Gmelin, Leopold

(b. Göttingen, Germany, 2 August 1788; d. Heidelberg, Germany, 13 April 1853)

chemistry.

Leopold Gmelin was the third and youngest son of Johann Friedrich Gmelin, professor variously of philosophy, medicine, chemistry, botany, and mineralogy at Tübingen and a distinguished historian of chemistry. (It was through the elder Gmelin’s efforts that a student chemistry laboratory was built at the university in 1783.) The family had been physicians, ministers, teachers, scientists, and apothecaries from the beginning of the sixteenth century.

Gmelin’s early education was at the hands of a private tutor, in addition to which he attended his father’s lectures at the university. He then attended the Göttingen Gymnasium, from which he graduated in 1804. The following summer his father sent him to work in the family apothecary shop in Tübingen, in accordance with long-standing tradition. At the same time he attended lectures on materia medica and pharmacology given by Ferdinand Gmelin (his cousin) and on medicine by K. F. Kielmeyer (husband of his cousin Lotte Gmelin). Both lecturers were professors of medicine at the University of Tübingen. He also met a number of other medical students and professors—including Justinus Kerner, Ludwig Uhland, and J. H. F. Autenrieth—with whom he was to maintain professional contact.

Johann Friedrich Gmelin died in November 1804; on his return to Göttingen in that year Gmelin worked with F. X. Stromeyer, his father’s successor at the university. He passed his examinations in 1809, then returned to Tübingen to study with his former teachers until Easter 1811. He simultaneously began his doctoral researches on the black pigmentation of cattle eyes, a study that he was to continue in the laboratory of Nicolas J. Jacquin in Vienna later in 1811. He was awarded the medical doctorate by Göttingen in 1812; he had also qualified himself as a chemist and had studied mathematics with Bernhard Thibaut.

Gmelin then decided to travel in Italy for a year to broaden his command of the natural sciences. He was particularly concerned with mineralogy and geology, and therefore concentrated his interest in the regions of Mt. Vesuvius and San Marco. He published his geological findings in 1815.

Upon his return to Göttingen he undertook the analysis of the mineral haüynite under the guidance of Stromeyer. At the same time he began his academic career; he was appointed docent at Heidelberg in fall of 1813, and soon thereafter, in 1814, became extraordinary professor. In a letter of that year, addressed to his mother, he stated that “medicine in Heidelberg is deplorably organized—but soon it will be better.”

Gmelin’s cousin Christian Gottlob Gmelin received his medical degree in the academic year 1814; together they then went to Paris to study and work in Vauquelin’s laboratory. They stayed in Paris until spring 1815; in addition to their laboratory work they attended lectures by Gay-Lussac, Thenard, Vauquelin, and occasionally those of Haüy himself.

When Gmelin returned to Heidelberg he replaced F. K. Nägele on the faculty. F. Tiedemann became teacher of anatomy and physiology in the same year. M. J. von Chelius came to Heidelberg in 1817, and these men together set about to establish scientific method in the curriculum. Gmelin was appointed director of the Chemical Institute—which still, however, remained part of the physical institute within the medical faculty. In 1817 he was made full professor, having refused an offer to succeed Klaproth in Berlin.

It is possible that Gmelin was influenced in his decision to stay in Heidelberg by his wife, Luise Maurer, whom he had married on 1 October 1816. She was a singer and the daughter of the pastor of the nearby Kirchheim church. (Certainly Gmelin turned down attractive offers not only from Berlin but also, later, from Göttingen.) They had four children.

In 1818 the Chemical Institute was transferred to its own quarters in a former Dominican cloister, an installation that also included an apartment for Gmelin. This move made the institute virtually independent of the medical faculty, and thus fulfilled one of Gmelin’s long-range plans. In a letter to his mother (28 February 1818) Gmelin described the auditorium of the new facility as being roomy and having elevated benches so that all the students could see the experiments, and added that the laboratory had running water and that there were four additional rooms, including a large one that could house the mineral collections. He further noted that he had thirty students in chemistry but only four in medicine.

Although Gmelin devoted a great deal of time in these early years to improving the teaching of chemistry, he also—and more importantly—made extensive laboratory studies that embraced physiology, organic chemistry, inorganic chemistry, and mineralogy, in addition to purely theoretical studies. He published papers on almost all these subjects, as well as teaching and publishing his great Handbuch, which first appeared in three volumes in 1817 and 1819. Tiedemann, Friedrich Wöhler, and Leonhard were his occasional collaborators. (It is interesting to note that Gmelin persuaded Wöhler, who was enrolled at Heidelberg as a medical student, to relinquish medicine and take up chemistry; and it was through Gmelin’s efforts that upon his graduation in 1823 Wöhler went to work with Berzelius.)

The Handbuch der theoretischen Chemie was Gmelin’s masterwork. The first edition bore that title; the fourth edition, of 1843–1852, had grown to five volumes (expanded to ten by 1870) and was entitled simply Handbuch der Chemie. Gmelin was solely responsible for the first three multivolume editions, and was sole author of the first four volumes of the fivevolume fourth edition, the fifth being compiled by Karl List and Karl Kraut.

