The Leipzig Research Group

As we did for the Marburg period, let us begin our analysis with some numerical measures of research productivity using the standard unit of productivity, the published paper. This time we take data across Kolbe's entire career, as shown in table 3.^[24]

Some patterns are apparent in this table. In the early Marburg period—before acquisition of the "carbonic acid theory"—Kolbe's research productivity was low, as was that of his students. The high point of Kolbe's career came during the 1860s, when he was publishing

around three good papers per year and his group authored about ten per year. This overall level of productivity roughly doubled after the great surge in enrollment in the early 1870s, so that he began to publish half a dozen or more solo papers per year and his group about twenty per year. However, this late period was not as productive as it might first appear. For one thing, he had far more students with which to work—five to ten times as many as in Marburg—so that in this light a doubling of total yield appears modest. Moreover, the great majority of his own publications after 1875 were either short notes with no experimental results or polemical critiques.

How does this overall productivity compare to his contemporaries and near contemporaries? His numbers were modest compared to those of Liebig or Wöhler a half generation earlier, to Hofmann in his generation, or to Baeyer a half generation later, each of whom had several hundred personal and collaborative papers; Baeyer's research group at Munich alone is said to have published over 1600 papers.^[25] However, Kekulé himself, certainly the most theoretically important chemist during the third quarter of the century, published only 131 papers, all but 18 of these during the years 1850-1873.^[26] As has often been rightly remarked, numbers of publications do not necessarily correlate to quality or significance.

So let us now attempt to characterize the Leipzig school in terms of subject matter and its significance. Two areas that we have already explored are the synthesis of natural products (chap. 10) and experimental investigations connected with theoretical issues involving romatic compounds (chap. 12), both of which were also represented in Marburg. Another continuation from the Marburg period

was the prediction and production of novel aliphatic isomers, especially secondary and tertiary alcohols and acids. One important field largely new to Leipzig and forming the topic of dozens of his students' dissertation projects was organosulfur compounds. Included in this group were studies on aliphatic and aromatic sulfides, sulfates, sulfonic acids and esters, sulfinic acids and esters, and other organic sulfonyl and sulfoxyl compounds. In the process, scores of new substances were discovered, including the first members of entirely new classes of compounds, such as the dialkyl sulfones, dialkyl sulfoxides, and nitroalkyls. One of the leading ideas motivating this research was Kolbe's conviction, contrary to Kekulé, that the valence of an element was not constant but rather could vary. Indeed, the novel organosulfur compounds named include substances containing divalent, tetravalent, and hexavalent sulfur. The last field that deserves mention is a long series of investigations after 1873 on the preservative and antiseptic properties of salicylic acid, as discussed in the preceding chapter.

In terms of quality and significance, nearly all of this large body of research was quite competent and most of it was scientifically important. However, little of the work done after around 1870 opened up new theoretically significant opportunities. The most exciting topics elsewhere in Germany—positional isomerism in the aromatic field, synthetic methods, structure determinations, and after 1876, stereochemistry—were all outgrowths of the classical structure theory that Kolbe so abhorred. Simply stated, in the 1840s and 1850s, Kolbe had been a principal founder of the investigation of "constitutions" of organic compounds; in the 1860s, he was well able to keep pace with the leaders of the field and to make substantial contributions; but after 1870, the contemporary significance of his work declined dramatically.

Besides research, the other significant activity of an academic institute is education, and so we must now turn to Kolbe's students and junior colleagues in Leipzig. Unfortunately, class lists have not survived, and so a complete analysis by name or even by precise statistics is not possible. From unsystematic indications of the course of overall enrollments, we can presume that Kolbe must have taught something like 1500-2000 Praktikum students during his nineteen years in Leipzig. Many of these were not chemistry majors and had no further contact with the science after their one brief exposure; even some of the chemistry and pharmacy majors doubtless had virtually no impact on the institute. How many people, then, can be considered members of Kolbe's "school"? The widest definition would include all of the following groups: (1) all who published at least one paper from the lab, regardless if they took a degree; (2) all who received a Ph.D. under Kolbe (for which records do exist), regardless if they published; (3) all

assistants, Privatdozenten, and postdoctoral guests, regardless if they published; and (4) all who were mentioned as having assisted in any of the 369 papers in table 3 that date from the Leipzig years. The Leipzig research group in this widest sense consists of 137 identifiable people, just half of whom (68) completed Ph.D. dissertations under Kolbe and all but a dozen of whom appeared as paper authors. These numbers suggest that an average of something like 30 of them were present at any given time, so that his group of advanced Praktikanten may have averaged around 40. Collating these numbers with those from Marburg gives the summary shown in table 4.

