Chapter 8 19th Century Science II: Justus von Liebig and the Rise of Organic Chemistry

The theory and practice of organic chemistry --simply defined as the chemistry of those compounds containing the carbon atom -- was substantially altered between 1800 and 1860. The relatively unspecific and inaccurate analyses and non-selective separations described in Fourcroy's 1801 System des connaissances chimiques were gradually supplanted by the specific analytical and separatory techniques introduced by Justus von Liebig, J.B. Dumas, Michael Chevereul and others. This scientific knowledge would provide one powerful engine for change in Western civilization, as new materials would be increasingly introduced into the economy, thus ultimately creating a new synthetic world that shaped the quality of life for both the rich and the poor by the early 20th century.

At the beginning of the nineteenth century, organic chemistry was normally associated with the extraction, isolation and identification of animal and vegetable matter for medicinal purposes. Also, it was thought that organic compounds could be synthesized only in living animals and plants--the result of the presence of a "vital force." And thus this concept of vitalism discouraged the application of chemical theory from mineral chemistry to the organic branch of the discipline. For example, J.J. Berzelius wrote in 1819 that his electrochemical theory could not be applied to organic matter, "because under the influence of the vital force the elements there possessed entirely different electro-chemical properties." In short, there was a great divide between the animal and mineral kingdoms, for in each domain different rules of chemical behavior applied. The viability of the concept of vitalism, however, was first seriously questioned after Friedrich Wohler's synthesis of urea from inorganic materials in 1828. And it remained for vitalism to be convincingly refuted during the 1840's and 1850's, after the experimental synthesis of acetic acid by Kolbe in 1844 and the synthesis of methane and acetylene by M. Berthelot in 1855 and 1856.

Between 1828 and 1860, the focal point of organic chemistry shifted from questions concerning vitalism to theoretical discussions related to the nature of the organic molecule and its characteristics reactions, and to the classification of compounds. The overriding purpose of the various theories of organic compounds proposed during this period was to impose order upon the current chaotic state of organic chemistry. These theoretical constructions implicitly recognized the nature of the organic molecule to be comprised either of (1) two oppositely charged radical units, or (2) a unitary entity, whole unto itself. Both the radical and unitary theories were attempts to organize organic chemistry by relating either groups of atoms or a fundamental atom to the properties of a compound.

The concept of the radical was not new--it was used by Lavoisier in describing the composition of acids in his Elements of Chemistry. During the 1830's, radicals were equated with elements in chemical reactions. They were stable atomic groupings of fixed composition that could combine with other elements and be transferred from one compound to another without being altered. These non-varying constituents of chemical compounds were composed of carbon and hydrogen, and possibly nitrogen. In the strict sense of Berzelius' dualism, radicals could not contain highly electronegative elements like chlorine or oxygen.

The fundamental assumption of radical theory was that organic compounds had a binary composition held together by attracting electrostatic forces. Berzelius was the most vigorous proponent of a dualistic theory of matter. In 1831 he wrote that

. . . all chemical combination depends solely on two opposing forces, positive and negative electricity, and that thus each combination should be composed of two parts united by the effect of their chemical action, provided that there exists no third force.

The radical theory created order by dividing complex compounds into binary units. This facilitated the classification of compounds, as well as enabled chemists to transpose their understanding of inorganic chemistry to the organic world. J.B. Dumas and Liebig, during a rare moment of truce between the two great scientific rivals, wrote in 1837 that

In a word, how can we with the aid of laws of mineral chemistry explain and classify the so varied substances obtained from living matter . . . ?

Actually, to produce with three or with four elements combinations as varied as and perhaps more varied than those which form the mineral kingdom, nature has taken a course as simple as it was unexpected; for with the elements she has made compounds which manifest all the properties of elementary substances themselves.

Thus, according to the radical theories of the nineteenth century, organic compounds were often seen as the union of two radicals. The radical formed the basis for a classification system in which a series of compounds could be arranged by combining the basic radical with a variety of negatively charged atomic groups as for example, when Dumas' etherin radical was added to water, hydrochloric acid, hydroiodic acid and hydrogen cyanide, respectively. A number of radicals were proposed during the 1820's and 1830's. Among them were etherin (C₄H₄), benzoyl (C₁₄H₁₀O₂), ethyl (C₄H₁₀), acetyl (C₄H₆) and cacodyl (C₄H₁₂As₂). Confusion concerning these radicals was multiplied by the lack of consensus in adopting atomic weights.

