The Crusade

Kolbe switched to the new atomic weights in 1868, at the same point that he decided to take a stand against the theory of chains, valence bonds, and benzene rings. Coincidentally, at the beginning of 1870 editorship of the Journal für praktische Chemie fell into his lap, which provided a bully pulpit for educating and haranguing the chemical world. He quickly penned a manifesto to open his first volume, then found repeated occasion during his first two years as editor to compare his views with those of the structuralists.

He now understood, correctly, that structure theory posited a sort of chemical "democracy," in which every atom is in principle as important as every other. Kolbe's own model was that of an army: a methyl group, for example, is like a "commando" unit consisting of a corporal (carbon) and three privates (hydrogen); in propane there are two more carbon atoms, but these are of higher rank than corporal and hence are chemically more central. The following year he used another metaphor, that of an autocratic state, which is effective precisely because it is hierarchical, in contrast to a democracy.^[37]

At first, these discussions were carried on without evident rancor on either side. At the 1867 Naturforscherversammlung in Frankfurt, Kekulé treated Kolbe with extreme cordiality and Kolbe resolved privately to reciprocate in the future. By 1874, this was more difficult; at a chance meeting at a resort in Interlaken, Kolbe brushed off Baeyer's friendliness.^[38] The transition appears to have been precipitated by national and personal events that occurred in 1870-1871.

Kolbe was unwell most of the summer of 1871, suffering from dizziness and nausea. Finally, he traveled to Marienbad for a five-week cure, which did him much good. Upon his return, he wrote Varrentrapp,

I used the involuntary leisure in Marienbad to give my chemical heart and conscience some relief and to expose the great flaws and weaknesses of the new chemical fashions. Much real mischief in this line is being done by both older and especially younger chemists, and since no one else is opening his mouth to stand up against this swindle, I have considered it my duty once more to burn all ten fingers by portraying this modern child in its true flaws.^[39]

In this new essay, "Fashions of Modern Chemistry," Kolbe indicted structure theory for being at once too empirical and too speculative. The structuralists were overly schematic, hence guilty of "crass empiricism," in immediately turning to pencil-and-paper manipulations once they had an empirical formula. They failed to investigate the hierarchy of radicals forming a molecule, merely drawing pretty pictures that purport to explain all chemical relationships of the compound. At the same time, he thought, they were overly speculative in that they presumed to have the ability to specify spatial arrangements of the constituent atoms. Once he gave his amanuensis the empirical formulas for three novel compounds for which their discoverer had just assigned structural formulas. The man reported back in a half hour with several more candidate structures, some of which looked more probable to Kolbe. Kolbe concluded that structure theory is a dangerous toy, especially for inexperienced chemists, and that structures are often assigned "in one's sleep," with little or no empirical warrant.^[40]

Privately, Frankland "entirely dissent[ed]" from this judgment:

[I]t seems to me that your experiment with your amanuensis resulted in a great triumph for these formulae; since, without any previous knowledge of the subject, he at once found the only possible constitutional formula for one of the compounds whilst his formulae for the two others would be at once modified by a chemist as unnecessarily complex. Surely the more simple, & free from possible misconstruction, such formulae can

be, the better. And I think they are generally used by chemists, not as means of investigation but as expressions of the writer's ideas of the constitution of the bodies he is describing· But even as instruments of investigation they are not altogether useless . . .^[41]

Volhard also objected privately; he joined Frankland in expressing regret over the personal character of many of Kolbe's remarks. Kolbe's response was straightforward:

Scientific matters must not be taken personally. I cannot help myself, I must criticize and contest the chemical ideas that I consider false and worthless, just as I tolerate others' opinions, and I am happy to see my views contested, when the controversy is pursued in a gentlemanly fashion. Science always benefits from that. . . . You say that my critiques will only succeed in gradually alienating all the chemists of Germany. That may be the case, if not for all, at least for many, i.e., for some time; but I ask you, did Liebig ever hesitate to express his convictions, in critiques and otherwise, for fear of thereby alienating many?

