¹ The school inspired by Lakatos' ideas has, with Clark, P., Atomism versus thermodynamics, in Howson, C. (ed.) Method and Appraisal in the Physical Sciences, Cambridge, 1976, pp. 41–105CrossRefGoogle Scholar, made Brownian motion the corner-stone of its own rational reconstruction of the victory of atomism. According to this the ‘kinetic programme’ only became ‘progressive’ with Einstein's theory.

² See, as an example, Gliozzi, M., Storia delle fisica, in Abbagnano, N. (ed.) Storia delle scienze, 4 vols, Torino, 1962, ii, p. 366.Google Scholar

³ See Kerker, M., ‘Brownian Movement and Molecular Reality prior to 1900’, Journal of Chemical Education, (1974), 51, pp. 764–768.CrossRefGoogle Scholar

⁴ Brown, R., ‘A Brief Account of Microscopical Observations made in the Months of June, July, August 1827, on the Particles contained in the Pollen of Plants; and on the General Existence of Active Molecules in Organic and Inorganic Bodies’, The Philosophical Magazine, (1828), 4, pp. 161–173CrossRefGoogle Scholar. On this subject see Goodman, D.C., ‘The Discovery of Brownian Motion’, Episteme, (1972), 6, pp. 12–29Google Scholar; Powles, J.G., ‘Brownian Motion, June, 1827’, Physical Education, (1978), 13, pp. 310–312.CrossRefGoogle Scholar

⁵ On these aspects see Nye, M.J., Molecular reality. A perspective on the scientific work of Jean Perrin, London & New York, 1972, especially pp. 9–13.Google Scholar

⁶ Inductivist histories underestimate this fundamental aspect of nineteenth-century research and speak of a completely false unanimity of opinion. For example Gliozzi says: ‘The most careful observers of the phenomenon (Brown himself, Gouy, Cantoni, Exner, Wiener) ascertained that the movement of each particle is absolutely independent of the neighbouring particles, that it is truly infinite and that it takes place in the same way whatever the precautions taken to ensure the mechanical and thermal equilibrium of the liquid in suspension. They also confirmed that the nature or intensity of the light used to observe the phenomenon has no effect on the movement of the particles, that the nature of the particles in suspension does not influence the phenomenon: only their mass does so, the motion of the smaller particles proving to be faster’ (Gliozzi, , op. cit. (2), p. 366Google Scholar). Also Nye describes the empirical research before Einstein in a form too clean and too clear-cut: in her opinion it was Gouy who established the theory's empirical bases, having with his research ‘definitively established’ and ‘demonstrated’ the main characteristics of Brown's phenomenon (Nye, , op. cit. (5), p. 28).Google Scholar

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⁹ Perrin, J., Les atomes, Paris, 1913, p. 172.Google Scholar

¹⁰ Jevons; Henri, V., ‘Influence du milieu sur les mouvements browniens’, Comptes Rendus, (1908), 147, pp. 62–65.Google Scholar

¹¹ Maltézos, see Appendix; Spring, see Appendix; Gouy, , ‘Le mouvement…’, see Appendix.Google Scholar

¹² Muncke, see Appendix; Cantoni, see Appendix.

¹³ Jevons, , ‘On the movements…’Google Scholar, see Appendix; Gouy, , ‘Le mouvement…’Google Scholar, see Appendix; for Carbonnelle see Thirion, , see Appendix, p. 53.Google Scholar

¹⁴ Cantoni, see Appendix.

¹⁵ Quincke, see Appendix; Gouy, , ‘Le mouvement…’Google Scholar, see Appendix; S. Exner, see Appendix.

¹⁶ For Carbonnelle see Thirion, , see Appendix, p. 53Google Scholar; Maltézos, see Appendix; Ehrenhaft, F., ‘Ueber eine der Brown'schen Molekularbewegung in den Flüssigkeiten…’, Sitzungsberichte der Mathematisch-Naturwissenschaftlichen Klasse der Kaiserlichen Akademie der Wissenschaften, (1907), 116, pp. 1139–1149Google Scholar, for Zsigmondy and Svedberg see below.

