ambix, Vol. 61 No. 1, February, 2014, 48–66

Pedagogical Progeniture or Tactical Translation? George Fordyce’s Additions and Modifications to William Cullen’s Philosophical Chemistry — Part I Georgette Taylor University College London, London

This article contributes to a growing body of research on the dissemination, dispersion or diffusion of scientific knowledge via pedagogical networks. By examining students’ handwritten lecture notes, I compare the eighteenthcentury chemistry lectures given by William Cullen (1710–1790) at Glasgow and Edinburgh Universities with those of his one-time student George Fordyce (1736–1802), in London, at first privately and then as part of the medical education of physicians at St. Thomas’s Hospital. Part I examines the broad structure of Cullen’s and Fordyce’s courses, comparing both course content and pedagogical approaches to ask how far knowledge flowed directly ‘downstream,’ and the extent to which it was transformed, translated or transmuted in the process of transmission. Part II (forthcoming) will approach the affinity theories of Cullen and Fordyce in greater depth, revealing the dynamics of knowledge transfer. The results shed light on the transmission of knowledge and skills between master and student, and reflect on whether Fordyce can be better described as Cullen’s pedagogical progeny, or less straightforwardly as a tactical translator.

Introduction Scientific pedagogy has become a topic of interest for historians of science in recent years, with the role of chemical textbooks in shaping the discipline and the dissemination of scientific knowledge through pedagogical networks having inspired a number of research studies.1 This paper explores what might be termed pedagogical 1

Antonio Garcia-Belmar et al., “The Power of Didactic Writings: French Chemistry Textbooks of the Nineteenth Century,” in Pedagogy and the Practice of Science: Historical and Contemporary Perspectives, ed. Wiebe

© Society for the History of Alchemy and Chemistry 2014

DOI 10.1179/0002698013Z.00000000045

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heredity, as displayed in the chemical teaching of William Cullen (1710–1790) and his erstwhile student, George Fordyce (1736–1802). Historians of chemistry are, for the most part, united in their assessment of Cullen’s chemical lectures as being highly influential, both on his students and on the discipline of chemistry. This view is upheld by the enthusiastic declarations of discipleship and gratitude of the students themselves, some of whose lecture notes survive. A pedagogical network can be charted, headed by Cullen in Scotland, via his students, and their students in turn, as far afield geographically as the United States, and temporally into the nineteenth century. Rather than focusing on the most famous of Cullen’s students to offer lectures on chemistry, Joseph Black (1728–1799), I here examine the teaching of George Fordyce. While Black remained in Scotland, in continued proximity to Cullen (for much of Black’s teaching career both were lecturing at Edinburgh University), Fordyce taught many miles from Scotland, in an initially somewhat unreceptive London, geographically isolated from his old master. These early pedagogical endeavours were subject to financial and social pressures that were largely lacking in Black’s illustrious career, making Fordyce’s pedagogical decisions of particular interest. The paper is divided into two parts. This first part examines the broad structure of Cullen’s and Fordyce’s chemistry courses, comparing their pedagogical strategies and course content to discover to what extent knowledge was merely transmitted ‘downstream,’ or whether a process of translation or even transmutation can be discerned. The second part will examine the affinity theories of Cullen and Fordyce in greater depth, with the aim of revealing the dynamics of knowledge flow between the two men.2 The paper as a whole offers a case study delineating one form of pedagogical genealogy.

Cullen and Fordyce’s pedagogy: the evidence From the late 1740s, William Cullen began to teach a new and distinctive kind of chemistry which was to prove highly influential.3 The period during which Cullen lectured on chemistry, from around 1747 to 1766, offers the historian a fairly uncluttered view of the birth of a pedagogical network. Although chemistry teaching in Britain at that time was relatively scarce, the popularity of Cullen’s lectures is 1

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Continued E. Bijker, W. Bernard Carlson, and Trevor Pinch (Cambridge, Mass.: The MIT Press, 2005); Bernadette BensaudeVincent, “College Chemistry: How a Textbook Can Reveal the Values Embedded in Chemistry,” Endeavour 31, no. 4 (2007): 140–44; Jan Frercks and Michael Markert, “The Invention of Theoretische Chemie: Forms and Uses of German Chemistry Textbooks, 1775–1820,” Ambix 54, no. 2 (2007): 146–71; David Kaiser, “Making Tools Travel: Pedagogy and the Transfer of Skills in Postwar Theoretical Physics,” in Pedagogy and the Practice of Science, ed. David Kaiser (Cambridge, Mass; London: MIT Press, 2005), 41–74. Georgette Taylor, “Pedagogical Progeniture or Tactical Translation? George Fordyce’s Additions and Modifications to William Cullen’s Philosophical Chemistry — Part II,” forthcoming in Ambix. Arthur L. Donovan, Roy Hutchinson Campbell, and Andrew S. Skinner, “William Cullen and the Research Tradition of Eighteenth-Century Scottish Chemistry,” in Origins and Nature of the Scottish Enlightenment (Edinburgh: John Donald, 1982), 98–114; Arthur L. Donovan, Philosophical Chemistry in the Scottish Enlightenment: The Doctrines and Discoveries of William Cullen and Joseph Black (Edinburgh: Edinburgh University Press, 1975).

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attested to by the unusually large number of sets of lecture notes held in libraries across the country.4 Perhaps the very dearth of chemistry courses in Britain made manuscript notes of available lectures precious enough for contemporaries to consider their preservation worthwhile. It is certainly the case that, as Cullen never published a textbook on chemistry, those students who might wish to refer to his ideas in later years would have to rely on accurate notes. Sets of lecture notes were routinely copied and often sold to interested parties, whether within or external to the student circle. Thus, Donovan and Golinski have argued that, in the context of the eighteenth century, both Cullen’s and his former student Joseph Black’s ideas as expounded in their lectures had effectively been placed in the public domain.5 The diarist Sylas Neville, himself a medical student under Cullen, writes of the copying of lecture notes and of a thriving trade in the sale and purchase of reliable sets of notes.6 Likewise, the apothecary and natural philosopher John Elliot admitted to having been able to study a set of Black’s lecture notes belonging to a friend, although he complained that he “only wished they had been more perfect.”7 The extent of these archives allows the historian to make a fair account of Cullen’s teaching despite the lack of published material. The notes tend to survive for particular years, and in some cases can be connected to particular students, although we cannot always assume that the student (or students — it was often a collaborative effort) who originally attended the lectures was necessarily the transcriber of the notes, or the same student whose name appears as ‘owner’ of the manuscript. Nevertheless, we can glean sufficient information to trace the development of the course over time, and in some cases follow the courses taken by a particular student. Since Cullen lectured in English rather than Latin, most of the notes of his chemistry lectures are in that language.8 This served to open up his lecture courses to a wider, non-student audience, and we know that a variety of “gentlemen engaged in any