As he later wrote Varrentrapp, he would rather be considered sharp-tongued than cowardly.^[42] He now fulfilled a longstanding desire to follow the examples of Berzelius and Liebig by starting a series of annual critical retrospective essays, published each December in his journal. These gave him additional opportunities for spicy polemical harangues.

In Kolbe's third and fourth retrospects, those for 1873 and 1874, he went after his favorite example of structuralist excess: Kekulé's benzene theory. He absolved Kekulé himself of much of the blame,^[43] for he was convinced that Kekulé regarded the theory merely as an intriguing and useful hypothesis. However, most chemists by this time viewed the hexagon as "infallible dogma," as "the Pope is for Catholics." They were true fanatics, Kolbe wrote, and viewed him (Kolbe) as a rank beginner, of weak understanding. They were right, he thought, for he could not understand arguments built "in the air" or "on loose shifting sand." The end of their sand castles was not distant. Kolbe continued,

The modern chemist, who knows exactly what a chemical compound looks like in its middle and its end, how the six carbon atoms of benzene are symmetrically linked together in a plane, who then further purports . . . to have a clear conception of the spatial arrangement of the atoms, of their ortho, meta, and para positions, who determines the positions of all of the atoms in the compound, has long since abandoned the solid ground of exact science; the scientist has become a metaphysician. Rhetoric which is bereft both of content and of value but which sounds profound has begun to displace solid research and sober judgment.^[44]

Kolbe later developed this image by defining true physicists as "ortho" physicists, versus "paraphysicists" who pursued fanciful notions such as kinetic theory and metaphysicists who have no use whatever for experimental confirmation. In his own view, he was an "orthochemist" and Kekulé was a "parachemist."^[45]

Kolbe found his ideal model for the "metachemist" pursuing "transcendental chemistry" when the then-unknown J. H. van't Hoff unveiled his theory of the asymmetric carbon atom, the first step toward chemistry considered in three dimensions—soon to be called stereo-chemistry. Van't Hoff, who had studied with Kekulé and Wurtz, first found employment at the Utrecht Veterinary College; in 1878 he was appointed at the University of Amsterdam. A sketch of the theory was published in Dutch in 1874, and a longer French version appeared the next year. The first enthusiastic advocate of van't Hoff's theory was Johannes Wislicenus, professor at Würzburg, who was a mid-career structural organic chemist with a fine reputation; he had even published some thoughts on three-dimensional (physical) isomerism himself. Wislicenus asked his student F. Herrmann to prepare a German translation of van't Hoff's "Chemistry in Space," wrote an enthusiastic preface, and sold the work to Vieweg Verlag.^[46] Kolbe found out about this translation almost immediately because the Vieweg company had a long-established policy of automatically sending proof sheets of all their organic-chemical publications to Kolbe.^[47]

Kolbe was not a happy man at this time. Suffering repeated bouts of ill health himself, he had seen in the past few years the deaths of many of his closest friends and relatives: Otto Erdmann and Eduard Vieweg in 1869, F. J. Otto in 1870, his own father also in 1870, and Liebig in 1873. By far the hardest blow was the death from cancer of his beloved wife on 26 December 1876. He heard about Franz Varrentrapp's death on 3 March 1877, while he was still severely depressed about his wife. Kolbe was close to sixty himself, exhausted and in poor health. To Heinrich Vieweg's business manager Herr Lücke Kolbe wrote, "The older one gets, the more frequently one looks around himself in the circle of his friends and close relatives, watching Death carry out his sad and terrible office, until one's own turn comes around."^[48] After losing out to Baeyer as Liebig's successor in Munich (1875), Kolbe knew that he was in Leipzig for the duration.

It was in such a mood, no doubt feeling that he no longer had anything to lose or anyone to please, nor any time to waste, that Kolbe sat down to compose under the heading "Sign of the Times" a thundering reproof against van't Hoff and Wislicenus, a devastating critique that would once and for all extirpate this "cancer" of structuralism (for that is what he considered and named it). Using another pathological

metaphor, he claimed that modern chemistry was nothing less than a revisiting of Naturphilosophie , the "plague of the century" as Liebig called it, promoted by pseudoscientists who wish to smuggle their wild notions into the science, like introducing a fashionably dressed prostitute "into good society where she does not belong."

