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
History of same-sex marriage in the United States voters approved a constitutional amendment banning same-sex marriage as well as all other types of same-sex unions. In the regular November 2012 elections, voters for the first time approved the legalization of same-sex marriage by popular vote in three states: Maine, Maryland, and Washington. Maine's law took effect on December 29, 2012. Maryland started allowing same-sex marriages on January 1, 2013, In Washington state, the first licenses were distributed on December 6, with the first marriages on December 9 following the mandatory three-day waiting period. In the same election, Minnesota rejected a constitutional ban on same-sex marriage. On June 26,