John Dalton

John Dalton

Born                                            :-             6 September 1766

                                                                   Eaglesfield, Cumberland, England

Died                                            :-             27 July 1844 (aged 77)

                                                                   Manchester, England

Notable students                          :-             James Prescott Joule

Known for                                   :-             Atomic theory, Law of Multiple Proportions,

                                                                   Dalton's Law of Partial Pressures, Daltonism

Influences                                     :-             John Gough

Notable awards                            :-             Royal Medal (1826)

Author abbrev. (botany)                :-             Jn.Dalton

John Dalton FRS (6 September 1766 – 27 July 1844) was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness (sometimes referred to as Daltonism, in his honour).

Early life

John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland, England.[1] The son of a weaver, he joined his older brother Jonathan at age 15 in running a Quaker school in Kendal, about forty five miles away. Around 1790 Dalton seems to have considered taking up law or medicine, but his projects were not met with encouragement from his relatives – Dissenters were barred from attending or teaching at English universities – and he remained at Kendal until, in the spring of 1793, he moved to Manchester. Mainly through John Gough, a blind philosopher and polymath to whose informal instruction he owed much of his scientific knowledge, Dalton was appointed teacher of mathematics and natural philosophy at the "New College" in Manchester, a dissenting academy. He remained in that position until 1800, when the college's worsening financial situation led him to resign his post and begin a new career in Manchester as a private tutor for mathematics and natural philosophy.

Atomic theory

In 1800, Dalton became a secretary of the Manchester Literary and Philosophical Society, and in the following year he orally presented an important series of papers, entitled "Experimental Essays" on the constitution of mixed gases; on the pressure of steam and other vapours at different temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases. These four essays were published in the Memoirs of the Lit & Phil in 1802.

There can scarcely be a doubt entertained respecting the reducibility of all elastic fluids of whatever kind, into liquids; and we ought not to despair of effecting it in low temperatures and by strong pressures exerted upon the unmixed gases further.After describing experiments to ascertain the pressure of steam at various points between 0 and 100 °C (32 and 212 °F), Dalton concluded from observations on the vapour pressure of six different liquids, that the variation of vapour pressure for all liquids is equivalent, for the same variation of temperature, reckoning from vapour of any given pressure. I see no sufficient reason why we may not conclude that all elastic fluids under the same pressure expand equally by heat and that for any given expansion of mercury, the corresponding expansion of air is proportionally something less, the higher the temperature. It seems, therefore, that general laws respecting the absolute quantity and the nature of heat are more likely to be derived from elastic fluids than from other substances.

Gas laws

 Joseph Louis Gay-Lussac

 Jacques Alexandre César Charles, 1820

He thus enunciated Gay-Lussac's law or J.A.C. Charles's law, published in 1802 by Joseph Louis Gay-Lussac. In the two or three years following the reading of these essays, Dalton published several papers on similar topics, that on the absorption of gases by water and other liquids (1803), containing his law of partial pressures now known as Dalton's law.

The most important of all Dalton's investigations are those concerned with the atomic theory in chemistry, with which his name is inseparably associated. It has been proposed that this theory was suggested to him either by researches on ethylene (olefiant gas) and methane (carburetted hydrogen) or by analysis of nitrous oxide (protoxide of azote) and nitrogen dioxide (deutoxide of azote), both views resting on the authority of Thomas Thomson. However, a study of Dalton's own laboratory notebooks, discovered in the rooms of the Lit & Phil,[10] concluded that so far from Dalton being led by his search for an explanation of the law of multiple proportions to the idea that chemical combination consists in the interaction of atoms of definite and characteristic weight, the idea of atoms arose in his mind as a purely physical concept, forced upon him by study of the physical properties of the atmosphere and other gases. The first published indications of this idea are to be found at the end of his paper on the absorption of gases already mentioned, which was read on 21 October 1803, though not published until 1805. Here he says:Why does not water admit its bulk of every kind of gas alike? This question I have duly considered, and though I am not able to satisfy myself completely I am nearly persuaded that the circumstance depends on the weight and number of the ultimate particles of the several gases.

Atomic weights

Dalton proceeded to print his first published table of relative atomic weights. Six elements appear in this table, namely hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus, with the atom of hydrogen conventionally assumed to weigh 1. Dalton provided no indication in this first paper how he had arrived at these numbers.[citation needed] However, in his laboratory notebook under the date 6 September 1803[11] there appears a list in which he sets out the relative weights of the atoms of a number of elements, derived from analysis of water, ammonia, carbon dioxide, etc. by chemists of the time. It appears, then, that confronted with the problem of calculating the relative diameter of the atoms of which, he was convinced, all gases were made, he used the results of chemical analysis. Assisted by the assumption that combination always takes place in the simplest possible way, he thus arrived at the idea that chemical combination takes place between particles of different weights, and it was this which differentiated his theory from the historic speculations of the Greeks, such as Democritus and Lucretius. The extension of this idea to substances in general necessarily led him to the law of multiple proportions, and the comparison with experiment brilliantly confirmed his deduction.[12] It may be noted that in a paper on the proportion of the gases or elastic fluids constituting the atmosphere, read by him in November 1802, the law of multiple proportions appears to be anticipated in the words: "The elements of oxygen may combine with a certain portion of nitrous gas or with twice that portion, but with no intermediate quantity", but there is reason to suspect that this sentence may have been added some time after the reading of the paper, which was not published until 1805. Compounds were listed as binary, ternary, quaternary, etc. (molecules composed of two, three, four, etc. atoms) in the New System of Chemical Philosophy depending on the number of atoms a compound had in its simplest, empirical form. 