Beginning in the 1830's, the fundamental assumption of the radical as an unalterable group of atoms was questioned. This was a result of the observation by a number of chemists that hydrogen could be substituted by an equal volume of chlorine in certain organic compounds. In 1834 Dumas stated his law of substitution, but it remained for his student, Laurent, to restructure organic theory. In 1836 Laurent advanced an alternative view of the organic molecule--one which denied the existence of radicals and viewed the molecule as a unit. This theory proposed that the positions of the atoms within a three dimensional molecular structure determined the physical properties of the molecule. Laurent's nucleus theory classified organic material in terms of original nuclei and derived nuclei. Derived nuclei were related to original nuclei and were the result of the substitution of hydrogen atoms by chlorine, bromine or oxygen atoms, or even by compound radicals like amide or nitro groups. Laurent's goal was to formulate a system of organic classification. He wrote in his textbook that

Be that as it may, I have endeavoured to ascertain whether there is not in all the different parts of our chemical tree, something analogous to this mother cell, in one word a nucleus which would enable us to understand why all these compounds can reciprocally engender one another.

Central to Laurent's interpretation of the unitary constitution of the molecule was his concept that the relative position of a functional atom within the nucleus determined the properties of the molecule. For example, if the oxygen atom was located outside the nucleus of the molecule, the compound was acifiable; if it was placed inside the nucleus, the compound was neutral. Laurent's work was heavily criticized by the proponents of the radical theory, including Berzelius, Dumas (initially) and Liebig. His ideas were attractive to Gerhardt, however, who saw in the unitary molecule a basis of organization.

Although Gerhardt initially subscribed to a modified form of the radical theory of the organic molecule, he gradually adopted the unitary view during the 1840's. In 1839, Gerhardt proposed his residue theory of organic reactions. He asserted that the inherent stability of certain inorganic compounds (water and ammonia, for example) led to their formation during the course of chemical reactions and to the subsequent combination reaction of the organic residues. For example, in the formation of nitrobenzene from benzene and nitric acid, a hydrogen atom from benzene and the OH group from nitric acid were abstracted and united to form water, with the subsequent combination of the two residues to form nitrobenzene.

C₆H₅ . H + HONO₂ --> HOH + C₆H₅ . NO₂

Gerhardt's residues, since they were not fixed entities, were capable of participating in substitution reactions. They were actually radicals capable of rearrangement. For example, substitution could be effected by replacement of a hydrogen atom by an equivalent atom or residue.

Gerhardt's work in the late 1840's and 1850's was aimed at classifying organic chemistry in terms of a limited number of "TYPES" of fundamental organic compounds. Gerhardt's theoretical construction was an extension of the work of Laurent, Wurtz, Hoffmann, Williamson and others. The type theories and type notation, so commonly applied during the 1840's and 1850's, were based upon the premise that the fundamental properties of an organic compound were related to a particular central atom. The central atom determined the chemical function of the substance, and the number of carbon atoms in the compound was secondary. Laurent was first to use type notation in 1846, when he classified compounds analogous to water.

H C₂H₅ C₂H₅ C₂H₅

O O O O

H H K C₂H₅

Hoffmann and Wurtz conducted studies which led to the formulation of the ammonia type, while Williamson's work led to the proposal of an ether type. In the ammonia type, one, two, or three hydrogen atoms in the molecule could be replaced by organic radicals. Williamson sought to replace the radical theory interpretations of alcohols and ethers with a more coherent view. He understood the reaction of potassium alcoholates with alkyl halides in terms of type notation:

C₂H₅ C₂H₅

O + C₂H₅I --> KI + O

K C₂H₅

Williamson extended type theory by asserting that most salts could be considered as a water type. This did not prove to be a problem for monobasic salts, but for dibasic salts this method created difficulties. As a solution, Williamson introduced a multiple water type:

H₂ SO₂ SO₂

O₂ O₂ O₂

H₂ H₂ HK

Gerhardt extended the work of Williamson by arguing that organic compounds could be classified by four types: water, hydrogen, hydrogen chloride and ammonia. For Gerhardt, these arrangements were convenient means of ordering chemical knowledge. However, this methodology carried with it no assumptions concerning the position of the atoms in molecular structures. He wrote:

It can be seen by this rapid summary how the application of the notion of series permits simplification of the general theory of organic compounds. They no longer terrify by their number and variety, for, instead of being formulated by special theories which lack any connection, as they are called ethers, amides, or acids, they become simply terms whose properties can be predicated according to the place they occupy in the series.

Many chemists viewed the theory of types as being artificial and inadequate in describing the realities of organic reactions. The type notation itself was only a fabrication for the convenience of classification; it conveyed no real sense of the relative positions of atoms of the reactive sites within the organic molecule. Type theory could not be used to explain chemical change on the molecular level.

