Justus Liebig

Liebig (1803-1873)^[27] was the son of a wholesale materials supplier in Darmstadt. Like Wöhler and Berzelius, from an early age Liebig desperately wanted to be a chemist, and he was largely self-taught. In his autobiography, Liebig described his youthful passion for reading every chemistry book he could find and his utter devotion to reproducing every experiment possible in his father's makeshift laboratory—and moreover, to performing the same experiment many times until he had absolutely mastered it. He also got to know all the local artisans in tanning, dyeing, soapmaking, and metallurgy, and he thoroughly learned their empirical chemical arts. However, he was a poor pupil. When asked by his teacher what would become of him and he replied, "a chemist," both his classmates and the teacher exploded in laughter be-

cause, Liebig said, no one then considered chemistry as a possible career.^[28]

An unsuccessful pharmaceutical apprenticeship in Heppenheim (1817-1818) was followed by enrollment at the Universities of Bonn and Erlangen (1820-1822). Liebig was attracted by the lectures of Schelling and Kastner, the former of whom was the leader of Naturphilosophie and the latter reputed to be one of the best chemists in Germany. In 1821 he purchased and read an early (partial) German edition of Berzelius' textbook. At this point, he followed Kastner's advice to study for a time in Paris, and through Kastner's connections he was granted a stipend from the Grand Duke of Hesse-Darmstadt that enabled him to do so.^[29]

During his years in Paris (1822-1824) Liebig heard lectures by Arago, Dulong, Thenard, and Gay-Lussac, which had for him an "indescribable charm." Alexander von Humboldt, then residing in Paris, made the acquaintance of the young man and recommended him to Gay-Lussac, who took Liebig into his laboratory for collaborative research. The two men produced several important contributions—Liebig's first successful research. These events, as Liebig wrote in letters home and recollected in his memoirs of old age, came as revelations of a hitherto unknown world of true science. He was overwhelmed by the sophistication of the methods, the experimentalist commitment, and above all, the conscientious avoidance of unnecessary hypotheses. This was in marked contrast to the speculative approach of Schelling, L. Oken, G. H. Schubert, and other Naturphilosophen he had previously so admired in Germany. As Wöhler was forging a personal bond with Berzelius, Liebig was simultaneously becoming warm friends with Berzelius' principal French rival.^[30]

While still at Erlangen, Liebig had hoped eventually to gain a chair at a German university and, as Kastner had suggested to him, to open a laboratory-based pharmaceutical-chemical institute similar to existing models (especially that of J. B. Trommsdorff at Erfurt).^[31] This possibility was realized in the spring of 1824, when the Grand Duke (without consulting the faculty) offered Liebig an ausserordentlicher professorship at Hesse-Darmstadt's single (and tiny) university at Giessen. That fall, Liebig began his teaching career with twelve eager listeners and two Praktikanten in the university's improvised chemical laboratory, newly established in the guardroom of an abandoned army barracks at the edge of town. It appears that he shared this space, none too amicably, with the ordentlicher professor of chemistry, Ludwig Wilhelm Zimmermann (1782-1825). The following summer semester both men advertised chemistry courses, but only Liebig got customers. Despondent, Zimmermann committed suicide in the Lahn

River, and Liebig ascended to the rank of Ordinarius at the amazing age of twenty-two. He also was given a raise to the extremely poor annual salary of only 800 florins (equivalent to around $300 U.S. at the time) .^[32]

In the summer of 1826, Liebig, in conjunction with two colleagues, achieved his goal of opening a pharmaceutical-chemical institute. Since the university refused financial support for such a narrow professionalist endeavor, it was initially run as a private venture. They were allowed to use the university's chemical laboratory, however. Although the proprietors rated the institute's capacity as twenty to thirty students, it appears that in its first decade, usually only about ten worked there at any one time. Recent work suggests that the institute was initially successful in its advertised function of pharmaceutical training but not in its ultimate function of advanced chemical education and research.^[33] However, from winter semester 1826/27 on, Liebig insisted that all students in his chemical institute spend an entire semester working all day every day in the laboratory. Hence, his later claim that his pedagogical philosophy that later became so famous originated at the beginning of his Giessen years may well be accurate, in spirit if not in detail.^[34]

