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Lavoisier and the Caloric Theory

  • Robert J. Morris


Professional historians of science generally recognize the importance of Lavoisier's theory of heat. However, it commonly receives scant attention in the historical treatment of his chemical theories except perhaps as an example illustrating his conservatism and giving the impression that the caloric theory, although perhaps important in the development of ideas on the nature of heat, is independent of and bears little relationship to his general chemistry or is incidental to an understanding of that chemistry.1 An examination of Lavoisier's writings suggests that the caloric theory is not merely a milestone in the development of physics; and rather than an omittable appendage, his concept of heat forms an integral part of his chemical system and plays a central, necessary role in his oxidation theory in particular. The purpose of this paper is to give a general description of Lavoisier's ideas on the nature and action of heat, the origin of these ideas, their development, and their relation to his general chemistry, pointing out his conservatism as well as his innovations.



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1 The following examples are illustrative. Heat theory is ignored in a discussion of Lavoisier's chemistry in Wolf, A., A History of Science, Technology & Philosophy in the 18th Century (2nd edn., 2 vols., New York: Harper, 1961), i. 366–75. It is all but ignored in this connexion in Hall, A. R., The Scientific Revolution, 1500–1800 (Boston: Beacon, 1956), pp. 328, 336–67. As an example of Lavoisier's conservatism, see Butterfield, H., The Origins of Modem Science, 1300–1800 (new edn., New York: Macmillan, 1960), p. 207. Certainly not all historians have ignored the chemical role of caloric; see Partington, J. R., A History of Chemistry (4 vols., London: Macmillan, 19611970), iii. 421–2.

2 ‘Expérience sur le passage de l'eau en glace communiquée à l'Académie des Sciences’, Introduction aux Observations sur la Physique, ii (1772), 510–11.

3 The report was made in August 1772 and subsequently published: ‘Expériences du docteur Black sur la march de la chaleur dans certaines circonstances’, Introduction aux Observations sur la Physique, ii (1772), 428–31. For the report on Black to the Academy see Guerlac, H., Lavoisier—The Crucial Year: The Background and Origin of his First Experiments on Combustion in 1772 (Ithaca, N.Y.: Cornell Univ. Press, 1961), pp. 68–9, 92–3.

4 This is the manuscript of July 1772 discussed below. Concerning its identity with that to which Lavoisier referred, see Guerlac, , op. cit. (3), pp. 93–7.

5 Lavoisier used various terms to indicate heat matter. In manuscripts of 1773 and in his Opuscules he referred to this fluid as phlogiston or an inflammable principle; see Fric, René, ‘Contribution à l'étude de l'évolution des idées de Lavoisier sur la nature de l'air et sur la calcination des métaux’, Arch. Int. Hist. Sci., xii (1959), 149–50, and Opuscules Physiques et Chymiques (Paris, 1774), pp. 279–80. However, Lavoisier's later denial of the existence of phlogiston resulted in his subsequent use of different terminology. Except for this restriction, prior to the nomenclature revision of 1787 (Guyton de Morveau, L. B. et al. , Méthode de Nomenclature Chimique proposée par MM. de Morveau, Lavoisier, Bertholet, & de Fourcroy [Paris, 1787], cited hereafter as Nomenclature Chimique), Lavoisier was indifferent to the terminology he used. He called heat the igneous fluid, fire matter, heat matter, the principle of heat, the matter of fire or light, the matter of fire, heat, and light, in addition to other similar phrases. In the manuscript preparation of his Traité de Chimie he proposed the terms ‘thermogéne’ and ‘principe échauffant’ (quoted in Daumas, M., ‘L'élaboration du Traité de Chimie de Lavoisier’, Arch. Int. Hist. Sci., iii [1950], 580, 584), although in the published Traité he used ‘calorique’, conforming to the new nomenclature (Nomenclature Chimique, p. 30). The term ‘calorique’ was probably Guyton's invention. The adjective ‘calorifique’ had seen widespread usage throughout the century. However, in 1785 Guyton had used it as a noun indicating the matter of heat or of fire; see Partington, , op. cit. (1), iii. 421. Cf. the same usage in Observations sur la Physique, xxx (1787), 45–6, and see Fox, R., The Caloric Theory of Gases from Lavoisier to Regnault (Oxford: Clarendon Press, 1971), p. 6n. Another change in the new nomenclature was the listing of light as a distinct element; see Nomenclature Chimique, pp. 2830. Lavoisier was indifferent to the problems of differentiating between heat and light and of specifying the chemical role of light: see, for example, ibid., p. 293n., and Traité Élémentaire de Chimie (2 vols., Paris, 1789), i. 200–2; also Metzger, H., ‘Newton: La théorie de l'émission de la lumière et la doctrine chimique au XVIIIème siècle’, Archeion, xi (1929), 24–5. He did state in a few places that the state of oxygen gas is due to both caloric and light combined in it: for example, in Nomenclature Chimique, p. 296; Traité, i. 201; ii. 523; and Mémoires de Chimie (2 vols., Paris, 1803?), ii. 155. In the Traité de Chimie, ii. 523, he gave as a basis for this some work by Berthollet showing that ‘obscure’ heat cannot produce oxygen gas from oxide of mercury.

6 Opuscules, p. 280.

7 Gough, J- B., ‘Lavoisier's early career in science: an examination of some new evidence’, Br. J. Hist. Sci., iv (19681969), 52–7.

