born Sept. 5 or 6, 1766, Eaglesfield, Cumberland, Eng.
died July 27, 1844, Manchester
British chemist and physicist.
He spent most of his life in private teaching and research. His work on gas es led him to state Dalton's law (see gas laws ). He devised a system of chemical symbol s, ascertained the relative weights of atoms, and arranged them into a table. His masterpiece of synthesis was the atomic theory
the theory that each element is composed of tiny, indestructible particles called atom s that are all alike and have the same atomic weight
which elevated chemistry to a quantitative science. He was also the first to describe colour blindness (1794), and his lifelong meteorological journal contains more than 200,000 observations. He is remembered as one of the fathers of modern physical science.
John Dalton, detail of an engraving by W. Worthington, after a portrait by William Allen, 1814.
By courtesy of the trustees of the British Museum; photograph, J.R. Freeman & Co. Ltd.