During the fall of 1830, Liebig invented an apparatus for elemental analysis that was to revolutionize organic chemistry—his Kaliapparat , or potash-bulb apparatus. Berzelius' third trip to Germany took place just at this time, and he was able to spend a few days with Liebig. Until this time, Berzelius had regarded Liebig as having been infected with the "geschwind aber schlecht" (fast but sloppy) methods of the French. Berzelius now changed his mind, and for the next decade, he and Liebig formed an extremely close bond.^[35] Liebig became an ardent Berzelian, but without yielding in his regard for Gay-Lussac. His friendships with Wöhler as well as Berzelius marked the time during which Liebig's loyalties were consolidated in the emerging German experimentalist school, of which he, Wöhler, and (slightly later) Bunsen were the most prominent members and of which Berzelius was the honorary dean. All of these men (with the possible exception of Bunsen) began to regard French chemistry of the new generation led by Dumas as sloppy, superficial, and self-aggrandizing.

By the early 1830s, Liebig had lost patience with his penurious administration, and he complained bitterly and tenaciously about the lack of financial and material resources in Giessen. Serious real and imagined illnesses added to the strain. Liebig's peremptory complaints, and even more so, his growing fame, made the administrators listen. In 1835 Liebig's laboratory institute was finally brought under the official aegis of the university, and funds were approved to renovate and ex-

pand it. Soon thereafter, Liebig himself received a substantial raise in salary, the laboratory was given a proper annual budget, and a new lecture hall was built. In 1838 the number of laboratory workers rose significantly—it reached twenty for the first time—and the composition of the practicum students shifted suddenly from nearly exclusively pharmacy to a mixture of pharmacy and chemistry majors. Within a few years they were nearly all chemists. Simultaneously, the lab began to attract foreign students. Liebig later suggested that the idea of practical chemical instruction "was at that time in the air," which constituted his explanation for the sudden popularity of his lab in the late 1830s.^[36]

Liebig's first students of note were Friedrich Knapp, who came to Giessen in 1835, and Heinrich Will and Hermann Fehling, who arrived in 1837. All three had successful academic careers in chemistry, Will becoming Liebig's successor. Up until then, only a handful of Ph.D. chemists had emerged from Liebig's laboratory; from this time on, large numbers of promising students were to come. This divide is also marked by a change in the sort of research projects that Liebig assigned. For years, Liebig had been using students to carry out analyses or isolated fragments of research in a similar way to what Wöhler did from about 1838. But for the first time in the late 1830s, we see Liebig organizing projects for multiple workers that were well articulated and coordinated around a single problem area of interest to Liebig. F. L. Holmes has plausibly suggested that this shift may have been related to a change in Liebig's own research orientation. From about 1836 Liebig became intensely involved in a variety of writing and editing projects, and in 1840 he gave up theoretical organic research entirely. As he began to find it difficult to maintain his personal research agenda, he began to trust that agenda more to his students.^[37]

He had more and more students to whom to turn. In 1839 Liebig's lab was again expanded and further renovated—the architect was J. P. Hofmann, whose son August Wilhelm entered Liebig's lab that same year—and his salary and budget were again increased. The renovation must have had something to do with a remarkable further increase in the quantity and quality of his students, traceable to that year. In addition to Hofmann, Hermann Kopp (already a Ph.D.) as well as Franz Varrentrapp, Lyon Playfair, and John Stenhouse all entered Liebig's lab that year, and Adolf Strecker came the next year. All became prominent academic chemists of the new generation. By 1841 Liebig had fifty workers, and in 1843 there were sixty-eight.^[38] In the latter year, a new branch laboratory for beginners was constructed to handle the crowds, which was physically separate from the old one, and it was placed under Will's directorship.^[39]

The great watershed in student demand for Liebig's lab was approximately simultaneous with that for the lab of his close friend Wöhler. The widespread assumption that Liebig must have enjoyed high popularity from the start appears not to survive careful scrutiny, for the transition to the pattern that became so famous, as we have seen, does not much predate 1840.^[40]