Thomas Graham was a Scottish inorganic and physical chemist. He was born on December 21, 1805 and died on September 16, 1869. In his career he had achieved becoming a professor of chemistry at Anderson's College in Glasgow and at University College, London and finally became Master of the Mint. Graham studied the diffusion of gases from 1828 to 1833 and in 1833 proposed GrahamÕs Law, which stated that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.