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The Wellcome Library for the History and Understanding of Medicine, London, holds at least four fairly complete sets of lectures, as well as a number of more fragmentary sets: William Cullen, “Notes Taken by Charles Blagden from Lectures on Chemistry 1765–6” (1766), MS 1922, Blagden Papers; Cullen, “Notes Taken by Will Falconer from Chemistry Lectures” (1765), MS 1919–1921; Cullen, “Notes Taken from Lectures on Chemistry” (n.d. [1760s]), MS/MSL/79a-c Medical Society of London; Cullen, “Lectures on Chemistry 1760” (1760), MS/MSL/ 7a-7b Medical Society of London. Glasgow University Library holds a vast number of manuscripts, comprising Cullen’s own notes as well as fragments of the lecture notes of students: too many to list here individually. Quotations from individual MSS will be specified hereafter. Edinburgh University Library and the Royal College of Physicians of Edinburgh are two further repositories for the copious number of Cullen papers still extant. Jan Golinski, Science as Public Culture: Chemistry and Enlightenment in Britain, 1760–1820 (Cambridge: Cambridge University Press, 1992), 42–3, and Donovan, Philosophical Chemistry in the Scottish Enlightenment, 271. Sylas Neville and Basil Cozens-Hardy, The Diary of Sylas Neville 1767–1788 (London: Oxford University Press, 1950), 151. John Elliot, Philosophical Observations on the Senses of Vision and Hearing to Which Are Added, a Treatise on Harmonic Sounds, and an Essay on Combustion and Animal Heat (London: Printed for J. Murray, 1780), 122–3. Neville wrote: “I find that Dr. Cullen notwithstanding his present eminence had but a poor education and had not acquired much learning before he was 40 years old. … Knowles heard that one J. Brown, a great Latinist, who writes many Theses for those who are not ashamed to bring out the composition of another as their own, assists Cullen in his Latin.” Neville and Cozens-Hardy, Diary of Sylas Neville, 144. Although Cullen lectured in English, examinations were still held in Latin, and Neville also testifies to the fact that in spite of Cullen’s alleged lack of facility with the language he was nevertheless sufficiently proficient to hear examinations without assistance.

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business connected with chemistry” from the manufacturing and commercial arenas bolstered Cullen’s student numbers, as well as his teaching income.9 In comparison, the evidence for Fordyce’s teaching is more meagre. However, there is one (admittedly slightly unusual) set of notes apparently dating from when Fordyce was still lecturing privately, from his home.10 His Elements of Agriculture also allows us to corroborate the notes as it includes much valuable evidence of his chemical thinking in the 1760s.11 There is also a tiny commonplace book of Jeremy Bentham in the British Library which contains chemistry notes taken in August and September of 1769.12 Although the notes are sparse, particular phrasings suggest that these were taken from Fordyce’s lectures, and indeed Bentham does report that when he first knew Fordyce, “his laboratory took fire, and he had nothing to exhibit with, but a small portable furnace, with a few vials and common things.”13 The libraries of the Royal College of Physicians in London, the Royal Society of Chemistry, and Kings College London all hold sets of notes taken from Fordyce’s lectures of the 1780s.14 A set of undated chemistry notes held at Glasgow University Library also bears the characteristic exemplars, phrases and illustrative experiments of Fordyce’s lectures. These seem to date from either the late 1760s or early 1770s.15 While these sources have been relatively little studied, sufficient notes survive to provide evidence of what, and to a lesser extent how, both Cullen and Fordyce taught their discipline.

Cullen: the pedagogy William Cullen began teaching chemistry in 1747 (as a rather last minute replacement for John Carrick who was originally supposed to lecture at Glasgow University on the subject16), moving in 1755 to Edinburgh University and giving his last course in chemistry in 1766. He did, however, continue to teach on materia medica and the theory and practice of medicine at Edinburgh until late 1789.17 Cullen was extremely well regarded throughout his life by his ex-students (and in many cases their 9

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Letter, Robert Wallace to John Thomson, 5 July 1811, quoted in J. Thompson, An Account of the Life, Lectures and Writings of William Cullen (Edinburgh: William Blackwood, 1832), vol. 1, 25. George Fordyce, “Notes Taken by John Samwell from Chemistry Lectures” (1765), MS Gen 786, Glasgow University Library. George Fordyce, Elements of Agriculture (Edinburgh, 1765). This work is undated, but evidence in other sources confirms it as having been published for the first time in 1765. Jeremy Bentham, “Commonplace Book” (1769), Add. MS 33564, British Library, London, fols. 55 ff. Jeremy Bentham, The Works of Jeremy Bentham, published under the superintendence of his Executor, John Bowring, 11 vols. (Edinburgh: Simkin, Marshall & Co, 1838–1843), vol. 10, 184. George Fordyce, “Lectures on Chemistry 1786” (1786), MSS 146–148, St Thomas’s Hospital, Henry Rumsey Papers, Royal College of Physicians, London; Fordyce, “Lectures on Chemistry 1786” (1786), MS E 146 G, Historical Collection, Royal Society of Chemistry Library, London; and Fordyce, “Notes Taken by Richard Whitfield from Chemistry Lectures” (1788), M58–M60, St Thomas’s Collection, King’s College Library, London. George Fordyce, “Lectures on Chemistry” (n.d. [1770s?]), Ferguson MS 172, Glasgow University Library, fol. 9. Donovan, Philosophical Chemistry in the Scottish Enlightenment, 62–64. William F. Bynum, “Cullen, William (1710–1790),” in Oxford Dictionary of National Biography, ed. Henry Colin Gray Matthew and Brian Harrison (Oxford: OUP, 2004), http://www.oxforddnb.com/view/article/6874 (accessed 11 June 2009).

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own ex-students)18 who did much to propagate their reverence for their master beyond Edinburgh. Thomas Thomson reported: The appearance of Dr. Cullen in the College of Edinburgh constituted a memorable era in the progress of that celebrated school. Hitherto chemistry being reckoned of little importance, had been attended by very few students; when Cullen began to lecture it became a favourite study, almost all the students flocking to hear him, and the chemical class becoming immediately more numerous than any other in the college, anatomy excepted.19

Although Thomson was writing 64 years after Cullen’s last chemistry course, his claim is well supported. Numbers of attendees at Cullen’s chemistry courses increased threefold, from 59 in his second year to 145 in 1764/5.20 As Donovan has emphasised, Cullen taught ‘philosophical chemistry,’21 that is, chemistry that was reasoned and rational with a careful blend of experimentally sanctioned theory and practical instruction. It thus presented a science that differed strongly from both the recipe-based type of artisanal practice and the highly speculative Newtonian or Cartesian chemistry that became fashionable in the early years of the eighteenth century.22 In Cullen’s hands, chemistry was to be rescued from its grubby and somewhat plebeian status and re-made as a science fit for the gentleman-scholar.23 Matthew Eddy has emphasised the strongly empiricist trend to Scottish natural science as influenced by the Scottish Enlightenment, and Cullen’s chemistry was typically a posteriori.24 Cullen sprinkled the history with which he began his later courses with remarks of approval or disdain according to whether the methods of earlier chemists accorded with his own view of how the discipline should be conducted. It says much about his philosophical chemistry that he reserved his most withering contempt for the alchemical writers, “fanaticks” and those Greeks who “without a stock of Facts to direct their Inquiries, … neglecting experiments, depended on uncertain fancies and rash Conjectures in the pursuit of Truth.”25 Those philosophers who excited his admiration, or at least a degree of approval, included Paracelsus, Van Helmont, Descartes and Boerhaave. Although the content of Cullen’s course inevitably changed over time, the balance between theory and practice and the broad structure of the course did not. Glasgow 18

