Until the time of John Dalton, the atomic conception remained purely qualitative, and until then it does not appear to have 1 Robert Boyle, The Sceptical Chymist (1661); The Usefulness of Natural Philosophy (1663).
Dalton (1803) gave the atomic theory a quantitative form, and showed that, by means of it, a vast number of the facts of chemistry could be predicted or explained.
Dalton lived in a period marked by great advances in experimental chemistry.
Dalton, who was a mathematical physicist even more than a chemist, had given much thought to the study of gases.
The Aristotelian would find no difficulty in such a variability; it is only the disciple of Dalton to whom it seems impossible.
The discovery of this law is due to Dalton; it is a direct deduction from his atomic theory.
As Dalton said, "The doctrine of definite proportions appears mysterious unless we adopt the atomic hypothesis."
Dalton himself made many analyses with the purpose of establishing his views, but his skill as an analyst was not very great.
To take the simplest possible case, if Dalton had been correct in assuming that the molecule of water was made up of one atom of oxygen and one of hydrogen, then the experimental fact that water contains eight parts by weight of oxygen to one part of hydrogen, would at once show that the atom of oxygen is eight times as heavy as the atom of hydrogen, or that, taking the atomic weight of hydrogen as the unit, the.
On account of this difficulty, the atomic weights published by Dalton, and the more accurate ones of Berzelius, were not always identical with the values now accepted, but were often simple multiples or submultiples of these.
The "symbols" for the elements used by Dalton, apparently suggested by those of the alchemists, have been rejected in favour of those which were introduced by Berzelius.
The symbol, like that of Dalton, always stands for the atomic weight of the element, that is, while H stands for one part by weight of hydrogen, 0 stands for 16 parts of oxygen, and so on.
The superiority of this notation over that of Dalton is not so obvious when we consider such simple cases as the above, but chemists are now acquainted with very complex molecules containing numerous atoms; cane sugar, for example, has the formula C 12 H 22 0, 1.
Dalton believed that the molecules of the elementary gases consisted each of one atom; his diagram for hydrogen gas makes the point clear.
Their hypothesis explains so many facts.
This principle at once enables the weights of molecules to be compared even when their composition is unknown; it is only 1 It will be seen that in the three gas diagrams of Dalton that are reproduced above, equal numbers of molecules are contained in equal volumes, but if Dalton held this view at one time he certainly afterwards abandoned it.
But modern discoveries in radioactivity 2 are in favour of the existence of the atom, although they lead to the belief that the atom is not so eternal and unchangeable a thing as Dalton and his predecessors imagined, and in fact, that the atom itself may be subject to that eternal law of growth and decay of which Lucretius speaks.
On the 10th of June 1875 he died in Dalton, Georgia, a city which in 1848 he had helped to found.
To this period also belong the labours of Richard Pococke and Richard Dalton, Richard Chandler, E.
The evolution of the notion of elements is treated under Element; the molecular hypothesis of matter under Molecule; and the genesis of, and deductions from, the atomic theory of Dalton receive detailed analysis in the article Atom.
The laws of chemical combination were solved, in a measure, by John Dalton, and the solution expressed as Dalton's " atomic theory."
This controversy was unfinished when Dalton published the first part of his New System of Chemical Philosophy in 1808, although the per saltum theory was the most popular.
Led thereto by speculations on gases, Dalton assumed that matter was composed of atoms, that in the elements the atoms were simple, and in compounds complex, being composed of elementary atoms. Dalton furthermore perceived that the same two elements or substances may combine in different proportions, and showed that these proportions had always a simple ratio to one another.
Berzelius, who, fired with enthusiasm by the original theory of Dalton and the law of multiple proportions, determined the equivalents of combining ratios of many elements in an enormous number of compounds.2 He prosecuted his labours in this field for thirty years; as proof of his industry it may be mentioned that as early as 1818 he had determined the combining ratios of about two thousand simple and compound substances.
2 Berzelius, however, appreciated the necessity of differentiating the atom and the molecule, and even urged Dalton to amend his doctrine, but without success.
A great advance was made by Dalton, who, besides introducing simpler symbols, regarded the symbol as representing not only the element or compound but also one atom of that element or compound; in other words, his symbol denoted equivalent weights.4 This system, which permitted the correct representation of molecular composition, was adopted by Berzelius in 1814, who, having replaced the geometric signs of Dalton by the initial letter (or letters) of the Latin names of the elements, represented a compound by placing a plus sign between the symbols of its components, and the number of atoms of each component (except in the case of only one atom) by placing Arabic numerals before the symbols; for example, copper oxide was Cu +0, sulphur trioxide S+30.
4 The following are the symbols employed by Dalton: which represent in order, hydrogen, nitrogen, carbon, oxygen, phosphorus, sulphur, magnesia, lime, soda, potash, strontia, baryta, mercury; iron, zinc, copper, lead, silver, platinum, and gold were represented by circles enclosing the initial letter of the element.
