[1][2] The method was designed by the French chemist Jean Baptiste André Dumas, after whom the procedure is now named.
Dumas used the method to determine the vapour densities of elements (mercury, phosphorus, sulfur) and inorganic compounds.
[3] Today, modern methods such as mass spectrometry and elemental analysis are used to determine the molecular weight of a substance.
The procedure entailed placing a small quantity of the unknown substance into a tared vessel of known volume.
The molecular weight of the chemical is then simply the mass in grams of the vapor within the vessel divided by the calculated number of mole.