As a reaction to the inadequacies of the type theory, Berzelius and his followers proposed a modified radical theory that not only accounted for substitution, but also explained chemical reactions in terms of the changing constituents within molecules. Although Berzelius died in 1848, his views were most notably advanced by Kolbe and Frankland. Kolbe maintained that radicals were "stable atomic groups" and accurately reflected the constitutional composition of organic molecules. Between 1855 and 1859, Kolbe developed Berzelius' view that organic compounds included copulae that were integral components of the formula. For example, acetic acid was comprised of the methyl radical copulated with oxalic acid and water. Acetic acid could thus be broken down into its functional components:

C₂H₃ + C₂O₃ + HO

The methyl group was a "passive partner" and the group subject to substitution. In a chlorine substitution reaction, the resulting radical, C₂Cl₃, did not alter the fundamental properties of the compound, because these properties depended on the "active" radical, C₂O₃. The strength of Kolbe's theory lay in his ability to designate relative positions in the molecule as reactive sites. Between 1857 and 1860, Kolbe developed a systematic approach to organic acids that related the constitutional structure of acids, aldehydes and ketones to the substitution of radicals at a central site in the molecule. For Kolbe, radicals were not merely a theoretical construct; they existed and were isolable.

Kolbe's work of the 1850's may be viewed as a refinement of Berzelius' understanding of the organic molecule, and thus it is merely a continuance of chemical thought from an earlier period. However, through the efforts of Kekule' and Cannizzaro, there occurred a significant conceptual break from this theoretical basis.

Kekule''s understanding of the binding capacity of carbon atoms and their ability to link to one another, along with Cannizzaro's re-employment of Avogadro's hypothesis for the determination of molecular weights, formed the basis for restructuring investigative studies in organic chemistry. Kekule''s early studies reflected the influence of both Gerhardt's and Frankland's work. Having proposed a mixed type theory of his own, Kekule' certainly showed an interest in classifying organic compounds. During the 1850's, Kekule' did not think in terms of constitutional formulae in the sense of Kolbe. Kekule''s understanding of combining capacity stemmed from his research into the reactions of phosphorus pentasulfide and phosphorus pentachloride with acetic acid. From a study of these reactions, he concluded that the equivalent combining capacity of oxygen and sulfur was two units in contrast to that of one unit for atoms like chlorine and hydrogen. He extended this concept of equivalence to his formulation of the marsh gas type, where carbon had four combining units.

Kekule''s ideas in 1858 were not merely rational formulas expressed in type notation. Although he did not conceptualize structure in terms of space and position, he viewed the organic molecule as a chain or network of vierbasisch carbon atoms in a skeletal arrangement, with substituents changing during substitution reactions. He wrote in 1858:

When comparisons are made between compounds which have an equal number of carbon atoms in the molecule and which can be changed into each other by simple transformations (e.g. alcohol, ethylchloride, aldehyde, glycolic acid, oxalic acid, etc.) the view is reached that carbon atom are arranged in the same way and only the atoms held to the carbon skeleton are changed.

When the homologous bodies are then considered, the carbon atoms (regardless of how many are held in a molecule) are arranged together in the same way, according to the same laws of symmetry.

Kekule''s work marked the beginning of a new phase of development for organic chemistry. However, his work must be understood within its historical context. Kekule' was chiefly interested in classifying organic compounds, and therefore he shared the goals of those propounding a chemistry based upon a theory of types. It should also be noted that Kekule''s 1858 paper on "The Constitution and the Metamorphoses of Chemical Compounds and the Chemical Nature of Carbon" focused on the constitution and stability of radicals. This discussion later developed into Kekule''s "form[ing] a picture of the nature of carbon." He not only recognized the existence of radicals, but also represented chemical formulas by type notation. His ability to construct a new view of the molecule was in part shaped by ideas from both the unitary and radical theories.

In summary, the four nineteenth century theories thus presented characterized organic molecules as: (1) the result of the presence of a vital force, (2) a binary combination of radicals, (3) a unitary entity useful for classification, or (4) an arrangement of carbon atoms. After the theory of vitalism was refuted, theoretical organic chemistry was increasingly directed toward the construction of classification systems and the conceptualization of organic molecules. Organic chemists began focusing on the components of the molecule, not only for the purpose of classification, but also to relate the fundamental properties of the molecule to the presence of specific atoms. The position of the atom, critical in both the unitary theory of Laurent and the radical theory of Kolbe, was an important conceptual development of this early period. After Kekule' described the organic molecule as based upon a framework of linking tetravalent carbon atoms, the position of substituent atoms became the focus of research during the last half of the nineteenth century. Yet, this apparently modern preoccupation with the relative position of atoms had its origins in the unitary and radical theories.