Whoever thinks this worry seems exaggerated should read, if he is capable of it, the recent phantasmagorically frivolous puffery . . . on "The Arrangement of Atoms in Space." . . . A Dr. J. H. van't Hoff, of the Veterinary School of Utrecht, finds, it seems, no taste for exact chemical research. He has considered it more convenient to mount Pegasus (apparently on loan from the Veterinary School) and to proclaim in his "La chimie dans l'espace" how, during his bold flight to the top of the chemical Parnassus, the atoms appeared to him to be arranged in cosmic space. The prosaic chemical world had no taste for these hallucinations, so Dr. F. Herrmann, assistant at the Heidelberg Agricultural Institute, undertook a German edition to give the work a wider audience. . . . It is typical of these uncritical and anti-critical times that two virtually unknown chemists, one of them at a veterinary school and the other at an agricultural institute, pursue and attempt to answer the deepest problems of chemistry which probably will never be resolved (especially the question of the spatial arrangement of atoms), and moreover with an assurance and an impudence which literally astounds the true scientist.

These notions would have been quietly buried, Kolbe noted, had not a chemist of reputation, Wislicenus, taken van't Hoff under his wing. Wislicenus had thereby placed himself in imminent danger of squandering that reputation, of no longer being considered a true scientist but a "spiritist of the first water."^[49] To his friend the publisher, Kolbe was unrepentant, for he wrote Heinrich Vieweg that his critique could only increase sales. "I don't understand Wislicenus," he added. "Sometimes I fear that he may not be of sound mind."^[50]

Wislicenus was understandably upset. A fundamentally kind and broadminded man, he wrote Kolbe a long, emotional letter, trying hard not to show open anger.

You cannot possibly have studied van't Hoff's essay . . . [for] how else could you have reproached me (by logic I do not understand) for a tendency toward spiritualism, or held against the young van't Hoff his position at a veterinary school, or against the translator Herrmann, who was my assistant and solely due to pressing external circumstances accepted a position at the agricultural institute in Heidelberg! I have never doubted that it is a holy zeal for the truth that guides your critical pen; but on the other hand I regret that you do not seem to concede any possibility of your own fallibility, which everyone must grant. . . . I

know that I can err, but I also know that I have no cause to allow myself to be struck from the ranks of exact scientists, for I as well as you have the will to serve the truth . . .^[51]

Van't Hoff responded publicly, and very effectively, in the pages of the Berichte :

A theory that so far is contradicted by no single fact can only be further examined experimentally. Thus when someone, even so fine a chemist as Kolbe, avers that a chemist who is not yet well known and who is employed at a veterinary school should not bother himself with theories . . . I can only say that such behavior fortunately is not a sign of the times, but rather must be regarded as a contribution to understanding a single individual.^[52]

Kolbe's critique of van't Hoff was his most famous diatribe, certainly his most humorous, and one of his most vicious. It was at this time that many began to wonder if Kolbe had become mentally ill.^[53] Whether literally ill or not, there is no question that he was sick at heart at what he saw happening to his beloved science. To be sure, he was not alone in thinking that structural chemists often went overboard. The following October he had a conversation with his old mentor Wöhler, during which Wöhler commented that "what is published these days as chemistry, is not chemistry at all." However, when Kolbe pleaded with him to allow his words to be quoted directly, Wöhler quickly and strongly demurred, saying that he hardly even read the literature any more. Kolbe responded that he didn't either, and had just as little understanding of "modern" chemistry. Similarly, Kolbe urged his true Doktorvater Bunsen, who was likewise sympathetic with Kolbe's position, to stand with him against the structuralists, but Bunsen also firmly declined, even (like Wöhler) to have his name mentioned. With Berzelius and Liebig dead and Wöhler and Bunsen unwilling even to be named, Kolbe felt very much alone.^[54] Ernst von Meyer, Kolbe's loyal assistant and loving son-in-law, became co-editor of the Journal für praktische Chemie at the beginning of 1879 and, as he later related, often tried to exert a moderating influence—only occasionally with success.^[55]