Whereas Kolbe's Marburg group was, until his last few years there, almost exclusively composed of Kurhessian students, the group in Leipzig was far more cosmopolitan. About one-fourth of the group was foreign, and of the Germans only about one-third came from Saxony. In his entire career, Kolbe could boast of having taught twenty-one Russian students, twenty Brits, ten Americans, seven Swiss, three Austrians, and a smattering from five other countries (but no French, Italian, or Spanish students). Of these, five Russian and seven British students took their Ph.D. degrees with Kolbe.^[27]

Indeed, it was with his foreign students that Kolbe had many of his greatest educational successes. Edward Frankland (as sort of an unofficial Kolbean) and Henry Armstrong (1848-1937) were two of the most influential science educators of their day in England, and they were considered the deans of late nineteenth- and early twentieth-century British chemistry, respectively. Zaitsev (1841-1910), Menshutkin (1842-1907), and Markovnikov (1838-1904), all world-class chemists, made a great impact in Kazan, St. Petersburg, and Moscow during and after the life of their teacher Butlerov. After receiving his Leipzig Ph.D., the Russian Constantin Fahlberg (1850-1910) bounced around several positions before spending a year as an assistant to Ira Remsen at Johns Hopkins University in Baltimore, where he (systematically)

discovered saccharin and (serendipitously) its sweetening properties. In 1886, he founded a factory near Magdeburg to manufacture the substance, with great success and profit.

As for Americans, we have noted that future Harvard president Charles Eliot (1834-1926) spent a semester with Kolbe in Marburg. H. P. Armsby (1853-1921), who became a noted agricultural chemist at the University of Wisconsin and at Pennsylvania State College, was a Leipzig Praktikant in 1875-1876, as was the New York private analyst Gideon Moore (1842-1895). One last American Praktikant worth mentioning is Sidney A. Norton (1835-1918), who for twenty years was head (and only member) of the chemistry department of Ohio State University.^[28] Perhaps the most curious foreign career path was traveled by the Bavarian Oscar Loew (1844-1941), who had stints at the City College of New York, the United States Geological Survey, the Department of Agriculture, and Tokyo University before returning to his homeland at the age of seventy as honorary professor at Berlin. He was the last significant Kolbe student to die.

The highest prestige that a German professor could wish for a student was that he become an ordentlicher professor himself at another German university. Here Kolbe had little success. Only three of his students ever gained a university Ordinarius: Ernst Beckmann (1853-1923) at Erlangen, Leipzig, and Berlin; Theodor Curtius (1857-1928) at Kiel, Bonn, and Heidelberg; and Ernst Schmidt (1845-1921) at Marburg. Schmidt, the only undistinguished chemist of the three, became the first to achieve this rank—ironically, at Kolbe's former university and in the very year of Kolbe's death (this was as Zwenger's successor as director of the pharmaceutical institute).^[29] This poor record of spawning new full professors contrasts with that of Liebig a half generation earlier, and with Baeyer a half generation later, each of whom taught close to thirty future German university Ordinarien.^[30]

This last enumeration counts only those who actually received a Ph.D. under Kolbe, not his entire research group. Moreover, there were other educational institutions besides universities, other ranks besides the Ordinarius, and other countries besides Germany. Of the total group of 137 students, 31 (twenty-three percent) pursued academic careers. Among the non-Ph.D. students in Leipzig were such future academics as Carl Graebe, Edmund Drechsel, Hermann Credner, and Gustav Hüfner, as well as many of the foreigners mentioned earlier. Among those who never made it to Ordinarius but nevertheless built reputations in chemistry were Conrad Laar (1853-1929), who coined the term tautomerism ; Rudolf Leuckart (1854-1889), who developed an eponymous synthetic reaction that yields complex aliphatic amines; and Friedrich Fittica (1850-1912) at Marburg.