8 Quoted in ibid., 54.

9 For the probable date of composition, see Guerlac, , op. cit. (3), pp. 100–1. The manuscript, originally published by Fric, in op. cit. (5), is reproduced in Guerlac, , pp. 215–23.

10 Quoted in Fric. op. cit. (5), 145. The words in brackets are those crossed out in the manuscript.

11 Dissolution was considered to be a chemical process; see Venel, G. F., ‘Menstrue & action menstruelle, ou dissolvant & dissolution’, Encyclopédie ou Dictionnaire Raisonné …, ed. Diderot and d'Alembert, x (1765), 339, 340. As far as I can tell, however, prior to Lavoisier, of all changes of state only evaporation (not vaporization in general) was considered to be a dissolution in which air (not fire) acts as the menstruum; see [Turgot, A. R. J.], ‘Expansibilité’, Encyclopédie, vi (1756), 282, and the corrections, p. 927.

12 Cooling was the single phenomenon which indicated to Lavoisier a combination of fire had taken place; the only fusion phenomenon which he associated with his theory of combination of fire was the cooling of an ice-salt mixture. See Fric, op. cit. (5), 141–2.

13 ibid., 147–51.

14 Guerlac argues that the appearance of the July memoir as being devoted primarily to explain the fixation of air is because the memoir was never completed; see ‘Lavoisier's draft memoir of July 1772’, Iris, lx (1969), 381–2. Cf. Morris, R. J., ‘Lavoisier on air and fire: the memoir of July 1772’, Isis, Ix (1969), 374–7.

15 ‘De l'élasticité et de la formation des fluides élastiques’, published by Gough, J. B., in ‘Nouvelle contribution à l'étude de l'évolution des idées de Lavoisier sur la nature de l'air et sur la calcination des métaux’, Arch. Int. Hist. Sci., xxii (1969), 271–5.

16 See Daumas, M., Lavoisier, Théoricien et Expérimentateur (Paris: Presses Universitaires de France, 1955), pp. 3841.

17 ‘De la combinaison de la matière du feu avec les fluides évaporables, et de la formation des fluides élastiques aëriformes’ [1778], Mémoires de l'Académie Royale des Sciences, 1777 (1780), p. 420. The date in brackets refers to the date the paper was first read. The date in parentheses is the publication date for the volume of Mémoires. Thus this paper, presented to the Academy in September 1777, was read in July 1778 (Daumas, , op. cit. [16], pp. 40, 42), and published in 1780 in the Mémoires for 1777.

18 Lavoisier cited Richman, George Wilhelm (17111753), de Mairan, Jean Jacques Dortous (16781771), Cullen, William (17101790), and Bauré, Antoinc (17281804) as having demonstrated evaporative cooling (ibid., p. 424, and footnotes). He had cited Cullen and Baumé in the same context in 1775 (Gough, , op. cit. [15], 271; see Gough's discussion).

19 Mém. Acad. R. Sci. 1777, p. 425. The concept of air as a state had been stated earlier by Turgot (loc. cit. [11]). For a brief discussion of the development of this concept, see Crosland, M. P., ‘The development of the concept of the gaseous state as a third state of matter’, Actes du Xe Congrès International d'Histoire des Sciences; Ithaca, 1962 (1964), pp. 852–53. For the possible influence of Turgot on Lavoisier, see Gough, , op. cit. (15), 269–70. Cf. Morris, , op. cit. (14), 377n.

20 Although a persistent theme since at least 1766, his only published reference to his idea prior to the Mémoires for 1777 was the short passage in the Opuscules quoted above. He may have mentioned the idea in May 1777; see Daumas, , op. cit. (16), p. 38. A memoir in the Oeuvres de Lavoisier (6 vols., Paris, 18621893; v. 271–81) purports to be a slightly modified version of the one read in May 1777. The original was not published.

21 Mém. Acad. R. Sci. 1777, pp. 429–32.

22 ‘Mémoire sur la combustion en général’ [1777], Mém. Acad. R. Sci. 1777, pp. 592600. The chronological difficulties with this paper are similar to the previous one; see n. 17 above. The paper was read in November 1777 and again in December 1779; see Daumas, , op. cit. (16), pp. 40, 44. Although the first reading preceded that of the memoir on the formation of elastic fluids (see n. 17), it was published in the Mémoires following the latter and was clearly written with the latter in mind.

23 Mém. Acad. R. Sci. 1777, p. 595.

25 In the Opuscules (p. 280) he had called the base of air ‘la partie fixe’ but he had used the terminology of the paper on combustion in preceding articles published in the Mémoires for 1777. He referred to the base of aeriform fluids in his ‘Mémoire sur la combustion des chandelles dans l'air atmosphérique et dans l'air éminemment respirable’ (Mém. Acad. R. Sci. 1777, p. 204), in ‘Expériences sur la combinaison de l'alun avec les matières charbonneuses et sur les altérations qui arrivent à l'air dans lequel on fait brûler du pyrophore’ (Mém. Acad. R. Sci. 1777, p. 371), and in his ‘Mémoire sur la vitriolisation des pyrites martiales’ (Mém. Acad. R. Sci. 1777, p. 399n.).

