John Dalton was born on September 6, 1766, in Eaglesfield, England. His father was a weaver, who owned a house and a small amount of land. Both of his parents were Quakers. Although Quakers were Christians, they were seen as dissenters by the established Church of England.
John Dalton was an intelligent child, who took an interest in the world around him and tried to learn as much as he could about everything. He attended his village school until he was 11, and then began helping as a teacher.
At age 15, he started helping his older brother John to run a Quaker boarding-school in the town of Kendal, 40 miles from his home. All the while, he continued teaching himself science, mathematics, Latin, Greek and French. By the time he was 19, he had become the school’s principal, continuing in this role until he was 26 years old.
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Becoming a Scientist
In the first half of 1793, aged 26, John Dalton took the position of teacher of mathematics and natural philosophy at Manchester’s New College, a dissenting college.
In 1794, he wrote his first scientific paper which he called: Extraordinary Facts Relating to the Vision of Colours. This was the first ever paper to discuss color blindness. Dalton had realized the condition was hereditary, because he and other members of his family had it.
Ultimately, Dalton’s theory for color blindness was wrong, but as he was the first person ever to research it, the condition became known as Daltonism.
Further research papers followed, in the physical sciences: heat conduction, gas expansion by heat, the properties of light, the aurora borealis, and meteorology.
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Atomic Theory
The Behavior of Gases
In 1801, John Dalton gave a series of lectures in Manchester whose contents were published in 1802. In these lectures he presented research he had been carrying out into gases and liquids. This research was groundbreaking, offering great new insights into the nature of gases.
Firstly, John Dalton stated correctly that he had no doubt that all gases could be liquified provided their temperature was sufficiently low and pressure sufficiently high. He then stated that when its volume is held constant in a container, the pressure of a gas varies in direct proportion to its temperature.
This was the first public statement of what eventually became known as Gay-Lussac’s Law, named after Joseph Gay-Lussac who published it in 1809.
In 1803, John Dalton published his Law of Partial Pressures, still used by every university chemistry student, which states that in a mixture of non-reacting gases, the total gas pressure is equal to the sum of the partial pressures of the individual gases.
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Dalton and Atoms
His study of gases led Dalton to wonder about what these invisible substances were actually made of. The idea of atoms had first been proposed more than 2000 years earlier by Democritus in Ancient Greece. Democritus believed that everything was made of tiny particles called atoms and that these atoms could not be split into smaller particles. John Dalton was now going to solve this 2000 year-old mystery.
He carried out countless chemical reactions, and in 1808 published what we now call Dalton’s Law in his book A New System of Chemical Philosophy:
If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.
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John Dalton Atomic Theory states that:
- The elements are made of atoms, which are tiny particles, too small to see.
- All atoms of a particular element are identical.
- Atoms of different elements have different properties: their masses are different, and their chemical reactions are different.
- Atoms cannot be created, destroyed or split.
- In a chemical reaction, atoms link to one another, or separate from one another.
- Atoms combine in simple whole-number ratios to form compounds.
Although we have learned that atoms of the same element can have different masses (isotopes), and can be split in nuclear reactions, most of Dalton’s Atomic Theory holds good today, over 200 years after John Dalton described it. It is the foundation on which modern chemistry has been built.
Honors
John Dalton did not marry. He remained a faithful Quaker all of his life, living modestly.
In 1810 he declined an invitation to become a member of the Royal Society. In 1822, he was elected without his knowledge. In 1826, he was awarded the Society’s Royal Medal for his Atomic Theory.
In 1833, the French Academy of Sciences elected him as one of its eight foreign members. In 1834, the American Academy of Arts and Sciences elected him as a foreign member.
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The End
When he was 71 years old, Dalton had a small stroke – or paralysis as it was known then. A year later, a more significant stroke left him unable to speak as clearly as he once could. In 1844, when he was 77, another stroke hit him. He died aged 77 on July 27, 1844.
His scientific reputation was so great that when his body was placed in Manchester Town Hall, it was visited by more than 40,000 people paying their respects. John Dalton was buried in Manchester in Ardwick cemetery.
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