GayLussac

Joseph Louis Gay-Lussac (1778–1850) was a French chemist and physicist known for his work on gas laws and gas reactions. Born in Saint-Lô, he studied at the École Polytechnique in Paris and worked with Louis-Jacques Thénard.

He formulated Gay-Lussac's law: at constant volume, the pressure of a gas is proportional to its temperature. He is also associated with the law of combining volumes, which states that gases reacting together do so in simple whole-number volume ratios. Through precision gas experiments, he advanced methods of gas thermometry and measurement, contributing to the broader development of quantitative chemistry and the understanding of gas behavior.

In 1808, Gay-Lussac and Thénard discovered boron by reducing boric oxide with potassium, one of the early isolations of a chemical element. Beyond boron, he contributed to chemical analysis and the study of various gases and vapors, helping to establish systematic experimental approaches in chemistry.

He held academic positions in Paris, including at the École Polytechnique, and was a member of the French Academy of Sciences. His work helped lay the foundations of modern chemical thermodynamics and stoichiometry, and his name remains attached to fundamental gas laws that describe how gases respond to changes in temperature, pressure, and volume.