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The pedagogical network headed by Cullen spanned Europe and America, and included such luminaries as Jeremy Bentham (discussed further in Part II) and Benjamin Rush. See Georgette Taylor, “Variations on a Theme: Patterns of Congruence and Divergence among Eighteenth-Century Chemical Affinity Theories” (Ph.D. dissertation, University of London, 2006), Appendix 2. Thomas Thomson, The History of Chemistry (London: Henry Colburn and Richard Bentley, 1830), 307. Donovan, Philosophical Chemistry in the Scottish Enlightenment, 65, and Golinski, Science as Public Culture, 17. Donovan, Philosophical Chemistry in the Scottish Enlightenment. See also Donovan, Campbell, and Skinner, “William Cullen and the Research Tradition of Eighteenth-Century Scottish Chemistry,” 98–114. For an example of this mechanical chemistry, see John Freind, Chymical Lectures: In Which Almost All the Operations of Chymistry Are Reduced to Their True Principles and the Laws of Nature. Read in the Museum at Oxford, 1704 (London: Jonah Bower, 1712). Golinski, Science as Public Culture, chapter 1. Matthew D. Eddy, The Language of Mineralogy: John Walker, Chemistry and the Edinburgh Medical School, 1750– 1800 (London: Ashgate, 2008), 8–9, 62–3. Lectures 4–7, William Cullen, “Notes Taken by Charles Blagden.”

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University Library holds a copy of a course plan that Cullen had printed for students attending his 1748 lectures.26 The course was divided into “Part First The General Doctrines of Chemistry,” and “Part Second The Particular Doctrines of Chemistry.” The first part began with a discussion of the “elements of bodies,” proceeding from there to the “objects” of chemistry. What appears to be a set of notes made by Cullen himself for the 1748 course indicates that under “elements” he offered a discussion of elements, mixts, compounds and aggregates, commenting on and comparing ideas of Stahl, Boerhaave, Boyle and Newton. He comments that he found the “supposed elements … doubtfull & we give them only as the Chemical Principles usefully known” as salt, sulphur, mercury, water and earth. Under “objects,” he gave a short summary of the tangible, familiar substances that were the objects of the chemists’ manipulations, classifying them into five classes corresponding to his “doubtful” elements or principles of salt, sulphur, mercury, earth and water.27 According to the syllabus of his 1748 course, this was followed by a discussion of “the primary causes of the changes of bodies occurring in chemical operations.”28 Under this heading, the syllabus lists “common and Elective Attraction,” “Fire,” “Air,” and “Ferments” as the causes of chemical change, seemingly arranged by Cullen in decreasing order of importance. Both attraction and fire were to maintain their crucial roles in Cullen’s teaching throughout his career, cited as the primary causes of chemical change. Air and ferments, on the other hand, received less emphasis in courses of later years, as Cullen came to believe that fermentation might perhaps be an effect of mixture (mixture being initiated by attraction), and that the action of air was also perhaps a result of elective attractions.29 In 1748, after completing his lectures on the causes of chemical change, Cullen proceeded to cover the operations and instruments of chemistry, mentioning in particular the processes of solution, distillation and fusion. And it is only after this general section that he began to teach the “particular doctrines of chemistry,” under which heading he recounted the detailed properties and behaviour of the substances that were the objects of chemists’ manipulations. These occupied the remainder of his course. We can compare this broad plan with notes taken at Cullen’s lectures in 1766, the last year in which he taught chemistry.30 The Wellcome Trust Library holds a set of fairly comprehensive notes taken by Charles Blagden of this year’s lectures, which numbered one hundred. By the time of his final course, Cullen was introducing his series of lectures with a history of chemistry,31 but from this he turned to a 26

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William Cullen, “The Plan of a Course of Chemical Lectures and Experiments to Be Given in the College of Glasgow During the Session Mdccxlviii” (1748), MS 1069, Cullen Papers, Glasgow University Library. William Cullen, “Lectures on Chemistry” (n.d. [1748/9]), Cullen 15, Cullen Papers, Royal College of Physicians of Edinburgh Library, lectures 4–6. William Cullen, “The Plan of a Course of Chemical Lectures and Experiments to Be Given in the College of Glasgow During the Session Mdccxlviii” (1748), MS 1069, Cullen Papers, Glasgow University Library. See, for example, lectures 28, 29 and 30 of Cullen, “Notes Taken by Charles Blagden” (op. cit. n. 4), London. Elective attraction, also known as affinity, is discussed further below, and in Part II of this paper. Ibid. For a useful discussion of Cullen’s history of chemistry as included in his lectures, see John R. R. Christie, “Historiography of Chemistry: Hermann Boerhaave and William Cullen,” Ambix 41, no. 1 (1994): 4–19.

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definition of chemistry and thence to the objects of chemistry, much as before. There is one change that is perhaps significant here. In the 1766 course, there is no specific section on “the elements of bodies” as there had been in 1748.32 Indeed, for most of the time Cullen lectured he tried to instil in his students a healthy scepticism concerning the various metaphysical systems or matter theories that were on offer. We gain an idea of his views on this from a set of lecture notes probably dating from the early 1760s, where he states: Opinions concerning Elements shou’d not be regarded as they mislead the Student. It has been inferr’d from the Classes I have mentioned, that there are as many Elements;’ & they have been very unluckily compar’d to Salt, Sulphur & Mercury. … our Business at present is only to know the meaning of the Classes already defined.33

Pedagogical pragmatism seems to have been the order of the day. Cullen was clear that his choice of terminology did not necessarily entail any particular metaphysical or ontological viewpoint, the use of philosophically loaded terms being difficult to avoid in teaching chemistry. Thus, for the majority of his courses after the first few years, Cullen used the terms ‘element’ and ‘principle’ broadly synonymously, and in his 1766 lectures stated that he used the term ‘attraction’ “to denote the phenomenon itself, not the cause.”34 In 1748, Cullen had proceeded from the objects to the operations and instruments of chemistry. By 1766, this heading also covered the agents of chemical change, previously dealt with under “primary causes.” For Cullen, changes in the qualities of bodies were all induced by either combination or separation of bodies: The changes of the Qualities of Bodies, produced by Ch[emistr]y, are all of them produced by, Combination, or Separation. The Office of Ch[emistr]y is to induce new qualities on bodies, & take away old ones; & this, I say, it does by Combination & Separation.35

