Gay-Lussac, Louis-Joseph

(1778-1850)

   physicist, chemist

   Born in Saint-Léonard-de-Noblat and educated at the École polytechnique and École des ponts et chaussées, Louis-Joseph Gay-Lussac is known for his studies on the physical properties of gases. in 1804, he made balloon ascents to study magnetic forces and the temperature and composition of air at different altitudes. He then (1809) formulated the law of gases that is associated with his name, which states that the ratios of volumes of gases involved in chemical reactions are in small whole numbers. in relation to this work, he studied, with the German naturalist baron Alexander von Hum-boldt, the composition of water, discovering that it consists of two parts hydrogen and one part oxygen. He also investigated (1809-16) the properties of potassium and boron and of chlorine and hydrocyanic acid. Guy-Lussac served in the Chamber of Deputies and in the Senate and, in 1806, was named to the Academy of Sciences.