An Etymological Dictionary of Astronomy and Astrophysics

1. Law of combining volumes. The volumes of gases used and produced in a chemical reaction, are in the ratio of small whole numbers when measured at constant temperature and pressure.
   

2. For a gas held at constant volume, there is a direct correlation between temperature and pressure: P₁/T₁ = P₂/T₂. Gay-Lussac’s law, → Boyle-Mariotte law, and → Charles’ law were later unified into the → ideal gas law.

See also: Named after Joseph Louis Gay-Lussac (1778-1850), a French chemist and physicist; → law.