26 Mém. Acad. R. Sci. 1777, pp. 595–8.

27 From early spring of 1777 he was assisted in his experimental work by Laplace, and their collaboration is often cited in subsequent papers; see Guerlac, H., ‘Laplace's collaboration with Lavoisier’, Actes du XIIe Congrès International d'Histoire des Sciences; Paris, 1968, iii B., 3136. In addition to the papers discussed, there are several others which stem from this period and express the same viewpoint. One is the manuscript mentioned in n. 20 above. Two others extend his theory of vapours to show that it is in accord with chemical phenomena of a variety of elastic fluids. The first is ‘De quelques substances qui sont constamment dans l'état de fluides aëriformes au degré de chaleur et de pression habituel de l'atmosphere’. Almost all the experiments cited were performed in February 1776. The paper was submitted to the Academy early in 1776 to be initialled, déposé in 1777 (Daumas, , op. cit. [16], pp. 36–7, 41), and published in Lavoisier, 's posthumous Mémoires de Chimie, i. 348–85. The second is entitled ‘Mémoire sur quelques fluides qu'on peut obtenir dans l'état aériforme à un degré de chaleur peu supérieur à la temperature moyenne de la terre’ [1780], Mém. Acad. R. Sci. 1780 (1784), pp. 334–43.Daumas, (op. cit. [16], p. 45) describes it as ‘la suite naturelle’ of the preceding paper.

28 Fric, op. cit. (5), 152. The date of this manuscript is uncertain although it must have been written before 1781. Its content suggests a close relation with the memoirs of July 1772 and April 1773.

29 ibid., italics mine. Cf. a similar statement in the paper of July 1772, ibid., 142.

30 Experiments and Observations on Animal Heat and the Inflammation of Combustible Bodies, being an Attempt to Resolve these Phaenomena into a General Law of Nature (London, 1779). He published a considerably expanded second edition in 1788, also in London.

31 Crawford acknowledged his indebtedness to these two men. For example, see Animal Heat (1779), pp. 2, 4, 12n., 17n., 49n. Irvine was professor of chemistry at Glasgow; see Kent, Andrew, ‘William Irvine, M.D.’, in An Eighteenth-Century Lectureship in Chemistry, ed. Kent, Andrew (Glasgow: Jackson, 1950), pp. 140–50. Crawford had gone to Scotland in 1776 where he attended Irvine's lectures. His experiments were begun in the summer of 1777 (Animal Heat [1779], p. 18). His theory was communicated to Irvine and others that autumn and explained to the faculty and students in Edinburgh during the 1777–8 session (Animal Heal [1788], p. 4). For a discussion of various aspects of Crawford's ideas ‘see Fox, R., ‘Dalton's caloric theory’, in John Dalton & the Progress of Science, ed. Cardwell, D. S. L. (Manchester: Manchester Univ. Press, 1968), pp. 190–2; Partington, J. R. and McKie, D., ‘Historical studies on the phlogiston theory. III: Light and heat in combustion’, Annals of Science, iii (1938), 346–50; and Mendelsohn, E., Heat and Life: The Development of the Theory of Animal Heat (Cambridge, Mass.: Harvard Univ. Press, 1964), pp. 123–33, and passim.

32 Crawford, (Animal Heat [1779], p. 16) defined capacity as the power of a given substance to collect and retain ‘the element of fire’, and it is determined by the change of temperature produced in the substance by a given quantity of fire compared to the change produced by the same quantity of fire in the temperature of some other substance (water) taken as a standard. He did not use the term ‘specific heat’. This term was introduced by Magellan; see below.

33 ibid., p. 51. Crawford was apparently the first person to determine the heat capacities of airs; see McKie, D. and Heathcote, N. H. de V., The Discovery of Specific and Latent Heats (London, 1935), p. 43, n. 4.

34 Animal Heat (1779), p. 58.

35 ibid., p. 61.

36 ibid., p. 76.

37 ibid., p. 15n.

38 ibid., p. 49n.

39 Magellan played a central role in introducing British ideas of pneumatic chemistry into France in 1771–2 (Guerlac, op. cit. [3], chapter II, passim.) and possibly transmitted to Paris the brief article published in 1772 (cited in n. 3) concerning Black's work on heat (ibid., pp. 68–9).

40 Magellan, J. H., ‘Essai sur la nouvelle théorie du feu élémentaire et de la chaleur des corps’, in Collection de Différens Traités sur des Instrumens d'Astronomie, Physique, etc. (London, 1780); ‘Essai sur la nouvelle théorie du feu élémentaire & de la chaleur des corps’, Observations sur la Physique, xvii (1781), 375–86; and ‘;Suite du mémoire de M. H. Magellan sur le feu élémentaire et la chaleur: Sommaire de l'ouvrage du docteur Crawford’, Observations sur la Physique, xvii (1781), 411–22. An announcement of the publication of Crawford's book and a brief summary of his theory appeared early in 1780; see ‘Extrait d'une lettre de M. Magellan de la Société Royale de Londres sur les montres nouvelles qui n'ont pas besoin d'être montées, sur celles de M. Mudge, & sur l'ouvrage de M. Crawford’, Observations sur la Physique, xvi (1780), 62–3. For a summary of Magellan's account see McKie, and Heathcote, , op. cit. (33), pp. 40–5.

41 Observations sur la Physique, xvii (1781), 375.

42 Observations sur la Physique, xvii (1781), 376. Its appearance in the 1780 edition of Magellan's paper (op. cit. [40], 167) is apparently the first published use of this term; see McKie, and Heathcote, , op. cit. (33), p. 42.