Justus Von Liebig: The Chemist Breeder

Although the above discussion has focused on the complex intellectual transformations that were associated with an understanding of organic materials, one key individual, working in a situation analogous to that of Faraday in electricity, made the major difference to the development of this field. Justus Von Liebig was a scientist who not only made important intellectual contributions to organic chemistry, but also created a new system of education that would from the basis of modern university graduate training. Liebig was the first of many chemistry professors who became "breeders" within their discipline, and Liebig's graduates used their knowledge to: 1) train a second generation of chemists and 2) create a new synthetic world of organic substances. With the coming of the industrial age various "types" of scientists and engineers emerged, like the "civic scientist," or "inventor-entrepreneur," or "science-manager," or "research director." Liebig's career typifies one of successful research director, and he possessed many, if not all, of the traits necessary for success:

1) charisma - esprit de corps

2) superior status within the scientific world

3) institutional support at home

4) a research program in which both the most brilliant and the average student can work within

5) control of a scholarly journal

6) a great deal of money

As we shall see, Liebig had all of these characteristics. In order to understand Liebig's achievement in chemical education, we must briefly examine what it was like to learn chemistry before him.

During the 18th century, the apothecary shop was the center for practical chemical education in Germany. A number of these shops trained the chemists and pharmacists who later held teaching positions in the early 19th century German universities. Two shops in particular, the Court Apothecary Shop in Weimar and Berlin's Shop by the White Swan have special historical significance. Important academic chemists who apprenticed at the Court Apothecary Shop included J. F. Gottling and J. B. Trommsdorf. And the Shop by White Swan had students including A. S. Margraff, Martin H. Klaproth, and Heinrich and Gustav Rose, who would teach at a number of German universities.

The significance of the apothecary shop as a training ground for scientists would decrease markedly between 1820 and 1850. More and more positions within the university were filled by academics trained at the university or recipients of advanced training from the laboratories of one of two giants in chemistry--either Gay-Lussac's laboratory in Paris or that of J. J. Berzelius in Stockholm. These two chemists emphasized rigorous explanation based upon laboratory chemical analysis. Thus, their approach to the study of chemical knowledge was markedly different from that taught at the apothecary shop, where preparation of substances was emphasized.

During the 1820's, Berzelius trained only one student a year in his laboratory. He emphasized the development of accurate and precise procedures and techniques, usually for the purpose of obtaining new data on atomic weights. Berzelius' students during this time included Mitscherlich, the Rose brothers(Heinrich and Gustav), and Wohler.

Although Berzelius was the dominant individual in chemistry during the first quarter of the 19th century, Paris was undoubtedly considered the center of academic research. However, as in Stockholm, the serious student had to gain admittance to one of the private laboratories if he was to learn practical chemistry. The master-apprentice relationship remained the primary means of chemical education. In this way, the French continued to produce a few brilliant chemists well-grounded in theory and experimentation. And it was in this tradition that the Justus Von Liebig (1803-1873) was trained.

Liebig was the son of a dealer in drugs, dyes, oils and chemicals in Darmstadt. As in Davy's case, early experiments probably led Liebig towards a chemical career. Watching an itinerant showman taught him how to prepare silver fulminate by dissolving silver in nitric acid and adding alcohol. After being apprenticed to a pharmacist, Liebig continued his experiments with the fulminates and successfully blew out the shop's window--whereupon he found himself removed from his apprenticeship. Liebig then enrolled at the University of Bonn in 1820. He described the laboratories there as:

kitchens filled with all sorts of furnaces and utensils for carrying out metallurgical and pharmaceutical processes. No one know how to teach chemical analysis.

After a brief stay in Erlangen, Liebig went to Paris, where he began attending the lectures of Gay-Lussac. He wrote:

What influenced me most in the French lectures was their inner truthfulness and careful omission of all mere semblance explanations; it was a complete contrast to the German lectures in which. . . the scientific doctrine had quite lost its rigid coherence.

Liebig's mentor, Gay-Lussac, was influenced by the legacy of Lavoisier, as well as by the work of Berthellot and La Place. He believed that chemistry was an exact science with mathematical foundations; however, he did not agree with La Place that all chemical phenomena could be reduced to mathematical representations. Gay-Lussac understood chemistry as an experimental science based upon physical measurements and chemical analysis. These views played an important role in German chemistry, since Liebig's strongest impressions concerning chemical research were the result of his association with Gay-Lussac.

Liebig's enthusiasm in Paris soon caught the attention of the German scientist and naturalist Alexander von Humboldt, who pressured the Grand Duke of Hesse to appoint the young man of twenty-one extraordinary professor of chemistry at the University of Giessen in 1824. Liebig's first laboratory there consisted of one unventilated room, containing a large coal oven in the center and benches around the walls. He had to pay for all of his supplies and the salary of his assistant from his own pocket. Yet this laboratory saw the beginning of a new mode of training scientists, for it was the first institution deliberately designed to enable a number of students to progress simultaneously from elementary operations to independent research under the guidance of an established scientist. At the heart of this new way of teaching was an instrument, or piece of equipment, the combustion apparatus.

