John Dalton
Dalton, John (1766-1844), an English chemist and physicist. Dalton made several significant contributions to science. He formulated a law regarding the pressure of mixed gases. .) He provided the basis of later research in nuclear physics with his atomic theory that matter consisted of small indivisible (and invisible) particles called atoms. Dalton also published the first paper on color blindness (1794), an affliction that he had observed in himself, and invented his own weather instruments.
Dalton worked out his atomic theory during 1803-04 and developed a table of atomic weights for elements. According to his theory, which he introduced in New System of Chemical Philosophy (1808-10; 1827), all atoms of the same element have the same weight, and the atomic weight of each element is different. Therefore, Dalton reasoned, atomic weight could be used to classify elements. Parts of his theory were later proved wrong, but his ideas about atomic weight remain a key concept in chemistry and nuclear physics.
Dalton was born in Eaglesfield, England. He attended school until about age 11, at which time he became a tutor. He supported himself as a tutor for the rest of his life.