Alexander William Williamson (1824-1904), British organic chemist. Williamson is famous for his work on the synthesis of ethers. He was the first to make 'mixed' ethers, those with two different alkyl groups attached. His method is known as the Williamson synthesis. He also made important contributions to theories of chemical reactions, describing how reversible reactions could be in a state of dynamic equilibrium. He also contributed to the theory of ionic dissociation. Williamson was a professor at University College, London, from 1849-1887. In 1862, he was awarded the Royal Medal of the Royal Society for his work on ethers.