Liebig simplified organic chemistry by basing his conclusions on data derived from combustion analysis. The potash bulb combustion apparatus was first used extensively by Liebig in Paris and was later perfected in Giessen. It became the primary tool of Liebig's research and teaching program. Provided he was trained properly, even the average student could use the combustion apparatus to obtain new and important knowledge. Thus, the apparatus became an integral component in the systematic training of Liebig's students. The novice was first exposed to qualitative analysis, quantitative analysis and preparative chemistry before being allowed to conduct independent research.

Thus, the new student at Giessen would first obtain a "speculative" acquaintance with chemistry by reading and attending introductory lectures. In the laboratory, he would: 1) observe the properties and reactions of known substances, 2) practice his new knowledge by examining a series of unknowns, each sample becoming more complex until the last contained a mixture of all inorganic bases and a number of acids, and 3), once 2) was accomplished, a research project would be tackled, in which the nature of the organic reactions would be characterized by the systematic application of the combustion apparatus.

The combustion apparatus was crucial to Liebig's emergence as the first chemist breeder, and in this sense he was prolific. His laboratory was open to all who were talented, at a very cheap price. Thus, by the 1850's, in Britain and Scotland, for example, almost all the "plum" academic jobs were filled with Liebig's former students, including positions at:

University of Glasgow

Queens College, Cork

Oxford

Owens College, Manchester

Edinburgh`

King's College, London

Durham

Queens College, Galway

University College, London

Royal College of Chemistry, London

These students, along with collaborators like Friedrich Wohler, quickly transformed 19th century organic chemistry, and indeed extended chemistry to agriculture and physiology.

Chemistry and Agriculture

Today, not many chemists would consider a career in agriculture. One would normally try to gain employment in the most dynamic sectors of the discipline--perhaps biochemistry or polymers. Yet, for most of the 19^th century, agricultural chemistry was one of the "hot" areas of the discipline. Two reasons come to mind--first, the 19^th century was the golden age of organic chemistry, and many of the substances studied by chemists were derived from natural products. Secondly, the 19^th century chemical industry was dominated by organic extractive industries--sugar, naval stores, coal tars and petroleum. Thus, the practical problems of these industries often served as the starting point of what would become more theoretical investigations. Thirdly, the industrial revolution was in part dependent upon a concurrent agricultural revolution that would enable the masses to migrate to urban areas.

Of course, the problem of soil fertility had great importance during the Roman period. Pliny and Columella had written treatises on agriculture. During the Middle Ages, practices like crop rotation and the fallowing of land were frequently adopted and improved.

However, until the 19^th century agriculture was based upon nonempirical methods. Also, explanations concerning plant growth and crop yields often drew from alchemical and speculative ideas.

While we can mention Lavoisier's experiments on his farm in the 1780's, the pioneering efforts of Albrecht Thaer in Hannover during the late 18^th century, and Humphrey Davy's 1813 Elements of Agricultural Chemistry, the injection of rigorous chemical ideas into agriculture first took place between 1820 and 1850. These three decades saw the development of improved analytical procedures, the establishment of journals that made possible the rapid dissemination of results, and the widespread acceptance of scientific agriculture by the landed classes of Europe and farmers in America.

I will spare you the details of the investigations that proceeded Liebig's publicized entrance into the field of agricultural chemistry in 1840. While a number of important studies were begun before 1840, serious problems remained to be solved. To begin with, until the appearance of Liebig on the scene, the role of humus in plant nutrition was a source of controversy. A number of botanists and plant physiologists had asserted that humus, a large-molecular weight compound, brown in color and soluble in alkali, that was the result of the decay of plant matter served as the source of carbon in the growth of plants. Secondly, considerable debate centered upon the presence of powers or vital force in plants that enabled them to transmute water and humus into the mineral elements requisite for their growth. This vitalistic concept was not abandoned until the 1840's, when it was conclusively shown that plants would not grow in a bed of purified quartz.

Without doubt Justus Liebig proved to be the pivotal figure in the development of agricultural chemistry. While other great scientists had dabbled in the field, for the most part agricultural improvers were "marginal men." Liebig's commitment to agricultural chemistry gave it an instant legitimacy as a scientific discipline worthy of the efforts of the best minds in chemistry. In the long run, agricultural chemistry, and agriculture in general, was considered an area of knowledge suitable for university teaching and research.

Liebig's interest in agricultural chemistry seems to be the direct consequence of his analytical investigations using his combustion apparatus. During the 1830's he studied the composition of many agricultural products, including malic acid, asparagine, aspartic acid, uric acid, hippuric acid and plant alkaloids.

