Antoine Lavoisier

Antoine Lavoisier was a French chemist and public official who did more than anyone to turn chemistry into a precise, quantitative science. Working in Paris in the last decades of the old monarchy, he explained combustion as a reaction with oxygen, overturning the older phlogiston theory, showed that water is a compound, and helped create the modern system for naming chemicals. A wealthy partner in the royal tax-collecting company, he was executed during the Reign of Terror in 1794.

Antoine-Laurent Lavoisier was born on 26 August 1743 in Paris; his father was a lawyer at the Parlement of Paris, and he inherited a large fortune when his mother died when he was five. At the Collège Mazarin he developed interests in chemistry, botany, astronomy and mathematics, shaped by the ideals of the Enlightenment. He qualified in law in 1764 but never practised. Instead he studied geology, read his first paper to the Academy of Sciences in 1764 and won a royal gold medal in 1766 for an essay on street lighting. In 1768 he joined the Academy.

Around the same time Lavoisier purchased a stake in the Ferme générale, the private company that advanced money to the crown in return for the right to collect certain taxes. The company was widely hated, but his income from it paid for his research and a costly, well-equipped laboratory. In 1771, aged 28, he married Marie-Anne Paulze, aged 13, whose father was a senior tax farmer. She became his close scientific partner, translating English chemical works, assisting in experiments and drawing his apparatus.

He served the state in many roles. For the tax company he designed checks against adulterated tobacco and had a customs wall built around Paris, both deeply unpopular. From 1775, as one of four commissioners of gunpowder, he greatly improved France's supply and lived and worked at the Royal Arsenal.

From 1772 Lavoisier studied burning and showed that phosphorus and sulfur gained weight when they burned because they combined with part of the air. In 1774 the English chemist Joseph Priestley visited Paris and described a gas that made things burn fiercely. Lavoisier repeated and extended the work, concluded that air is a mixture of two different gases, and in 1778 named the active one oxygen. In 1783 he publicly attacked the phlogiston theory and, with Pierre-Simon Laplace, showed by experiment that water is made of hydrogen and oxygen. With Laplace he also used an ice calorimeter to show that breathing is a slow form of combustion.

His careful weighing in sealed vessels supported the principle that mass is neither created nor destroyed in a chemical reaction, which is still called Lavoisier's law in France. In 1787 he and three colleagues published a new chemical nomenclature, giving names such as copper sulfate in place of older terms. His Elementary Treatise on Chemistry of 1789 listed some 33 substances as elements and is often seen as the first modern chemistry textbook.

Lavoisier at first worked within the French Revolution. He chaired the commission that in 1791 recommended the metric system. But the Ferme générale was abolished in 1791, the Academy of Sciences was suppressed in 1793, and in November that year the arrest of all former tax farmers was ordered. Charged with defrauding the state and with watering tobacco, Lavoisier was convicted and guillotined in Paris on 8 May 1794, aged 50, along with other former tax farmers. The mathematician Joseph-Louis Lagrange lamented that a century might not be enough to produce another head like his. About a year and a half later the French government declared him wrongly convicted.

Lavoisier's insistence on measurement, his oxygen theory and his new language of chemistry shaped the science for the next generation, though his belief that all acids contain oxygen proved wrong. He is widely seen as the central figure of the chemical revolution of the 18th century.

Our 1783 map shows the Kingdom of France during his greatest discoveries, and the 1800 map shows the French First Republic a few years after his execution.