Preferred Citation: Rocke, Alan J. The Quiet Revolution: Hermann Kolbe and the Science of Organic Chemistry. Berkeley:  University of California Press,  c1993 1993.

8— Carbonic Acid and Natural Types

The Response

On the day the article was officially published, Kolbe wrote Vieweg, concerned about the general course of battle in his war with the reformers. The majority of chemists were now following Gerhardt—even his good friend, the otherwise sober and reasonable Strecker—and Kolbe was isolated in his opposition.

In my view this whole movement has already outlived its usefulness. Such mindless ideas as are to be found in Weltzien are its dying echoes. The adherents of Gerhardt's school in Germany as in France have shot their bolt. They are riding to death the poor old nag that carried Gerhardt forward for a time, without producing anything other than variations on the old theme. Not even the entire great Göttingen school has educated anything approaching a capable and intelligent chemist. Limpricht has created a spectacle, but produced not a single piece of work that shows anything like ingenuity or sharpness of intellect. Fully as unthinking a man, but correspondingly foolish a chatterer, is Kekulé. In a word, the whole mindless business, on which I expressed my judgment in the beginning and concluding sentence of the article just now appearing, is bankrupt and has been outlived. What people of this kind are doing is not science, but a game.— But I see I am letting myself go on too long. The future will tell.[63]

Considering these views, it must have been extraordinarily discouraging to Kolbe to see that the initial response of many of his colleagues was to place Kolbe himself in the midst of the "whole mindless business" of newer type theory and polyatomic radicals. Wurtz was the only member of the reformist camp to reply in print. In a review of the article in his Répertoire de chimie pure , he wrote: "Monsieur Kolbe has so fully adopted the fundamental idea of types that not only does he want to multiply them, but even, with Gerhardt, to assume condensed types, as are represented by [his] molecules of carbonic acid." The carbonic acid type, Wurtz affirmed, is nothing more than the water type with diatomic carbonic oxide functioning as the oxygen atom, as Williamson had formulated it in 1851.

Wurtz thought Kolbe's argument that Gerhardt's four types are artificial was not a trivial one; nature should indeed not be limited in this way. But what Kolbe did not see, Wurtz argued, was that a more general principle lurks behind these types, namely, successive degrees


of condensation of matter. Hydrogen, water, ammonia, and marsh gas represent hydrogen once, twice, thrice, and four times condensed, with the oxygen, nitrogen, and carbon atoms representing two, three, and four atoms of hydrogen, respectively, in one unit of action. This is what he had meant to express in his subatomic speculation of 1855. Wurtz thought that the idea of types ought to be replaced by the idea of the atomicity of the elements, which is the foundation of the phenomena that types attempted to express. "Here is a clear, simple, and general principle, which deserves for this reason to be placed at the base of a system of chemistry." Kolbe's approach was fundamentally the same, Wurtz urged, whether he was aware of this or not. "If, then, the ideas this chemist presents are novel, the innovation resides rather in the form than in the essence, and I believe that I have shown that even the form is not fortunate; in truth, he combats Gerhardt's types by counterfeiting them."[64]

Kolbe's friend Hermann Kopp saw the matter similarly, although he phrased his criticism more kindly. Reviewing the 1860 paper in the Jahresbericht , Kopp wrote: "Kolbe still argues against relating organic compounds in general to the hydrogen, water, and ammonia types, as also against the recent assumption of mixed types. But he reveals himself as a de facto adherent of the 'type theory' by conceiving organic compounds as derivatives of inorganic compounds." Kopp also pointed out that Kolbe had used multiple types to formulate diacids, and suggested the influence of Gerhardt. Three years earlier Kopp had also referred to the Gerhardtian and Williamsonian elements in the Kolbe-Frankland carbonic acid paper.[65]

However, Kolbe's paper impressed one very important reader: Justus Liebig. Liebig wrote Kolbe on 3 April 1860 to express his "great satisfaction" with the paper; the schematic derivation of malic and tartaric acids from succinic acid was "the triumph of your theory."[66] Liebig himself never penetrated the sense of newer type and structural formulas. To Wöhler he admitted his disinterest in modern chemical theory and complained about the thoughtless manipulation of formulas that was going on around him. Wöhler's opinion was similar.[67] In the 1860s Kolbe's and Frankland's articles were some of the few that excited Liebig. He told each of them separately that only in their work could he see the guiding influence of "a large scientific idea" directing the experimental program. To Frankland he wrote: "What Wöhler and I saw thirty years ago in dreams, that is, in our imagination, you are now on the road to realizing. . ." To Kolbe he sympathized regarding the "Formelspielerei" of many who were not on the correct path.[68] Ironically, by the time Liebig was writing this letter Frankland had become a full-fledged member of the structuralist school, whose


manipulation of formulas was entirely in their spirit, while Kolbe was making a sharp distinction between his and nearly everyone else's formulas.

