Antoine-Laurent de Lavoisier

Antoine-Laurent de Lavoisier (1743–1794), working in his magnificent laboratory at the Paris Arsenal alongside his brilliant wife Marie-Anne Pierrette Paulze, transformed chemistry into a rigorous quantitative science. By sealing chemical reactions in closed vessels and weighing reactants and products on precision balances, he formulated the fundamental law: 'Nothing is lost, nothing is created, everything is transformed' (*Rien ne se perd, rien ne se crée, tout se transforme*).

Lavoisier recognized that combustion and respiration are chemical reactions with a distinct gas that he named oxygen (acid-former), disproving the long-held phlogiston theory. In his 1789 Traité Élémentaire de Chimie, he published the first modern list of chemical elements. Tragically guillotined during the Reign of Terror due to his tax-farming post, mathematician Lagrange lamented: 'It took them only an instant to cut off that head, and a hundred years may not produce another like it.'