1766 - 1844
John Dalton was born into a Quaker family in Eaglesfield, near Cockermouth in northeast England. His father was a handloom weaver and the family were comparatively poor. Like his brother, Dalton was born colour blind, something that would prove significant in later life.
Dalton attended the Quaker school in his village, but was only 12 years old when he began teaching the younger children there. At fourteen, he began work as a farmhand for fellow Quaker and scientist Elihu Robinson, who soon recognised Dalton's potential.
At 15 Dalton became an assistant teacher at a Quaker boarding school in the nearby town of Kendal. There he was encouraged and taught Latin, Greek, French and Maths by another Quaker, John Gough. At only 19, he became the principal of the school.
Dalton was profoundly interested in meteorology. He kept detailed records of weather observations all his adult life. In 1793, he published Meteorological Reflections and Essays. This led to Dalton being offered a post as a tutor in maths and philosophy at New College, Manchester. This was one of the ‘dissenting academies’ being set up to provide higher education for non-conformists (those who did not belong to the Church of England) who were barred from entering the universities. (After several changes of location, it ended up in Oxford, as Harris Manchester College).
A few years later, he joined the Manchester Literary and Philosophical Society, where he had the use of laboratories to carry out his research. The first paper he delivered there, in 1794, was on the hereditary nature of colour blindness – sometimes still referred to as ‘Daltonism – and techniques for diagnosing it.
Dalton’s meteorological observations had led him to conclude that our atmosphere is mechanical system, where the pressure exerted by each gas in a mixture is independent of the pressure exerted by the other gases, and where the total pressure is the sum of the pressures of each gas. From this understanding, he developed the concept of atoms, and the idea that atoms of different elements were of different size and complexity.
Dalton was the first to calculate the atomic weights of different elements, as published in his New System of Chemical Philosophy (1808). He set out five basic principles, namely:
6. Atoms combine in simple whole-number ratios to form compounds.
Although later chemists revised these principles (atoms can be split and one element may have several different isotopes) Dalton laid the foundations for much of modern chemistry. His discoveries also enabled chemical manufacturing processes to be carried out efficiently, by providing a ‘recipe’ for the correct chemical proportions needed in a given compound.
As a Quaker, Dalton lived modestly, and tried (largely unsuccessfully) to avoid honour and recognition. In 1810, he turned down an invitation to join the Royal Society, though in 1822 the Society proceeded to elect him without his knowledge, and in 1826 awarded him its Royal Medal. Both the French Academy of Sciences and the American Academy of Arts and Sciences elected him as a foreign member. In 1832, he did accept an honorary degree of Doctor of Science from Oxford University.
In 1837, Dalton suffered from a stroke, which left his speech impaired. After a second stroke in 1844, he died quietly at home. He was given a civic funeral by the city of Manchester in honour of his contributions to science. Reportedly, 40 thousand people attended the procession.
Dalton bequeathed his eyes to be preserved and studied to see what could be learnt from them about colour blindness.