Subatomic Speculations and the Origin of Structure Theory

REFERENCES

• By "theory of chemical structure" or "structure theory" I mean the application of valency rules in the schematic construction of molecules from constituent atoms, and especially the exploration of the consequences of the tetravalency and self-linking of carbon atoms. Structure theory, then, is dependent upon the prior development of valency theory, but extends further. For back-ground, see C. A. Russell's excellent History of Valency, Leicester University Press, 1971, and my PhD dissertation, "Origins of the Structural Theory in Organic Chemistry", University of Wisconsin, 1975.
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• The standard and influential (but partisan) biography is Richard Anschütz, August Kehuld, 2 vols, Berlin, 1929, hereafter cited simply "Anschiitz". A perceptive analysis of competing claims is provided by Russell (I), pp. 108–34; for a refutation of the common view that A. M. Butlerov originated or co-originated structure theory, see my "Kekule, Butlerov, and the Historiography of the Theory of Chemical Structure", Brit. J. Hist. Sci., 14 (1981), 27–57.
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• Kekulé, "Ueber die Constitution und die Metamorphosen der chemischen Verbindungen und iiber die chemische Natur des Kohlenstoffs", Ann. Chem., 106 (1858), 529–59; rpt. in Anschütz, 2, 97–119 (102). He later emphasized in a letter to Wurtz that he meant only that the further development of his views was made possible by Wurtz's work (15 February 1859, printed in Anschiitz, 1, 147).
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• Anschütz, 2, 945.
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• For details see M. Crosland and J. Brooke, "Charles Gerhardt", Diet. Sci. Biog., 5 (1972), 369–75; H. Kopp, Entzoicklung der Chemie in der neueren Zeit, Munich, 1873, pp. 707–839 passim; and E. Grimaux, Charles Gerhardt, Paris, two, passim.
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• In elementary molecules, of course, monads as well as dyads appear in pairs. Laurent, "Recherches sur les combinaisons azotées", Ann. chins. phys., [3], 18 (1846), 266–98, (267–8, 294–5); idem, Méthode de chinzie, Paris, 1854, pp. 57–8, 77, 82–7; Chemical Method, London, 1855, pp. 46–7, 62, 66–70. In modern terminology, the rule states that the number of atoms of odd valency in a molecule must always be even. The reason for the rule is simple: since each chemical bond engages two valencies, the total number of valencies of all the atoms in a stable molecule must be even, hence atoms with odd valencies cannot be present in odd numbers. It is puzzling why this rule, which constitutes an important empirical step towards valency theory, has been largely ignored by historians of chemistry.
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• Laurent, Mdthode (6), p. 125; Method (6), p. tot.
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• Méthode (6), p. 527; Method (6), p. 103. Laurent's atomic weight for iron was 28, half the modern value, hence his Fe2 is identical to modern Fe. Each subatom would thus weigh 28/12 = 2.33.
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• Laurent's symbol for ferricum was actually Fey; I have written it fe to conform with later usage.
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• Laurent to Berzelius, 1 January 1844, in H. G. Söderbaum, ed., Berzelius Beef, Uppsala, 1912–61, 3, ii, 199–200. I have somewhat altered the original notation for the sake of clarity. Indeed, Söderbaum committed an obvious error in transcribing what must have appeared in the original as "0.4mn6" as "0.4; that is, instead of Laurent's four mn° combined with oxygen, S6derbaumhas four-tenths mn6! Note that Laurent was then still using Berzelian atomic weights. He did not begin to advocate Gerhardt's reformed weights until later that year. For a discussion of Laurent's letter see J. H. Brooke, "Chlorine Substitution and the Future of Organic Chemistry", Studies in the History and Philosophy of Science, 4 (1973), 47–94 (60–4); Laurent elaborated on these speculations in his article, "Sur la série naphthalique", Revue scientifique, 14 (1843), 74–113, pp. 102–3.
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• Laurent, Méthode (6), pp. 128–32; Method (6), pp. 103–7; Gerhardt, Traité de chimie organique, 4 vols, Paris, 1853–56, 4, 602–4, 712.
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• The papers referred to are too well known to require explicit citation here: see Russell, History (t), pp. 44–57; W. H. Brock, "A. W. Williamson", Diet. Sci. Biog., 14 (1976), 394–6; and J. R. Partington, History of Chemistry, 4 vols, London, 1961–70, 4, 448–535 passim.