One can see the increase in Liebig's attention to agriculture by studying his contributions to the literature during the 1830's. In 1832 Liebig had established the Annalen der Pharmacie which later changed its title to the Annalen der Chemie and Pharmacie in 1840. Between 1832 and 1840 Liebig examined the composition of plants, and isolated and analyzed alkaloids and organic acids extracted from plant materials.

Liebig's 1837 study on the manufacture of vinegar proved to be of great significance. He studied the conversion of the alcohol of wine, cider and beet into acetic acid, and showed that the first step in the reaction was the formation of an aldehyde intermediate that he isolated and identified.

So, while Liebig was not an expert on agricultural chemistry, he was familiar enough with the field to address to the British Association on the subject in 1840. These lectures formed the basis of his Organic Chemistry and Its Application to Agriculture and Physiology which became so popular that seventeen editions were published by 1848.

The first edition of the Organic Chemistry was mostly a review of the work done in agricultural chemistry prior to 1840. Liebig himself lacked farm experience, but with a manner so characteristic of this overly confident but newly crowned master of organic chemistry, he charged forward. He attacked botanists and physiologists because they knew no chemistry and asserted that there had been no application of chemistry since the publication of Davy's book. He wrote:

In botany, the talent and labor of inquiries has been wholly spent in the examination of form and structure; chemistry and physics have not been allowed to sit in council upon the explanation of the most simple processes; their experience and laws have not been employed, though the most powerful means of help in the acquirement of true knowledge. They have not been used, because their study has been neglected.

The first part of Liebig's treatise dealt with the process of vegetable nutrition; the second part with the processes that result in the death and destruction of plants, namely fermentation, putrefaction and decay. After stating that plants are composed of: woody fiber, starch, sugar, gum, oils, waxes, resins, and albumens, he argued that the carbon used in the building up of plant tissues came from the CO₂ of the atmosphere, and not from the humus of the soil. Liebig also asserted that the hydrogen necessary for plant development came from water, while excess O₂ was released during the process of respiration.

Liebig also felt that nitrogen used by the plant came from the atmosphere, in the form of ammonia dissolved in rainwater. Here he would come in sharp conflict with other agricultural scientists who claimed that nitrogen would enter the plant through its roots.

It was after this preliminary discussion of C, H, and N that Liebig maintained his so-called "mineral theory of manures."

"Carbonic acid, water, and ammonia, are necessary for the existence of plants, because they contain the elements from which their organs are formed; but other substances are likewise requisite for the formation of certain organs destined for special functions peculiar to each family of plants. Plants obtain these substances from inorganic nature. In the ashes left after the incineration of plants, the same substances are found, although in a changed condition.

Many of these inorganic constituents vary according to the soil in which the plants grow, but a certain number of them are indispensable to their development. All substances in solution in soil are absorbed by the roots of plants, exactly as a sponge imbibes a liquid, and all that it contains, without selection. These substances thus conveyed to the plants are retained in greater or lesser quantity, or are essentially separated when not suited for assimilation. Therefore, Liebig stressed the role of inorganic elements in plant nutrition, emphasizing the need for phosphates, potash, lime, soda and magnesia.

Despite the shortcomings of his work, Liebig must be counted a major contributor. By emphasizing the importance of inorganic elements, particularly phosphorus and potassium, he stimulated the growth of the fertilized industry. By criticizing his contemporaries, he forced them to clarify their thinking and improve their experiments. His enthusiasm created an interest in soil chemistry and plant nutrition which resulted in widespread research. And the growth of the agricultural experiment stations in Germany and following the passage of the Marshall Act in 1862 in America, resulted in large part from the influence of Liebig and his students.

In the final analysis, Liebig was successful not only because of his brilliance as a scientist, but also because he had charisma. One tribute of Liebig was by a former student, A. W. Hofmann, at his famous Faraday Lecture of 1875:

Like all the great generals of every age, Liebig was the spirit as well as the leader of his battalions; and if he was followed so heartily it was because, much as he was admired, he was loved still more. . . I am sure that he loved us in return. Each word of his carried instruction, every intonation of his voice bespoke regard; his approval was a mark of honor, and of whatever else we might be proud, our greatest pride of all was in having him for our master.

In addition, Liebig's success was due to his preeminent position in the new field of organic chemistry. Further, he controlled his own journal, the Annalen der Chemie und Pharmacie, which by 1846 as many as 15 students in his laboratory published no less than 32 papers in one year! And, Liebig also succeeded in receiving institutional support at Giessen, so that he had little extra teaching duties and plenty of money to pay assistants to monitor the work of students.

In 1852, Liebig left Giessen for a modern well-equipped laboratory in Munich, where he continued to write and lecture primarily in the areas of agriculture and nutrition until his death in 1873. And although the latter stages of his career was not as brilliant as his early years, his legacy in terms of ideas and followers was crucial to the shaping of modern civilization.

