Claude Louis Berthollet

Claude Louis Berthollet was born in Savoy on 9 December 1748 and trained as a chemist in an era when the field was still shaking off alchemy's shadow. His theoretical work on reverse reactions laid groundwork for understanding chemical equilibria, the push-and-pull that governs how far a reaction will go. He also helped rebuild chemical nomenclature into something rational. But his most immediate mark was practical: he demonstrated that chlorine gas could bleach, then developed sodium hypochlorite as a solution that could do the job without the fumes. By 1804 he'd risen to vice president of the French Senate. He died on 6 November 1822.