Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution; 26 August 1743 – 8 May 1794; French pronunciation: [ɑ̃twan lɔʁɑ̃ də lavwazje]), the “father of modern chemistry”, was a French nobleman prominent in the histories of chemistry and biology. He named both oxygen (1778) and hydrogen (1783) and helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature. He was also the first to establish that sulfur was an element (1777) rather than a compound. He discovered that, although matter may change its form or shape, its mass always remains the same.
He was an administrator of the Ferme Générale and a powerful member of a number of other aristocratic councils. All of these political and economic activities enabled him to fund his scientific research. At the height of the French Revolution, he was accused by Jean-Paul Marat of selling watered-down tobacco, and of other crimes and was eventually guillotined a year after Marat’s death. Benjamin Franklin was familiar with Antoine, as they were both members of the “Benjamin Franklin inquiries” into Mesmer and animal magnetism.