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• Wurtz, "Sur une nouvelle classe de radicaux organiques", Ann. chim. phys., [3], 44 (1855), 275–313 (300). For development of this point, see Rocke, "Origins" (s), pp. 225–6 and passim; for a general discussion of Wurtz's relation to atomism, see A. Yoshida, "Charles Adolphe Wurtz et la theorie atomique", Jap. Stud. Hist. Sci., 16 (1977), 129–35.
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• Wurtz, op cit. (12), pp. 306–7n.
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• Wurtz, Lecons de chimie professées en 1863, Paris, 1864, p. 14n ("petites atomes"); La thdorie atomique, Paris, 1879, pp. 148-9n ("sous-atomes").
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• Rocke, "Atoms and Equivalents: The Early Development of the Chemical Atomic Theory", Hist. Stud. Phys. Sci., 9 (1978), 225–63; idem, Chemical Atomism in the Nineteenth Century, Colum-bus: Ohio State University Press, in press.
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• Wurtz, "Sur le glycol ou alcool diatomique", Comptes rendus, 43 (1856), 199–204; Gerhardt, Traité (io), 4, 600, 712; Berthelot, "Sur les combinaisons des matieres sucrées avec les acides", Comptes rendus, 42 (1856), titt--14; Wurtz, "Histoire des doctrines chimiques depuis Lavoisier", in Wurtz, ed., Dictionnaire de chimie, 1, Paris, 1868, lxiv—lxv, xciii; Kekulé, "Ueber die s.g. gepaarten Verbindungen und die Theorie der mehratomigen Radicale", Ann. Chem., 104 (1857), 129–50.
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• M. A. Gaudin, "Recherches sur la structure intime des corps inorganiques définis . . .", Ann. chim. phys., [2], 53 (1833), 113–33.
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• Anschütz (2), 2, 943, 949. In a letter to Erlenmeyer dated 16 June 1859 he wrote of Wurtz, "Excellent chap! It is impossible for two people to agree more regarding general conceptions of a science than we two" (Anschütz, 1, 152).
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• Anschütz (2), 2, 940, 951.
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• Ibid., 941–2.
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• E.g., by Partington, History (II), 4, 537.
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• "Chemischer Werth" or "Wertigkeit" was then, and still is, a common German synonym for valency.
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• Kekulé, "Ueber die Constitution des Mesitylens," Zeitschr. Chem., 10 (1867), 214–18 (217); Anschütz (2), 2, 530.
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• Anschfitz (2), 1, 71–2, 162; Kekulé, Lehrbuch der organischen Chemie, 2 vols, Erlangen, 1861–66, 1, passim (the first fascicle of the first volume—pp. 1-240—appeared in June 1859).
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• Anschiltz (2), 1, 64–5, 70.
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• Ibid., 2, 940—I. The date of the paper by Limpricht might be used to date the manuscript were it not for the fact that there were two papers by Limpricht, in numbers issued 26 May 1857 and 27 February 1858, and two replies by Kekulé, issued 30 November 1857 and 19 May 1858 (Ann. Chem., 102, 239; 104, 129; 105, 177; and 106, 129). I know of no way to tell for sure which Kelulé meant. The possibilities for the date of the manuscript from this evidence alone range from early 1856 to early 1857.
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• Anschiltz (2), 1, 624.
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• Ibid., 1, 39, 50; 2, 941.
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• That the July 1855 number of the Annales did in fact appear in July is documented by its mention in the Comptes rendus, 41, 158.
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• Dating the dream 1854 would leave an awkward two-year interval between the conception and the first manuscript draft of the structure theory. This is another circumstance that favours an 1855 date.
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• Kekulé, Lehrbuch (22), 1, 159–60n.
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• Ibid., p. 162n.
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• Ibid., pp. 164-5nn.
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• Ibid., 1, 164n, 174n (1859); 2, 2n, 7 (1863), 246, and 250 (1864).
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• This was on the occasion of the first publication of the benzene theory: "Sur la constitution des substances aromatiques", Bull. soc. chins., [2] 3 (1865), 98–110, and "Untersuchungen iiber aromatische Verbindungen", Ann. Chem., 137 (1866), 129–96.
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• Wurtz, Levons de chimie (14), pp. 133–8; A. Naquet, Principes de chimie, 1st ed., Paris, 1865, pp. 39, 155, 337, 570–2, etc.; 2nd ed., 2 VON, Paris, 1867, 1, 42–64, etc.; J. Wilbrand, "Ueber die Constitution der Allyl- und Glycerylverbindungen; Ueber kettenförmige, ringförmige und iso-mere Kohlenstoffskelette", Zeitschr. Chem., 8 (1865), 683–7 (685); Paul Havrez, "Principes de la chimie unitaire", Revue universelle des mines, 18 (1865), 318–51, 433–48 (cited by Kekulé, Lehrbuch, 2, 515n); G. C. Foster, "Classification", in H. Watts, ed., Dictionary of Chemistry, 5 vols., 1, London, 1866, 1007–23 (roroff); C. Blomstrand, Die Chemie der Jetztzeit vom Standpunkte der elektrochemischen Auffassung aus Berzelius Lehre entwickelt, Heidelberg, 1869, pp. 4o, 65–71.