43 Observations sur la Physique, xvii (1781), 381.

44 ibid., 384. This is apparently the first published table of specific heats; see McKie, and Heathcote, , op. cit. (33), p. 43.

45 Deluc, J. A., ‘To the conductors of the Edinburgh Review’, The Edinburgh Review, vi (1805), 511. In fact, Deluc stated that the Academy gave Monge and Vandermonde ‘the special commission to examine and follow that new view [Crawford's].’

46 Daumas, , op. cit. (16), p. 45. The vaporization was produced by heated mercury and the temperature change of the latter was measured.

47 ibid., p. 46.

48 ibid., p. 47. The ‘seconde séance’ of experiments with the calorimeter is dated 27 July; the ‘première séance’ is mentioned but not dated.

49 ibid., p. 48; Lavoisier, and Laplace, , ‘Mémoire sur la chaleur’ [1783], Mém. Acad. R. Sci. 1780 (1784), pp. 355408. Discussions of this paper are common in secondary literature; for example see Wolf, op. cit. (1), i. 183–8.

50 Lavoisier, and Laplace, , op. cit. (49), p. 388. The term latent heat was not used. Magellan had rejected the term on the grounds that, strictly speaking, the effects of heat in this form are sensible not latent (Observations sur la Physique, xvii [1781], 381; cf. 385).

51 ibid., pp. 356, 383–4, 394. In addition to the terminology and explicit references to Crawford and his theory, the citation of Kirwan (‘Kirven’, pp. 385, 387, 390) is further indication of Magellan as their source of information.

52 ibid., pp. 385–9. The calculations of absolute zero are further indications that Lavoisier and Laplace had read Magellan's articles. Although the calculational technique can be derived from Crawford's discussion and although, judging from William Irvine's posthumously published Essays (McKie, and Heathcote, , op. cit. [33], pp. 130–4), Crawford might well have learned the method during his stay in Glasgow, he made no mention of it and only referred in passing to the ‘point of total privation’ of heat (Animal Heat, p. 97n.). Magellan, on the other hand, discussed the theory and as an example calculated the total quantity of heat in ice at its melting point; see Observations sur la Physique, xvii (1781), 383–4. He stated further that he had obtained the method from Kirwan (ibid., 384). For a discussion of the technique of calculation, see McKie, and Heathcote, , op. cit., pp. 130–7.

53 Mém. Acad. R. Sci. 1780, p. 394. Although they described a method to determine the specific heat of airs (pp. 295–6), none were given. Such work was carried out during the winter of 1783–4 but not published until the Mémoires de Chimie.

54 Mém. Acad. R. Sci. 1780, p. 406. The authors cited no experimental data to support this explanation; see Mendelsohn, , op. cit. (31), pp. 150–1.

55 Mém. Acad. R. Sci. 1780, p. 387.

56 Daumas, , op. cit. (16), pp. 45, 46. The account of this work was published in Lavoisier, 's Mémoires de Chimie, i. 246–80, 295311.

57 Mém. Acad. R. Sci. 1780, p. 374.

58 ibid., pp. 391–2. Lavoisier and Laplace continued their experiments with the ice-calorimeter during the late autumn and winter of 1783–4 (Daumas, , op. cit. [16], p. 51), but the results were published much later in the Mémoires de Chimie, i. 121–47.

59 Mémoire sur l'affinité du principe oxygine avec les différentes substances auxquelles il est susceptible de s'unir’ [1785], Mém. Acad. R. Sci. 1782 (1785), pp. 530–40. It was presented in December 1783 and read in 1785; see Daumas, , op. cit. (16), pp. 51, 56.

60 ibid., pp. 531–2. The forces of affinity and atmospheric pressure are opposed by that of heat matter, and the solid, liquid, and aeriform states depend upon whether the latter is weaker, equal to, or stronger than the former.

61 ibid., pp. 534–5.

62 For a general discussion of Lavoisier's ideas on affinity see Daumas, M., ‘Les conceptions de Lavoisier sur les affinités chimique et la constitution de la matière’, Thalès, vi (19491950), 6980. Daumas virtually ignores the role of caloric in this context.

63 ‘Réflexions sur le phlogistique pour servir de développement à la théorie de la combustion & de la calcination publiée en 1777’ [1785], Mém. Acad. R. Sci. 1783 (1786), pp. 505–38; Daumas, , op. cit. (16), p. 58.

64 Mém. Acad. R. Sci. 1783, p. 505.

65 ibid., pp. 509, 517; see below for Lavoisier's ideas on the weight of heat fluid.

66 ibid., p. 506; cf. ‘Sur la combustion’ [1777], Mém. Acad. R. Sci. 1777, pp. 595–6 for a similar argument (see above).

67 Mém. Acad. R. Sci. 1783, pp. 509–10.

68 ibid., p. 519. Wilcke, Johan Karl (17321796). Wilcke's work on specific heat was published in the memoirs of the Swedish Academy for 1781; see McKie, and Heathcote, , op. cit. (33), pp. 95108. Lavoisier and Laplace had referred to this paper in the joint memoir stating they had seen it after reading their own in June 1783 (Mém. Acad. R. Sci. 1780, p. 373n.). Wilcke mentioned Black, Crawford, and Kirwan, deriving his information from Magellan (McKie, and Heathcote, , op. cit., p. 108).

