences (1806). Graduated from the Ecole Polytechnique in Paris in 1800. Student of C. Berthollet. Became professor of chemistry at the Ecole Polytechnique and professor of physics at the Sorbonne (Paris) in 1809 and professor of chemistry at the Paris Botanical Garden in 1832. Member of the Chamber of Deputies, where he made speeches only on scientific subjects, from 1831 to 1839. Edited the French journal Annales de chimie et de physique with D. F. Arago from 1815 to 1850. Foreign honorary member of the St. Petersburg Academy of Sciences (1826).

In 1802, independently of J. Dalton, Gay-Lussac discovered the law of thermal expansion of gases. After la. D. Zakharov’s balloon flight for scientific purposes (June 30, 1804), Gay-Lussac made two such flights (Aug. 24, 1804, with J. Biot, and Sept. 16, 1804). During the second flight, he discovered that at an altitude of about 7,000 m the intensity of the earth’s magnetism is undiminished and established that the air has the same composition as at the earth’s surface. In 1808 he discovered the law of combining volumes in reactions between gases. During the same year, Gay-Lussac and L. Thénard developed a method for the production of potassium and sodium by heating potassium hydroxide or caustic soda to high temperatures with iron filings and produced free (impure) boron by heating boric anhydride with potassium. They also demonstrated the elemental nature of chlorine (1808) and potassium and sodium (1810). In 1813-14, simultaneously with H. Davy, Gay-Lussac demonstrated that iodine is a chemical element closely resembling chlorine, and he prepared iodine compounds, such as hydrogen iodide. Having prepared pure prussic acid (1811), Gay-Lussac recognized it as a hydrogen compound of the complex radical cyanogen. In that same year he prepared cyanogen (dicyan) from mercuric cyanide. The existence of oxygen-free acids, which Gay-Lussac proposed to call the hydrogen acids, was established at about this time.

Simultaneously with J. Berzelius and J. Döbereiner, Gay-Lussac refined organic elemental analysis (1815), using copper oxide for the combustion of organic materials.

In 1819, on the basis of his definitions, Gay-Lussac constructed the first diagrams for the solubility of salts in water and observed the existence of two separate solubility curves for anhydrous sodium sulfate and its decahydrate. From 1824 to 1832 he refined the methods of titration (alkalimetry, acidimetry, and chlorometry). In 1827 he invented a tower for absorbing the nitrogen oxides released in lead chambers during the production of sulfuric acid. The towers, which bear his name, were first used in 1842.


Arago, F. Biografii znamenitykh astronomov, fizikov i geometrov, vol. 2. St. Petersburg, 1860. (Translated from French.)
Giua, M. Istoria khimii. Moscow, 1966. (Translated from Italian.)
Blanc, E., and L. Delhoume. La Vie émouvante et noble de Gay-Lussac. Limoges, 1950.