7— Kekulé, Wurtz, and the Rise of Structure Theory
1. Williamson mentioned that he had established this convention for himself and his students in a letter of 5 December 1853 to H. E. Roscoe (Roscoe Collection).è [BACK]
2. For background on this French tradition, see S. H. Mauskopf, Crystals and Compounds: Molecular Structure and Composition in Nineteenth Century French Science (Philadelphia: American Philosophical Society, 1976). On Dumas' ideas on submolecularity, see A. J. Rocke, Chemical Atomism in the Nineteenth Century (Columbus: Ohio State Univ. Press, 1984), pp. 115-118. The passage quoted is from Dumas, Leons de philosophie chimique (Pads: Bechet, 1837), p. 290. [BACK]
3. Laurent, "Sur les combinaisons organiques azotées," C.r. , 20 (1845), 850-855 (854); idem, "Recherches sur les combinaisons azotées," Ann. chim. , [3] 18 (1846), 266-298 (on pp. 267-268 and 294-295); idem, Chemical Method (London, 1855), pp. 46-48 and 69. [BACK]
4. Laurent, Method , p. 101.
5. Ibid., p. 103. [BACK]
4. Laurent, Method , p. 101.
5. Ibid., p. 103. [BACK]
6. Laurent, "Sur la série naphthalique," Revue scientifique , 14 (1843), 74-113 (on pp. 102-103); Method , pp. 103-107; Gerhardt, Traité de chimie orga-
nique , 4 vols. (Paris: Didot, 1853-1856), 4 , 602-604, 712. Laurent's speculations are discussed by Mauskopf, Crystals and Compounds , pp. 50-51. Laurent wrote Berzelius on this subject on 5 January 1844: H. G. Söderbaum, ed., Berzelius Bref , 6 vols. (Uppsala: Almqvist & Wiksell, 1912-1961), 3 :2, 199-200. On this 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 (on pp. 60-64). [BACK]
7. Laurent, Method , pp. 1-16. This is a major thesis of my Chemical Atomism in the Nineteenth Century . [BACK]
8. For Williamson, see the preceding chapter; William Odling, "On the Constitution of Acids and Salts," JCS , 7 (1854), 1-22; Edward Frankland, "On a New Series of Organic Bodies Containing Metals," PTRS , 142 (1852), 417-444. [BACK]
9. Williamson, "Note sur la trinitroglycerine," Ann. chim. , [3] 43 (1855), 492 (originally published in Proceedings of the Royal Society , 7 [June 1854], 130-138); Wurtz, "Théorie des combinaisons glycériques," Ann. chim. , [3] 43 (1855), 492-496.è [BACK]
10. Wurtz, "Sur le glycol ou alcool diatomique," C.r. , 43 (1856), 199-204. The historical comments, including the date of the experiment, were given in Wurtz, "Histoire générale des glycols," in Société Chimique de Paris, ed., Leons de chimie professées en 1860 (Paris: Hachette, 1861), pp. 101-139 (103-109). The assertion that Wurtz had made himself a prediction in this manner was also stated in Wurtz, Ann. chim. , [3] 55 (1859), 401. [BACK]
11. Wurtz, "Sur une nouvelle classe de radicaux organiques," Ann. chim. , [3] 44 (1855), 275-313 (on pp. 304-309). The idea was first broached in his "Théorie des combinaisons glycériques," pp. 495-496. [BACK]
12. Wurtz, "Radicaux organiques," pp. 306-307 and 306-307n.è [BACK]
13. Wurtz, Répertoire de chimie pure , 3 (1861), 419; Leons de philosophie chimique (Paris: Hachette, 1864), pp. 114-115; Cours de philosophie chimique (Paris: Renou et Maulde, 1864), pp. 74-76; "Histoire des doctrines chimiques depuis Lavoisier," in Wurtz, ed., Dictionnaire de chimie pure et appliquée , 3 vols. in 5 (Paris: Hachette, 1868-1878), 1 , lxx; La théorie atomique (Paris: Baillière, 1879), pp. 148-149. [BACK]