Wislicenus' and van't Hoff's complaints may have had some influence, at least in redirecting Kolbe's fire toward more prominent chemists. Kolbe decided, after all, that the only way to destroy the weed was to get to its roots, so from this time on he went right after Kekulé, as well as Kekulé's most famous student, Baeyer. Seven months after the van't Hoff polemic, Kolbe published a "Confidential Letter to Professor Kolbe," purportedly written by a structuralist

named "Dr. R.," but in fact written by himself as a parody of structure theory.^[56] Kekulé, whose recent rectoral address at Bonn (18 October 1877) was well roasted in the piece and who could easily divine the real author, wrote an "open letter" in rebuttal and asked Kolbe to publish it. To twist the sword in the wound as best he could, Kekulé pretended ignorance of the identity of "Dr. R." and added that, in contrast to Dr. R., he should be identified as the author of the rebuttal, for "I have always been of the opinion that anyone who respects himself must also have the courage to accept responsibility for his actions and words." He then said that he did not doubt that Kolbe would print the piece, knowing Kolbe's sense of fair play.^[57]

Kekulé had trapped Kolbe, but Kolbe was resourceful and squirmed away. As it happens, he had just composed a "Critique of Kekulé's Rectoral Address," and so he published this together with Kekulé's rebuttal in the same issue.^[58] Kolbe now really let loose. Kekulé's speech was poorly constructed, he said, almost illiterate, the obvious product of a former Realschüler ;^[59] Kolbe cited a number of what he thought were egregious solecisms. More substantively, Kekulé's chemistry was not only colored by "crude Haekelism" but was also filled with "wild phantasies without any real basis." His latest hypothesis of intramolecular atomic vibrations illustrated to Kolbe "to what monstrosities an intellectually gifted man can let himself be carried, who has not learned early to order his thoughts, to think logically, and to rein his imagination." He twice ridiculed Kekulé's "chemical dreams" and concluded by offering a "dream" of his own. The carbon atoms of benzene, you see, are constrained by three bonds each, so they must move in the fourth dimension! "Das ist meine Theorie, " Kolbe proclaimed triumphantly, but confessed that he had not the courage to develop this idea any further, so he would leave it to the "most modern chemists" to do so.^[60] Graebe was dismayed by this article. He wrote Rudolf Schmitt, "I always regret that such a significant scientist, who is personally so amiable, puts himself in such a false light with articles like this. Those who don't know him imagine him to be an unpleasant person."^[61]

A few months after this episode, Kolbe found occasion to heap ridicule on Baeyer in a similar fashion. Baeyer had given an address on chemical synthesis in honor of King Ludwig's thirty-second birthday, in which he portrayed for a lay audience some of the leading ideas of recent chemistry and physics. To make the concepts accessible, he eschewed scientific terminology and epistemologically cautious circumlocutions, speaking, for example, of valence bonds as analogous to "fishhooks," atomic "glue," and so on. In his published critique, Kolbe made much of Baeyer following his teacher's example—the speech was

just as baroque, illogical, and dreamlike.^[62] He wrote Wöhler, "I'm no spiritist, but I would not have been surprised if Liebig's ghost had seized him by the collar after this speech and thrown him from the podium as an unworthy successor." He told Frankland to read it for amusement—"much wilder than Kekulé's rectoral address . . . I think my critique will somewhat ameliorate his obscurity; Kekulé has also already become tamer." He thought Baeyer might be suffering from softening of the brain or megalomania.^[63]

Volhard, like Graebe, was appalled by Kolbe's attacks and wrote his former mentor: "I ask you please for all the world no more critiques like that of Kekulé's rectoral address! I cannot agree with this critique in any way." He pointed out that an annual address is compulsory for the university's rector and that it must be directed to a lay audience; consequently, "es ist nicht fair zu kritisieren" as if it were a chemical treatise.

And as for the form, I ask you: What do you care about Kekulé's style, or his classical education? Consideration for K's scientific accomplishments, indeed mere collegial respect ought to have stopped you from treating this man as if you were a teacher looking over a schoolboy's assignments and correcting his mistakes. . . . I beseech you, no more such intemperate critiques! More tolerance and respect for scientists who have made and are still making their contributions!

