Elements of ChemistryAntoine Lavoisier
About Elements of Chemistry
Lavoisier published the Traité élémentaire de chimie in 1789, the same year as the French Revolution. The book revolutionized chemistry no less thoroughly. It replaced the phlogiston theory with the oxygen theory of combustion and established the modern conception of a chemical element.
An element, Lavoisier declared, is any substance that cannot be decomposed by chemical analysis. This operational definition swept away the classical four elements (earth, water, air, fire) and replaced them with a table of thirty-three substances, including oxygen, hydrogen, nitrogen, carbon, sulfur, and phosphorus. Some entries proved wrong (light and caloric appear on the list), but the method was right: classification by experimental evidence rather than speculative philosophy.
The book also codifies the principle of conservation of mass. In every chemical reaction, the total weight of the products equals the total weight of the reactants. Lavoisier insisted on precise measurement with the balance, transforming chemistry from a qualitative art into a quantitative science. His systematic nomenclature (developed with Guyton de Morveau, Berthollet, and Fourcroy) gave chemistry a rational language that replaced the alchemical vocabulary of sulfurs, mercuries, and earths.
The did for chemistry what Newton's had done for physics: it made the discipline rigorous, cumulative, and modern.