William Allen, an English chemist, born Aug. 29, 1770, died near Lindfield, Sussex, Dec. 30, 1843. He was the son of a Quaker silk manufacturer in Spitalfields, and learned chemistry in the pharmacy of Mr. Bevan, in London, to whose business he eventually succeeded, He was for many years lecturer on chemistry and experimental philosophy at Guy's hospital, a fellow of the royal society, and president and one of the founders of the pharmaceutical society. In conjunction with his friend Mr. Pepys he established the proportion of carbon in carbonic acid, and demonstrated that the diamond was pure carbon. Having purchased an estate in Sussex, he devoted himself for many years to improving the condition of his tenantry and poor neighbors, founding schools, building model cottages, and laying out gardens and playgrounds.