Liebig's support fortified Kolbe's spirits at a time when it appeared all the world was converting to the reform. Led by Kekulé, a small cabal including Weltzien, Baeyer, Roscoe, and Wurtz planned an international conference whose ulterior motive was to attempt a world standardization of the Gerhardt-Laurent atomic weights and molecular formulas.[69] The need for such a meeting was by no means uniformly conceded. Some, such as Leopold von Pebal who had been a confirmed Gerhardtian for years, thought such a degree of unity already prevailed that it was not necessary. He expressed this sentiment in a letter to Roscoe, adding "Kolbe will hardly be converted!"[70] Others, including some reformers themselves such as Williamson and Brodie, thought it was unseemly to attempt, or even to give the impression of attempting, to legislate scientific conviction. Several, including Erdmann and Kopp, espoused such sentiments at the meeting itself.[71]

Lothar Meyer, a leader of the reform movement after 1860 and a good friend of Pebal and Roscoe from their Heidelberg period, occupied an ambivalent and interesting position before the meeting. He was still studying with Bunsen in Heidelberg when Kekulé arrived there early in 1856, and Kekulé's eager advocacy for Gerhardt's type theory made a strong impression on Meyer, according to his later reminiscences. "How very well I remember even today," he recalled,

. . . the debates lasting hours and days, in which he won ground step by step. The authority of the accepted dualistic theory and the decided aversion of our honored master to get involved with the new business with formulas [Formelkram] explains why we gradually came over to the other side only after energetic resistance.[72]

But in Meyer's case, it would appear, this did not happen before the Karlsruhe Congress. In July 1860 he wrote Roscoe saying he felt obliged to come to the "idiotic church counsel, to propose the election of an infallible formula-pope," but feared what the edicts of the "Committee of Public Safety" at such a "National Convention" might prove to be.

The good Gerhardt, if he only knew what kind of scandal is being made of his innocent types! . . . These "types" are a dangerous toy for fools; but the expression "type theory " is an insult to science, which recognizes a theory of gravitation, of light, of capillarity, etc., but which can never agree to having a notation called a "theory."[73]


As a matter of form, Weltzien wrote Kolbe to ask for his support. Kolbe replied that since the science was so dominated at the moment by the Gerhardt-Williamson-Kekulé-Wurtz school such a conference would do more harm than good. Any resolutions taken at the meeting would have to be overturned upon the fall of the reform movement, an event Kolbe expected to see "in the very near future."[74] Kolbe had every intention of skipping the meeting, but at the last minute he let himself be persuaded by Fehling to go for one day of the three-day conference. It was, he wrote Vieweg, a real "farce," just as he predicted it would be.

Weltzien let himself be used by Kekulé, to give the latter the opportunity to pass himself off to the assembled chemists as the great chemist of the future. Instead of some kind of result or agreement (the most important questions were never even raised), only a general dissatisfaction and disappointment was achieved. Kekulé gained precisely the opposite of what he wanted; he made a real fool of himself and turned everyone against him.[75]

This was, of course, a jaundiced point of view, but the organizers themselves were likewise somewhat disappointed by the absence of concrete results. However, the conference had long-term effects that were not visible in the fall of 1860. Lothar Meyer, who had been so cynical in July, was profoundly affected, not so much by the events themselves in Karlsruhe, but by having been handed an offprint of Cannizzaro's Sunto di un corso di filosofia chimica . He read it on his journey from Karlsruhe and "repeatedly" after his arrival home. He "was astonished by the clearness that the brochure provided concerning the most important points at issue. It was like blinders being removed from my eyes; doubts disappeared, and a quiet feeling of certainty replaced them."[76] The Russian chemist Mendeleev related a similar story regarding Cannizzaro's influence.[77]

The general historical impression that Cannizzaro was the decisive personality in Karlsruhe and that his brochure helped achieve completion of the reform is probably accurate. The work also appears to have had a strong effect on Frankland. In assessing the relative contributions of various chemists to the formulation of structure theory, he gave Cannizzaro a higher place than Kekulé, for it was Cannizzaro, he said, who established the atomic weights that made structure theory viable—a point made by Meyer as well.[78] In any event, Frankland's publications show that in the months before Karlsruhe he had still not accepted some important elements of the reform, whereas by 1862 he was fully in the modernist camp. Wurtz and Hofmann, who had been reformers for years, only began to use the two-volume atomic weights


in their published papers around the time of the conference, and this may also have had some impact on Frankland's thinking.

But it would be erroneous to conclude that Kolbe was the only holdout after Karlsruhe. The elder spokesmen, especially Liebig, Wöhler, Bunsen, and Dumas, continued to prefer the apparently more empirical conventional equivalents. This was partially because they held themselves aloof from the theoretical trends of the day, as they themselves, as well as their ardent defenders such as Kolbe, often admitted. But exceptions existed even among the younger active chemists. Among the French, Marcellin Berthelot was just as contemptuous of the reform movement as Kolbe was. The empirically minded Friedrich Beilstein, another friend of Kekulé's from his Heidelberg period, accepted the new atomic weights, but was disgusted by the facile manipulation of structural formulas.[79] Even Kekulé complained to Meyer, shortly after the Karlsruhe Conference, of "Constitutions-formel-spieler."[80] Indeed, there were many who were happy multiplying possible formulas far beyond necessity—Kolbe himself was susceptible to this charge. In fact, it was surely to Kolbe that Kekulé was referring in the phrase just cited.

8— Carbonic Acid and Natural Types

Preferred Citation: Rocke, Alan J. The Quiet Revolution: Hermann Kolbe and the Science of Organic Chemistry. Berkeley:  University of California Press,  c1993 1993.