The last group of academics comprises those who worked at the trade schools and technische Hochschulen, which were gradually raising their status during the latter part of the century. Kolbe's Marburg student Rudolf Schmitt had an excellent career at the Dresden Polytechnic, and when ill health forced him to retire, his successor was Ernst von Meyer (1847-1916). Hermann Ost (1852-1931) was at the Hanover Technische Hochschule for nearly forty years, and in all, about a dozen of the 137 Leipzig Kolbeans spent major portions of their careers at technical schools.

It has been noted that only twenty-three percent of Kolbe's Leipzig group—or to put the matter more starkly, only two percent of his Praktikanten—had a subsequent academic career of any sort. The majority of Kolbe's Praktikanten were instead future physicians, pharmacists, schoolteachers, businessmen, civil servants, and so on, no doubt even including a few law and theology students.^[31] The future academics were in the minority even among the future professional chemists, for in the last third of the century, a university education was becoming common, even expected, preparation for a career in the chemical industry. Unfortunately, biographical sources for industrial employees are poor in comparison to reference works for academics, and so it is difficult to identify Kolbe's budding industrialists even from an accurate list of names.

However, some identifications, at least, are clear. Kolbe's Marburg student Wilhelm Kalle founded what would become an extremely successful dye firm two years after obtaining his Ph.D., in 1863. Ludwig Mond, the later ammonia-soda magnate, also studied in Marburg. Griess, Graebe, and Gerland were all Marburg students who worked in the chemical industry. In Leipzig, there was a larger (and increasing) percentage of technical students. The case of Fahlberg has already been mentioned, but this example is only representative. Some two dozen of the Leipzig students can be shown to have entered industry, but the true number is certainly very much higher. A rough estimation can be made that perhaps twenty-five percent (around 400) of his Leipzig Praktikanten became industrial chemists, contrasting with perhaps nine percent (about 20-25) of his Marburg students.^[32]

Meyer, Ost, and other junior colleagues contributed far more to the liveliness and success of Kolbe's institute than has been appreciated. Both Meyer and Ost were assistants and Privatdozenten in the institute from the early 1870s until Kolbe's death in 1884, Meyer being promoted to Extraordinarius in 1878. They had capable colleagues in fellow long-term assistants Anton Weddige (1843-ca. 1904) and Ernst Carstanjen (1836-1884), both of whom also became ausserordentlicher

professors at Leipzig, but neither of whom progressed further along the academic ladder.

Although all doctoral degrees in chemistry were officially granted with the Kolbe imprimatur, it appears that Ost and especially Meyer began increasingly to take over day-to-day direction of the Doktoranden, especially after Meyer's promotion to Extraordinarius. Judging by acknowledgments in doctoral dissertations and by Meyer's later statements, it seems that the majority of the doctoral students after 1877 got most of their advice, and even many of their original topics, from the junior members of the institute. Meyer mentioned that his Ph.D. topic, selected in 1871, was of his own devising. However, the trend was certainly stronger after the mid-1870s, a period that corresponds to a serious decline in Kolbe's health. The fact that the two most eminent Kolbe students, Ernst Beckmann and Theodor Curtius, were in this late group, speaks to the quality of Meyer's mentoring.^[33]

During the first Leipzig decade, of course, Kolbe's role was stronger and more direct. There are many indications (from Kolbe's acknowledgments of specific students' assistance in some of his papers, from students' acknowledgments to Kolbe in their papers, and from retrospective accounts) that Kolbe often used his students as his "hands" to pursue his own concerns; examples include much of the organosulfur research and his search for aromatic isomers. Indeed, Kolbe's Leipzig period might be viewed as exhibiting all the prerequisties for an ideal research school. Taking Jack Morrell's well-known criteria for such an entity,^[34] we can affirm that Kolbe was a man of eminence and personal charm if not charisma; that his students formed a cohesive group with excellent esprit; that they were allowed to publish under their own names, and after 1870, in Kolbe's own proprietary journal; that Kolbe had a distinctive theoretical research program to be elaborated, with a set of dependable and predictable techniques; and finally, that he had plenty of manpower, more than adequate physical facilities, and generous institutional and financial support. Why, then, was the Leipzig school not more successful than it was?

