French chemist and physicist (1778–1850)

Gay-Lussac was the son of a judge who was later imprisoned during the French Revolution. Born at St. Léonard in France, he entered the recently founded Ecole Polytechnique in 1797 and graduated in 1800. His career was thereafter one of steady promotion. Originally studying engineering, in 1801 he attracted the attention of the chemist Claude-Louis Berthollet who made him his assistant at Arcueil, near Paris. The science of chemistry was then in its infancy. Few chemists were actively engaged in research, and the equipment used was primitive. Chemical symbols had just been introduced, and no chemical formulae were known with certainty. During his career Gay-Lussac contributed to the advancement of all branches of chemistry by his discoveries, and greatly improved and developed experimental techniques.

In 1802, following the researches of the chemist Jacques Charles, Gay-Lussac formulated the law now alternatively attributed to himself and Charles – that gases expand equally with the same change of temperature, provided the pressure remains constant. By using superior experimental techniques, Gay-Lussac largely eliminated the errors of his predecessors in this field, in particular by developing a method of drying the gases. He measured the coefficient of expansion of gases between 0°C and 100°C, thus forming the basis for the idea of the absolute zero of temperature. His law was received with satisfaction as complementary to Boyle's law. It was later shown that Gay-Lussac's and Boyle's laws applied exactly only to a hypothetical ‘ideal gas’; real gases obey the law approximately.

Gay-Lussac made his first daring balloon ascent in 1804 with Jean Biot, during which they made scientific observations and established that there was no change in either the composition of the air or in the Earth's magnetic force at the heights they reached. Gay-Lussac made a second ascent alone, reaching a height of 23,018 feet.

In 1805, by exploding together given volumes of hydrogen and oxygen, Gay-Lussac discovered that one volume of oxygen combined with two volumes of hydrogen to form water. In 1808, after researches using other gases, he formulated his famous law of combining volumes – that when gases combine their relative volumes bear a simple numerical relation to each other (e.g., 1:1, 2:1) and to the volumes of their gaseous product, provided pressure and temperature remain constant. The English chemist John Dalton was immediately interested in Gay-Lussac's discovery, but when, on investigation, the law appeared to conflict with his own theory of the indivisibility of atoms, Dalton rejected the law and sought to discredit Gay-Lussac's experimental methods. The reason for the apparent conflict was that the difference between an atom and a molecule was not clearly understood, and it was left to the Italian chemist Amedeo Avogadro to formulate a theory reconciling the two laws, thus laying the basis of modern molecular theory.

From 1808 Gay-Lussac worked with the chemist Louis Thenard. Following Humphry Davy's isolation of minute amounts of sodium and potassium, the two chemists in 1808 prepared these metals in reasonable quantities. It was during his experiments with potassium as a reagent that Gay-Lussac blew up his laboratory, temporarily blinding himself. In collaboration with Thenard he isolated and named the element boron. Simultaneously with Davy, Gay-Lussac investigated in 1813 a substance first isolated by Bernard Courtois and established that it was an element similar to chlorine. He named it iodine from the Greek ‘iode’ meaning violet. In 1815 he prepared cyanogen and described it as a compound radical. He proved that prussic acid (hydrogen cyanide) was made up of this radical and hydrogen, completing the overthrow of Lavoisier's theory that all acids must contain oxygen. His recognition of compound radicals laid the basis of modern organic chemistry.

Gay-Lussac also investigated fermentation, the phenomenon of supercooling, the growth of alum crystals in solution, the compounds of sulfur, and the various stages of oxidation of nitrogen. With the young student Justus von Liebig he investigated the fulminates. In his later years he improved on experimental techniques, and laid the basis of modern volumetric analysis.

In 1827 he devised the Gay-Lussac tower. Oxides of nitrogen arising from the preparation of sulfuric acid by the lead-chamber process, which formerly escaped into the atmosphere, are absorbed by passing them up a chimney packed with coke, over which concentrated sulfuric acid is trickled. This tower and its modifications are used in many chemically-based industries today.

Gay-Lussac was a chemist of brilliance and determination. Although said to be cold and reserved as a man, as a researcher he was bold and energetic. Shortly before his death he expressed regret at the experiments that he would never be able to perform.

The French chemist and physicist Joseph Louis Gay-Lussac (1778-1850) is distinguished for his work on gas laws and for his studies of the properties of cyanogen and iodine.

