Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution); 26 August 1743 – 8 May 1794), the "father of modern chemistry", is a French nobleman prominent in the histories of chemistry and biology.

He names both oxygen (1778) and hydrogen (1783) and helps construct the metric system, puts together the first extensive list of elements, and helps to reform chemical nomenclature.

He is also the first to establish that sulfur is an element (1777) rather than a compound.

He discovers that, although matter may change its form or shape, its mass always remains the same.

He is an administrator of the "Ferme Générale" and a powerful member of a number of other aristocratic councils.

All of these political and economic activities enable him to fund his scientific research.

At the height of the French Revolution, he is accused by Jean-Paul Marat of selling watered-down tobacco, and of other crimes and is eventually guillotined a year after Marat's death.

Benjamin Franklin is familiar with Lavoisier, as they are both members of the "Benjamin Franklin inquiries" into Mesmer and animal magnetism.