He hypothesized the structure of compounds can be represented in whole number ratios. So, one atom of element X combining with one atom of element Y is a binary compound. Furthermore, one atom of element X combining with two elements of Y or vice versa, is a ternary compound. Many of the first compounds listed in the New System of Chemical Philosophy correspond to modern views, although many others do not. Various atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy (1808).

Dalton used his own symbols to visually represent the atomic structure of compounds. These have made it in New System of Chemical Philosophy where Dalton listed a number of elements, and common compounds. 

Dalton communicated his atomic theory to Thomson who, by consent, included an outline of it in the third edition of his System of Chemistry (1807), and Dalton gave a further account of it in the first part of the first volume of his New System of Chemical Philosophy (1808). The second part of this volume appeared in 1810, but the first part of the second volume was not issued till 1827. This delay is not explained by any excess of care in preparation, for much of the matter was out of date and the appendix giving the author's latest views is the only portion of special interest. The second part of vol. ii. never appeared. For Rees's Cyclopædia Dalton contributed articles on Chemistry and Meteorology, but the topics are not known.

         He was president of the Lit & Phil from 1817 until his death, contributing 116 memoirs. Of these the earlier are the most important. In one of them, read in 1814, he explains the principles of volumetric analysis, in which he was one of the earliest workers. In 1840 a paper on the phosphates and arsenates, often regarded as a weaker work, was refused by the Royal Society, and he was so incensed that he published it himself. He took the same course soon afterwards with four other papers, two of which (On the quantity of acids, bases and salts in different varieties of salts and On a new and easy method of analysing sugar) contain his discovery, regarded by him as second in importance only to the atomic theory, that certain anhydrates, when dissolved in water, cause no increase in its volume, his inference being that the salt enters into the pores of the water.

Public & Personal Life

Before he had propounded the atomic theory, he had already attained a considerable scientific reputation. In 1803, he was chosen to give a course of lectures on natural philosophy at the Royal Institution in London, where he delivered another course in 1809–1810. However, some witnesses reported that he was deficient in the qualities that make an attractive lecturer, being harsh and indistinct in voice, ineffective in the treatment of his subject, and singularly wanting in the language and power of illustration.

In 1810, Sir Humphry Davy asked him to offer himself as a candidate for the fellowship of the Royal Society, but Dalton declined, possibly for financial reasons. However, in 1822 he was proposed without his knowledge, and on election paid the usual fee. Six years previously he had been made a corresponding member of the French Académie des Sciences, and in 1830 he was elected as one of its eight foreign associates in place of Davy. In 1833, Earl Grey's government conferred on him a pension of £150, raised in 1836 to £300.Dalton never married and had only a few close friends, all in all as a Quaker he lived a modest and unassuming life. 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 resident scientists. He attended several of the earlier meetings of the British Association at York, Oxford, Dublin and Bristol. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1834.

Death and legacy         

Dalton suffered a minor stroke in 1837, and a second one in 1838 left him with a speech impediment, though he remained able to do experiments. In May 1844 he had yet another stroke; on 26 July he recorded with trembling hand his last meteorological observation. On 27 July, in Manchester, Dalton fell from his bed and was found lifeless by his attendant. Approximately 40,000 people filed by his coffin as it was laid in state in the Manchester Town Hall.[15] He was buried in Manchester in Ardwick cemetery. The cemetery is now a playing field, but pictures of the original grave are in published materials. A bust of Dalton, by Chantrey, was publicly subscribed for[18] and placed in the entrance hall of the Royal Manchester Institution. Chantrey also crafted a large statue of Dalton, now in the Manchester Town Hall. The statue was erected while Dalton was still alive and it has been said: "He is probably the only scientist who got a statue in his lifetime". In honour of Dalton's work, many chemists and biochemists use the (as yet unofficial) unit dalton (abbreviated Da) to denote one atomic mass unit, or 1/12 the weight of a neutral atom of carbon-12. There is a John Dalton Street connecting Deansgate and Albert Square in the centre of Manchester. Manchester Metropolitan University has a building named after John Dalton and occupied by the Faculty of Science and Engineering, in which the majority of its Science & Engineering lectures and classes take place. A statue is outside the John Dalton Building of the Manchester Metropolitan University in Chester Street which has been moved from Piccadilly. It was the work of William Theed (after Chantrey) and is dated 1855 (it was in Piccadilly until 1966).

The University of Manchester has a hall of residence called Dalton Hall; it also established two Dalton Chemical Scholarships, two Dalton Mathematical Scholarships, and a Dalton Prize for Natural History. There is a Dalton Medal awarded occasionally by the Manchester Literary and Philosophical Society (only 12 times altogether). Dalton Township in southern Ontario was named for Dalton. It has, since 2001, been absorbed into the City of Kawartha Lakes. However the township name was used in a massive new park: Dalton Digby Wildlands Provincial Park, itself renamed since 2002. A lunar crater has been named after Dalton. "Daltonism" became a common term for colour blindness and "Daltonien" is the actual French word for "colour blind". The inorganic section of the UK's Royal Society of Chemistry is named after Dalton (Dalton Division), and the Society's academic journal for inorganic chemistry also bears his name (Dalton Transactions). The name Dalton can often be heard in the halls of many Quaker schools, for example, one of the school houses in Coram House, the primary sector of Ackworth School, is called Dalton. Much of his collected work was damaged during the bombing of the Manchester Literary and Philosophical Society on 24 December 1940. This event prompted Isaac Asimov to say, "John Dalton's records, carefully preserved for 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 are now in the John Rylands Library having been deposited in the university library by the Society.