Volhard was a good friend who had enormous respect for Kolbe; indeed, he regarded Kolbe as one of the greatest chemists of the century, and Kolbe knew it.^[64] Kolbe also liked and respected Volhard. Only such a man could direct such words to Kolbe.

Even so, they put Kolbe in a rage, answering Volhard with visible effort to control his pen. It particularly galled him that Volhard had accused him of being unfair , when in fact he was placing himself bravely and alone in the line of fire for the sake of his beloved science, while Volhard and everyone else were sitting comfortably on the sidelines. This time there were no horsey metaphors, but sexual, militaristic, religious, and political ones. Kolbe wrote,

Your letter troubled me, for I see from it that you now number yourself among the (in a word) weaklings who are not troubled when our chemical social democrats, Kekulé and Baeyer, slap the face of our science and soil it, but who break out in a sweat when a pure hand is raised to put a stop to it. . . . I cannot sit quietly and see these two make our science a footstool of their vanity and misuse it to satisfy their arrogance. Have you too really come so far in these feeble materialistic times that you can no longer be inspired by higher goals, by ideals? . . . Believe me, I enjoy criticizing; can you not imagine, since all others out of convenience or

cowardice are silent, that someone feels the calling and the obligation to science to stand up for it publicly? . . . I close by assuring you that wherever our science is violated you will always find me, as long as I have the power, as the first of her defenders.^[65]

Kolbe was increasingly frustrated. He continued to write to friends, seeking comrades for his crusade, but found at best silent support, more commonly demurs and even rebukes. These made no difference to his actions, for he became if possible even more personal. One of his favorite hobby horses in the last few years of his life was linguistic critiques. Kolbe was an excellent writer; however, he harbored the common delusions (consistent with his conservatism in other areas) that there was a happy time, long before the present corrupt age, when all educated people wrote "classic" German, and that philology was properly a prescriptive rather than a descriptive enterprise. In some cases his remarks were well founded, even if petty and unnecessary; in other cases he was simply closed-minded and parochial.^[66] He often exclaimed m print, sarcastically remarking on his victims' lapses, "This is how a professor at a German university writes!" He also campaigned against Realschulen, for he was convinced that only exposure to classical neohumanism in the traditional Gymnasium could truly educate.

Kolbe's old friend and comrade-in-arms Frankland provided the final straw. The first sign of real trouble was when Kolbe heard that Frankland was sending his ion Percy to study with Wislicenus, rather than with him or Bunsen. Kolbe could hardly believe it. Wislicenus "has long since ceased to be an exact scientist, but rather is a Naturphilosoph, a metaphysician"; a boring chemist, even if a fine man.^[67] Then Kolbe found out from reading proofs from Vieweg that, in a historical introduction to Roscoe and Schorlemmer's major treatise of organic chemistry, they had uncritically accepted Kekulé's view of the last forty years. This was highly worrisome to Kolbe, for Roscoe and Schorlemmer had both been Bunsen students, and the inorganic portion of their textbook had already proven to be influential. He fired off a letter to Roscoe. "Kekulé has deliberately falsified history, in order to place himself and the French chemists he is so fond of in the foreground." It is Frankland and he, Kolbe continued, who deserve credit for valence theory. Moreover, Kekulé is uneducated, cannot think clearly, lies, steals, and seeks to derogate and slander great men such as Berzelius. His Lehrbuch is the "worst textbook that we have." Roscoe sent Kolbe's letter to Schorlemmer, who was simply amused, and thought Kolbe to be "mad as a march-hare." His accusation that Kekulé had stolen carbon tetravalence from him and Frankland was "best proof that he is mad!"^[68]

