John Dalton - Biography, Facts and Inventions - Famous Scientists.


John Dalton - Biography, Facts and Pictures - Famous Scientists

John Dalton laid the foundation of one of the most important theories of science—the atomic theory. It became the cornerstone for modern chemistry and physics. However, he was not the first to propose the idea of the atom. It was the Greek philosopher Leucippus, who first proposed the idea of the atom, which was elaborated by his student Democritus. However, Democritus* idea was speculative based on pure reasoning and not on scientific facts.

John Dalton Biography
Dalton was the first to define the atom in terms of its weight. He provided chemical evidence for its existence. Dalton also proposed the law of partial pressures. Using the atomic theory, Dalton was able to rationalize the various laws of chemical combination namely, Law of Conservation of Mass, Law of Definite Proportions and Law of Multiple Proportions. Some aspects of Dalton's atomic theory were later rejected but its core features—that each atom has a characteristic mass and the atoms of the elements do not change by chemical reactions—survived.
Dalton was the first to give a description of colour blindness. His findings relating to colour blindness were published in his work Extraordinary Facts Relating to the Vision of Colours (1794). Dalton observed that the defect in colour perception was due to discoloration of the liquid medium of the eyeball. Commenting on his own colour blindness Dalton wrote: “...that part of the image which others call red appears to me little more than a shade or defect of light. After that the orange, yellow and green seem one colour which descends petty uniformly from an intense to a rare yellow, making what I should call different shades of yellow.”

It may be noted that before Dalton wrote about his own case of colour blindness, the defect of colour perception was not even formally described or officially noticed. Colour blindness is also referred to as Daltonism’ in his honour.

Dalton was an early meteorologist. Over a span of 57 years, he recorded over 200,000 observations of the atmosphere. His interest in rain and water content of the atmosphere was apparently the origin of all his work on gases. He presented his weather observations in his book Meteorological Observations and Essays, published in 1793. This was his first book to be published.

Dalton had an abiding and deep interest in physiology and natural history. In 1801, Dalton published Elements of English Grammar. He was the president of the Manchester Literary and Philosophical Society from 1817 until his death.

Dalton’s works were damaged when the building of the Manchester Literary and Philosophical Society was bombed on 24 December 1940 during the Second World War. This incident prompted the celebrated science fiction writer Isaac Asimov to say: “John Statue of John Dalton in the Dalton's records, carefully preserved for Manchester Town Hall a century were destroyed during the World War II bombing of Manchester. It is not only the living who are killed in war.” The damaged papers now can be found in the John Rylands Library of the Manchester University.

John Dalton was born on 6 September 1766 in a Quaker family at Eaglesfield in Cumberland, England. His parents were Joseph Dalton and Deborah Greenup and they had three children: Jonathon, John and Mary. His father was a weaver. John Dalton, like his older brother Jonathan, helped his father weave and work in the field. The brothers also studied at a local Quaker school. Dalton's teacher was John Fletcher. At the Quaker school, Dalton learned English, arithmetic, the Bible, and a little geography and history. He was a bright student and very quick in solving mathematical problems. This was brought to the attention of a wealthy Quaker named Elihu Robinson, who mentored him further in mathematics, science and meteorology.

Dalton took over as teacher when John Fletcher retired. At the time Dalton was 12 years old. He had trouble controlling the older students, who were not happy to receive instructions from a younger boy. The income was also meager, being only about five shillings a week. In 1781, Dalton left his home to become an assistant in a boarding school at Kendal. The school was run by his cousin. Kendal was a large town and allowed Dalton many opportunities, including exposure to leading figures in the scientific and mathematical world.

[next] The school’s library had a good collection of scientific literature. It was also equipped with Leucipриs scientific apparatuses. Dalton made good use of these. A self-taught experimenter, he devised simple but effective apparatuses for his well-planned tests too. Although critics have complained about the crudeness of his results, much of his data is remarkably accurate.

John dalton atom drawing
When his cousin left the school, Dalton and his brother ran the school as joint principals. Dalton remained in this school for 12 years. While teaching in the school Dalton continued to study mathematics and science under the guidance of the blind English natural and experimental philosopher John Gough (1757–1825.) It was Gough who encouraged Dalton to keep a record of the daily weather observations, including ambient temperatures, air pressure, humidity, and rainfall.