14. Rocke, Chemical Atomism , pp. 11-12, 299-307. [BACK]
15. For details, see Rocke, "Subatomic Speculations and the Origin of Structure Theory," Ambix , 30 (1983), 1-18. [BACK]
16. The following biographical details are largely based on Richard Anschütz' monumental, partisan, but indispensable biography August Kekulé , 2 vols. (Berlin: Verlag Chemie, 1929), and on two autobiographical speeches that Kekulé gave in his old age, reprinted in ibid., 2 , 937-947 and 947-952. For convenience, I will usually cite Anschütz' collection (cited as Kekulé ) rather than the original literature. [BACK]
17. Kekulé , 1 , 16-17 (from a letter to Anschütz, no date cited but probably shortly after the turn of the century, from Reinhold Hoffmann). [BACK]
22. Kekulé to Planta, 3 March 1854, August-Kekulé-Sammlung. [BACK]
23. Kekulé , 2 , 943-944. [BACK]
24. Kekulé, "On a New Series of Sulphuretted Acids," Proceedings of the Royal Society , 7 (1854), 37-40; "Notiz über eine neue Reihe schwefelhaltiger organischer Säuren," Annalen , 90 (1854), 309-316. [BACK]
25. Odling, "On the Constitution of the Hydro-Carbons," Proceedings of the Royal Institution , 2 (1855), 63-66. Anschütz ( 1 , 109) comments that Kekulé could not have been aware of Odling's article because this journal was unknown in Germany, but Kekulé was still in London when Odling presented his paper (16 March 1855), and as Kekulé and Odling were friends, it is probable that Kekulé knew the details of this paper. [BACK]
26. Kekulé , 2 , 941-942. [BACK]
27. This is a thesis argued in Rocke, "Subatomic Speculations." [BACK]
28. Kekulé, "Über die Constitution des Mesitylens," ZfC , 10 (1867), 214-218 (on p. 217); Kekulé , 2 , 530. [BACK]
29. Kekulé , 2 , 102. [BACK]
30. That the July 1855 number of the Annales de chimie et de physique did in fact appear in July is documented by its mention in the Comptes rendus , 41 , 158 (dated 30 July 1855). [BACK]
31. Kekulé , 1 , 60-63. Kekulé's relations with his brother Charles are described in his letters to Planta of 28 October and 28 December 1854 and especially 9 February 1856, August-Kekulé-Sammlung. The words in quotation marks are August Kekulé's. [BACK]
32. On Erlenmeyer, see Otto Krätz, "Emil Erlenmeyer, 1825-1909," Chemie in unserer Zeit , 6 (1972), 52-58, and idem, ed., Beilstein-Erlenmeyer: Briefe zur Geschichte der chemischen Dokumentation und des chemischen Zeitschriftenwesens (Munich: Fritsch, 1972). [BACK]
33. Kekulé , 2 , 940. [BACK]
34. Kekulé, "Über die Constitution des Knallquecksilbers," Annalen , 101 (1857), 200-213, and 105 (1858), 279-286; Adolf Baeyer, "Über die organischen Arsenverbindungen," Annalen , 105 (1858), 265-276. Gerhardt recognized the same distinction by disowning the "mechanical type" concept of Dumas, which implied arrangement: Traité de chimie organique , 4 (Paris: Didot, 1856), 586. [BACK]
35. Limpricht and von Uslar, "Über die Sulfobenzoësäure," Annalen , 102 (1857), 239-259; Mendius, "Über gepaarte Säuren und insbesondere über Sulfosalicylsäure," Annalen , 103 (1857), 39-80. [BACK]