69 The Traité de Chimie (i. 13) opens with a similar statement which is repeated in the Mémoires de Chimie (i. 34).

70 Mém. Acad. R. Sci. 1783, p. 524. In his Mémoires de Chimie (i. 5) he identified the force as universal gravitation.

71 Indeed, heat capacity was the term most generally used.

72 Mém. Acad. R. Sci. 1783, pp. 527–8.

73 ibid., pp. 529–30.

74 ibid., pp. 532–3.

75 This was mentioned in the joint memoir on heat (Mém. Acad. R. Sci. 1780, p. 401) and repeated in his ‘Mémoire sur la formation de l'acide nommé air fixe ou acide crayeux’, Mém. Acad. R. Sci. 1781, p. 454, where he stated that the change in volume is proportional to the change in density. According to modern theory, the volume should not change.

76 Mém. Acad. R. Sci. 1783, pp. 530–2. His knowledge of the relative specific heats of the two airs probably came from Crawford. Apparently Lavoisier and Laplace only determined the specific heats of vital and atmospheric air (see n. 83).

77 ibid., pp. 535–6.

78 ibid., p. 536. Lavoisier added (p. 537) that the ideas relating absorption and release of heat to volumetric changes ‘ne me sont point propres. Mrs. Vandermonde & Monge ont avancé la même chose dans un Mémoire lü à l'Académie.’ I have not been able to locate this paper. Lavoisier stated that Monge, among others, considered all mixtures and combinations in which there is a release of the matter of heat as species of combustion, and the example given was the mixing of water with various substances causing a reduction in volume accompanied by a release of heat. Lavoisier again referred to the ideas of Monge and Vandermonde in his Mémoires de Chimie (i. 8). In discussing his idea that the capacity of a substance to contain heat fluid depends upon the internal pore-space within the substance, Lavoisier stated that the consequence ‘qui se trouve confirmée par les expériences de MM. Wilk [sic], Vandermonde, Monge, de la Place, et par les miennes, ne me paroit pas moins exacte; c'est que si on rapproche, par une force égale quelconque, les molécules de plusieurs corps, la quantité de calorique qui en sortira, sera différente.’ An incomplete manuscript by Monge describing a theory of heat has been published by Taton, R., ‘A propos de l'oeuvre de Monge en physique’, Rev. Hist. Sci., iii (1950), 177–9. It was purportedly written around 1783 (ibid., 177) although use of the term ‘calorique’ suggests a later date. It expresses the same ideas and uses the same terminology as the first part of a 1790 paper published in the second volume (1816) of the Dictionnaire de Physique [Encyclopédie Méthodique] (4 vols., Paris, 17931822), pp. 170–1; discussed in Taton, R., L'Oeuvre Scientifique de Monge (Paris: Presses Universitaires de France, 1951), pp. 323–5. In it Monge explained heat phenomena entirely in terms of forces: the mutual attraction among the particles of a substance, the attraction between these particles and caloric, and external pressure. Any change in the first of these which causes the particles of a substance to come closer together will result in the extrusion of some of the interposed caloric (Dictionnaire, ii. 171–2). The origin of these ideas is not known; see n. 45 above, for Monge's possible knowledge of Crawford's theory.

79 Mém. Acad. R. Sci. 1783, pp. 537–8. In 1773 in Rozier's journal, he had published an account of temperature changes accompanying the crystallization and solution of salts (‘Observations lues par M. Lavoisier à l'Académie Royale des Sciences sur quelques circonstances de la crystallisation des sels’, Observations sur la Physique, i [1773], 1013) probably based on experiments performed late in 1771 (Daumas, , op. cit. [16], p. 27). There is no indication in this article nor in his reference to the phenomena in the manuscript memoir of July 1772 (Fric, op. cit. [5], 141–2) that he considered the solution of salt to be simply a change of state like fusion.

80 Mém. Acad. R. Sci. 1783, pp. 527, 528.

81 ibid., p. 536.

82 See the discussion above.

83 Although not published until the Mémoires de Chimie (i. 136–7), in February 1784 (Daumas, , op. cit. [16], p. 51) a value of 0.65 was determined for the specific heat of vital air, a figure considerably less than the value Crawford had given and which Lavoisier had tentatively accepted in 1783.

84 Mém. Acad. R. Sci. 1783, p. 535; note that the heat in vital air is free heat (specific heat) and combined heat.

85 Traité, i. 57. The discussion of heat is unchanged in the second edition (2 vols., Paris, 1793) and in the third (2 vols., Paris, an IX [1801]).

86 Mém. Acad. R. Sci. 1783, pp. 524–5. This can be deduced from the role of air pressure discussed in the 1778 paper on the formation of elastic fluids (Mém. Acad. R. Sci. 1777, pp. 425, 429).

87 Traité, i. 8; cf. the somewhat stronger statement in the Mémoires de Chimie (i. 296–7): ‘Il ne faut point perdre de vue que l'état de liquide n'est, en quelque façon, qu'un état précaire qui est soumis à toutes les variations de pesanteur de l'atmosphère, et qui n'existeroit pas sans cette pesanteur.’

