n :  a law in physics and chemistry: the specific heats of most solid elements multiplied by their atomic weights are nearly the same averaging a little over six calories per degree Celsius per gram-atomic weight
 
Du•long, Pierre-Louis (1785-1838), and Pe*tit, Alexis-Thérèse (1791-1820), French physicists. Dulong and Petit collaborated on important studies of temperature measurement and heat transfer. In 1815 they made the first accurate comparison between air and mercury thermometers. Two years later they showed that Newton's law of cooling is true only for small differences in temperature. In 1819 they demonstrated that the heat produced in the compression of a gas is proportional to the work done. In that same year they formulated the law concerning specific heats that now bears their names.
 
   
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.