In about 1790 he seems to have thought of taking up law or medicine, but his projects met with no encouragement from his relatives and he remained at Kendal till he moved to Manchester in 1793, where he spent the rest of his life. He joined the New College at Manchester, where he taught mathematics and chemistry. He also became a member of the Manchester Literary and Philosophical Society.

Dalton is known for his atomic theory. The concept of the atom that appears so apparent to us now was not so obvious, really. The fact that there were different kinds of materials was obvious to early humans because they could see different materials like stone, sand, water and so on. 

However, they did not comprehend much about the substances that made up different kinds of objects. For centuries, ancient peoples including Indians contemplated that different objects encountered by them were made up of some basic substances. It was the Greek philosopher Empedocles (ca. 490–430 BCE) who proposed that all matter was composed of four fundamental substances—fire, air, water, and earth.

These fundamental substances were called “elements”. This was the first attempt to describe the things around us. Empedocles thought that the ratio of these four elements present in a particular matter determined its properties. For example, stone was believed to contain a high amount of earth and a rabbit was supposed to have higher ratio of both water and fire, which made it soft and gave it life.

The most obvious limitation of Empedocles' concept was that no matter how many times a substance, (say stone), one breaks, the pieces never resemble any of the four core elements. In spite of many shortcomings, however, Empedocles theory found wide support. Today the theory is outdated but it was a milestone in scientific thinking because for the first time it was suggested that a substances like stone, which looked like pure material, was actually made up of different “elements”.

Around 5th century BCE, Greek philosopher Leucippus contemplated what would happen if one broke a substance down to its smallest possible particle. He proposed that if one reached the smallest possible particle it would be too small to be visible. He called this particle (then a hypothetical one) “atom”, a Greek word meaning *indivisible". The concept ofatom proposed by Leucippus was further elaborated by his student Democritus (c.470-c.380 BCE).

The Arab scientist Rhazes (born c.CE 852) put forward the idea of atom on the similar lines to that of Democritus. Rhazes proposed that the atoms gave rise to the four elements. This idea was rejected by Plato and Aristotle, the two most influential philosophers of ancient Greece. They lent their support to theory earlier proposed by Empedocles.

[next] A new feature was added by them. They proposed that the four core elements could transform into one another. Philosophers and thinkers of India developed a unique atomic theory with combinations formed in dyads and triads.

Because of Aristotle's great influence, Democritus' theory was ignored till it was established by Dalton. Dalton first presented his idea of the atom in a paper presented to the Manchester Literary and Philosophical Society in 1803. He described his idea on atom in detail in his classic work A New System of Chemical Philosophy. It was in two parts. The first part was published in 1808 and the second part in 1810.

Much of this classic work was devoted to heat. While elaborating on the concept of the atom Dalton wrote: “ There are three distinctions in the kinds of bodies, or three states, which have more specially claimed the attention of philosophical chemists, namely, those which are marked by the terms elastic fluids (gases), liquids, and solids.

A very famous instance is exhibited to us in water, or a body, which in certain circumstances, is capable of assuming all three states. In steam we recognize a perfect elastic fluid, in water a perfect liquid, and in ice a complete solid. These observations have tacitly led to the conclusion which seems universally adopted, that all bodies of sensible magnitude, whether liquid or solid, are constituted of a vast number of extremely small particles, or atoms of matter bound together by a force of attraction, which is more or less powerful according to circumstances...”

Democritus believed that the atoms of different substances differed in shape but Dalton observed that they differed in weight. He clearly stated that that each element has a weight of its own, characteristic of thus element. Dalton persuaded the chemists to accept that there were disserent types of atoms and that all the atoms of a given element were similar with similar properties. The basic postulates of Dalton' alomic theory are:

1. All matter is composed of small individual particles called atoms.
2. All atoms of a given element are identical.
3. The atoms of a given element are different from those of any other element.
4. The atoms of different elements can be distinguished from one another by respective relative atomic weights.
5. Chemical reactions involve the combination of atoms; not the destruction of atoms.
6. When elements react to form compounds, they react in defined, whole-number ratios.

Dalton used his own symbols to visually represent the atoms and the atomic structure of compounds. He developed a system of chemical notation involving circles with differentletters or symbols inside these circles. Dalton’s method of representing atoms and chemical compounds made it easier to write out chemical reactions.