36. Kekulé , 2 , 80-82, 97-102.
37. Ibid., p. 101. [BACK]
36. Kekulé , 2 , 80-82, 97-102.
37. Ibid., p. 101. [BACK]
38. Kekulé's criticism of Limpricht's formulas was that, with an atomic weight for oxygen of eight, his water type had to be H 2 O 2 , which meant that there was no longer a single integral oxygen atom that could form a material link between two hydrogens. As for Gerhardt, both in this paper ( Kekulé , 2 , 84n.) and two years later in his Lehrbuch der organischen Chemie (2 vols. [Erlangen: Enke, 1859-1866], 1 , 94), Kekulé singled out formulas of Gerhardt that could not be expressed in a valence-linked manner, calling them "inconsis-
tent" and "inadmissible" according to the theory of polyatomic radicals (such formulas as appear, for instance, in Gerhardt, C.r. , 36 [1853], 1053, and Traité , 4 , 629 and 749). Kekulé's disapproval of similar nonlinkable type formulas in Odling's 1854 paper can be inferred. Kekulé's offprint copy of this paper is preserved in the August-Kekulé-Sammlung, and there are penciled marginal annotations in Kekulé's hand ("sic!" and "!!!') every time such a structurally impossible formula appears (Odling, "Constitution,'' pp. 7-9). [BACK]
39. Kekulé, "Über die s.g. gepaarten Verbindungen und die Theorie der mehratomigen Radicale," Annalen , 104 (1857), 129-150; Kekulé , 2 , 80-96. [BACK]
40. What we now call valence was referred to by Kekulé variously as "basicity" (from Williamson, 1851), "atomicity" (from Wurtz and others, 1856), "affinity," "affinity units," "chemical units," and "units." Other designations include "value" ("Wertigkeit," Erlenmeyer, 1860), "monaffin," etc. (Wislicenus, 1863), "monad," etc. (Odling, 1864, following Laurent), "hydrogen equivalence" (Gerhardt, 1856), "quantivalence," "monovalent," etc. (Hofmann, 1865), and "valence" (Claus, 1866). The latter term gained currency only in the course of the 1870s. See C. A. Russell, The History of Valency (Leicester: Leicester Univ. Press, 1971), pp. 83-89, some of which is modified by the previous data. Russell's book is excellent on the development of valence ideas from Dalton through the first third of the twentieth century. [BACK]
41. Kekulé , 2 , 83n. [BACK]
42. Limpricht, "Einige Bemerkungen zu der von A. Kekulé veröffentlichten Abhandlung 'Uber die s.g. gepaarten Verbindungen und die Theorie der mehratomigen Radicale,'" Annalen , 105 (1858), 177-186. [BACK]
43. Kekulé, "Über die Constitution und die Metamorphosen der chemischen Verbindungen und über die chemische Natur des Kohlenstoffs," Annalen , 106 (1858), 129-159; Kekulé , 2 , 97-119. An annotated English translation was published by O. T. Benfey, in his edited work Classics in the Theory of Chemical Combination (New York: Dover, 1963), pp. 109-131. [BACK]
44. Kekulé , 2 , 102.
45. Ibid., pp. 114-116.
46. Ibid., pp. 109, 116-119, 138-141, 153, and 204; Lehrbuch der organischen Chemie , 1 (1859), 131, 156-157, 164, 174, and 224; 2 (1864), 244-245. [BACK]
44. Kekulé , 2 , 102.
45. Ibid., pp. 114-116.
46. Ibid., pp. 109, 116-119, 138-141, 153, and 204; Lehrbuch der organischen Chemie , 1 (1859), 131, 156-157, 164, 174, and 224; 2 (1864), 244-245. [BACK]
44. Kekulé , 2 , 102.
45. Ibid., pp. 114-116.
46. Ibid., pp. 109, 116-119, 138-141, 153, and 204; Lehrbuch der organischen Chemie , 1 (1859), 131, 156-157, 164, 174, and 224; 2 (1864), 244-245. [BACK]
47. Kekulé , 2 , 110n. and 112.
48. Ibid., pp. 116-117.
49. Ibid., pp. 118-119. Wurtz' words were, "In conclusion, I must say that I do not attach more importance than necessary to the ideas I have tried to develop, and that I am very far from considering them as the absolute expression of truth. In the physical sciences theories must not aim that high. The best are those that embrace the largest number of facts, that account for them in the most satisfactory fashion, and that give rise to predictions of new facts. Chemical theories that tend to prevail today appear to me to fit this pattern: they are good to the extent that they are fruitful." Wurtz, "Radicaux organiques" (see n. 11), p. 313. [BACK]