Having failed to receive satisfaction from Roscoe, Kolbe now set to work to fight the historical record, also with the intent of defending Frankland. He wrote a long essay on "My Participation in the Development of Theoretical Chemistry" and published it piecemeal in his journal.^[69] Here he portrayed the whole of modern chemistry as a highly injurious product of the unscientific and sterile French chemistry of Dumas, Laurent, and Gerhardt. Kekulé, Baeyer, Wislicenus, Fischer, and others had substituted flights of fancy and the painting of pretty pictures for the exact scientific principles that Berzelius had introduced into chemistry and whose further development had been due to such men as Liebig, Wöhler, Bunsen, Frankland, and himself. Kolbe felt that his seminal work had been systematically ignored by the structuralists—which is not far from the truth. He did not hesitate to accuse Kekulé of both the largest and the smallest transgressions: he repeatedly and explicitly proclaimed that Kekulé's conduct could only be viewed as intentional usurpation of the theories of others, then added insult to injury by filling page after page with stylistic criticisms. He even cruelly drew attention to Kekulé's premature aging, which he maliciously ascribed to his guilt for self-consciously leading German chemistry down the structuralist cul de sac.^[70]

As for structural formulas, he characterized them no fewer than three times as "grob sinnlich" (coarsely sensual) and materialistic, moreover, as a symbol of an unachievable goal.

The sober prudent scientist will tell [Kekulé] that the object for which he and the majority of modern chemists strive is a chimera, that we will never succeed in gaining a conception of the arrangement of the atoms in the molecule, and that chemists should set for themselves a more modest goal: the investigation of chemical constitution in the sense of Berzelius . The goal for which Kekulé strives, and which he considers accessible, is actually even more inaccessible for us than the moon, for we can see the moon and determine its form, but atoms we cannot see, and their form is perceivable with none of our senses.^[71]

These words were echoed (and partly contradicted) in the foreword to Kolbe's abridged organic chemistry textbook, written in February 1883. Structural formulas are mechanical and coarsely sensual, a symptom of the modern "crassly materialistic treatment of scientific matters; the latter ought to be conceived by the mind and not mechanically."^[72]

Having defended Frankland's priority, Kolbe now tried to get him on board. He asked Frankland for permission to title the brochure version of his essay "Frankland's and My Participation in the Development of Theoretical Chemistry." Frankland had no objection, as long

as Kolbe would state clearly in the preface that he alone was responsible for the contents. Kolbe was taken aback at this request and withdrew his suggestion. "Why are you so fearful? You want me to pull your chestnuts out of the fire; I do not hesitate to do that, having no fear of the fire of truth. . . . We should have stood up against the insolent behavior of these people years ago. But perhaps even now it is not too late."^[73] Now it was Frankland's turn to feel a bit insulted. He replied that he was perfectly capable of taking care of his own chestnuts; indeed, he had been the first, four years earlier, to assert his and Kolbe's fight to valence theory; but by "mixing up Dumas and Wurtz with the protest," he felt (no doubt rightly) that this would weaken the case that needed to be reiterated.^[74]

Here the matter rested for two years. Finally, Kolbe dusted off the chestnuts once more and wrote his friend. "If only other chemists, and above all I am thinking of you, would not always leave me alone to pull the chestnuts from the fire, but would instead come to my aid in energetically fighting Baeyer and the thoughtless hollow schematism of structural chemistry." We could "finish Kekulé off" once and for all, Kolbe promised, and show structuralism for the humbug it is. Frank-land was incredulous.

Your letter astonished me not a little for it had never entered my head to imagine that you could for one moment think of me as in any degree an antistruktur Chemiker. Still less that you should think of me as one likely gegen die Strukturchemie "energisch zu kämpfen " or as one sharing your opinion that die Strukturchemie ein Humbug ist! Turn over the leaves of my "Lecture Notes for Chemical Students" and you see Strukturchemie in its extremest development on almost every page! . . . That there should be no more such mistake in future, I here record my Glaubensbekänntniss: Chemistry owes its progress from empiricism to exact science entirely (so far as theoretical conceptions are concerned) to Strukturchemie. Without Strukturchemie there is no science of chemistry . And allow me to add,—two of the first Strukturchemiker to whom this progress is due were Berzelius & Kolbe!^[75]

And now it was Kolbe's turn to be astonished. Who had seduced his friend (or, rather, former friend), "you , who were once upon a time, with me, a champion of positive exact chemistry," into becoming a "spiritist"? Did not Frankland remember those golden days of great scientific discovery in Marburg? And now Frankland had not only turned tail, but had insulted Kolbe by branding him with the despised epithet "structuralist." "I now see that we do not understand each other."^[76] This was the end of their correspondence.

