Joseph Louis Gay-Lussac

Gay-Lussac, Joseph Louis (1778–1850), French chemist and physicist. He is best known for Gay-Lussac's law (1808), which states that when gases combine to give a gaseous product, the ratio of the volumes of the reacting gases to that of the product is a simple, integral one. He also showed that all gases increase in volume by the same fraction for the same increase in temperature, 1/273.2 for 33.8°F (1°C), and made 2 balloon ascents to investigate atmospheric composition and the intensity of the earth's magnetic field at altitude. His many important contributions to inorganic chemistry include the identification of cyanogen gas (1815).