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• A. Crum Brown, "On the Use of Graphic Representations of Chemical Formulae", Proc. Roy. Soc. Edinburgh, 5 (1865), 429–31; O. N. Witt, in the lampoon Berichte der durstigen chemischen Gesellschaft, unerhörter Jahrgang Nr. zo, pp. 3563–64 (1886); H. Kolbe, "Meine Betheiligung an der Entwicklung der theoretischen Chemie", J. prakt. Chem., [2] 24 (r88i), 375–6. O. J. Walker's suggestion ("Kekule's 'Sausage' Formulae", J. Chem. Educ., 53 (1976), 27–8) that the "sausage" (Würste) epithet was due to a misreading of "bulges" (Wulste) is unlikely, since the two words differ in two letters. Kolbe compared the formulae to bread-rolls (Semmeln). The sausage idea probably arose soon after their introduction, and existed in oral tradition long before their first mention in print, by Witt.
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• Kekulé, "Untersuchungen fiber organische Sauren", Ann. Chem. Suppl., 2 (1862), 85–116 (115n.).
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• Kekulé, Lehrbuch (22), 2, 498, 502, 510, etc. Kekulé had been hinting at such a representation of carbon—carbon bonding since 1858. Furthermore, multiple bonding of oxygen and nitrogen had been graphically depicted ever since the first fascicle of 1859.
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• Kekulé, op. cit. (33, "Untersuchungen"), p. 134n.
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• Kekulé, Lehrbuch (22), 1, 160.
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• Foster, Rep. chins, pure, 3 (1861), 273n.
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• Wurtz, ibid., pp. 419–20.
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• Erlenmeyer, review of Erdmann's "Ueber das Studium der Chemie", Zeitschr. Chem., 5 (1862), 27.
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• Kekulé, Lehrbuch (22), 1, 1620.
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• Kekule first discussed this theory in 1864 ("Sur l'atomicite des elements", Comptes rendus, 58, 510–14), although a schematic presentation appeared in the second fascicle of his Lehrbuch (186o), illustrated by graphic formula (1, 444n.). Erlenmeyer was very critical of the idea: Zeitschr. Chem., 5, 30; 7, 689–94.
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• 12 February 1862, in Anschütz (2), 1, 218.
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• Russell, History (t), pp. 171–223; G. B. Kauffman, "Werner, Kekule, and the Demise of the Doctrine of Constant Valency", J. Chem. Educ., 49 (1972), 813–17.
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• Anschiitz, "Archibald Scott Couper", Arch. Gesch. Nal. Tech., 1 (1909), 219–61.
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• Couper, "On a New Chemical Theory", Phil. Meg., [4] 16 (1858), 104–16 (coq—so).
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• A. Crum Brown, "On the Theory of Chemical Combination", M.D. Thesis, University of Edin-burgh, 1861; published Edinburgh, 1879 (the quotations are taken from the preface). See D. Larder, "Alexander Crum Brown and His Doctoral Thesis of 1861", Ambix, 14 (1967), 112–32. Larder, who appears to be one of the few modern historians to have examined this thesis, did not perceive the significance of the subatomic speculations.
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• Crum Brown, Thesis (49), p. ii. Six years later he was more cautious on this point. Writing to B. C. Brodie, he said he would "not be greatly surprised" if the elements ultimately were found to be complex; letter of P9 August 1867, in W. Brock, ed., The Atomic Debates, Leicester, 1967, p. 529.
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• Thesis (49), p. 16.
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• Ibid., pp. 17–18.
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• Wurtz, Rep, chins, pure, 2 (1860), 354–9; 3 (I86r), 418–21.
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• Crum Brown to Kekulé, 18 February 1869, August Kekulé-Zimmer, Technische Hochschule, Darmstadt. Crum Brown got the job.
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• Crum Brown, Thesis (49), p. 23 (cf. Kekules Lehrbuch (22), 1, 174). He noted in a footnote: "there can be no doubt that the diagrams in [my] text are what he would have given as the representation" of the three molecules.
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• Thesis (22), pp. 23–4. The alternative formulae assume what would now be called epoxide rings.
