¹ Dalton, J., A New System of Chemical Philosophy (Part 1, London, 1808)Google Scholar, referred to hereafter as the New System. For the June dating see Neville, R. G., “Unrecorded Daltoniana”, Ambix, viii (1960), 42–45.CrossRefGoogle Scholar

² Manchester Memoirs, lv (1911), No. 19, pp. 2, 3.Google Scholar The series of papers on “The development of the atomic theory”, which A. N. Meldrum read to the Manchester Literary and Philosophical Society over the period 1909–11, still remains an important study of the issues involved.

³ See my “Documents relating to the origins of Dalton's chemical atomic theory”, Manchester Memoirs (in the press).

⁴ Nash, L. K., “The origin of Dalton's chemical atomic theory”, Isis, xlvii (1956), 101–116.CrossRefGoogle Scholar

⁵ Principally by Guerlac, H. E., “Some Daltonian doubts”, Isis, lii (1961), 544–554CrossRefGoogle Scholar; Siegfried, R., “Further Daltonian doubts”, Isis, liv (1963), 480–481Google Scholar; and Thackray, A. W., “The origin of Dalton's chemical atomic theory: Daltonian doubts resolved”, Isis (in the press).Google Scholar

⁶ A brief consideration is provided in my Isis paper. A more exhaustive study will appear in my thesis on “The development of atomism from Newton to Dalton”, now in preparation.

⁷ Manchester Memoirs, lv (1911), No. 3, p. 12.Google Scholar

⁸ In the narrative that follows I shall weave together Dalton's statements at the time and his recollections five, ten or even twenty-five years later.

A separate issue from the reliability of Dalton's chronological statements is his habit of altering papers between their initial reading and their subsequent publication in the Manchester Memoirs. As secretary of the Manchester Literary and Philosophical Society from 1800, Dalton was in a position to bring his papers up to date before publication. That he availed himself of this opportunity was first pointed out by Roscoe and Harden (op. cit. infra., (10), 31). In this paper I shall produce additional evidence of Dalton's extensive use of this practice.

⁹ Points 4 and 5 were originally developed in my Isis paper.

¹⁰ The earliest, inductivist, account saw Dalton's 1804 work on marsh gas as the crucial event. See Thomson, T., The History of Chemistry (London, 1830–1831), ii, 291.Google Scholar Recognizing the inadequacies of Thomson's account, Meldrum sought in his 1909-11 papers to remodel the inductivist version, basing it on Dalton's 1803 work on the nitrogen oxides. See A. N. Meldrum, op.cit. (2). The inadequacy of Meldrum's own account was, however, well demonstrated by L. K. Nash, who instead saw particular significance in the work arising from Henry's Law, and in the 1804 visit of Thomas Thomson. See L. K. Nash, op.cit. (4). Though Nash's general thesis is very important, neither of his crucial events appears quite so crucial on examination. See below and A. W. Thackray, op.cit. (5).

An alternative approach to the question of where Dalton's originality lay was made by H. E. Roscoe and A. Harden who explained how Dalton “…arrived at the idea that chemical combination takes place between particles of different weights, and this it was which differentiated his theory from the historic speculations of the Greeks…” See A New View of the Origin of Dalton's Atomic Theory (London, 1896), 51.Google Scholar This belief, though persistent, lacks adequate foundation. (Roscoe and Harden's account does, however, have the merit of not demanding a crucial event.) A recent example of this viewpoint is Guerlac's statement that “sometime in the summer of 1803…Dalton must have hit upon the idea that the different atomic species…had characteristic weights…”. See Guerlac, H. E., op.cit. (5), 551.Google Scholar Guerlac argues for the crucial significance of Richter's table of equivalents.

¹¹ Reproduced in Henry, W. C., Memoirs of the Life and Scientific Researches of John Dalton (London, 1854), 9–10.Google Scholar

¹² Details of John Gough (1757–1825) are given in the Dictionary of National Biography.