This method also revealed a bit of information on the mechanics of each chemical reaction; for example, number ofatoms ofeach elementina compound. Today we use the logical alphabetical system of chemical symbols developed by the Swedish chemist Baron Jons Jakob Berzelius (1779-1848).

However, Dalton refused to accept Berzelius’ system. He listed compounds as binary, ternary, quaternary, etc., in his A New System of Chemical Philosophy. A binary compound is formed when one atom of element A combines with one atom of element B. Similarly a ternary compound is produced when one atom of element A combines with two atoms of element B or vice versa.

Dalton also included an additional postulate to the Laws he had proposed: “When atoms combine in only one ratio, it must be a binary one – unless some cause appears to the contrary’. This was found to be controversial. It delayed the acceptance of Dalton's atomic theory for many years.

[next] Dalton had made a mistake by assuming “greatest simplicity” that is, the simplest compound of two elements must be binary. This assumption created controversy as no evidence could be produced in favour of it. This was a pure assumption and it was derived from his faith in the simplicity of nature. By this assumption, water was HO and ammonia, NH.

The mostimportant contribution of A New System of Chemical Philosophy was the proposed method of establishing relative atomic weights from chemical data of chemical composition. However, one should remember that Dalton had no way to determine the ratios in which the different atoms combine to form compounds. He published a table of relative atomic masses but the atomic weights given by Dalton were not always correct. Unlike the other theories of the atom Dalton's atomic theory succeeded because it provided a model based on which definite predictions could be made. The overall picture of Dalton's atomic theory remains as the central basis of modern chemistry and physics.

Dalton remained a bachelor all his life. On being asked why he never married, his reply was: “I haven’t time. My head is too full of triangles, chemical processes and electrical elements to think of any such nonsense.” He lived for more than a quarter of a century with his friend, the Rev. W. Johns (1771-1845), in George Street, Manchester, where his daily round of laboratory work and tuition was broken only by annual excursions to the Lake District and occasional visits to London. 

In 1822, he paid a short visit to Paris, where he met many distinguished scientists. Dalton was a Fellow of the Royal Society of London (1822). He was one of the eight foreign associates of the French Academy of Sciences (1830). He was awarded doctorate degrees by the Oxford University in 1832 and by Edinburgh University in 1834. In 1833, the government granted him a pension of 150 pounds per year, which was raised to 300 pounds in 1836. I le was also a co-founder of the British Association for the Advancement of Science.

John Dalton lived a very simple life. His health started to deteriorate in 1837 and he suffered a second stroke in 1838, which left him with speech impediment. He died on 27 July 1844 and was buried in Ardwick cemetery in Manchester, which is now a play ground. Dalton had requested on that his eyes be examined after his Postal stamp on Dalton death, in an attempt to discover the cause of his colour blindness. 

He had hypothesised that his aqueous humor might be colored blue. Post-mortem examination showed that the it was not so. However, an eye was preserved at the Royal Institution, and a 1990s study on DNA extracted from the eye showed that he had lacked the pigment that gives sensitivity to green; the classic condition known as deuteranopia.

John Dalton was lucky in the sense that his work got recognition in his lifetime. When his body lay in state and more than 40,000 people came to pay their last respects. The City of Manchester was fully aware of Dalton's fame and gave him a funeral fit for a king.

The dalton (symbol: Da) is a unit that is used for indicating mass on an atomic or molecular scale. The Dalton Minimum was a period of low solar activity. A hall of residence in the Manchester University is named after John Dalton. The University has also established two Dalton Chemical Scholarships, two Dalton Mathematical Scholarships and a Dalton Prize for Natural History. Manchester Metropolitan University has a building named after Dalton. 

There is a large statue of Dalton in the Manchester Town Hall. Alunar crater has been named after Dalton. A bust of Dalton was crafted by English sculptor Sir Francis Legatt Chantrey (1781–1841) which was publicly subscribed. The John Dalton Medal has been established by the Division on Hydrological Sciences in recognition of the scientific achievements of John Dalton. It is awarded by the European Geosciences Union for distinguished research in Hydrology.

-Subodh Mahanti
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TechGape: John Dalton - Biography, Facts and Inventions - Famous Scientists.
John Dalton - Biography, Facts and Inventions - Famous Scientists.
John Dalton - Biography, Facts and Pictures - Famous Scientists
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