Gay-Lussac, Joseph Louis
. Gay-Lussac, Joseph Louis (1778-1850), French chemist and physicist, known for his studies on the physical properties of gases . He was born in Saint Léonard and educated at the École Polytechnique and the École des Ponts et Chaussées in Paris. After holding several professorships he became professor of physics at the Sorbonne from 1808 to 1832. In 1804 he made balloon ascensions to study magnetic forces and to observe the composition and temperature of the air at different altitudes. In 1809 he formulated a law of gases that is still associated with his name. Gay-Lussac's law of combining volumes states that the volumes of the gases involved in a chemical reaction (both reactants and products) are in the ratio of small whole numbers. In connection with these studies he investigated, with German naturalist Baron Alexander von Humboldt, the composition of water and found it forms when two parts of hydrogen and one of oxygen unite. In 1809 Gay-Lussac worked on the preparation of pot