¹³ Henry, W. C., op.cit. (11), 16.Google Scholar

¹⁴ Brockbank, E. M., John Dalton, Experimental Physiologist and would-be Physician (Manchester, 1929), 6–7.Google Scholar

¹⁵ Apart from the lecture on fire, Dalton had given a similar course in 1787. See Henry, W. C., op.cit. (11), 16.Google Scholar A photograph of the 1791 syllabus is given in “John Dalton's Lectures and Lecture Illustrations” by Gee, W. W. H., Coward, H. F. and Harden, A., Manchester Memoirs, lix (1915), No. 12, Plate I.Google Scholar

¹⁶ As he described himself on the title-page of his first book, the Meteorological Observations and Essays (London, 1793).Google Scholar

* referred to hereafter as the Lit. and Phil.

¹⁷ Smith, R. A., “Memoir of John Dalton and History of the Atomic Theory up to his time”, Manchester Memoirs, xiii (1856), 27.Google Scholar

¹⁸ Thomas Percival (1740–1804) was educated at the Warrington Academy, and went on to study medicine in Edinburgh and Leyden. He settled in Manchester in 1767, becoming a founder member of the Lit. and Phil. See the Dictionary of National Biography for further details.

¹⁹ Thomas Henry, F.R.S. (1734–1816), though only trained as an apothecary, had a decided interest in chemistry on which he lectured in Manchester in the 1780's. See Manchester Memoirs, iii (1819), 204–240.Google Scholar

²⁰ William Henry, F.R.S. (1774–1836). His son, W. C. Henry, Dalton's first biographer, refers to Dalton's “almost lifelong friendship with my father, never shadowed by even a passing cloud” (Henry, W. C., op. cit. (11), xii).Google Scholar

²¹ Details of Thomas Garnett (1766–1802) are given in the Dictionary of National Biography.

²² Henry, W. C., op. cit. (11), 47.Google Scholar

²³ On page 11 of Dalton's notebook of “Expenses of Journeys”, which is in the possession of the Lit. and Phil.

²⁴ Lonsdale, H., The Worthies of Cumberland. John Dalton (London, 1874), 129.Google Scholar

²⁵ Smith, R. A., op. cit. (17), 18.Google Scholar

²⁶ Roscoe, H. E., John Dalton and the Rise of Modern Chemistry (London, 1901), 51.Google Scholar

²⁷ McLachlan, H., “John Dalton and Manchester”, Manchester Memoirs, lxxxvi (1945), 170.Google Scholar

²⁸ For Dalton's borrowing of books from, and interest in, the library of the Lit. and Phil., see Greenaway, F., “The Biographical Approach to John Dalton”, Manchester Memoirs, c (1959), 20.Google Scholar Dalton's account book for the period 1794–1803, at present on loan to the Science Museum, London, contains regular catalogues of his possessions. That of 5 September 1800 shows him in possession of a library of 53 works, 16 being “philosophical”, 15 “mathematical” and 22 “literary”.

²⁹ E.g. “Glass Retorts, Receivers, etc. etc. 30 at 1/6…Druggs, etc. £1–1–0…a Large Wooden Trough 5/-…”

³⁰ See the Appendix given in Lonsdale, op. cit. (24), for a list of the papers (many never published) which Dalton read to the Lit. and Phil. For reasons explained in Meldrum, op. cit. (2), No. 5, p. 12, Lonsdale appears to have misdated many of these papers by one or two weeks. J. R. Partington in his very valuable study of Dalton (A History of Chemistry (London, 1961-), iii, 755–822) provides evidence that Dalton's idea of aqueous vapour being mechanically mixed with the atmosphere, not chemically combined, dates back to 1793.

³¹ About which he read a paper to the Lit. and Phil. on 17 October 1800. A previous paper on the subject was read on 7 April 1798. See Lonsdale, op. cit. (24).

³² Lonsdale, , op. cit. (24), 144.Google Scholar

³³ Dalton, J., Elements of English Grammar (London, 1801).Google Scholar The “Preliminary Observations” are dated 10 March 1801.

³⁴ Unpublished letter from J. Dalton to J. Fell, 5 April 1801. On loan to the Science Museum, London.

³⁵ Henry, W. C., Manchester Memoirs, vi (1842), 99–141.Google Scholar

³⁶ His thesis De aere atmosphaerico is dated 12 September 1799.

³⁷ See Smith, R. A., “A Centenary of Science in Manchester”, Manchester Memoirs, ix (1883).Google Scholar

³⁸ For Henry's eventually realized medical ambitions, see Henry, W. C., op. cit. (35)Google Scholar; for Dalton's permanently disappointed ambitions see Brockbank, E. M., op. cit. (14)Google Scholar, and Greenaway, F., op. cit. (28)Google Scholar.

