Graham's law has come to denote an important class of finely divided materials. Around the time Graham did his work, the concept of molecular weight was being established largely through the measurements of gases. Daniel Bernoulli suggested in 1738 in his book Hydrodynamica that heat increases in proportion to the velocity, and thus kinetic energy, of gas particles. Italian physicist Amedeo Avogadro also suggested in 1811 that equal volumes of different gases contain equal numbers of molecules. Thus, the relative molecular weights of two gases are equal to the ratio of weights of equal volumes of the gases. Avogadro's insight together with
Status of same-sex marriage recognition of same-sex marriages performed in other states. DOMA also denied federal recognition to same-sex couples who were legally married under state law. On 26 June 2013, the U.S. Supreme Court declared Section 3 of DOMA to be unconstitutional in "United States v. Windsor". The court said that the provision was "a deprivation of the equal liberty of persons that is protected by the Fifth Amendment." With this ruling the federal government recognized same-sex marriages performed by states that allowed same-sex marriage. It also affected several federal rights, including enabling a U.S. citizen to petition a same-sex spouse for immigration.