88 Traité, ii. 534. Cf. the statement by Guyton de Morveau: ‘Le feu est exactement aux métaux ce que l'eau est aux sels; la fusion est une dissolution; le refroidissement n'est autre chose qu'une évaporation d'une portion de la matière ignée’ (‘Lettre de M. de Morveau à l'auteur de ce recueil sur les crystallisations métalliques’, Observations sur la Physique, xiii [1779], 90). Lavoisier consistently referred to the action of the matter of fire as a dissolution process; and it is clear that he considered dissolution in caloric and combination with caloric to be equivalent (for example, see Mémoires it Chimie, i. 322). The novelty of the concept of fire as a dissolvent is suggested by the debate during the 1770s over whether crystals formed upon the solidification of molten metals are true crystals or whether that true crystals come only from aqueous solutions; Smith, C. S., ‘The development of ideas on the structure of metals’, Critical Problems in the History of Science, ed. Clagett, M. (Madison: Univ. of Wisconsin Press, 1959), p. 488.

89 Traité ii. 422–8, 432–3, 437–9.

90 Mém. Acad. R. Sci. 1780, pp. 399400.

91 In 1787 he had indicated that the combustion of inflammable gas evolves more heat than the combustion of phosphorus (Nomenclature Chimique, pp. 294–7).

92 Traité i. 103–15. Similar calculations are given in the joint memoir on heat; however, their purpose was to give a quantitative demonstration of the general principle that when the product of combustion is a solid, more heat is released than when the product is a gas (Mém. Acad. R. Sci. 1780, pp. 398–9). Lavoisier returned to this subject in his Memoires de Chimie (i. 137–41) where he repeated many of his earlier computations. In discussing the presence of caloric combined in solids, he admitted that oxygen in uniting even with phosphorus may not give up all its caloric; hence caloric is probably combined in phosphoric acid and perhaps even in carbon.

93 Madame Lavoisier, in the brief introduction, said that work on this was begun in 1792 (i. p. iii). In one of the memoirs Lavoisier stated that he was writing in 1793 (i. 122). Although the date of publication is usually given as 1805, Partington has shown that the book was distributed in or before 1803 (op. cit. [1], iii. 372). For a discussion of the facts of publication and a résumé of the articles, see Duveen, D. I. and Klickstein, H. S., A Bibliography of the Works of Antoine Laurent Lavoisier, 1743–1794 (London: Dawson, 1954), pp. 199214, and Duveen, D. I., Supplement to a Bibliography of the Works of Antoine Laurent Lavoisier, 1743–1794 (London: Dawson, 1965), pp. 113–14. W. A. Smeaton in his review of the Duveen and Klickstein Bibliography argues that Lavoisier intended the title to be Mémoires de Physique et de Chimie; see The Library, xi (1956), 133.

94 Mémoires de Chimie, i. p. iii.

95 The volume (‘Part I’ of the Mémoires) is entitled ‘Vues générales sur le calorique, ou principe de la chaleur, sur ses effets, sur leur mesure, et sur la formation des liquides et des fluides’ (ibid., p. 1). Part I is incomplete, ending on p. 416 in mid-sentence. However, considering the length of the volume and the development of ideas, it is likely that the missing part is comparatively insignificant. The second volume (‘Part II’ of the Mémoires) is entitled ‘De la décomposition de l'air de l'atmosphère …’ (ibid., ii. 1). The purpose of the first few papers is the same as Chapter III of the Traité to demonstrate that atmospheric air is not a simple substance but a mixture. Indeed, the opening sentences of the first paper in Part II indicates the purpose of Part I. ‘Je n'ai présenté jusqu'ici [that is, in Part I] que des considérations générales sur la formation des fluides élastiques aëriformes; j'ai cherché à établir qu'ils sont tous formés de la solution d'une substance quelconque, dans le calorique et la lumiére. Il est résulté des principes que j'ai posés, que notre atmosphère devoit être un mélange, un composé de toutes les substances susceptibles d'être tenues dans l'état aëriforme aux degrés de chaleur et de pression que nous éprouvons’ (ibid., ii. 1–2).

96 The increased length is due to the inclusion of four papers by an associate Armand Seguin (which comprise over a fourth of the entire volume) and of papers by Lavoisier, the contents of most of which had been only summarized or alluded to in his earlier works.

97 Mém. Acad. R. Sci. 1783, p. 526; Mém. Acad. R. Sci. 1780, pp. 399400.

98 A major part of the manuscript of 1775 is devoted to a discussion of the different degrees of affinity that fire has for substances with which it is combined in forming the vaporous state; see Gough, , op. cit. (15), 272–5.

99 In the 1785 essay on phlogiston, he had indicated that, strictly speaking, heat can never be absolutely free because of the mutual adherence between it and the particles of other substances (Mém. Acad. R. Sci. 1783, pp. 526–7).

100 Mémoires de Chimie, i. 14.

101 ibid., i. 137.

102 ibid., i. 286–8.

103 The same inconsistency occurs in Lavoisier's use of the term ‘dissolution’. The dissolution of metals in acids is different from the dissolution of salts in water. In the former, the elementary constituents of both metal and acid are affected, whereas in the latter the individual particles of the salt are separated without affecting their original identity. In the Traité de Chimie (ii. 423–4), Lavoisier attempted to distinguish these two kinds of reactions by restricting the term ‘dissolution’ to apply to the former and using the term ‘solution’ for the latter. Unfortunately this distinction was not rigidly maintained either in the Traité or in his other works. Robert Kerr in his translation was more precise in his use of the terminology than was Lavoisier in the original: Elements of Chemistry in a New Systematic Order Containing All the Modern Discoveries (Edinburgh, 1790). Compare Kerr's translation (pp. 368–72, 375, 380) with the corresponding sections in the Traité (ii. 423–8, 432, 438).