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¹⁹ Ibid., p. 30.

²⁰ Gouy, , ‘Note …’, see Appendix, p. 563.Google Scholar

²¹ For an account of nineteenth-century theories of Brownian motion see Nye, , op. cit. (5), especially pp. 9–13Google Scholar; Kerker, , op. cit. (3)Google Scholar; Brush, S.G., The Kind of Motion we call Heat; a History of the Kinetic Theory of Gases in the 19th Century, 2 vols, Amsterdam, Oxford and New York, 1976, chapter 15.Google Scholar

²² Maltézos, see Appendix.

²³ Nägeli, see Appendix.

²⁴ Gouy, , ‘Note …’, see Appendix, p. 563Google Scholar; Ramsay, , ‘Pedetic …’, see Appendix.Google Scholar

²⁵ F. Exner, see Appendix.

²⁶ Clark, , op. cit. (1), p. 96.Google Scholar

²⁷ Kerker, , op. cit. (3), p. 768.Google Scholar

²⁸ Exner, F., see Appendix, p. 846.Google Scholar

²⁹ Ibid., p. 549.

³⁰ Einstein, A., ‘Ueber die von der molekularkinetischen Theorie der Wärme Bewegungen von in ruhenden Flüssigkeiten suspendierten Teilchen’, Annalen der Physik, (1905), 17, pp. 549–560.CrossRefGoogle Scholar

³¹ Ibid., p. 549.

³² As is well known the law states that a spherically shaped body of radius P which moves with a velocity V in a fluid with a coefficient of viscosity μ experiences a braking force equal to 6πμP V.

³³ Smoluchowski, M., ‘Essai d'une thérorie cinétique du mouvement brownien et des milieux troubles’, Krakau Anzeiger, (1906), 7, pp. 577–602.Google Scholar

³⁴ Ibid., pp. 585–586.

³⁵ Svedberg, T., ‘Studien zur Lehre von den kolloiden Lösungen’, Nova Acta Regiae Societatis Scientiarum Uppsala, (1907), 2, pp. 1–160.Google Scholar

³⁶ The only mention of a numerical verification, contained in the article, is a brief one regarding the calculation of λ_x in one second for a spherical particle of 0·001 mm in diameter in water at 17°C, which gives a value of 0·8 μ. Einstein does not give any empirical value with which to compare this result. It is noticeable that F. Exner (see Appendix), for an analogous case, had measured a velocity of 3–2 μ a second, a value four times greater than that calculated by Einstein if we assume that Exner's values can be used as terms of comparison for λ_x.

³⁷ Einstein, , op. cit. (30), p. 560.Google Scholar

³⁸ This work was published the following year: Einstein, A., ‘Eine neue Bestimmung der Moleküldimensionen’, Annalen der Physik, (1906), 19, pp. 289–306.CrossRefGoogle Scholar

³⁹ Ibid., p. 305.

⁴⁰ It is to be stressed, however, that for Einstein there was no substantial difference between molecules in solution (sugar) and spherical particles of any substance whatsoever: ‘According to the kinetic-molecular conception there is no essential difference between a dissolved molecule and a suspended particle. We will therefore consider the equation [for λ_x] valid for all cases involving spherical suspended particles of any type’ (Einstein, A., ‘Elementare Theorie der Brownschen Bewegung’, Zeitschrift für Elektrochcmie (1908), quoted from Fürth, R. (ed.) Investigations on the Theory of the Brownian Movement, New York, 1973, p. 82).Google Scholar

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⁴³ Ibid., p. 371.

⁴⁴ Idem.

⁴⁵ Idem.

⁴⁶ Smoluchowski, , op. cit. (33), p. 597 ff.Google Scholar

⁴⁷ Ibid., p. 591.

⁴⁸ Ibid., p. 597.

