The Battle Lost

There is considerable evidence here of defensiveness, along with often emotional and even shrill counterattacks. Despite Kolbe's brief sense of triumph with Guthrie's electrolyses, there continued to be good reason for his discomfort. Four months after the premiere of Kolbe's textbook and a month after the appearance in German of Wil-

liamson's and Gerhardt's rebuttals, Heinrich Will published a devastating critique of Kolbe's views. Will (1812-1890) had been a Liebig student in the late 1830s, subsequently becoming Privatdozent and first assistant in Giessen. When Liebig opened a branch laboratory for beginners in 1843, Will was placed in charge. As a consequence, he taught large numbers of students, many of whom achieved prominence in the next decade. Many of those who are counted (and counted themselves) as Liebig students actually were taught mostly by Will, including Williamson, Hofmann, Strecker, Kekulé, and Erlenmeyer.

Although Will had a strongly empirical approach, it is interesting to note that the topic of his disputation for Habilitation (1844) was the thesis that no compounds exist that have an odd number of equivalents of carbon—a cardinal thesis of Gerhardt's chemistry.^[50] A fellow student and confidant of Kekulé's during the years 1849-1851 reported that Will's lectures opened many windows.

Later our discussions, both in private and in the larger circle of our friends, moved increasingly into the purely theoretical realm. At that time in our circle the perception was already stirring, partly still unconsciously, that the strict radical theory was not the sole all-redeeming dogma of chemistry. The seed of this perception, I believe, was to be found in Will's lectures on organic chemistry.^[51]

Will succeeded Liebig as ordentlicher Professor when Liebig transferred to Munich in 1852. By 1853, according to his student Volhard, Will was giving a "clear, convincing, indeed enthusiastic portrayal" of Gerhardt's system in his lectures, to the point that Volhard and his comrades came to swear on type theory and honor Gerhardt as the reformer of organic chemistry.^[52] The next year Will published his commentary "On the Theory of the Constitution of Organic Compounds" in the Annalen .^[53]

Will argued that Gerhardt's atomic weight reform must be adopted simply because it was becoming ever clearer that formulas written in conventional equivalents always have even numbers of carbon and oxygen atoms. There was thus no empirical justification for retaining C₂ in preference to C (i.e., C = 6 in preference to C = 12). Furthermore, the asymmetric synthesis argument as applied by Williamson and Gerhardt, and the new bases of Wurtz and Hofmann, had placed the molecular magnitude issue (the doubled sizes of ethers and acid anhydrides with respect to alcohols and acids) beyond any question.

Unlike Williamson, Will understood that Kolbe's depiction of ethyl methyl ether as a compound of ethyl oxide with methyl oxide was not intended to apply to ordinary ether. But if the asymmetric Williamson reaction links these two compounds together so firmly, then it must

also link ethyl oxide with itself in the symmetrical reaction, which is the equivalent of Williamson's ether formula. The latter makes much more chemical sense, Will argued, for a dimerized ethyl oxide has no analog in either organic or inorganic chemistry.

As for Kolbe's crucial electrolysis argument, Will suggested that it would have some force if directed against the existence of such oxygenated radicals as Williamson's othyl or ethoxide. But since Kolbe had now conceded the existence of oxygenated radicals, his and Williamson's formulas were equivalent. Translating Williamson's formula for acetic acid into Kolbe's notation, the two were

These formulas depict the same atoms combined in the same way. The only significant difference between them is that Kolbe suggested a chemical distinction between the two extra-radical oxygen atoms, a distinction, Will noted, that has no empirical basis. But even conceding this distinction, any electrochemical argument that applies to one of these formulas must perforce apply to the other. If Kolbe had disproved Williamson's formula, he had simultaneously disproved his own.

The issue here as elsewhere, Will concluded, was that inorganic chemistry could no longer remain the analogical guide to organic chemistry. The reform of organic chemistry, begun by Gerhardt, provided the entree into the chemistry of the future, and it could no longer be in doubt that his reform would win the day. Will, the model of the mid-career establishment German chemist and the newly appointed successor to Liebig as ordentlicher Professor at Giessen, was declaring himself for the young (French and English) Turks.

