Pierre Louis Dulong FRS FRSE was a French physicist and chemist. He is remembered today largely for the law of Dulong and Petit, although he was much-lauded by his contemporaries for his studies into the elasticity of steam, conduction of heat, and specific heats of gases. He worked most extensively on the specific heat capacity and the expansion and refractive indices of gases. He collaborated several times with fellow scientist Alexis Petit, the co-creator of the Dulong–Petit law.

Rouen is a city on the River Seine in northern France. It is the prefecture of the region of Normandy and the department of Seine-Maritime. Formerly one of the largest and most prosperous cities of medieval Europe, the population of the metropolitan area is 702,945 (2018). People from Rouen are known as Rouennais.