Neither Kekulé nor Baeyer ever really responded to Kolbe's insults. Kekulé wrote up a long response, and sent it to his friend Volhard, then editor of the Annalen . Volhard strongly urged him to withdraw it.

Don't you see that you will only thereby legitimize his attack, which can only properly be condemned by maintaining silence. You may be sure that no one will welcome your defense more than Kolbe himself, for it would finally break this terrifying silence, and give him the opportunity for a salty reply. And, as before, you will be sure to draw the short end of the stick, for you are no match for Kolbe when it comes to coarseness and ruthlessness.

"That's what I call friendship," Kekulé gratefully replied, and took Volhard's advice.^[77] As regards Baeyer, Volhard again offered advice and consolation, this time to Baeyer's wife.

My old friend Kolbe is behaving truly irresponsibly. A pity on the man; since he began to devote himself to insults he has produced nothing more of value. Moreover, one is in good company when one is up-braided by him, so one may always console oneself this way. Everyone who has achieved some reputation in science should take K. as a cautionary example: he believes it sincerely, considers it his duty to behave this way; he does not see what immoderate overestimation of himself is involved, although he is otherwise a very clever and intelligent man.^[78]

As Volhard had predicted in 1876, Kolbe had now succeeded in alienating himself from most prominent German chemists, including several hitherto good friends (we will see how he and Hofmann parted ways in the next chapter). Volhard was still left, but not for long. On 20 July 1884, they had a conversation during which apparently they could agree on nothing; Kolbe's letter the following day (one of his last surviving letters) complained that Volhard, too, had now been "badly infected by Kekulé's and Baeyer's dogmas."^[79]

Kolbe had other shocks as well. Even after his devastating denunciation of van't Hoff's small book, Heinrich Vieweg accepted a larger work by the same author, Ansichten über die organische Chemie , just a year later. ("The greatest nonsense I have ever read," fumed Kolbe to Vieweg. "The author is definitely out of his mind, ready for the madhouse.") Then Vieweg selected Wislicenus to edit—and structuralize!—Strecker's organic chemistry, which had been Kolbe's favorite text. Kolbe was appalled at this "disfigurement." He feared that Wislicenus might be called to Halle as Heintz' successor, thus making him a close neighbor (in fact, Volhard was called to Halle, but Wislicenus became Kolbe's successor three years later!). The Hand-

wörterbuch der reinen und angewandten Chemie , for years Kolbe's brainchild, had long since become a structuralist reference work. Kolbe made Vieweg add a clause to his contract for his own Kurzes Lehrbuch der Chemie , stipulating that in the event of his death, Vieweg would not choose a structuralist editor.^[80] He now knew that he would not live to see the revolution that for the last quarter century he had been predicting as imminent. "We live now in a time of barbarization [Verwilderung ] in chemistry, like never before," Kolbe mused sadly. "Soon the crash will come, and then the loudmouths will vanish from the scene."^[81]

The last meeting between Kekulé and Kolbe was bitter, although Kolbe enjoyed every moment. On 4 April 1884, Kekulé and his wife arrived at a resort (in Bodighera, on the Italian Riviera) where Kolbe also happened to be vacationing. "You should have seen his pale, frightened face the next morning . . . when he first saw me," Kolbe wrote his nephew. "He is an old man , stooped over; I would never have recognized him had I not known it was him." The Kekulés had intended to stay a week, but left after three days: "I smoked him out," Kolbe related gleefully.^[82] Kekulé was then fifty-four, Kolbe sixty-five. We do not know Kekulé's reaction when he heard of Kolbe's death seven months later.

It is now time to take a step back from the fray and directly ask an important question that we have been skirting. Was Kolbe simply a sour old man whose crusade was motivated by an irrational obsession or monomania (as Armstrong later called it)—in short, was he acting as a poor scientist? As much as this places one under vehement suspicion of Whiggery—for Kolbe was so unfortunate as to contest much of what constitutes organic chemical theory today—it is difficult to avoid giving an affirmative response to this question. In defending oneself from Whig opprobrium, one might note that as regards contemporary opinion after 1870, Kolbe lost nearly all of his specific factual arguments and convinced absolutely no one of the truth of his modified radical theory of organic constitutions, even his own students and closest friends. Moreover, the previous discussion has shown that he himself recognized the completeness of his defeat by the time of his death.