47. Kekulé , 2 , 110n. and 112.
48. Ibid., pp. 116-117.
49. Ibid., pp. 118-119. Wurtz' words were, "In conclusion, I must say that I do not attach more importance than necessary to the ideas I have tried to develop, and that I am very far from considering them as the absolute expression of truth. In the physical sciences theories must not aim that high. The best are those that embrace the largest number of facts, that account for them in the most satisfactory fashion, and that give rise to predictions of new facts. Chemical theories that tend to prevail today appear to me to fit this pattern: they are good to the extent that they are fruitful." Wurtz, "Radicaux organiques" (see n. 11), p. 313. [BACK]
47. Kekulé , 2 , 110n. and 112.
48. Ibid., pp. 116-117.
49. Ibid., pp. 118-119. Wurtz' words were, "In conclusion, I must say that I do not attach more importance than necessary to the ideas I have tried to develop, and that I am very far from considering them as the absolute expression of truth. In the physical sciences theories must not aim that high. The best are those that embrace the largest number of facts, that account for them in the most satisfactory fashion, and that give rise to predictions of new facts. Chemical theories that tend to prevail today appear to me to fit this pattern: they are good to the extent that they are fruitful." Wurtz, "Radicaux organiques" (see n. 11), p. 313. [BACK]
50. This information is from Erlenmeyer's letter to Roscoe, no date but ca. 1859, Roscoe Collection. [BACK]
51. Krätz remarks ("Erlenmeyer," p. 52) that Erlenmeyer, too, was an avid cigar smoker. Kekulé's salary in Ghent, noted Anschütz ( 1 , 151n.), was 6000 francs. The Belgian franc was equal in value to the French franc, about a fourth of a thaler, so Kekulé's salary was two and a half times Kolbe's, more than sufficient for a bachelor with a modest lifestyle. [BACK]
52. Kekulé to Erlenmeyer, 29 January 1859 Dingler Nachlass; a copy is held in the August-Kekulé-Sammlung, and most of the letter is printed in Kekulé 1 , 150-151. [BACK]
53. Cited from Fittig's diary in F. Fichter, "R. Fittig," Berichte , 44 (1911), 1339-1401 (on p. 1361). [BACK]
54. Kolbe, JpC , 131 (1881), 37. [BACK]
55. Couper, "Sur une nouvelle théorie chimique," C.r. , 46 (1858), 1157-1160; "On a New Chemical Theory," Philosophical Magazine , [4] 16 (1858), 104-116. On seeing the paper, Kekulé fired off some "Remarques de M. A. Kekulé à l'occasion d'une note de M. Couper sur une nouvelle théorie chimique,'' C.r. , 47 (1858), 378, in which he criticized some of Couper's ideas and also pointed out that both of his papers were earlier than Couper's first publication (the second even if only by a month). [BACK]
56. Rocke, "Subatomic Speculations," pp. 9-10. [BACK]
57. Odling, "Remarks on the Doctrine of Equivalents," Philosophical Magazine , [4] 16 (1858), 37-45 (on pp. 43-44). [BACK]
58. He said this in a letter to Wurtz of 1 July 1859 ( Kekulé , 1 , 158), and in an unpublished document written in 1883, found among Kekulé's papers by Anschüitz and printed in his biography, 1 , 540-569 (on p. 554). [BACK]
59. Wurtz, Répertoire de chimie pure , 1 (1858), 20-24 (on pp. 24 and 24n.). [BACK]
60. Kekulé to Wurtz, 15 February 1859, August-Kekulé-Sammlung, printed in Kekulé , 1 , 146-148. Anschütz reproduces a facsimile of the letter, which shows he made two small errors in transcription. [BACK]
61. Wurtz to Kekulé, 7 March 1859, August-Kekulé-Sammlung; Kekulé , 1 , 148-149; Wurtz, Ann. chim. , [3] 55 (1859), 470n. [BACK]