⁴⁹ Kerker, , op. cit. (3), is essential on Svedberg's experiments regarding Brownian motion.Google Scholar

⁵⁰ Nobel Lectures, including Presentation Speeches and Laureates's Biographies, Chemistry,1 922–1941, Amsterdam, London and New York, 1966, pp. 63.Google Scholar

⁵¹ Nobel Lectures, including Presentation Speeches and Laureates's Biographies, Physics, 1922–1941, Amsterdam, London and New York, 1965, p. 136.Google Scholar

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⁵⁴ Zsigmondy, , see Appendix, p. 134 of English translation.Google Scholar

⁵⁵ Ramsay, see Appendix.

⁵⁶ Svedberg, , op. cit. (53), p. 859.Google Scholar

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⁵⁸ Ibid., p. 910.

⁵⁹ Idem.

⁶⁰ Svedberg, T., ‘Einige Bemerkungen über die Brownsche Bewegung’, Zeitschrift für Physiklalische Chemie (1910), 71, pp. 571–576Google Scholar; also Die Existenz der Moleküle, Leipzig, 1912Google Scholar; also ‘Neurere Untersuchungen über die Brownsche Bewegung’, Jahrbuch der Radioaktivität und Elektronik, (1913), 10, pp. 467–515.Google Scholar

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⁶² Langevin, P., ‘Sur la théorie du mouvement brownien’, Comptes Rendus, (1908), 146, p. 533.Google Scholar

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⁶⁷ Kerker, , op. cit. (3), p. 207Google Scholar. Kerker attributes a similar opinion even to Cotton, A., ‘Recherches récentes sur les mouvements browniens’, Revue du Mois, (1908), 5, pp. 737–741Google Scholar, but Seddig is not even cited in Cotton's work.

⁶⁸ Seddig, see Appendix.

⁶⁹ Ibid., p. 365 (italics mine).

⁷⁰ Ibid., pp. 365–366 (Seddig's italics).

⁷¹ Seddig, of course, realized this experimental imperfection thanks to the theory: when he found data in disagreement with Einstein's formula he looked for the flaws in the experimental procedure. The formula thus provided him with indications regarding the correctness or not of experimental procedure.

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⁸⁰ Henri, V., ‘Etude cinématographique des mouvements browniens’, Comptes Rendus, (1908), 146, pp. 1024–1026.Google Scholar

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⁸⁶ The slowing down measured by Henri is quite considerable: the addition of 1/32 of HCI to neutral water caused a slowing down of Brownian motion by a factor of about nine times!

⁸⁷ Duclaux, J., ‘Pression osmotique et mouvement brownien’, Comptes Rendus, (1908), 147, pp. 131–134.Google Scholar

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⁹⁴ Perrin, , op. cit. (18), p. 69.Google Scholar

⁹⁵ Perrin's measures raised the problem of reconsidering Stokes' law in the light of the kinetic theory of the gases. Various authors dealt with the topic: Cunningham, Zerner, McKeehan, Arnold, etc. A detailed analysis of the modifications of Stokes' law on the basis of the kinetic theory of gases can be found in Weyssenhoff, J., ‘Betrachtungen über de Gültigkeitsbereich der Stokes-Cunninghamschen Formel. I Hydrodynamischer Teil’, Annalen der Physik, (1920), 62, pp. 1–45CrossRefGoogle Scholar. Duclaux was never convinced by Perrin's ‘reply’ and continued to criticize the use of Stokes' law; see Duclaux, J., Mouvement brownien. I: Partie expérimentale, Paris, 1937, especially pp. 17–18.Google Scholar

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⁹⁹ Perrin, , op. cit. (9), pp. 119–120.Google Scholar

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¹⁰¹ Chaudesaigues, M., ‘Le mouvement brownien et la formule d'Einstein’, Comptes Rendus, (1908), 147, pp. 1044–1046.Google Scholar

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¹⁰⁴ Perrin, , op. cit. (18), p. 76.Google Scholar

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