Much later, in a biography of Will, Hofmann wrote of this period of rapid gains for the new views: "With some, this transition happened silently, they slipped as it were right into the new theory; in fact there were some who the night before had been implacable opponents of Gerhardt and Laurent, and awoke the next morning completely converted." In his biography of Wurtz, Hofmann chose similar language to describe the period: "The time had arrived in which, one after another, the most ardent opponents—often overnight, and without providing any reasons whatever for their conversions—made their pronouncements."^[54] Hofmann later affirmed that a "revolution" had taken place during the 1850s—and he was not the only one to apply this word.^[55] The evidence presented here suggests that this transition came earlier, faster, and more completely in Germany than has hith-

erto been thought. Most active and theoretically oriented German chemists had converted several years before the Karlsruhe Congress of 1860, the event usually described as the turning point.

Wurtz's discovery in 1855 of the asymmetrical or "mixed" radicals was the final blow for Kolbe. Kolbe may have been able to satisfy himself that ethyl oxide and methyl oxide are sufficiently distinct electrochemically to provide a basis for combination, but it was difficult to imagine such a distinction between, say, the eight-carbon butyl and the ten-carbon amyl, especially considering the absence of any heteroatoms and the extreme stability of their combination. Butyl-amyl's exact fulfillment of Hofmann's boiling point prediction—based on Kopp's laws—was another problem for Kolbe. It was fortunate that the imminent publication of the fascicle of volume six of the Handwörterbuch der reinen und angewandten Chemie that contained the beginning of letter "R" gave Kolbe the impetus to write a summary article on "radicals," further modifying his views. He wrote the article in late December 1855, immediately after a summary of Wurtz' paper appeared in Liebig's Annalen .^[56]

The piece contains a strong affirmation of the complete substitutability of the hydrogen of organic radicals by virtually any element, even electrochemical opposites, sometimes with minimal alteration of properties. How this undeniable truth can be reconciled with electrochemistry "remains for the moment still an open question," but by no means falsities that theory. He portrayed the issue of monomeric versus dimeric radicals likewise as open, and rehearsed all his previous rebuttals to Gerhardt, Laurent, Hofmann, and Brodie.

However, Wurtz' new research was "without a doubt . . . of much greater significance for this question" than the earlier boiling point argument. The vapor density and boiling point of the mixed radical butyl-amyl, for instance, fit right between butyl and amyl, and it just matched Hofmann's prediction, which strongly suggested that the symmetrical radicals were butyl-butyl and amyl-amyl. But after fairly summarizing this evidence, Kolbe still demurred: "It remains for the moment undecided and questionable whether these facts have sufficient probative force" to compel a doubling of the radical formulas. After proclaiming Wurtz' evidence highly important, he did not even attempt a reasoned refutation, but rather simply judged the issue still open.

Frankland later stated that through correspondence during the year 1856 he was able to persuade his friend Kolbe to retract the critique of the law of maximum combining capacities that had appeared in his textbook in June 1854.^[57] Unfortunately, none of these letters have been found. It would seem, however, that at least the beginning of the correspondence on this subject may have been earlier than Frankland in-

dicated, for this article reveals that Kolbe's conversion dates from the end of 1855. Significantly, Kolbe now not only accepted Frankland's law for metals, nitrogen, phosphorus, antimony, and arsenic but expanded it to include carbon as well. If one takes as one's type carbonic acid, formulated as 2HO.C₂ O₄ , and assumes that it has a maximum combining capacity of four, then replacement of one oxygen atom by methyl results in acetic acid, HO.(C₂ H₃ )C₂ ,O₃ . (In Berzelian fashion, the half-molecules of water HO were considered external and not essential to the composition of the acid. One needed simply to omit an HO group in moving from a dibasic to a monobasic acid.) A second methyl in the place of oxygen would yield the neutral substance acetone, (C₂ H₃ )₂ C₂ C₂ (omitting the second half-molecule of water).^[58]

Kolbe's "carbonic acid theory," as it evolved into its final formulation by 1860, is described in detail in chapter 8. Here it suffices to note that it was essentially a "newer type theory" very similar to, and clearly influenced by, those of Williamson, Gerhardt, Hofmann, Frankland, and Wurtz. Kolbe later conceded that he had become a type theorist (but always insisted that his types were sharply distinct from those of Gerhardt and his followers). He also eventually conceded that he had been wrong when in 1854 he attacked Williamson's interpretation of his ether synthesis.^[59]