The development of the atomic theory and its concomitants - the laws of chemical combination and the notion of atoms and equivalents - at the hands of Dalton and Berzelius, the extension to the modern theory of the atom and molecule, and to atomic and molecular weights by Avogadro, Ampere, Dumas, Laurent, Gerhardt, Cannizzaro and others, have been noted.
The formulation of the atomic theory by John Dalton gave a fresh impetus to the development of quantitative analysis; and the determination of combining or equivalent weights by Berzelius led to the perfecting of the methods of gravimetric analysis.
After the Confederate retreat from Dalton in May 1864, General William T.
At first this work was merely a compilation, but in the later editions many of his original results were incorporated; the third edition (1807) is noteworthy as containing the first detailed account of the atomic theory, communicated to him by John Dalton himself.
Later in 1863, when the battle of Chattanooga brought the Federals to the borders of Georgia, Johnston was assigned to command the Army of Tennessee at Dalton, and in the early days of May 1864 the combined armies of the North under Sherman advanced against his lines.
At Pittsfield and at Dalton is centred the manufacture of fine writing papers, including that of paper used by the national government for bonds and paper money.
Since the period, a century ago, when Dalton and his contemporaries constructed from this idea a scientific basis for chemistry, the progress of that subject has been wonderful beyond any conception that could previously have been entertained; and the atomic theory in some form appears to be an indispensable part of the framework of physical science.
There he made the acquaintance of John Dalton, and began those inquiries into the strength of materials which formed the work of his life.
Among the institutions generally grouped as denominational are - Baptist: Mercer University, at Macon (Penfield, 1837; Macon, 1871), Shorter College (1877) at Rome, Spelman Seminary (1881) in Atlanta for negro women and girls, and Bessie Tift College, formerly Monroe College (1849) for women, at Forsyth; Methodist Episcopal: Emory College (1836), at Oxford, and Wesleyan Female College (1836) at Macon, both largely endowed by George Ingraham Seney (1837-1893), and the latter one of the earliest colleges for women in the country; Methodist Episcopal Church, South: Young Harris College (r855) at Young Harris, Andrew Female College (1854) at Cuthbert, and Dalton Female College (1872) at Dalton; Presbyterian: Agnes Scott College at Decatur; and African Methodist Episcopal: Morris Brown College (1885) at Atlanta.
He also made the first rough experiments on the diffusion of gases, a phenomenon first pointed out by John Dalton, the physical importance of which was more fully brought to light by Thomas Graham and Joseph Loschmidt.
Solutions were not distinguished from definite chemical compounds till John Dalton discovered the laws of definite and multiple proportions, but many earlier observations on the solubility of solids in water and the density of the resulting solutions had been made.
411, &c.; Dalton and Chaplin, P.E.F.
After the destruction of Furness Abbey, Ulverston succeeded Dalton as the most important town in Furness, but the rapid rise of Barrow surpassed it in modern times.
DALTON, JOHN (1766-1844), English chemist and physicist, was born about the 6th of September 1766 at Eaglesfield, near Cockermouth in Cumberland.
His father, Joseph Dalton, was a weaver in poor circumstances, who, with his wife (Deborah Greenup), belonged to the Society of Friends; they had three children - Jonathan, John and Mary.
During his residence in Kendal, Dalton had contributed solutions of problems and questions on various subjects to the Gentlemen's and Ladies' Diaries, and in 1787 he began to keep a meteorological diary in which during the succeeding fifty-seven VII.
But from a study of Dalton's own MS. laboratory notebooks, discovered in the rooms of the Manchester society, Roscoe and Harden (A New View of the Origin of Dalton's Atomic Theor y, 1896) conclude that so far from Dalton being led to the idea that chemical combination consists in the approximation of atoms of definite and characteristic weight by his search for an explanation of the law of combination in multiple proportions, the idea of atomic structure arose in his mind as a purely physical conception, forced upon him by study of the physical properties of the atmosphere and other gases.
Dalton communicated his atomic theory to Dr 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).
Altogether Dalton contributed 116 memoirs to the Manchester Literary and Philosophical Society, of which from 1817 till his death he was the president.
As an investigator, Dalton was content with rough and in accurate instruments, though better ones were readily attainable.
See Henry, Life of Dalton, Cavendish Society (1854); Angus Smith, Memoir of John Dalton and History of the Atomic Theory (1856), which on pp. 253-263 gives a list of Dalton's publications; and Roscoe and Harden, A New View of the Origin of Dalton's Atomic Theory (1896); also Atom.
At Dalton, near Rotherham, he was recognized by John de Dalton, who had been at Oxford with him.
DALTON-IN-FURNESS, a market town in the North Lonsdale parliamentary division of Lancashire, England, 4 m.