Dulongand Petits Law

Dulong and Petit's Law, in chemical Physics, was discovered by these experimenters in 1819. The law states that for most elements the specific heat multiplied by the atomic weight gives a constant number. This number is about 6.2 as the following table shows, the differences actually obtained being readily accounted for by experimental errors. The constant is known as the atomic heat of simple substances.

Neumann and Regnault found that all compound bodies of similar atomic composition follow the same sort of law, though the actual constant varies in different types of compounds.