62. Kekulé to Erlenmeyer, 16 June 1859, Dingler Nachlass; printed in Kekulé , 1 , 152. [BACK]
63. A. Ladenburg, Lebenserinnerungen (Breslau: Trewendt, 1912), p. 26. [BACK]
64. Kekulé to Wurtz, 1 July 1859, in Kekulé , 1 , 157-159. [BACK]
65. Kekulé, Lehrbuch , 1 , 94. [BACK]
66. Wurtz to Kekulé, 21 July 1859, August-Kekulé-Sammlung, in Kekulé , 1 , 159.è
67. ibid. Wurtz, Répertoire de chimie pure , 2 (1860), 354-359; ibid., 3 (1861), 418-421; "Histoire des glycols" (1861), pp. 138-139; Leons (1864), pp. 100, 113-114, and 120-121; Cours (1864), pp. 50-51, 56, and 74-76; "Histoire des doctrines" (1868), p. lxx; Wurtz to Williamson, 25 December 1868, Harris Collection, Univ. College London Archives; Théorie atomique (1879), pp. 145-149. [BACK]
66. Wurtz to Kekulé, 21 July 1859, August-Kekulé-Sammlung, in Kekulé , 1 , 159.è
67. ibid. Wurtz, Répertoire de chimie pure , 2 (1860), 354-359; ibid., 3 (1861), 418-421; "Histoire des glycols" (1861), pp. 138-139; Leons (1864), pp. 100, 113-114, and 120-121; Cours (1864), pp. 50-51, 56, and 74-76; "Histoire des doctrines" (1868), p. lxx; Wurtz to Williamson, 25 December 1868, Harris Collection, Univ. College London Archives; Théorie atomique (1879), pp. 145-149. [BACK]
68. Wurtz, "Mémoire sur les glycols ou alcools diatomique," Ann. chim. , [3] 55 (presented 3 January, published April 1859), 400-478 (on pp. 471 and 474-478). Wurtz did indeed use the French word structure here, which he may
have picked up from Butlerov. The word had been used occasionally before Butlerov, for example, by Frankland ( Proceedings of the Royal Institution , 2 [1854], 454), Gaudin, and Berzelius. [BACK]
69. The Société des Amis de la Science was essentially a monetary fund formed after the death of Laurent, and increased in size after Gerhardt's death, to support the dependents of the two chemists. The Archives of the Académie des Science has some documents regarding this society in the Fonds Dumas. A letter from Wurtz to Dumas of 22 July 1864 takes the part of Jane Gerhardt, which suggests that Wurtz was Madame Gerhardt's chief link to the society.è [BACK]
70. Wurtz, "Histoire des glycols" (1861); "Éloge de Laurent et de Gerhardt" (13 March 1862); "On Oxide of Ethylene, Considered as a Link Between Organic and Mineral Chemistry," JCS , 15 (1862), 387-406; Leons (1864); Cours (1864); Leçons élémentaires de chimie moderne (Paris: Masson, 1867-1868); Dictionnaire de chimie (1869-1878); Théorie atomique (1879). [BACK]
71. The best biography in English is G. V. Bykov, "A. M. Butlerov," DSB , 2 , 620-625. Butlerov's February 1858 paper was never published, but it is described in Jacques, "Boutlerov, Couper et la Société Chimique de Paris," BSC , 1953, pp. 528-530; Butlerov's commentary on Couper is "Bemerkungen über A. S. Couper's neue chemische Theorie," Annalen , 110 (1859), 51-66. For further literature and historiography, see Rocke, "Kekulé, Butlerov, and the Historiography of the Theory of Chemical Structure," British Journal for the History of Science , 14 (1981), 27-57. A perceptive reply and commentary on this article is Bykov, "K istoriografii teorii khimicheskogo stroeniia,'' Voprosy istorii estestvoznaniia i tekhniki , 1982 :4, 121-130, which was completed shortly before his death. [BACK]
72. Butlerov, "Einiges über die chemische Struktur der Körper," ZfC , 4 (1861), 549-560. [BACK]
73. Brodie, "On the Conditions of Certain Elements at the Moment of Chemical Change," PTRS , 140 (1850), 759-804; Couper, "New Chemical Theory," pp. 112-113. [BACK]
74. Kekulé, 2 , 944. [BACK]