Combination and separation, in turn, could be produced by the judicious use of the two agents of the chemist — fire and attraction. Cullen explained that combination was produced due to a natural tendency present in all bodies or substances to approach each other. Separation was due to the action of either fire or affinity (or elective attraction as he preferred to call it) or both.36 Fire was, of course, the traditional agent in the analysis of bodies, but while heat was still used cautiously in operations such as distillation to analyse compounds, it had been recognised that fire was a rather blunt instrument for many separations. For Cullen, elective attraction was a more precise tool for separating chemically combined bodies. 32 33 34 35 36

Cullen, “The Plan of a Course of Chemical Lectures,” 1. Cullen, “Notes Taken from Lectures on Chemistry,” fol. 29. Cullen, “Notes Taken by Charles Blagden,” lecture 21. Cullen, “Notes Taken by Charles Blagden,” lecture 19. Square brackets denote expansion of abbreviated words. William Cullen, “Lectures on Chemistry,” unknown [1764?], MS/MSL 79a–c, Medical Society of London (MSL), Wellcome Library, London, fols. 66–67. See also Cullen, “Notes Taken by Charles Blagden,” lectures 19–21

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Cullen also classified the specific operations and processes in terms of his affinity theory. In both separation and combination, the primary tool of the chemist was the power apparently inherent in substances to combine together, but fire also had a place in his particular theory of attraction, promoting fusion or solution to enable the affinities to act: Combination depends upon Attraction, and this upon Fluidity, wch is employ’d in Solution or Fusion Separation depends upon Elective Attraction or the Action of Fire.37

Cullen’s theory included an additional assumption drawn from the fact that the vast majority of chemical changes were produced when one or more of the substances concerned were in a fluid state.38 From this he inferred that the particles of bodies had to be physically close together to exercise their attractions. In a fluid state, the particles of each substance could mingle and approach one other closely enough for their natural attractions to act. ‘Fluid,’ in this context, meant either in fusion, in solution, or in the form of an elastic fluid, or vapour. Thus, Cullen’s affinity theory determined the specific operations to be carried out and he grouped chemical processes and operations under three headings accordingly.39 Combination could be performed either by solution, fusion or exhalation (a term he used for evaporation), and separation could similarly be performed by solution, fusion, or exhalation. In all operations, though, the chemist made use of the agents of affinity and fire. After his lectures on the various operations of chemistry, which in 1766 concluded with a lengthy discussion of the different kinds of furnaces that the chemist might use, Cullen proceeded, as in 1748, to discuss the particular qualities of the substances most often encountered by chemists under a section he called “the chemical history of bodies.” In this section, which occupied over half of the course, he took his students methodically through five classes of bodies: salts, inflammables, metals, earths and waters. Although he discussed the relatively novel fixed air, it appeared only in passing in the discussions of alkalis as the substance responsible for conferring either mildness (when present) or causticity (when absent), and as a possible component of phlogiston under “inflammables.”40 For each body he gave its source, methods for its extraction, its nomenclature and its chemical properties. The latter, for the most part, consisted of a careful enumeration of its attractions — how each body behaved in conjunction with others. 37 38

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Cullen, “Notes Taken from Lectures on Chemistry,” fol. 66. See John R. R. Christie, Geoffrey N. Cantor, and M. Jonathan S. Hodge, “Ether and the Science of Chemistry,” in Conceptions of Ether: Studies in the History of Ether Theories 1740–1900, ed. Geoffrey N. Cantor and M. Jonathan S. Hodge (Cambridge: Cambridge University Press, 1981), 85–110. Cullen, “Notes Taken from Lectures on Chemistry,” fols. 66–67. Cullen, “Notes Taken by Charles Blagden,” lectures 60–63 and 81. Fixed air (or carbon dioxide) had been described for the first time by Black in his MD dissertation of 1754. Cullen often called it “mephitic air” and for a while at least suggested that it might be an ingredient of phlogiston. See Georgette Taylor, “Unification Achieved: William Cullen’s Theory of Heat and Phlogiston as an Example of His Philosophical Chemistry,” British Journal for the History of Science 39, no. 4 (2006): 477–501.

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Although many accounts of eighteenth-century chemistry imply that phlogiston lay at the heart of the discipline, this is not, in fact, supported by an examination of Cullen’s lectures.41 The section of his course dealing with the history of bodies was natural historical in tone, carefully empirical with little, if any, speculative content. It is therefore perhaps not surprising that for most of his lecturing career Cullen made no bones about his doubts concerning phlogiston. He adopted a strikingly ambivalent attitude towards traditional phlogiston theory, pointing out to his students that phlogiston had “never been got by itself.”42 On the other hand, as he explained in his later lectures, he did not reject the concept of a particular matter that, in combination, conferred the property of inflammability on bodies. In 1765, he set forth a complicated and unique phlogiston theory that postulated that the so-called phlogiston was in fact a combination of an acid and mephitic or fixed air.43 Cullen occasionally invoked phlogiston in his lectures as part of a generalised explanation of phenomena, but always with the caveat that it should not be taken as the simple, elemental substance it had traditionally been supposed to be. Rather than phlogiston, it is clear from all the extant sets of Cullen’s lectures that his affinity theory took the leading role as a useful pedagogical as well as explanatory and predictive tool. We have seen how it provided a theoretical basis for the ordering and explanation of the practical processes and operations that occupied so much of the chemist’s time. Beyond this, it also assisted in the demarcation of chemistry and its methods from the mechanical philosophy. Every year, towards the start of each of his courses, Cullen offered an example to help his students distinguish between mechanical and chemical methods. As he explained, If I have a mixture of common sand & finely powdered chalks & want to separate these each from the other, one way of doing it is by affusing water, which will keep the chalk suspended after the sand had subsided; this is mechanical: the other way by Chemistry is by pouring on Vinegar, which will unite with the Chalk but leave the sand untouch’d.44

Bearing in mind that Cullen was not paid a salary for his chemical lectures, but relied on the fees charged to his students for much of his income, and the vagaries of patrons for his reputation and continuing advancement, it was extremely important for his discipline to be seen as useful, important and, perhaps most importantly, autonomous.45 It was crucial to Cullen’s success at Glasgow and Edinburgh that his 41

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Most popular works on the history of chemistry, as well as the vast number of published papers on the Chemical Revolution, claim that the overthrow of phlogiston was the crucial event of the late eighteenth century. This kind of argument in many cases emanates from the Kuhnian account of scientific revolutions, particularly the chemical revolution: Thomas Kuhn, The Structure of Scientific Revolutions (Chicago and London: University of Chicago Press, 1996). Cullen, “Notes Taken by Will Falconer,” fol. 72v. For more details on Cullen’s novel ‘phlogiston theory,’ see Taylor, “Unification Achieved.” Cullen, “Notes Taken by Charles Blagden,” lecture 9. On Cullen’s emphasis of the usefulness of chemistry, see Jan Golinski, “Utility and Audience in Eighteenth Century Chemistry: Case Studies of William Cullen and Joseph Priestley,” British Journal for the History of Science 21 (1988): 1–31; Donovan, Philosophical Chemistry in the Scottish Enlightenment, 65–66; John R. R. Christie et al., “William Cullen and the Practice of Chemistry,” in William Cullen and the Eighteenth Century Medical World, ed. A. Doig, J. P. S. Ferguson, E. A. Milne, and R. Passmore (Edinburgh: Edinburgh University Press, 1993), 98–109; Stephen