104 Traité ii. 422–3.

105 Duveen, and Klickstein, , op. cit. (93), p. 201, describe it as a ‘monograph on physics’.

106 Mémoires de Chimie, i. 246–80, 295311.

107 Mém. Acad. R. Sci. 1780, p. 374. In the opening paragraph of the memoir on the expansion of liquids, Lavoisier stated ‘il sembleroit done qu'il existe une sorte de relation entre l'augmentation de capacité de chaleur qui a lieu dans les changemens d'état, et l'augmentation de dilatabilité’ (Mémoires de Chimie, i. 295).

108 Mém. Acad. R. Sci. 1780, p. 391.

109 Mémoires de Chimie, i. 281. Seguin denied there is a direct relationship between heat capacity and expansion (Annales de Chimie, iii [1789], 154n.) and in 1790 claimed that he had discussed the matter several times with Lavoisier and had persuaded him to abandon the view that there is a correlation between the two effects; see ‘Résponse de M. Seguin à la lettre de M. de Luc insérée dans le Journal de Physique du mois de mars 1790’, Observations sur la Physique, xxxvi (1790), 420. However, influence of the idea is seen in the opening lines of the paper on the expansion of fluids (n. 107 above).

110 See Morris, , op. cit. (14), 377–9; cf. Guerlac, , op. cit. (14), 380–2.

111 Partington, (op. cit. [1], iii. 131) described Lavoisier's concept of air as a state as ‘an extension of Black's theory of latent heat’. See similar statements in McKie's introduction to Lavoisier, 's Elements of Chemistry (op. cit. [103], pp. xxiii, xxviii) and in Duveen, and Klickstein, , op. cit. (93), pp. 52, 54.

112 Black explained changes of state in terms of combined fire in his Lectures on the Elements of Chemistry, ed. Robison, J. (2 vols., Edinburgh. 1809), i. 49, 129, 157, 176, 192–5. Although there is some doubt as to whose ideas are stated in Black's Lectures, a statement of this particular version of Black's views appeared in the second edition of the Encyclopaedia Britannica (10 vols., Edinburgh, 17781783; ‘Congelation’, iii [1778], 2189; ‘Evaporation’, iv [1779], 2847, 2848; ‘Heat’, v [1780], 3539). However, the article of 1772 (loc. cit. [3]) states only that heat is absorbed and becomes hidden during changes of state. The same idea is contained in Cochrane, Thomas, Notes from Doctor Black's Lectures on Chemistry, 1767/8, ed. McKie, D. (Cheshire: Imperial Chemical Industries Ltd., 1966), pp. 12, 13, 15, and in the anonymous account of Black's ideas published in 1770: An Enquiry into the General Effects of Heat, with Observations on the Theories of Mixture (London), pp. 40, 48.

113 Lavoisier was not alone in explaining changes of state in terms of the combination of fire matter. In 1772 Wilcke published his theory of the latent heat of fusion; see McKie, and Heathcote, , op. cit. (33), pp. 7894. Wilcke and Black seem to have arrived at the concept of latent heat by consideration of times and quantities of heat required to melt ice and snow (ibid., pp. 16, 78). A conclusion similar to Lavoisier's and based on the same kinds of evidence that Lavoisier used was published in 1772 in Deluc, Recherches sur les Modifications de l'Atmosphere (2 vols., Geneva). Deluc cited evaporative cooling and the condensation of water vapour on a cold surface to demonstrate that vaporization is caused by a combination of the matter of fire with water (ibid., i. 178, 180, 182–3, 264–5; ii. 175).

114 See a discussion of this point in Morris, , op. cit. (14), 378–9; cf. Guerlac, , op. cit. (14), pp. 380–1.

115 Cited in n. 2 above.

116 Fric, op. cit. (5), 142.

117 ibid., 152.

118 The major point on which Lavoisier and Crawford disagreed was on whether fire is combined or not.

119 Or Monge's interpretation?

120 Mém. Acad. R. Sci. 1777, p. 420.

121 Mém. Acad. R. Sci. 1780, p. 358.

122 See for example his discussion of heat combined in various substances (ibid., pp. 394, 399–400). If Lavoisier wavered in his view, he did so only in the first half of this memoir.

123 ‘Sur le phlogistique’ [1785], Mém. Acad. R. Sci. 1783, p. 524.

124 Trailé, i. 6.

125 Mémoires de Chimie, i. 2.

126 Venel, , ‘Feu (Chimie)’, Encyclopédie, vi. 609; Macquer, , Elémens de Chymie-théorique (new edn., Paris, 1753), p. 16. For a discussion of Rouelle and his significance in this connexion, see Rappaport, R., ‘Rouelle and Stahl: the phlogistic revolution in France,’ Chymia, vii (1961), 76–7, 85–6.

127 Indeed, Joseph Black attributed the qualities of softness, ductility, and malleability to latent heat (Lectures, i. 138–40).

128 For example, the idea of opposing forces was stated by Boerhaave, (A New Method of Chemistry, trans. Shaw, P. [3rd edn., 2 vols., London, 1753], i. 246–7) and Turgot (op. cit. [11], p. 282). The latter (p. 277) described changes of state as nuances of the general expansive action of heat.

