Attack and Counterattack:
Kolbe Versus Williamson

As we saw at the end of chapter 5, Kolbe was taken by surprise by Gerhardt's and Williamson's papers of the early 1850s and he recognized their importance. Kolbe was far from alone in seeing the compelling character of the new research, and he became increasingly alarmed by the rapid gains that Gerhardt seemed to be making. In France, establishment figures such as Fremy, Regnault, and especially Dumas and Thenard ceased quarreling with Gerhardt and began to support his academic career. Not only did Gerhardt's students such as Chancel and Chiozza adopt elements of his system but also Wurtz, Cahours, Pelouze, Malaguti, and Quesneville. A few Russians and Americans, as well as such Britishers as Odling, Brodie, Henry Roscoe, and Williamson, became converts.

Of even greater concern to Kolbe, there were obvious signs that Gerhardt's views were gaining currency among younger and mid-career German chemists as well. Leopold Gmelin had adopted Laurent's classification scheme in 1848, and Liebig had had high praise for Gerhardt's acid anhydride research. Worse, Kolbe's good friends Hofmann and (German-educated) Frankland had clearly been moving toward the "typist" camp since 1849. Hofmann privately opined at the time of the acid anhydride work that this sort of argument "removes the last support for the idea that [alcohols and acids] contain water." Later he characterized the argument as "irresistibly convincing."^[20] A new generation of German chemists—including Kekulé, Karl Weltzien, Emil Erlenmeyer, Heinrich Limpricht, Ludwig Carius, Lothar Meyer, Adolf Baeyer, and Leopold von Pebal—were declaring themselves as converts during the early to mid-1850s.

Kolbe could take little comfort that the éminences gris of German chemistry had not signed on, for he well knew that they were uninterested in the theoretical dialectic in general. "What opinion Liebig now has on the subject [of Gerhardt's work] I do not know," he wrote Vieweg. "I suspect none at all, like Wöhler, since neither one seems to have much interest for such matters."^[21] The same was true for Bunsen, as Kolbe well recognized.^[22] One member of the "classical" generation who did convert to Gerhardt's system, if not to his notation, was Otto Erdmann, Gerhardt's first chemistry teacher and founder of the Journal för praktische Chemie .^[23] In sum, Gerhardt's views were making headway in the early 1850s in major chemical centers such as Heidelberg and Göttingen and were establishing outposts all over the Germanic lands.

In addition, virtually the entire chemical faculty at Giessen became

Gerhardtians. Heinrich Will, Liebig's successor, is discussed shortly. Adolf Strecker had been successively student, assistant, and Privatdozent under Liebig before his call to Christiania (Oslo) in 1851 and had written Kolbe's favorite short organic chemistry textbook. Strecker had always been favorably inclined toward Gerhardt's and Laurent's research, and by 1854 he was clearly a convert; at the Karlsruhe Congress he was quite vocal in his defense of the new chemistry.^[24] He was a talented chemist, much respected in his day. Finally, it took little reading between the lines of the annual Jahresbericht der Chemie to perceive that its editor Hermann Kopp, Ordinarius for theoretical chemistry at Giessen after Liebig's departure, had by about 1854 become attracted by the French ideas. The sober and cautious Kopp, seven years older than Williamson, later recalled the latter's work as providing "brilliant confirmation" of the new chemistry, "demonstrating beyond question" the Gerhardtian constitutions and quickly garnering willing converts.^[25] The defections of Strecker and Kopp were particularly bad blows for Kolbe. They were both intimate friends of his (Duzfreunde ), and Kolbe had always admired their careful conservative approaches.

Kolbe worried about how to respond to the new research, especially because he was writing the critical theoretical sections of his textbook in 1853, just as the tide appeared to be turning against him. During the spring, summer, and early fall of that year, Kolbe worked furiously to devise counterarguments to the Williamson-Gerhardt theory. When he thought he had the desired disproofs, he incorporated them into his first textbook installment, which appeared in June 1854. But he was so concerned at the signs of revolution in the air that he decided to hurry his critiques into print as articles at the earliest possible moment.

The first of these was an attempt to disprove Williamson's theory that acetic acid consists of Williamson's "othyl" radical C₂ H₃ O united to oxygen, the latter atom also linked to a hydrogen atom.^[26] Erroneously translating his own conventional equivalents into Williamson's atomic weights by doubling the number of his hydrogen atoms (rather than using the correct transformation algorithm of halving the numbers of his carbon and oxygen atoms), Kolbe concluded that Williamson's acetic acid formula implied the presence of two methyl groups. If that formula were true, then one of the methyls could in principle be replaced by another radical, ethyl for instance. But experiment failed to achieve this end, so Williamson's theory was at least weakened, if not directly falsified.