³⁹ Phil. Trans. (1797), 401–415.Google Scholar

⁴⁰ Henry, W., A general view… (Manchester, 1799), 10.Google Scholar

⁴¹ Henry, W., An Epitome of Chemistry (London, 1801), 25.Google Scholar

* A Journal of Natural Philosophy, Chemistry and the Arts; edited by W. Nicholson. I shall use its familiar title, Nicholson's Journal.

⁴² Nicholson's Journal (first series), v (1802), 244.Google Scholar From the manuscript, which is in the possession of the Lit. and Phil., it appears that Dalton wrote this letter in haste.

⁴³ Manchester Memoirs (first series), v (1802), 535–602.Google Scholar This series of essays seems to present the earliest example of (and also Dalton's first opportunity for!) alteration before publication. As well as the papers read in 1801, the published account appears to incorporate material from Dalton's earlier paper, read in April 1800. This is seen from a comparison of the titles of the papers as read (Lonsdale, op. cit. (24)), and as published in 1802.

⁴⁴ Op. cit. (43), 536.

⁴⁵ Ibid., 600.

⁴⁶ For his early mathematical interests see Wilkinson, T. T., Manchester Memoirs, xii (1855), 1–30.Google Scholar His early meteorological interests are well displayed in all the standard biographies.

⁴⁷ Henry, W., Nicholson's Journal, viii (1804), 297–301.Google Scholar

⁴⁸ Letter of 26 October 1802. See Paris, J. A., The Life of Sir Humphry Davy (London, 1831), i, 157.Google Scholar

⁴⁹ (1st ed., Edinburgh, 1802), iii, 270.

⁵⁰ Nicholson's Journal, iii (1802), 267–271Google Scholar and Philosophical Magazine, xiv (1802), 169–173.Google Scholar

⁵¹ Letter of 22 March 1802; Lonsdale, , op. cit. (24), 153.Google Scholar

⁵² New System, 182–183.

⁵³ Under “Absorption of Gases by water” (one of its few entries) this Index has “1802 & 1803” frequently. The Index is in the possession of the Lit. and Phil.

⁵⁴ Roscoe, and Harden, , op. cit. (10), 55.Google Scholar No notebooks were found for the period prior to September 1802. Thus it is quite possible that Dalton was working on water-solubility even earlier in 1802.

⁵⁵ See Brown, I. V., Joseph Priestley (Pennsylvania, 1962), 236.Google Scholar

⁵⁶ Lonsdale, op. cit. (24). Once again the paper was considerably altered before publication—the second half of the paper seems to have been amalgamated with Dalton's paper of October 1803 on gas solubilities, before publication. Compare the titles in Lonsdale with the Manchester Memoirs, i (1805), 244 and 271Google Scholar; and see reference 71.

⁵⁷ See Nicholson's Journal, iii (1802), 271Google Scholar, for this quotation from a letter written by Dalton six days after reading the paper.

⁵⁸ Henry, W., op. cit. (47), 299.Google Scholar

⁵⁹ Phil. Trans., 1803, 41.Google Scholar For evidence that Henry's work was being done with Dalton's knowledge and interest, see ibid., p. 33.

⁶⁰ New System, 183.

⁶¹ Phil. Trans. (1803), 274–276.Google Scholar A March date for this “Appendix to Mr. William Henry's Paper” seems most likely, as the paper preceding it in the Phil. Trans. was read on 24 February, and the one following it on 23 April.

⁶² Roscoe, and Harden, , op. cit. (10), 55.Google Scholar A paper providing supporting evidence for the theory of mixed gases from work on diffusion was read to the Lit. and Phil. in January, but the experimental work was apparently done before September 1802. (Ibid., 54.) For the changed titles of this paper see Lonsdale, op. cit. (24) and Manchester Memoirs, i (1805), 259.Google Scholar

⁶³ Henry, W. C., op. cit. (11), 47.Google Scholar

⁶⁴ Roscoe, and Harden, , op. cit. (10), 57–58.Google Scholar

⁶⁵ Nicholson's Journal, iv (1803), 220–224.Google Scholar

⁶⁶ Ibid., v (1803), 34–36.