In the course of a compelling endorsement of research schools as a unit of historical analysis, Gerald Geison notes some inherent difficulties with this kind of approach, to which additional ones may be added.^[35] For instance, it is by no means clear that research groups are always the cohesive and distinctive units they are sometimes assumed to be. Indications of transmission of ideas from teacher to student may be inferred, but dependable statistical data can rarely if ever be constructed. Exactly which themes were suggested by Kolbe, which by his assistants, and which by the students themselves? A formal ac-

knowledgment by a student to the group leader does not really tell us very much. Even for those cases where we can determine that the project started as a definite assignment, scientific research is such that few projects lead in a straight line from conception to conclusion, and the twists and turns along the way are often the real points of interest; who was doing the twisting at each point?

If such are typical of the historian's analytical problems for the Doktoranden, the difficulties are even worse for guest Ph.D. workers, assistants, Privatdozenten, and other junior colleagues. The German university system was fluid; junior colleagues frequently traveled from university to university, and many had not been Kolbe's students originally. Nor was it just the junior colleagues, for the Doktoranden themselves were also often a peripatetic lot. Moreover, organic chemistry, at least, had developed a national scientific culture that was highly similar at the various German universities. Enough has been said in this chapter (and in chaps. 5, 11, and 12) to demonstrate that structural chemistry was alive and well in Kolbe's institute, even while Kolbe was turning apoplectic over it. Themes of students' projects were frquently irrelevant (or even contrary) to Kolbe's pet concerns, and this is true even in the early Leipzig period. As extreme cases of independence, some notable disagreements between Kolbe and his students were published under the auspices of the Leipzig lab.^[36]

Kolbe's group research was notably moribund until he acquired a powerful theory, largely equivalent to structure theory, which he then exploited with energy and mastery. He transferred to Leipzig in the middle of the period of his greatest productivity. The sudden and dramatic change in institutional setting, resources, and numbers of students—nicely paralleling the maturation of the field of organic chemistry in Germany—made remarkably little difference to his success rate and overall standing in the field, or even to the productivity of his group research if measured by a proper (intensive) yardstick. Productivity and standing only began to decline when Kolbe began to focus exclusively on those points of difference between his and the structuralists' theories.

In this context, it must be reiterated that Kolbe's theoretical approach was so distinctive as to be characteristic of only himself, for he did not convince even his students of the advantages of his approach to the study of chemical constitutions. Kolbe's ideas were not powerful in comparison to those of his competitors at other universities. To speak more precisely and with only a touch of hyperbole, the ideas were powerful only to the extent that they happened to coincide with structuralist notions. The projects that were predicated on Kolbe's conviction of a difference between carbon valences, on a

denial of chain formation, on his trimethine-trimethane benzene theory, or on the uniqueness of the Stammradikale , all proved scientifically sterile.

Here, finally, is the principal reason why the Leipzig research school was not more scientifically productive and influential. For Kolbe, at least, the focus should not be on distinctiveness as an advantage—especially not as an essential prerequisite for a successful school as some have viewed it—for we have seen that in this case his distinctiveness could only hurt him in the long run. Rather, attention needs to be directed to the power and empirical stature of the ideas driving the research. Kolbe's increasing concern—virtually an obsession—with precisely those details of his carbonic acid theory that proved most sterile ensured that his own research would be moribund. One consequence was that direction of the laboratory in more fruitful areas was left exclusively to junior associates, who were less able to lead and inspire. Another was that as Kolbe's stature in the field fell, his word meant less in recommendations for his students. The net result was that Kolbe's Leipzig school was gradually transformed from an exciting and productive example of group research into a combination of a quixotic personal research program of the director and an undistinguished mass-research group of a rather conventional character. What made his decline even more precipitous was the holy war he waged against his adversaries during the last sixteen years of his life.