129 Mémoires de Chimie, i. 404–11. These fluids differ from gases in that they have varying abilities to penetrate the pores of different substances such as glass and metals. Caloric is more subtle than the electric and magnetic fluids.

130 Traité, ii. 526–7.

131 ‘Sur le phlogistique’ [1785], Mém. Acad. R. Sci. 1783, p. 509. As Seguin remarked, ‘notre idée se refuse à l'existence d'un corps dont la pesanteur est absolument nulle’ (Annales de Chimie, iii [1789], 185; cf. a similar statement by him in Lavoisier, 's Mémoires de Chimie, i. 158–9, note).

132 Mémoires de Chimie, i. 408. Cf. similar statements in ‘Mémoire dans lequel on a pour objet de prouver que l'eau n'est point une substance simple, un élément proprement dit, mais qu'elle est susceptible de décomposition & de récomposition, Mém. Acad. R. Sci. 1781, p. 473; ‘Nouvelles réflexions sur l'augmentation de poids qu'acquièrent en brûlant le soufre & le phosphore, & sur la cause à laquelle on doit l'attribuer’, Mém. Acad. R. Sci. 1783, pp. 419–21; ‘Sur la pesanteur de la matière de la chaleur’, Oeuvres, v. 293.

133 Macquer had remarked that without heat all matter would be ‘une seule masse immense, homogene, & d'une dureté absolue’ (Dictionnaire de Chymie [2 vols., Paris, 1766], i. 498).

134 Traité, i. 24–7. Regarding repulsion as being in reality an effect of attraction, see Seguin's views in Lavoisier, 's Mémoires de Chimie, i. 158–9, note.

135 Mémoires de Chimie, i. 67, 1925.

136 For example see Boerhaave, , Method of Chemistry, i. 359–64; and Macquer, , Dictionnaire (1766), i. 498; ii. 203. This feature gave Lavoisier's predecessors greater-latitude in accounting for heat phenomena, for temperature could be related to either the quantity of fire matter or the degree of its own internal motion.

137 Fric, op. cit. (5), 142.

138 The motion feature was absent in most material theories of heat discussed during the last quarter of the century. This resulted in a weakness in the explanations of mechanical production of heat, a weakness not present in the earlier material heat theories and one which Count Rumford exploited in his unsuccessful attempt to revive a vibratory theory in 1798. Most writers simply ignored the question of the motion of fire matter. The few who argued against it did so on the grounds that fire, being matter, should not possess a property which is not characteristic of matter in general; see ‘Fire’, Encyclopaedia Britannica (2nd edn.), iv (1779), 3003; and Pierre, Jean Baptistede Monet, Antoinede Lamarck, , Recherches sur les Causes des Principaux Faits Physiques … (2 vols., Paris, an II [1794]), i. 51, 66–7.

139 ‘Sur la combustion’ [1777], Mém,. Acad. R. Sci. 1777, p. 598.

140 According to Macquer (Elémens de Chymie-théorique [1753], P. 16), fire can be fixed only in the form of phlogiston which does not change the state of either solids or fluids; see also n. 128.

141 Fric, op. cit. (5), 149–50. Cf. the same argument in the Opuscules, p. 280.

142 The first volume of Mémoires de Chimie comes closest to conforming to this description and these papers together contain a discussion of virtually all Lavoisier had to say on the subject. Yet in spite of the breadth indicated by the titles of the various memoirs, the treatment in many is very restricted.

143 The association was also chemical. Lavoisier's treatment of the heat phenomena of chemical reactions most commonly occurs in a context discussing the reactions of oxygen gas. In part as a result of this, he gives the impression that he believed caloric and oxygen to have a unique relationship which is maintained even when both are combined with other components. In this context, caloric is never treated as simply one of several chemical constituents united in a given compound. Caloric in these compounds is that retained by oxygen when the latter combines, and it is by virtue of its prior union with oxygen that caloric is carried over and becomes a constituent in other combinations: vital air ‘retient plus ou moins de calorique, suivant la nature des substances avec lesquelles il se combine’ (Mémoires de Chimie, i. 140).

144 Quoted in Eyles, V. A., ‘The evolution of a chemist, Sir James Hall, Bt. F.R.S., P.R.S.E., of Dunglass, Haddingtonshire (1761–1832), and his relations with Joseph Black, Antoine Lavoisier, and other scientists of the period’, Annals of Science, xix (1963), 167, 169–70.

145 ‘Sur la combustion des chandelles’, Mém. Acad. R. Sci. 1777, P. 204; cf. a similar statement, ibid., p. 399 n.

146 ‘Introduction et plan d'un deuxiéme volume des Opuscules Physiques et Chimiques’, Oeuvres, v. 268.

147 Nomenclature Chimique, pp. 292–7.

148 Kirwan, Richard, An Essay on Phlogiston and the Constitution of Acids [1784] … To which are added Notes Exhibiting and Defending the Antiphlogistic Theory and Annexed to the French Edition of this Work [1788] … With Additional Remarks by the Author, trans. Nicholson, W. (London, 1789 [London: Cass, 1968]), pp. 1122; cf. similar arguments by Lavoisier, , pp. 4552.

Lavoisier and the Caloric Theory

  • Robert J. Morris


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