Chemist, born in Haddington, grandson of John Brown of Haddington, whose life was devoted, with the zeal of a mediæval alchemist, to a reconstruction of the science of atomics, which he did not live to see realised: a man of genius, a brilliant conversationist and an associate of the most intellectual men of his time, among the number De Quincey, Carlyle, and Emerson; wrote "Lay Sermons on the Theory of Christianity," "Lectures on the Atomic Theory," and two volumes of "Essays, Scientific and Literary" (1817-1856).