Dalton, John

English chemist

Born: Eaglesfield, Cumberland, September 6, 1766

Died: Manchester, July 27, 1844

Lecoq De Boisbaudran

Dalton was born into a Quaker family and remained a practicing Quaker all his life. He began teaching at a Quaker school in 1778 and studied the weather using instruments he designed himself. In 1793 he wrote a book entitled Meteorological Observations and Essays, which makes him one of the pioneers in meteorology.

Dalton was color-blind and described the condition in a publication in 1794. As a result of this condition, he was a rather poor experimenter and relied on theory to make a name for himself. Dalton considered the belief held by Newton and others, that gases consisted of tiny particles, and concluded that all matter must consist of these small particles.

Dalton recognized the similarity of this theory to that advanced by Democritus some twenty-one centuries earlier, and therefore called these tiny particles atoms. He maintained that atoms differed from each other only in mass. This was something that could be measured, and so Dalton was the first to advance a quantitative atomic theory, a sort of wedding between Democritus and Galileo. He was also the first to prepare a table of atomic weights.

Dalton first advanced his atomic ideas in 1803, and in 1808 published a book, New System of Chemical Philosophy, in which he spelled out his theories in detail.

As a Quaker, Dalton was unable to accept awards for his achievements, and he was elected to the Royal Society in 1822, without his knowledge. He was later presented with a Doctors degree from Oxford.

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