In sum, Liebig was the first of a new type that was a part of modern 19th and 20th century science. His story is a tale of a man overcoming many obstacles to transform science and education, and much can be learned from it.

Dmitri Mendeleev and the Relationship Between the Elements

No 19^th century history of chemistry can be complete without at least a mention of the achievements of Dmitri Mendeleev(1834-1907) in classifying the elements and his construction of the Periodic Table.

New Institutions Serving a New Industrial Culture

The Rise of the Industrial Research Laboratory

Previously we discussed Liebig in the context of an educational innovator and as the ideal type of research director. However, his influence went far beyond education. His ideas on organic chemistry were at the heart of a revolution in that field. He also transformed agricultural chemistry and biological chemistry. But in addition to all of these contributions, Liebig left a legacy that was transmitted through his students to future generations of scientists. And this legacy of inquiry and organization formed the basis of the agricultural experiment station and the industrial research laboratory of the late 19^th century. Above all it was organization -- the systematic attack by scientists upon a stated problem -- that was the heart of Liebig's success and much of what followed in 19th century Germany both in the academic and industrial spheres. It was this approach that ultimately separated the late 19th century Germans from the British, accelerated technological change and the social changes that inevitably follow. And it all started with colors from the synthetic dye industry that consumers so desperately desired.

Today, we take for granted the many products that have improved the quality of our lives, and with some debate, have made our lives more complex and risk-laden. Colors, pharmaceuticals and polymers are classes of substances whose success was dependent upon research and development work in the industrial research laboratory. What I would like to explore with you are the historical roots of this organization and how, between 1875-1910, it rapidly took the form which is in some ways indistinguishable from labs like those of DuPont, Kodak, and Dow.

The significance of the industrial research laboratories set up in the German and Swiss dyestuff factories is that they were the first great research institutions as we know them today. They resulted from: 1) the insatiable demand for new and better colors and 2) the ability of organic chemistry to meet the demand. What are the institutional advantages of the industrial research laboratory?

1) The isolation of research investigators away from plant activities. The plant central lab handles day to day priorities with the assurance that these goals will be reached; researchers do not have to "fight fires." As an integral subunit of a company's operations, scientists the research director can make decisions that are not influenced totally by corporate managers and manufacturing engineers.

2) One brilliant chemist can keep a dozen less talented individuals busy and productive using his key idea.

3) A multi-sided approach to problems can take place. For example, organic, physical, and pharmaceutical chemists can each contribute their unique views to the solution of a research problem or to the answer of a perceived need.

4) Also, within a research team, the strengths of certain individuals can be coupled with the weaknesses of other members in forming a cohesive and effective group. Each good lab has:

a) tinkerer or good instrumental chemist-electrical and mechanical

b) an intuitive thinker

c) a logician

d) good experimentalist

e) an organizer

5) The Industrial Research Facility has equipment which no one individual can afford.

6) Good scientists can depend on plenty of support personnel--librarians, analysts, clerks, stockroom workers and bottle men

What are the disadvantages of the Industrial Research Laboratory?

1) overspecialization

2) If you have poor communications, you can duplicate work.

3) It leads to the squandering of good minds on administrative duties

4) secrecy - often, one cannot publish findings in prestigious journals; patents are most important

5) One's individual freedom to pursue certain lines of work is very limited

Let us examine the history of Bayer and Co., the seminal institution in the history of industrial research, drawing directly from the leading scholar in this area, John J. Beer.

Friedrich Bayer began producing fuchsin and related aniline colors in 1861. His early success was in part due to his association with a local dyer, Friedrich Weskott, who knew a great deal about the practical science and technology of making these types of substances. Weskott was a good experimenter and organizer, and he knew how to take information from patent literature and scientific journals and produce aniline dyes. Weskott began by working on either his or Bayer's kitchen stoves while doing small scale experiments, and later he took charge of selling the factories' output.

In 1864, a Dr. Schonfeld became the first Ph.D. chemist to work for Bayer. He stayed there only a short period of time, and with his vacancy, this position remained unfilled. There was a good reason for this. In 1864, Bayer and other dyestuff makers did not need to rely upon the chemist to improve existing processes or to create new colors. Methods were improved by trial and error, and this task was left in the hands of the intelligent foreman. Since compounds were not protected under the current patent laws in Germany, anyone with reasonable intelligence could copy existing processes and improvise the necessary apparatus.

In a new industry like that of the dyestuff trade, it is astonishing that the foremen, or Meisters, gained control of the plant processes as quickly as they did during the 1860's. In some plants, the Meister had power similar to that of the Baron in the Middle Ages. What he said, went. He was answerable almost to no one, and he kept various process tricks secret to anyone else in the company. The foreman was so important during the early years of the dyestuff industry that next to managers and directors, he received the highest pay. It would be disastrous to a company if a foreman possessing company secrets left to work for a competitor.

