Henri Victor Regnault, a French physicist, born in Aix-la-Chapelle, July 21, 1810. He studied at the polytechnic school of Paris from 1830 to 1832, and was professor at Lyons till 1840, when his Mémoire sur l'action du chlore sur l'éther chlorhydrique secured his admission to the academy of sciences and his appointment to the chair of physical sciences in the polytechnic school, and in 1841 in the collége de France. He was chief engineer of mines from 1847 to 1854, when he became director of the porcelain works at Sèvres. In 1848 he received the Rumford medal from the royal society of London for his "Experiments to determine the Laws and the Numerical Data which enter into the Calculation of Steam Engines," and subsequently became one of the 50 foreign members of that body, which presented him with the Copley medal in November, 1869. His attention has been devoted chiefly to heat, and he was the first to demonstrate that the latent heat of steam diminishes as the sensible heat increases, but in a slower ratio. He has also verified the law of Mari-otte and Boyle on the compressibility of the gases. Accounts of his investigations on these subjects fill the 21st and 26th volumes of the Mémoires of the French academy of sciences.

His Cours élémentaire de chimie (2 vols. in 4 parts, Paris, 1847-'9; 5th ed., 4 vols., 1859-'60) has been translated into several languages. Among his other works is an abstract of the preceding, Premiers éléments de chimie (1850; 4th ed., 1861).