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discipline be clearly separated from natural philosophy, and there can be no question that he was conscious of the need to ensure that his students were made fully aware of the distinction, as well as of the usefulness of chemistry. Although those who wished to graduate in medicine were required to learn chemistry, Cullen’s student numbers were swelled by those from outside the medical school, and he took care to extend chemistry’s utility into other realms, such as agriculture and industry. Affinity was thoroughly embedded in Cullen’s philosophical chemistry, and its utility was, as he taught it, self-evident. It was also distinctively chemical, as a form of attraction that differed from the mechanical forces of attraction that acted on all matter irrespective of its kind. The details of Cullen’s affinity theory will be explored in the second part of this paper, but in brief, it provided a coherent framework for the explanation and prediction of chemical behaviour when both simple and more complex substances were mixed together.46 Thus Cullen’s ‘history’ of each chemical body included affinities as the primary chemical ‘facts’ about each substance. It has been claimed, not least by Cullen’s contemporaries, that Lavoisier’s and his colleagues’ framing of oxygen chemistry in their newly coined nomenclature did much to ensure its acceptance.47 The same might be said of Cullen’s philosophical chemistry. Cullen’s course was saturated in the language and theory of affinity or elective attraction. Every demonstration and every explanation he offered was described and interpreted in terms of the elective attractions of the bodies concerned. It simply was not possible to do ‘philosophical chemistry’ without recourse to affinity and affinity tables. Cullen’s pedagogy thus did not simply bring a generation of chemists into being, but a generation of affinity theorists, who applied the philosophical chemistry they had been taught to their own endeavours, utilising affinity theory to understand, explain and predict chemical action. As we shall see, they also used it in turn as a pedagogical tool.

George Fordyce: chemical pedagogy in London George Fordyce was by no means the only one of Cullen’s students to become a chemistry lecturer;48 Cullen’s most famous pupil was Joseph Black, who succeeded him first at Glasgow and then at Edinburgh.49 Nor was Fordyce the only one of 45

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Continued Shapin, “The Audience for Science in Eighteenth Century Edinburgh,” History of Science 12 (1974): 95–121; and Golinski, Science as Public Culture. Briefly, affinity theory was concerned with with the varying tendencies of different substances to combine together, and the apparently preferential nature of chemical combination so that one substance could be used to separate two others in combination. Wilda Anderson, Between the Library and the Laboratory (Baltimore and London: Johns Hopkins University Press, 1984). See also Maurice Crosland, Historical Studies in the Language of Chemistry (London: Heinemann, 1962). We are indebted for much of the biographical information on Fordyce to Noel Coley, whose entry for Fordyce in the Dictionary of National Biography and Notes and Records paper are invaluable: Noel G. Coley, “Fordyce, George (1736–1802),” ODNB, http://www.oxforddnb.com/view/article/9878 (accessed 6 February 2010); Coley, “George Fordyce MD FRS (1736–1802): Physician-Chemist and Eccentric,” Notes and Records of the Royal Society of London 55, no. 3 (2001): 395–409. Golinski, Science as Public Culture, 38.

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them who lectured on chemistry in London — William Saunders also gave chemistry lectures; first privately, and later at Guy’s Hospital to which he was elected physician in 1770.50 Nevertheless, Fordyce was one of the earliest of Cullen’s students to take this route, and as such might be regarded as a pioneer in the importation of Cullen’s philosophical chemistry to the capital.51 Fordyce was born in Aberdeen in 1736, graduating MA from Aberdeen University at 14, and heading for Edinburgh University in 1754, at the age of 18. Here he was probably taught chemistry by Black in the first instance, since Cullen did not start to teach at Edinburgh until January 1756. Thus, Fordyce arrived at Edinburgh two years before Cullen, stayed for the first three years of Cullen’s chemistry lectureship, and graduated MD in 1758. After graduating, he spent a period in Leiden and then returned to London later in 1759, where he began teaching chemistry from his home almost immediately. At this time the London medical marketplace was both crowded and competitive, and as Fordyce was not a member of the Royal College of Physicians he was not entitled to practice as a physician.52 However, although chemistry had been taught at both Glasgow and Edinburgh for a considerable time, when Fordyce first came to London in 1759 he found few competitors in the field of chemical pedagogy in London, or indeed in England. Although a Chair in Cambridge had been established in 1702, teaching at that institution was not highly regarded, and had been intermittent at best.53 John Hadley was lecturing at Cambridge in 1759, but his lectures would probably have been regarded as somewhat old fashioned, being based in part on Aristotelian matter theory.54 Peter Shaw was still alive, and still publishing on chemistry, but had long ceased to lecture in the subject, and it is unclear whether William Lewis was still offering public lectures from his laboratory in Kingston.55 Fordyce was thus able to offer something that was largely lacking in London. This combination of circumstances may explain why Fordyce lectured first on chemistry (although it still took a while for his name to become known — his first class numbered only nine pupils).56 From 1764 he also gave lectures on materia medica and the practice of physic, and as such was one of the first to offer private medical teaching in London. This was the start of a lecturing career that verged

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53

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Coley, “George Fordyce Md Frs (1736–1802).” William Saunders (1743–1817) was a pupil of Cullen’s at Edinburgh, graduating in 1765. He was elected physician to Guy’s Hospital in 1770. See Norman Moore, “Saunders, William (1743–1817),” rev. Jean Loudon, ODNB, http://www.oxforddnb.com/view/article/24705 (accessed 23 December 2013). Golinski, Science as Public Culture, 65–66. Coley, “George Fordyce MD FRS (1736–1802).” On the medical marketplace in eighteenth-century London, see Richard Barnett, Sick City: Two Thousand Years of Life and Death in London (London: Strange Attractor Press, 2008), in particular chapter 2. Also, Roy Porter, “Medical Lecturing in Georgian London,” British Journal for the History of Science 28, no. 1 (1995): 91–99. See Mary D. Archer and Christopher D. Haley, eds., The 1702 Chair of Chemistry at Cambridge: Transformation and Change (Cambridge: Cambridge University Press, 2003). John Hadley, An Introduction to Chemistry Being the Substance of a Course of Lectures Read Two Years Successively in the Laboratory at Cambridge, MS R.1.50/51 (1759), Trinity College Library, Cambridge. Jan Golinski, “Peter Shaw: Chemistry and Communication in Augustan England,” Ambix 30, no. 1 (1983): 19–29. Coley, “George Fordyce MD FRS (1736–1802).”