During the 1860's, foremen were able to adapt new colors, like Hofmann's violet, methyl and iodine greens to large scale production. Their greatest triumph came in the early 1870's when the Alizarin process was installed at Bayer. These men experimented by varying parameters or ingredients during production runs, and they did this on a small bench located next to the vats, pumps and filters in the plant. They did not:

a) improve ways of testing new colors for fastness and

b) discover new organic dye materials

Beginning in the mid-1870's, the Bayer Company began hiring Ph.D. chemists, and these newcomers to the work force were met with immediate and constant opposition from the Meister's. It was a struggle over the control of the process, but it soon became clear that the chemists had won the approval of management. Thus, they were placed in positions of authority over the foremen. Why did this new need for chemists within the dye industry emerge? First, the German patent law of 1876 protected the compounds that were newly synthesized. Bayer's competitors rushed to hire chemists, and if the company were to survive, it had to follow suit. Secondly, in 1876 a new class of dyes--azo dyes--were discovered. It became apparent to those in the industry that survival depended upon the synthesis of azo dyes, and Ph.D. chemists, not foremen, could provide this expertise.

At first, Bayer was slow to react to the changing legal and scientific situations. It hired Ph.D.'s to improve processes, but none of their employees synthesized new colors. The chemists hired had been employed with other Dye works, and while they made improvements in the process, their originality was burned out. Also, since they left the employ of a dye company, Bayer managers felt that they could not be trusted, since they had already been traitors once before.

Thus, Bayer management decided to invest in 3 young post-docs, who were sent to various German universities, where they would be expected to solve problems assigned to them by the company. This idea failed miserably, in part because the problems given them were impossible to solve by even the leaders in the field of dye chemistry at that time. After the year was up, the three were recalled to the Bayer plant at Eberfield, where they were assigned projects in a lab next to the production facility. One of these three was so gifted that his discoveries would propel Bayer to a position of leadership within the industry and convince company directors that research would lead to enormous profits.

Carl Duisberg (1861-1935) was the young chemist whose work was integral to Bayer's future. Educated at Gottingen and Jena, and a lineal descendant of Liebig, Duisberg discovered three important dyes in one year-1884. Within a year, Bayer had a new lease on life financially, and the company was no longer considered inferior to its chief competitors, Hochst and BASF. Almost at once, Duisberg became the focal point for the emergence of a research organization.

It began by providing him with a support staff to relieve Duisberg of annoying and time consuming tasks. It grew quickly, because chemists were hired to synthesize innumerable compounds that were similar in formula and properties to the one's that Duisberg had originally made. Patent protection became an integral part of the activities of the lab, as all conceivable related compounds were made and patented. Duisberg was relieved of patent paperwork, and other chemists took over his responsibilities in making the material in the plant on a commercial scale.

Year by year the number of chemists increased:

1881 - 15

1885 - 24

1890 - 58

1895 - 90

1896 - 104

With the increase in the number of chemists, a new laboratory facility for Bayer was built in 1891. Duisberg designed the lab, and innovatively placed each research chemist in a box or U, where he had privacy and his own reagents and equipment. Since these U's did not totally isolate the chemist, it made for esprit de corps and cross fertilization of ideas among chemists. Practically, it made it very difficult for the chemist to hide a discovery, and then try to sell his new color to a competing firm.

The laboratory had a good library, that enabled the chemists to keep up with recent advances and to use as a research tool. The bimonthly seminar also was instituted at Bayer, in part to maintain an academic atmosphere at an industrial facility.

With the growing number of new employees, Duisberg began to institute a regular training program in which all new Ph.D.'s would spend the first year in the experimental printing and dyeing department. There they learned how dyes were made and how to go about testing them for shading and fastness. They then were sent to the research laboratory, where they were first assigned exercises in the synthesis of well-known dyes. They were then given colors from competing firms to analyze and synthesize.

During the second year, these relative newcomers were slowly and gradually directed to a special branch of color chemistry, where they normally stayed for the next several years.

As this research laboratory grew, it split into specialized divisions, including: specialty groups, focused on work in one kind of dye, a color testing group, a pharmaceutical group, and a photographic group. This type of organization was often copied abroad, and the early 20th century research chemical laboratory in industry often copied much of Duisberg's ideas concerning layout and specialization.

In summary then, a modified version of Liebig's original laboratory became a part of the industrial research facility of the late 19th century. While some of the features of the systematic training were retained, the complex world of modern organic chemistry and competitive business pressures forced specialization to take place. The organizational structure of Bayer's laboratory would soon be initiated elsewhere, including

the United States.