This line of thought demonstrates both that Kolbe fully grasped the import and compelling nature of the asymmetric synthesis argument in particular—he was after all trying to turn Williamson's own powerful

gun upon him—but also that he had only a superficial understanding of the new chemistry in more general terms. Two years earlier, upon publication of the German translation of Williamson's third ether paper, Liebig had even provided his readers with two versions of the correct transformation algorithm, but Kolbe must have misunderstood it.^[27] Having rejected the atomic weight reform years earlier as a passing French fancy and supremely confident of the truth of the older system, he had simply never successfully worked through the details of the arguments.

Kolbe's attempted refutation was actually performed and written by an English student of Kolbe's, Francis Wrightson, who is otherwise little known; Kolbe later affirmed that the reasoning was his. The research was complete by about June 1853 and was published in the August issue of the Philosophical Magazine . The following month a reply by Williamson appeared. Without explaining the precise character of the fallacy committed by Wrightson, Williamson contented himself with demonstrating that "the result which he failed in obtaining is incompatible with the othyle theory of which he conceived it a consequence, and the result he obtained is decidedly confirmatory of the theory which he expected it to upset."^[28] Wrightson's confused and ungracious rebuttal shows that he had not understood Williamson's reply^[29] —nor apparently did his teacher, who repeated the same arguments the following year.

In the July and August 1853 issues of the Annalen der Chemie , a two-part German translation of Gerhardt's detailed memoir on acid anhydrides appeared, and in September a German translation of his and Chiozza's work on amides was published. It was to these articles in particular that Kolbe must have been referring when he wrote Vieweg of the "research of the very greatest scientific importance . . . which threatens to overturn" the entire existing theoretical foundation of chemistry. By the time he wrote this letter (on 16 October 1853), he thought he had hit upon "the strongest proofs against Gerhardt's theory" without having had to enter the laboratory.^[30] But that fall, Wrightson having left Marburg, Kolbe put another English student, Frederick Guthrie, to work on additional organic electrolyses to refute Williamson. By late fall he had written a detailed critique, which he read to the Marburg Naturforschende Gesellschaft and sent to Liebig for the Annalen and to Hofmann for the Journal of the Chemical Society .^[31]

Kolbe brought a number of points to bear against Williamson (and secondarily against Gerhardt). Williamson had taken no notice, it seemed, of his proof that methyl exists in acetic acid and its derivatives. Synthetic methods of the sort Williamson had used are untrust-

worthy indicators of constitutions, Kolbe felt, less certain at least than analyses. In addition, Wrightson's evidence, he thought, had not been effectively countered in Williamson's rebuttal. As for the new asymmetric compounds, nothing prevented one from assuming that the new methyl ethyl ether, for instance, was a combination of ethyl oxide (ethyl ether) and methyl oxide (methyl ether), i.e., C₄ H₅ O.C₂ H₃ O. To the possible objection that such electrochemically similar molecules would have no reason to cohere, Kolbe responded that many other similar instances were known, such as compounds of chlorine and iodine. Another point of difference between the two theories was that Kolbe's acetic anhydride formula posited three methyl hydrogens, whereas Gerhardt's and Williamson's had six. Were the latter correct, acetic anhydride with an odd number of chlorine atoms would be possible; conversely, such compounds would be excluded by Kolbe's formula because they could not be represented without use of non-integral atomic coefficients. But no such compounds were known to exist.

Finally, Kolbe regarded the electrolysis of acetic acid as irrefutably falsifying Williamson's theory. According to Williamson, the constitution of acetic acid was analogous to water, with the othyl radical taking the place of one of water's hydrogen atoms. Accordingly, electrolysis of the acid ought to proceed analogously to that of water, with othyl and potassium (or at least their decomposition products) appearing at the negative electrode and oxygen emerging at the positive pole. In fact, nothing but hydrogen is found on the negative side, with methyl and carbonic acid appearing at the positive. Especially for this reason, Kolbe concluded that Williamson's theory was "easily refuted."