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on the heroic. Coley tells us that “for almost 30 years [Fordyce] lectured from 7am to 10am six days a week, devoting an hour to each subject. Each course of one hundred lectures lasted four months and he repeated them three times a year.”57 This punishing schedule testifies to the demand for chemistry teaching in England, as well as to Fordyce’s apparent success in the field, although it may also indicate that Fordyce was unable to command a significant sum as a registration fee, requiring him to work hard to earn a living. Although his first year’s class numbers must have been disappointing, Fordyce seems to have quickly gained a reputation as a chemistry lecturer, with class sizes rising swiftly. He wrote to Cullen in 1762 to say that he had had nineteen pupils in the first course of the year and another fifteen over the summer.58 He also explained that he planned to publish his own affinity tables to “serve in some measure as a syllabus to the chemical history” part of his course from late 1762.59 Like Cullen, it would appear that Fordyce intended from the start to found his chemistry course on elective attraction. Similarly, when William Saunders began lecturing in London, he too published a syllabus for the use of his students. The syllabus published for his Guy’s Hospital students is notably more substantial than either Cullen’s 1748 leaflet or Fordyce’s table, including both an outline of the course and the crucial affinity table.60 In spite of a slow start — it took some years for his medical practice to grow even after he was allowed to practice — Fordyce eventually fashioned an impressive career as a physician and lecturer, being appointed physician to St Thomas’s Hospital in 1770, although he continued to lecture on chemistry, apparently from his home. Throughout his career, Fordyce emphasised his debt to Cullen, regularly referring in his lectures to his teacher’s greatness both in the discipline and as a man. As late as 1786, he told his students: The first Dawn of Science in Chemistry was introduced into it by Dr Cullen & hardly any Improvement has been made in the Science since his time … the Science of Chemistry as far as it is render’d perfect is entirely owing to him.61

Of course it would do Fordyce no harm at all to advertise to his own students that he had himself been taught by the great Dr Cullen. This fact probably added value to his own teaching, besides implying that the students were likely to hear some of Cullen’s ideas for themselves. Having said that, to replicate Cullen’s course entirely would not have be advantageous for Fordyce. Students were quick to spot such things, and in Philadelphia, Adam Kuhn was pronounced by one student, Charles Caldwell, to be simply paraphrasing Cullen’s lectures, “and not a few of them

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59 60 61

Coley, “George Fordyce MD FRS (1736–1802),” 398. Letter from Fordyce to William Cullen, 4 September 1762, in George Fordyce, “Five Letters to William Cullen” (1759–1774), MS 180, Cullen Papers, Glasgow University Library. Fordyce to Cullen, 4 September 1762. William Saunders, A Syllabus of Lectures on Chymistry ([London?]: [1770?]). Fordyce, “Lectures on Chemistry 1786,” MSS 146–148, Lecture 1st.

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actual copies of his lectures.”62 A careful balance of Cullen’s authority with Fordyce’s own original thoughts was apparently called for, and it appears that that is what Fordyce sought to provide. The 1765 manuscript at Glasgow University is archived as The theory and practice of chemistry. Notes of lectures by George Fordyce, taken by John Samwell, M. D.63 However, alongside Fordyce’s lectures this includes parallel extracts from Cullen’s lectures, clearly labelled as such. The volume opens with a series of affinity tables, presumably Fordyce’s, which are immediately followed by “Dr Cullen’s table of elective attractions.” This pattern continues throughout the volume. So, folio 46 provides “Of Chemical Combination according to Dr Cullen,” while Fordyce’s lectures on the same subject appear opposite it on folio 47. Mr Samwell’s aim, for whatever reason, seems to have been to carry out a fairly detailed comparison of Fordyce’s lectures with Cullen’s. As Fordyce’s lectures appear on the right-hand page, while Cullen’s appear on the left, it seems likely that Fordyce’s were transcribed first. Details of the notes of Cullen’s lectures suggest that they are taken from quite an early course, probably from the late 1750s, either from notes taken by Mr Samwell in person or obtained by other means. When Fordyce’s lectures are thus placed literally alongside those of Cullen, the parallels between their courses become more apparent. Fordyce’s course followed a similar trajectory to Cullen’s. Although he did not include a history of chemistry, he began with a definition and an account of the aims and intentions of the science. He followed this with a description of what Cullen had called the “particular objects” of the chemist; that is, the substances that were the object of the chemist’s manipulations, although under the heading of “chemical elements.” This was followed by an account of the causes or powers of chemical action — primarily chemical attraction and heat.64 Fordyce’s commitment to presenting his students with a philosophical chemistry was as strong as Cullen’s, and the balance of theory and practice is similar to that found in Cullen’s lectures. Like Cullen, Fordyce saw affinity and heat as the primary chemical agents, and both loomed large in his lectures as the causes of chemical change. Continuing with the operations of chemistry, as in Cullen’s lectures, the second half of Fordyce’s lecture course consisted of more detailed descriptions of the familiar chemical substances.65 If the parallels are indeed made obvious by this manuscript, the differences between Cullen’s and Fordyce’s pedagogy are thrown into higher relief. Where Cullen had sought to avoid emphasising ideas of elements, Fordyce made abundant use of the term to describe the real, tangible substances that chemists worked with daily. According to the 1765 lecture notes, he explained, 62

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Charles Caldwell, Autobiography, with Preface, Notes, and Appendix by Harriot W. Warner (Philadelphia, PA: Lippincott, Grambo, and Co., 1855), 124. Fordyce, “Notes Taken by John Samwell”; cf. n. 10. Fordyce, “Notes Taken by John Samwell,” fols. 37–67. Fordyce, “Lectures on Chemistry,” Ferguson MS 172.

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Chemical Elements are form’d of ye ultimate division as yet made; & tho they may be in y[e]mselves compounds, yet as we can’t decompose y[e]m, we consider them as simple elements. This distinction is best illustrated by ye follow[in]g example, if we take a piece of blue vitriol & divide it mechanically we reduce it into smaller pieces, wch may be again reduced into smaller parts, wch may again be subdivided ad infinitum, but yet each of these parts are similar to each other. If we divide this compound chemicaly we reduce it into its Elements, wch are vitriolic acid, copper & water, each of wch may be separated from ye rest; thus if we disolve it in water & apply iron to ye solution, it will be more strongly attracted by ye acid than the copper wch will be detatch’d from it, & form a metalline crust on the Iron; in the same manner either of its other Elements may be separated – but we can’t divide these component Parts any further, & therefore we call y[e]m Chemical Elements.66