Born at Saint-Léonard in the department of Vienne, Joseph Gay-Lussac came from a solidly bourgeois family. The storms of the French Revolution delayed his education, but largely by his own disciplined self-teaching, he passed the examinations and was admitted to the prestigious École Polytechnique in 1797. Here he became the protégé of Claude Louis Berthollet.

In these early years Gay-Lussac's skill as an experimenter and scientific instrument maker was well developed. In 1802 he published a law of the expansion of gases by heat, which became known as Charles' law. In 1804 he made an ascent of 23,000 feet in a balloon to collect samples of the atmosphere for chemical analyses and to measure the dependence of the earth's magnetic field on elevation. In 1806 Gay-Lussac was elected to the Institut de France, and in 1809 he became a professor of chemistry at the École Polytechnique and professor of physics at the Sorbonne. He invented the portable barometer, steam injector pump, and air thermometer and improved the spirit lamp and the chemist's furnace. In addition to his work on these laboratory devices, he contributed to the production and improvement of industrial chemical machinery and processes, above all in the important sulfuric acid tower which bears his name.

In 1805-1806, through the intervention of Berthollet, Gay-Lussac accompanied the scientific explorer Alexander von Humboldt on his expedition through Italy and Germany making measurements of terrestrial magnetism. While in Rome, the young chemist was able to use the laboratory of Wilhelm von Humboldt, on which occasion he discovered the presence of fluorides and phosphates in the bones of fish. Not long after this, Gay-Lussac met a beautiful girl in a Paris draper's shop, soon became engaged, and then sent his fiancée to school to complete her chemistry education. In 1808 he married her. The marriage lasted for 40 years and was marked by the closest collaboration of hearts and minds.

In addition to his well-known work on the combining properties of gases, Gay-Lussac also worked on the determination of vapor densities, and the coefficients of expansion of gases, in which he pioneered the procedures, and contributed to the careful quantitative measurements that in later years were so useful for grounding the kinetic theory of gases and thermal physics. He published his most influential work in 1808, the law of combining volumes of gases.

Electrolysis and Iodine

Some of Gay-Lussac's best work, however, was done in close collaboration with Louis Jacques Thénard, the chemist who created the foundations of organic analysis. Together they produced the alkali metals in quantity by reacting fused alkalis with red-hot iron. Napoleon made considerable sums available to the École Polytechnique to support their work on electrolysis. However, though aware of the theoretical importance of the electrolytic process, they elaborated a more efficient method of producing the alkali metals.

Gay-Lussac investigated (1813-1814) the chemical properties of iodine and described his findings in a number of papers presented to the Institut de France. However, Sir Humphry Davy, visiting in Paris at the time, wrote a particularly insulting note to the scientific world claiming priority for the discovery of the elemental nature of iodine, asserting that Gay-Lussac had learned the fundamental properties of iodine from him. In yet another controversy Gay-Lussac and Thénard claimed a priority of 36 hours for their isolation of boron. They claimed that the experiment was completed on June 21, 1800, and the results sent to Geneva for publication, whereas Davy's announcement was supposedly dated June 30. It should be noted that the potassium that Davy used to treat borax was produced by using the Thénard-Gay-Lussac method.

Other Achievements

The French partners also carried out extensive investigations on the composition of hydrochloric acid. Individual work by Gay-Lussac on the properties of the sulfates and sulfides, as well as other salts, was an important step in the perfection of what later became known as volumetric analysis. He compiled extensive solubility charts for numerous compounds. Classic work on cyanogen compounds was carried out by him largely on his own. He was also the first to recognize that the CN combination was stable and behaved as a radical in the various combinations into which it entered.

Gay-Lussac served in 1818 as superintendent of the government gunpowder plant and as chief assayer of the national mint in 1829. King Louis Philippe raised him to the peerage in 1839. The honor had been delayed for 17 years, for, argued the old aristocracy, Gay-Lussac worked with his hands. He died on May 9, 1850.

Further Reading

Gay-Lussac is discussed in Sir William A. Tilden, Famous Chemists: The Men and Their Work (1921); Edward Farber, ed., Great Chemists (1961); and Maurice Crosland, The Society of Arcueil: A View of French Science at the Time of Napoleon I (1967).

For more information on Joseph-Louis Gay-Lussac, visit Britannica.com.

(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 laws). 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.

IN BRIEF: n. - French chemist and physicist who first isolated boron and who formulated the law describing the behavior of gases under constant pressure (1778-1850).

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)