Kolbe's paper was read at a meeting of the Chemical Society on 20 February 1854; there was an element of drama as Williamson had prepared a reply to be read immediately following. Henry Watts wrote to H. E. Roscoe at Heidelberg shortly before the event, very much looking forward to the "jolly row" in store.^[32] Williamson wrote the same correspondent

Of course I will answer [Kolbe's paper], though from what I have seen of its contents there seems little chance of my converting him to more rational views on the subject, as he does not enter into or understand the point of view opposed to his view.^[33]

Williamson's reply was a polemical masterpiece, in which carefully reasoned refutations alternate with less substantive forms of verbal pyrotechnics.^[34] In response to Kolbe's methodological critique of synthesis as a valid means of determining constitutions, Williamson

attacked Kolbe's favorite approach, analysis, at the same time blasting his use of undefined and empirically illfounded symbolic distinctions:

It would be just as reasonable to describe an oak-tree as composed of the blocks and chips and shavings to which it may be reduced by the hatchet, as by Dr. Kolbe's formula to describe acetic acid as containing the products which may be obtained from it by destructive influences. A Kolbe botanist would say that half the chips are united with some of the blocks by the force parenthesis ; the other half joined to this group in a different way, described by a buckle ; shavings stuck on to these in a third manner, comma ; and finally, a compound of shavings and blocks united together by a fourth force, juxtaposition , is joined on to the main body by a fifth force, full stop . The general use of unmeaning signs has become so habitual to Dr. Kolbe, that whenever anything has to be explained, he performs the task to his own satisfaction by inventing a sign for its unknown cause. . . . Signs and words are doubtless indispensable means for the expression of facts or thoughts; but Dr. Kolbe uses them instead of facts, and as a substitute for ideas.^[35]

Williamson averred that in admitting the existence of the new compound ethyl methyl ether, however he may wish to formulate it, Kolbe had thereby conceded the essential point at issue, the doubled size of ethers relative to alcohols. (This is an example of rhetorical sleight of hand, as Williamson must have been aware that Kolbe intended his argument about the combination of ethyl and methyl "oxides" to apply only to the asymmetric compounds, not to ordinary ether itself.) He reaffirmed his response to Wrightson, expressing satisfaction at being permitted now to direct his rebuttal to the real source of that fallacious reasoning. Finally, he pointed out that the crucial experiment that Kolbe had conceded would win the day for the Williamson-Gerhardt theory—production of an acetic acid anhydride with an odd number of chlorine atoms—was easily produced from the reaction of trichloroacetyl chloride with sodium acetate.

Williamson's mastery of both the rhetorical and substantive forms of scientific discourse is highlighted by comparing his reply to Kolbe with Gerhardt's response.^[36] Published in the same issue of the Annalen immediately preceding Williamson's, Gerhardt could only sputter with indignation that Kolbe had attacked "Williamson's" theory, when the ideas that the "overly sensitive" Kolbe opposed so vehemently were his (Gerhardt's) alone. The matter was serious because, by appearing in Liebig's journal, the German public might infer that Kolbe's views were shared by the master (here Liebig added a footnote cautioning that "This should not be assumed"^[37] ). Gerhardt's outburst once more indicates his tragic flaws: arrogance, bad grace, and lack of tact. His

priority claim was not unreasonable, but here it served only to alienate his friends. And he did not bother to attempt to refute Kolbe's arguments rationally.

While all these events were taking up Kolbe's attention, his friend Edward Frankland was also directing a friendly but devastating critique at the copula theory. Frankland's most famous memoir, which contains a limited statement of the concept of valence, was published in the Philosophical Transactions in 1852, but in German not until March 1853, when presumably Kolbe first read it.^[38] In this work, Frankland argued not only that the reactions of organometallic compounds showed that metal atoms have a maximum combining capacity with other atoms or radicals. He also suggested that the only proper way to envision the reactions is to depict organic radicals as replacing inorganic atoms such as oxygen, rather than simply adding to the metal without altering its chemistry, as in the copula theory.

For instance, according to the copula theory, it should have been easy to oxidize or halogenate the highly electropositive zinc methyl, but all such attempts failed. The only way further combination predicted by the theory could take place was if the organic copulas became detached from the metal atom. In this way, Frankland demonstrated that metal atoms were very much chemically altered by their "copulation" and that their combining capacity was indeed reduced—moreover, precisely by the number of copulas. This applied even to the prototype of copulated radicals, cacodylic acid, in which arsenic was connected to three oxygen atoms and could not be further oxidized to the five-oxygen analog of uncopulated arsenic acid. In Frank-land's new type-theoretical interpretation, this was because two methyl groups had taken the place of two oxygens. In short, the postulates and predictions of the copula theory had been systematically contradicted at every turn. Only an application of type theory could save the phenomena.