Although, like Cullen, he classed substances into salts, earths, inflammable substances, metals, water and air, Fordyce’s use of the term ‘element’ was clearly defined and based on the pragmatic fact of whether or not a body could be decompounded any further. Fordyce’s thinking on affinity theory will be explored in more detail in the second part of this paper. For Fordyce, as for Cullen, affinity theory was absolutely central to chemistry and to any understanding of matter and its behaviour. Like Cullen, he taught his students that for a chemical combination to take place, one or both substances must be in a fluid state. However, he extended the theory somewhat, stating in 1765 that vaporous substances could also combine, and in 1786 that “If two solids combine so as to form a fluid, these two solids will act upon one another.”67 This latter circumstance describes, amongst other things, the phenomenon that occurred upon the mixing of ice and salt. Given this link between affinity and the states of matter, it followed for Fordyce, as it had for Cullen, that the various chemical operations or processes could be classified on the basis of affinity theory. He arranged the first part of his 1765 lectures by dividing up common chemical operations according to whether they provoked affinities to act through heat or solution. Fordyce was much more specific (and speculative) than Cullen about the mechanics of how affinities or attractions acted, as we can see both from the 1765 lecture notes and from his Elements of Agriculture published in the same year. In both he claimed that affinities acted between particles of substances. In chemical combination, one particle of one substance united with one (or perhaps more than one) particle of another. The 1765 lectures explain that: Chemical Combination is so intimate yt every particle of one Elem[en]t is united to every particle of ye other Element. Thus if we take but a small drop of ye compound of muriatic acid & chalk, & apply it to a solution of ye fix’d alkali; a precipitation will take place wch shews yt ye chalk is united with the acid in yt quant[it]y.68 66 67 68

Fordyce, “Notes Taken by John Samwell,” fol. 37. Fordyce, “Notes Taken by John Samwell,” fol. 53; Fordyce, “Lectures on Chemistry 1786,” MS E 146 G, fol. 62. Fordyce, “Notes Taken by John Samwell,” fol. 53

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Similarly, in the Elements, he stated that “a particle of Each Element unite together, so as to form but one Particle considered Mechanically.”69 He even provided plates to show what he meant. These showed how a particle of volatile alkali combined with a particle of acid to form a particle of sal ammoniac, “in which they have one common sphere of Chemical Attraction.” This compound particle, as he explained, could itself “become an element” by virtue of its common sphere of chemical attraction and combine with copper to form the pigment known as Brunswick Green. The three particles so combined had, as before, “one sphere of mechanical action.”70 Fordyce continued to present this apparently original ontology, and indeed this very example, to his students throughout his teaching career. In these lectures, he states: Every Drop of the Combination of the Calcareaous Earth and muriatic acid contains a proportional Part of the Calcareous Earth for if we take a Drop of it & mix it with a Glass of Water & add to it fixed Alcali the calcareous Earth will be decomposed and fall to the Bottom.71

We find his emphasis on real, tangible, and contingent elements in all these lectures. Indeed, the student taking down notes in 1786 included a carefully compiled table of “chymical elements.” Fordyce’s description of the combining together of specific numbers of particles of these elements also remained, although he seems to have mused on this over the years, and by 1786 had taken his theory to its logical conclusion, specifically acknowledging what had only been implied in 1765: since each of the smallest integral parts of one body unites with the smallest integral parts of another body it is clear as we have shown you, that two substances can only combine with one another in one proportion. … One of the smallest integral particles of one body, may unite with only one of the smallest integral parts of another body so as to form a compound that will have an equal number of particles of each of its Elements; or one particle of one body may unite with two particles of another body, so that there would be only half the quantity of one that there was of the other.72

However, he continued, It is true that a compound is capable of becoming an Element & a compound may unite with one of its Elements so as to form a different Compound: as for example Mercury unites with Muriatic Acid so as to form Corrosive sublimate, & corrosive sublimate is capable of combining with the Solvend (mercury) so as to form Calomel; so that altho’ Muriatic acid appears to combine in two proportions with Mercury yet it does not.73 69 70 71 72 73

Fordyce, Elements of Agriculture, 3. Fordyce, Elements of Agriculture, Plate 3rd and explanation of 3rd Plate, fig. VII. Fordyce, “Lectures on Chemistry,” Ferguson MS 172, fol. 9. Fordyce, “Lectures on Chemistry 1786,” MS E 146 G, fol. 70. Fordyce, “Lectures on Chemistry 1786,” MS E 146 G, fol. 72.

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An alternative scenario is included in the anonymous notes from the early 1770s, which explain, “two substances can only be chymically combined in one proportion, the Compound frequently may be diffused thro a greater Quantity of one of the Elements or thro both.”74 In another set of notes, dating from 1786, We can easily conceive (therefore ‘tis possible) that one of the smallest integrant parts of one body may unite with 2 of the smallest integrant Parts of another Body so as to form a comp[oun]d. The Proportions of the number of ye smallest Integ[ran]t Particles of one Body together yth ye smallest Integ[ran]t Parts of another yt may unite, so as to form ye smallest integ[ran]t Part we cannot well determine.75

But again, he continued, still using, it is interesting to note, the example contained in his diagram in Elements: We are next to consider whether 3 elementary Particles may combine so as to form one Comp[oun]d simply. An instance of this does not occur in Chemistry. … We have hardly any instances of this kind excepting in solutions of neutral salts. If we take Sal: Am: (Comp[oun]d of Muriat: Acid & Vol: Alk:[)] & put into it Copper the Sal: Am: will dissolve the Copper in a few Days. There then is a Comp[oun]d of 3 Bodies viz Muriatic Acid, Vol: Alk: & Copper. But in this case the Muriat: Acid unites with vol: Alk: & forms a Comp[oun]d which combines with the Copper so that a smallest integrant part of Sal: Am: is united with ye Copper. For if we unite Copper with the Acid & apply the alk the alk will precipitate the Copper from ye acid in ye form of a blue powder (which is ye calx of ye Copper). If we have Copper combined with the Alk & apply an Acid, the acid will also precipitate the Copper from the alk in the form of a blue powder. It is clear then that the Copper is neither united with the acid nor with the alk: of Sal Am: but when Sal Am: dissolves Copper the smallest integrant part of Sal Am is united with the smallest integrant part of Copper. A comp[oun]d may therefore become an Elem[en]t.76

Fordyce’s particulate speculations were not just based on philosophical musings, but on his observations of the actual behaviour of substances with which he was entirely familiar. Although speculative, his conclusions were built on a foundation of observation and empiricism of which Cullen would probably have approved. This kind of thinking was present, as we can see, in Fordyce’s chemistry lectures from the earliest years, and was also implied by the diagrams included in Elements. We cannot, however, ascribe these ideas to Cullen. Although Cullen has rightly been given credit for being the first to mix affinity theory coherently with a Newtonian ontology, Fordyce took this further than his old master.77 Historians of science are rightly wary of pointing to precursors of great theories or discoveries, and indeed it would be wrong to interpret Fordyce’s thinking in Daltonian terms. There is no sign, after all, that he 74 75 76 77

Fordyce, “Lectures on Chemistry,” Ferguson MS 172, fol. 20–21 Fordyce, “Lectures on Chemistry 1786,” MSS 146–148, Lecture 5. Fordyce, “Lectures on Chemistry 1786,” MSS 146–148, Lecture 5. Henry Guerlac, “The Background to Dalton’s Atomic Theory,” in John Dalton and the Progress of Science, ed. D. S. Cardwell (New York: Manchester University Press, 1968), 57–91.

