The New International Encyclopædia/Dulong, Pierre Louis
DULONG, dụ′lôN′, Pierre Louis (1785-1838). A French physicist and chemist, known chiefly for the law which he discovered, jointly with Petit, in 1819. According to the law of Dulong and Petit, the specific heat of an element, multiplied by its atomic weight, is the same for all solid elements. The law was established empirically, and no theoretical explanation of it has yet been found. Dulong received his education at the Ecole Polytechnique, where he became, in 1820, professor of physics. In 1823 he was admitted into the Academy of Sciences. While investigating the composition of the chloride of nitrogen, he lost an eye through the explosion of a quantity of this substance.