That said, it must be noted that while most of Kolbe's theoretical affirmations after 1870 were unsuccessful, by no means did all of his criticisms of his opponents miss the mark. We have seen that Kolbe had substantial silent support for many of these criticisms among such men as Liebig, Erdmann, Varrentrapp, Wöhler, Bunsen, Beilstein, Erlenmeyer, Frankland, and even Volhard and Lother Meyer on occasion. I have found no Kolbe correspondent who denied that there was

a great deal of inferior, sloppy, and excessively conjectural work being published, and they all agreed that the amount of such unsatisfactory research was increasing. (Volhard believed that this had nothing to do with structure theory but rather simply with the great expansion of the field; it was no longer a self-selected elite group, as it was a generation earlier, but a mass of average workers creating mass-produced science.^[83] ) In fact, Kolbe was justified in his accusation that structural formulas were sometimes bandied about thoughtlessly and superficially, with little regard to empirical evidence and reasoned justification.^[84]

Of course, the same charge could be laid at Kolbe's door, to the extent that he may be considered a structural chemist himself. Was he? Contemporary opinion on this point was unanimously in the affirmative, not only in the view of structuralist opponents such as Kekulé, Wislicenus, Lothar Meyer, and so on but also in the opinion of those who knew him best: his students, former students, friends, colleagues, and family members, including Frankland, Claus, Crum Brown, Volhard, Ernst von Meyer, and Ost.

But despite this unanimity, the assertion is not strictly true. To be sure, Kolbe's views and those of the structuralists coincided on many points, and formula translation was always possible between the two systems. However, there were also real differences, as I have been at pains to argue in this and the preceding five chapters. In the course of his career, Kolbe made many predictions of the possible existence of new compounds and new isomers; some of these predictions were fulfilled, some were not. Some of his predictions were fully equivalent to those of the structuralists, while some highlighted the distinctions between the two systems. It is remarkable that every time Kolbe attempted a crucial test, that is, of a prediction of the latter type, the result disappointed him.

Let us review some examples, most of which we have seen before. As early as 1857 and 1858, Kolbe was predicting the existence of a variety of isomers of alcohols, glycols, acids, and aldehydes, including isomers of oxalic, glycolic, and lactic acids. He thought that Wurtz' glycol ought to be dehydratable to aldehyde, but that it could never be oxidized to an acid. In his 1868 treatise, he predicted two isomeric propylenes and no fewer than fifteen isomeric pentanes.^[85] He tried to find an isomalonic acid and a second carbon oxysulfide, and he thought that a chemical distinction between the two chlorine atoms in 1,3-dichloropropylene ought to be demonstrable. He looked for reduction products of benzene, an isomer of benzene, and isomers of all monosubstituted benzenes, and he thought there should be four isomers of each disubstituted benzene. He was able to find none of these compounds or reactions.

Kolbe was continually predicting isomers in excess of those envisioned by classical structure theory because of his hierarchical view of organic molecules (each carbon atom in a molecule, considered as the Stammradikal , should give rise to a distinct series of isomers) and because he was convinced that the four valences of carbon were intrinsically distinct. Chemists of the 1860s and 1870s were already being deluged by a flood of new isomers, and most greeted the apparent proof of equivalence of carbon valences with considerable relief. But Kolbe simply refused to accept the evidence provided by the nonexistence of isomers. This was true even though many positive refutations of his predictions emanated from his own laboratory (for some examples, see note 36 in this chapter). Logically, his position was impeccable: the missing isomers are simply too labile to be isolated, transforming themselves into known isomers before they can be characterized; or we simply have failed to find the right reagents or conditions to produce them. But the accumulating empirical evidence became more and more difficult to ignore or brush aside. It is little wonder that he was unable to convince his colleagues in the field, and even his own students, of the advantages of his system over that of the structuralists.