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pursued his ideas to the extent of working out the proportional weights of any of his combining substances. But the idea was nevertheless present in Fordyce’s lectures and publications, implicitly from 1765, and explicitly from (at the latest) 1786, that chemical elements (understood as contingent, operational simple substances rather than as ideal, metaphysical entities) combine one particle with another or one particle with two others, and that (as he stated in 1786, and quite possibly much earlier) this would dictate the ‘quantity’ of each present in the compound.78 Given Fordyce’s lecturing schedule and very active social life, we should note that these ideas were not kept from the world, but were effectively publicised, if not published. In this regard, Bryan Higgins also merits mention. Higgins is often cited by historians as having pioneered a particulate ontology of combining elements in the late eighteenth century. It is true that he also taught chemistry in London, but he did not graduate from Leiden until late in 1765 and did not settle in London until 1770, only setting up his school of chemistry in London in 1774.79 Fordyce was, as we can see, clearly in advance of Higgins in this regard. It is possible to view the pre-Lavoisierian period as phlogisticated chaos within which only pneumatic discoveries merit historical interest. However, phlogiston was not the only contemporary theory, and ideas were evidently circulating from the early 1760s that sought to interpret chemistry in terms of combining particles. The quantified and atomic chemistry that developed in the next century did not spring forth fully formed from the heads of either Lavoisier or Dalton, but instead probably owed much to the speculations and hypotheses of relatively neglected figures such as Fordyce. Fordyce, after all, was a lecturer giving hundreds, if not thousands, of students their basic grounding in chemistry. As historians appreciate Cullen’s role in disseminating a new kind of chemistry in the mid-eighteenth century, so we should also take account of the teaching of Fordyce and his contemporaries, many of whom were also students of Cullen, who were teaching the discipline to the next generation of chemists, including Dalton and his contemporaries.

Conclusion Like Cullen, Fordyce offered his students a philosophical chemistry, blending theory and practice carefully and consistently. However, where Cullen had exercised a certain restraint in his pedagogy in the matters of metaphysical elements and 78

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Glasgow University Library holds another set of lectures, undated and with the lecturer not specified, but it is clear from internal evidence that the lecturer was Fordyce, and that they should be dated between 1765 and 1780s — probably from the early 1770s. These include the above example of muriatic acid’s combinations with mercury, so it seems likely that these ideas were being disseminated much earlier than 1786. Fordyce, “Lectures on Chemistry,” Ferguson MS 172. Brian B. Kelham and Donald S. Cardwell, “Atomic Speculation in the Late Eighteenth Century,” in John Dalton and the Progress of Science, ed. Cardwell, Ignore GT’s interpolation here, since the book was cited earlier, in n.77. 109– 24, is the most often cited paper claiming Higgins as a pioneer in atomic thinking. For more on Bryan Higgins and his nephew William, also commonly regarded, not least by William himself, as pre-empting Dalton’s atomic theory, see Thomas Sherlock Wheeler and James Riddick Partington, The Life and Work of William Higgins Chemist (1763– 1825) Including Reprints of ‘a Comparative View of the Phlogistic and Antiphlogistic Theories’ and ‘Observations on the Atomic Theory and Electrical Phenomena’ by William Higgins (London: Pergamon Press, 1960).

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speculative matter theories, Fordyce seems to have been more daring. There was a generational gap between the two, and it might be argued that Cullen’s notably nondogmatic attitude towards systems and speculations freed Fordyce, as his student, from the mistrust of systems of the first half of the century. Cullen’s teaching was also based in a (by then) august institution, which, while offering him a certain status and a ready supply of students, may well have cramped his speculative style. Fordyce, on the other hand, who taught out of his own home for much of his career, had to find his own students and thus needed to forge his own path. His lack of institutional ties in the early years may have been a mixed blessing; while his course benefited, his pocket suffered. Cullen’s pragmatic ontological agnosticism had left Fordyce free to draw his own ontological conclusions. However, Fordyce’s own pragmatism led him to present his students with a notably operational and contingent notion of chemical elements and his experimentally sanctioned speculations on combining particles. Fordyce might be said to have been at the forefront of chemical teaching in London from the 1760s, perhaps the first to import Cullen’s chemical pedagogy into the nation’s capital. However, as we have seen, he did not simply appropriate Cullen’s lectures as a whole and repeat them to his own students. He could have done so, and having only recently left Edinburgh himself, he was probably in possession of at least one set of notes of Cullen’s lectures. But Fordyce wished to forge his own path in chemistry. He had a reputation to build, and a living to earn, and while he clearly believed that Cullen’s pedagogical methodology should be broadly adopted, he also modified, and indeed augmented, Cullen’s approach to suit his own ideas and assumptions. Having outlined some of the differences between Cullen’s and Fordyce’s pedagogy, it is important to bear in mind that these divergences can only be distinguished because, as the transcribers of Cullen’s and Fordyce’s lectures no doubt appreciated, the structure and much of the content of their courses were broadly the same. For both, their courses rested on their affinity theories (to be explored further in the second part of this paper) and their similar methodological commitments to a philosophical chemistry. Fordyce can indeed be seen as Cullen’s pedagogical heir, but while he inherited much from Cullen, his chemical pedagogy nevertheless had its own character, distinct from Cullen’s, just as Fordyce’s own circumstances differed from those of his pedagogical progenitor.

Acknowledgements This research formed part of my PhD and I must gratefully thank the Arts and Humanities Research Board/Council for its funding of my doctoral research, and the staff of the STS Department at UCL for their kind support throughout my PhD and ever since. Thanks are also due to all the various libraries and archives that have allowed me to make use of their wonderful collections. Also I must thank the anonymous referees for their careful reading and helpful suggestions

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from which this paper has benefitted greatly. My gratitude is also extended to all those historians of chemistry who have offered their advice, help and copious knowledge, and most particularly to Professor Hasok Chang, whose unfailing faith in me continues to inspire me.

Notes on contributor Georgette Taylor completed her PhD in 2006 at University College London, on the affinity theories that were prevalent in the chemistry of eighteenth-century Britain. Her research explored the teaching of chemistry, in particular by William Cullen and by many of his ex-students. She won the 2008 Partington Prize awarded by the Society for the History of Alchemy and Chemistry for “Tracing Influence in Small Steps: Richard Kirwan’s Quantified Affinity Theory.” A post-doctoral fellowship followed with the project “Analysis and Synthesis in Nineteenth-Century Chemistry: Towards a New Philosophical History of Scientific Practice.” At present, she is an honorary research associate at UCL, while also working as a research and development manager at a software company, pursuing a degree in mathematics, and continuing her research on eighteenth- and nineteenth-century chemistry. Address: 5 Dobson Walk, Wimblington, March, PE15 0PN; E-mail: [email protected].

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