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• Erlenmeyer, op. cit. (42), p. 31.
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• Erlenmeyer, "Betrachtungen tiber Aequivalent, Atom, Molekiil und Volum", Zeitschr. Chem., 6 (1863), 65–75, 97–504, 609–20.
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• Ibid., pp. 67–73, 103.
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• Erlenmeyer, "Ueber die Sättigungscapacität (Atomigkeit) der Elemente", 7 (1864), 628–35.
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• Erlenmeyer, "Bemerkungen . . .", Zeitschr. Chem., 6 (1863), 422–3; "Vorläufige Notiz . . .", ibid., 728–35; "Hypothesen iiber chemische Isomeric . . .", ibid., 7 (1864), 1–30.
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• Butlerov, "Einiges fiber die chemische Struktur der Körper", Zeitschr. Chem., 4 (1861), 549–60 (556); idem, "Ueber die Verwandtschaft der mehraffinen Atome", ibid., 5 (1862), 297–304; Crum Brown, "On the Theory of Isomeric Compounds", Trans. Roy. Soc. Edinburgh, 23 (1864), 707–19 (718–19).
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• A. Naquet, "Sur l'atomicité de Foxigene, du soufre, du selenium et du tellure", Comptes rendus, 58 (1864), 381–3.
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• Naquet, Principes de chimie, fondde sur les theories modernes, Paris, 1865, pp. 39, 159, 337, etc.
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• C. Delavaud, "Sur l'atomicite", Bull. Soc. Chins., [2] 4 (1865), 421–9, esp. 424–7. Adolf Claus may have been referring to this idea (first suggested in 1861 by Crum Brown) when he cryptically suggested that the variable valency of atoms implies that "atoms" are complex, and that the explanation may be similar to that of the variable atomicity of radicals: Theoretische Betrach-tungen und deren Anwendung zur Systematik der organischen Chemie, Freiburg, 1866, pp. 22–3.
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• Naquet, Principes (64), 2nd ed., 2 vols, Paris, 1867, 1,
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• E.g., ibid., 1, 55–6, 366; 2, 31–6, 314–18, 372–84.
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• Blomstrand, Chemie der Jetztzeit (34), pp. 40, 65–71.
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• A. W. Hofmann used the word to describe recent developments, in the Preface to his Introduction to Modern Chemistry, London, 1865.
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• Kekulé, Lehrbuch (22), 1, passim; idem, "Sur la théorie atomique et la theorie de l'atomicité", Comptes rendus, 60 (1865), 174–7; idem, "Aequivalent und Aequivalenz", in H. von Fehling, ed., Neues Handwörterbuch der Chemie, Brunswick, 1871, pp. 77–89; Erlenmeyer, op. cit. (58); Hofmann, Introduction (69); Wurtz, Lecons de chimie (14); Williamson, "On the Atomic Theory", J. Chem. Soc., 22 (1869), 328–65.
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• Berthelot, "Réponse . . .", Comptes rendus, 84 (1877), 1189–95; Wurtz, "Sur la notation atomique", ibid., pp. 1264–8, 1349-52.
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• J. B. Dumas, Lecons sur la philosophie chimique, Paris, 1837, p. 290. For a discussion of other such early chemical speculations, see for example Seymour Mauskopf, "The Atomic Structural Theories of Ampere and Gaudin: Molecular Speculation and Avogadro's Hypothesis", Isis, 60 (1969), 61–74.
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• See W. H. Brock, "William Prout", Diet. Sci. Biog., 11 (1975), 172–4, and references cited therein. The literature on nineteenth-century Proutian speculations is large. Representative examples include W. V. Farrar, "Nineteenth-Century Speculations on the Complexity of the Chemical Elements'', Brit. J. Hist. Sci., 2 (1965), 297–323, and D. M. Knight, The Transcendental Part of Chemistry, Folkestone, 1978.
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• T. H. Levere, Affinity and Matter: Elements of Chemical Philosophy, 1800—1865, Oxford, 1971; and Rocke, "Origins" (i).
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• This point has been made regarding the tetrahedral carbon atom, e.g., by A. Sementsov, Amer. Sci., 43 (1955), 97–100, but it is also relevant for the simple tetravalent carbon atom.
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• Wilson L. Scott, The Conflict Between Atomism and Conservation Theory 1644 to 1860; London, 1970; William McGucken, Nineteenth-Century Spectroscopy, Baltimore, 1969. For a nineteenth-century perspective on these doubts regarding the adequacy of simple Daltonian atomism, see J. B. Stallo, The Concepts and Theories of Modern Physics, New York, 1881.
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