⁶⁷ Recorded in Dalton's “Expenses of Journeys”, p. 25 (see reference 23).

⁶⁸ Gee, , Coward, and Harden, , op. cit. (15), 4.Google Scholar

⁶⁹ Jones, B., The Royal Institution (London, 1871), 216.Google Scholar

⁷⁰ Nicholson's Journal, vi (1803), 118–120.Google Scholar This note again illustrates Dalton's early interest in chemistry, for he refers to (p. 119) “…the great service that Dr. Kirwan has rendered to meteorology and chemistry, and my own obligations to him on those accounts…” For Dalton's reading of Kirwan in 1799, see Greenaway, op. cit. (28).

⁷¹ When read, the paper was entitled “On the Absorption of Gases by Water”—Lonsdale, op. cit. (24); when published, “On the Absorption of Gases by Water and other Liquids”—Manchester Memoirs, i (1805), 271. See also reference 56. These alterations naturally raise the question of how trustworthy a guide to Dalton's 1803 paper the 1805 printed version is. I shall assume the 1805 version to adequately reflect Dalton's 1803 thought, as his notebooks appear to support such an interpretation.

⁷² Manchester Memoirs, i (1805), 286.Google Scholar

⁷³ Op. cit. (4).

⁷⁴ Quoted from a paper Dalton read to the Lit. and Phil. in 1830. (See Thackray, op. cit. (3).) Dalton's dates appear to be two or three days out.

⁷⁵ See Thackray, op. cit. (5).

* my italics.

⁷⁶ Roscoe, and Harden, , op. cit. (10), 45–46.Google Scholar

⁷⁷ Thus there is no record of any enquiry made by Dalton to provide evidence for his 1807 assertions about the relations of salts and sub-salts. See below.

⁷⁸ See Thackray, op. cit. (3).

⁷⁹ Roscoe, and Harden, , op. cit. (10), 35Google Scholar; Nash, L. K., op. cit. (4), 104–105.Google Scholar

⁸⁰ Roscoe, and Harden, , op. cit. (10), 59–60.Google Scholar His researches embraced ether, alcohol, and charcoal, as well as the carbon oxides and “carb. hyd.”.

⁸¹ Apart from his 1797 paper (reference 39), William Henry published work on these gases in Nicholson's Journal, xi (1805), 65–74Google Scholar and xix (1808), 149–153; and also Phil. Trans. (1808), 282–303 and (1821), 136–161.Google Scholar

⁸² Roscoe, and Harden, , op. cit. (10), 60.Google Scholar

⁸³ Manchester Memoirs, i (1805), 296–316.Google Scholar

⁸⁴ Ibid., 405. The controversy resulting from Gough's letter is considered in my Isis article (reference 5).

⁸⁵ New System, Preface, p. v.

⁸⁶ Roscoe, and Harden, , op. cit. (10), 43–44.Google Scholar

⁸⁷ Nicholson's Journal, xxix (1811), 143–151.Google Scholar

⁸⁸ See Thackray, op. cit. (3), in which I have attempted to reconstruct the syllabus for the course.

⁸⁹ Manchester Memoirs, i (1805), 405–424.Google Scholar

⁹⁰ Henry, W. C., op. cit. (11), 50.Google Scholar

⁹¹ Catalogue of Scientific Papers (1800–1863) (London, 1867–1872), ii, 133.

⁹² Roscoe, and Harden, , op. cit. (10), 61.Google Scholar

⁹³ (Edinburgh, 1804), iii, 314–317. Dalton is referred to as “…This excellent philosopher, distinguished by the simplicity and decisiveness of his experiments, and the happy talent of deducing from them general and important principles…”

⁹⁴ Dalton, J., Nicholson's Journal, viii (1804), 145–149Google Scholar; Philosophical Magazine, xix (1804), 79–83.Google ScholarHenry, W., Nicholson's Journal, viii (1804), 297–301Google Scholar; Philosophical Magazine, xix (1804), 193–196.Google Scholar

⁹⁵ Lonsdale, op. cit. (24). The date of its reading was probably August 17, two weeks after the date Lonsdale gives.

⁹⁶ Roscoe, and Harden, , op. cit. (10), 62–63.Google Scholar

⁹⁷ Thomson, T., op. cit. (10), ii, 289–292.Google Scholar

⁹⁸ Roscoe, and Harden, , op. cit. (10), 63–64.Google Scholar

⁹⁹ Ibid., 65.

