British Dictionary definitions for j. louis gay-lussac
/ˈɡeɪˈluːsæk; French ɡɛlysak/
Joseph Louis (ʒozɛf lwi). 1778–1850, French physicist and chemist: discovered the law named after him (1808), investigated the effects of terrestrial magnetism, isolated boron and cyanogen, and discovered methods of manufacturing sulphuric and oxalic acids
(gā'lə-sāk') French chemist and physicist who in 1808 developed a law governing the ratio of volumes of gases participating in chemical reactions. In that same year, with Louis Jacques Thénard, he discovered the element boron.