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John Dalton is the father of modern atomic theory

Posted in Historical articles, History, Science on Wednesday, 18 December 2013

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This edited article about science first appeared in Look and Learn issue number 496 published on 17 July 1971.

John Dalton, picture, image, illustration

John Dalton, founder of chemical atomic theory by Peter Jackson

John Dalton was curious about every subject under the sun. He was born in 1766 in a small Cumberland village called Eaglesfield, where his father was a poor hand-loom weaver. His family were Quakers and, throughout his life, Dalton remained true to his beliefs, taking his place at the Society of Friends’ meeting house twice a day on Sundays. What little schooling he had ceased when he was 12, at which age he graduated from the position of pupil and took over as teacher at the little village school.

Dalton was possessed by an unusually studious nature and a patient application to matters of detail which marked him out as a natural mathematician. Apart from some tuition from a distant relative and help from John Gough, a blind philosopher who encouraged his thirst for scientific knowledge, Dalton was self-taught. He liked always to think things out for himself, disdaining the advice and findings of others, claiming that he would have nothing to do with anything which he could not know and test from his own experience.

His time as a teacher ended when he was 14. It had earned him an average of five shillings a week and there seemed no chance of improvement. He had a brief spell working on a farm, for which he was quite obviously unsuited. Finally, he left his native village in 1781 at the invitation of his cousin George Bewley, who kept a school at Kendal. Dalton worked as an assistant master, and when Bewley retired in 1785 became joint head of the school with his brother Jonathan, who had joined him. This lasted until 1793 when he moved to Manchester, where he was to remain for the rest of his life, first to work in a college and then to become a freelance teacher of mathematics and science.

One of the first discoveries Dalton made was of his own colour blindness. As a boy he was at a military review and heard onlookers comment on the brilliant colours of the soldiers’ uniforms. This he could not understand since to him the colours looked much the same as the sombre shade of the grass on which they paraded. He could not, at the time, understand why this was so but it was a problem that continued to occupy his mind.

At the age of 28, he read a paper before the Manchester Literary and Philosophical Society, of which he was later to become secretary, on the nature of colour blindness, or “Daltonism” as it was known.

No doubt such defects in vision had existed since the beginning of time, but Dalton was the first man to remark upon it and write about its characteristics. He could recognise blue and shades of yellow, but little else. There is a story that Dalton unwittingly attracted attention to himself at a meeting of the British Association, to which he had been elected, by wearing the flaming red robes of a Doctor of Civil Law, when all about him were garbed in solemn black. He, of course, was unaware of being in any way conspicuous.

His other great interest, which stayed with him all his life, was the science of weather. He began a meteorological diary in 1787 which he entered up meticulously every day for 57 years, making in all over 200,000 separate observations. It was his interest in weather which led to his study of the air, and then of gases, and so to the formation of his Atomic Theory, for which he is most remembered.

The word “atom” originally meant a fundamental particle, or something which cannot be broken up into smaller parts. It was in this sense that the word was used by the ancient Greeks for their atomic theories of the universe.

Modern atomic theory starts with Dalton. His chemical experiments led him to the conclusion that all matter in the universe was made up of a number of elements, such as hydrogen, iron, mercury and oxygen, and that each element consisted of indivisible atoms, and that the atom of each elementary substance had its own particular weight. This weight never varied, so that any one atom of iron is equal to any other atom of iron.

He had also observed that the elements of certain chemical compounds unite in constant proportion; for example, water is made up in weight of one part hydrogen and eight parts oxygen, and in any amount would always be so composed.

Dalton and many of his contemporaries believed that the atom was the ultimate and indivisible form of matter, and for about a hundred years this notion was unchallenged. The fact that today we know that atoms are made up of electrons, which are particles up to 2,000 times smaller in mass than the lightest atom, does not discredit the belief that John Dalton, a simple, untutored schoolmaster, was one of the greatest of chemists.

In May 1844, Dalton suffered a stroke from which he never recovered. He was shattered both mentally and physically, but somehow he managed to keep up the one chore he had always performed – the daily entry in his meteorological diary. On 26th July he recorded a final observation in a trembling hand. On 27th he had another stroke and fell from his bed, lifeless.

Dalton gained a great scientific reputation towards the end of his life. Apart from his lectures at the Royal Institution he was elected a fellow of the Royal Society and the French Academy of Sciences. In 1833 the government recognised his services to science and awarded him a pension.

Throughout his life he remained an unobtrusive and to outward appearances, an insignificant figure. His needs were modest; he had no expensive tastes, few interests outside his work, and little use for money. He remained a bachelor of quiet and regular habits, and once said he had “never found time to marry.”

His only recreation was a game of bowls which he played every Thursday afternoon with unremitting regularity. Apart from annual walking tours in his native Cumberland, for he loved the countryside, he rarely travelled from his home in George Street, Manchester. He once visited fellow scientists in Paris and did make very occasional visits to London. Of that city he said: “a surprising place and well worth one’s while to see once, but the most disagreeable place on earth to reside in constantly.”

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