¹⁰⁰ Nash, L. K., op. cit. (4), 114–115.Google Scholar

¹⁰¹ Letter of 14 July 1804; quoted in Thackray, op. cit. (3).

¹⁰² Quoted from Dalton's prospectus for the course, dated 2 January 1805. Reproduced by Roscoe, and Harden, , op. cit. (10), 66–67.Google Scholar

¹⁰³ See Thackray, op. cit. (5).

¹⁰⁴ The whole syllabus is reproduced in Thackray, op. cit. (3).

¹⁰⁵ Roscoe, and Harden, , op. cit. (10), 16–17.Google Scholar The quotations come from Dalton's lectures in 1810/11.

¹⁰⁶ The two tables appear on pages 41 and 65 of Roscoe and Harden, op. cit. (10). The reasons for believing that the second table dates from 1805 not 1804 are set out in Thackray, op. cit. (5).

¹⁰⁷ New System, 188–189.

¹⁰⁸ This is apparent from the second table. Three of the fifteen gases listed have particles of the same size!

¹⁰⁹ See Partington, J. R. and Wheeler, T. S., The Life and Work of William Higgins (London, 1960).Google Scholar

¹¹⁰ Henry, W. C., op. cit. (11), 64.Google Scholar

¹¹¹ Lonsdale, , op. cit. (24).Google Scholar

¹¹² Nicholson's Journal, xiii (1806), 377–380.Google Scholar

¹¹³ Op. cit. (10), 71.

¹¹⁴ Ibid., 74.

¹¹⁵ Gee, , Coward, and Harden, , op. cit. (15), 8.Google Scholar

¹¹⁶ Roscoe, and Harden, , op. cit. (10), 76–77.Google Scholar

¹¹⁷ Roscoe, , op. cit. (26), 166–167.Google Scholar

¹¹⁸ See Thackray, op. cit. (3). The lectures took place in “Dr. Thomson's Class Room” and began on 2 April.

¹¹⁹ See e.g. Nash, L. K., op. cit. (4), 114Google Scholar; and Guerlac, H., op. cit. (5), 553.Google Scholar

¹²⁰ Thomson, T., A System of Chemistry (3rd ed., Edinburgh, 1807)Google Scholar. The “dedication” is dated 5 May 1807. See especially Vol. iii, pp. 424–628.

¹²¹ Roscoe, and Harden, , op. cit. (10), 141–143.Google Scholar Thomson's letter is dated 8 March 1807.

¹²² Op. cit. (5).

¹²³ Nicholson's Journal, viii (1804), 280–293.Google Scholar

¹²⁴ Thomson's 1807 letter to Dalton (see reference 121) implies an earlier correspondence, of which I have now traced one letter. See “Fragmentary Remains of John Dalton. Part I: Letters”, Annals of Science (in the press). For T. C. Hope, who succeeded to Joseph Black's chair at Edinburgh, see Partington, J. R., A History of Chemistry (London, 1961-, iii, 721–722.Google Scholar For extracts from his correspondence with Dalton see Roscoe and Harden, op. cit. (10).

¹²⁵ Henry, W. C., op. cit. (35).Google Scholar

¹²⁶ See Henry, W., An Epitome of Chemistry (4th ed., Edinburgh, 1806), preface p. viii.Google Scholar

¹²⁷ See Nicholson's Journal, xix (1808), 149–153.Google Scholar

¹²⁸ Roscoe, and Harden, , op. cit. (10), 142–143.Google Scholar

¹²⁹ Phil. Trans. (1808), 63–95.Google Scholar

¹³⁰ Thomson, T., op. cit. (120), iii, 425.Google Scholar

¹³¹ Thomson merely altered his 1807 footnote to “Mr. Dalton has not yet published a detailed account of his hypothesis, though he has noticed it in the 1st Volume of his New System of Chemical Philosophy…”: see A System of Chemistry (4th ed., Edinburgh, 1810), iii, 441.Google Scholar

¹³² See Thomson, T., op. cit. (10), ii, 286Google Scholar, and contrast this with his detailed account of their 1804 meeting.

¹³³ New System, preface, p. vi.

¹³⁴ Neville, R. G., op. cit. (1), Plate 1Google Scholar