Little is known about how or when Gmelin decided to start work on the project that became the Handbuch. As early as 1808 Berzelius had begun work on a textbook of several volumes but had himself realized that it could not be an all-inclusive systematic presentation. Indeed, Gmelin’s father had noted the difficulty involved in such a work as early as 1780. Gmelin sought the complete, objective presentation of the prevailing state of chemistry. His father had found the science in a state of flux, with each author altering his textbook to reflect his own ideas; it was Gmelin’s task to unify it through his own knowledge And—more important—the existing literature. He planned, then, to adduce all pertinent facts, arrange them by element and compound, and give appropriate references. It was necessary for him to bring calm, scholarship, and a critical eye to the data at his disposal; it was likewise necessary that he avoid speculation, which he considered to be hazardous as well as demanding of an inappropriate amount of time and effort. He kept a card-file index, and it is said of him that whenever he found that a compound did not exist as a separate entity or that it was identical to another named substance, he would remark, “Thank God, that there is one less acid.”

Gmelin was unable to objectify chemistry completely, however, and some confusion about atomic weights, equivalents, and molecular theories and compounds is evident in his book. He constantly sought means to simplify or resolve these conflicts, not always with success; some of the formulas he gave reflect such irresolution. Nor did he escape the charge of supporting certain theories above others, despite his announced intention to avoid personal advocacy.

The first edition of the Handbuch reported on only forty-eight elements; two volumes of this edition were devoted to inorganic chemistry and one to organic. By the fourth edition (1843), fifty-five elements were discussed and the work had grown to nine volumes, of which three were devoted to inorganic chemistry and six to organic—thus demonstrating the growth of interest in organic substances and the increase in their known number.

Gmelin was aware from the time of the first edition that the major problem that he must confront would be in the treatment of organic substances. He maintained that inorganic and organic compounds must be distinguished from each other and began working toward their definition. He first suggested that while simple inorganic compounds are composed of two elements, simple organic compounds require three, and accordingly considered methane, cyanogen, and other like compounds as inorganic. In addition, inorganic compounds could be created by the chemist out of their constituent elements, while organic compounds required a plant or animal for their synthesis, the chemist being able to produce only minor modifications in them.

In the first three editions of his book Gmelin used the terms stoichiometric number, combining weight, chemical equivalent, or mixing weight to obtain equivalents. He accepted Döbereiner’s idea of triads, opposed Berthollet’s theory of affinities, and accepted Laurent’s nucleus theory as a basis for the systematization of organic compounds (a system that Beilstein was in turn to adopt in arranging organic compounds in his Handbuch). He devised a system in which compounds were assigned formulas on the basis of equivalents present, and suggested smaller values for them. By the fourth edition Gmelin had adopted the atomic hypothesis and had proposed that the chemical definition of an organic substance might be that it always includes in its composition carbon and hydrogen, with the frequent addition of oxygen or nitrogen or both.

Although the Handbuch may quite properly be considered Gmelin’s masterwork, he did a considerable amount of original research throughout his career. With Tiedemann he did pioneering work in the chemistry of digestion, reported in their twovolume Die Verdauung nach Versuchen (Heidelberg–Leipzig, 1826); in this work they identified choline in bile cholesterol, hematin in blood, and taurine, which Gmelin had found in ox gall in 1824 (it was later synthesized by Kolbe)—to mention but a few of their discoveries. They also studied saliva and changes in the blood. By himself Gmelin prepared potassium ferricyanide (red prussiate of potash, or Gmelin’s salt); cobalticyanides, platinocyanides, croconic acid (which resulted when potassium carbonate and coal were heated); rhodizonic acid; formic acid (by distilling alcohol with manganese dioxide and dilute sulfuric acid); uric acid; and selenium. In addition he developed a test for bile pigments.

Gmelin designed and described some chemical apparatus—a drying tube for gases, a straight tube condenser, and an inverted flask to contain water for washing precipitates—and introduced the terms “racemic acid,” “ester,” and “ketone” into the literature. He suggested that minerals should be classified by form and composition, and reported a number of experiments on galvanism.

Gmelin was highly regarded as a teacher. He was an engaging person with a friendly face surrounded by an aureole of snow-white hair—his friends compared him to a blossoming cherry tree. His stature as a scientist won him membership in many learned societies. He resigned from the Heidelberg faculty in 1851, because of failing health, and sought to obtain the appointment of Robert Bunsen as his successor. His efforts were rewarded when Bunsen became director of the Chemical Institute in 1852. Gmelin died the following year.

The fifth edition of the Handbuch was under way at the time of Gmelin’s death. It appeared in three volumes and five parts (1871–1886), under the editorship of Karl Kraut. In this edition the organic section of the work was dropped and the remainder entitled Handbuch der anorganische Chemie. In 1922 the Deutsche Chemische Gesellschaft assumed the obligation to continue the monumental work; the eighth edition, now entitled Gmelins Handbuch der anorganische Chemie, began publication in 1924 and is still being published. The book maintains the same authoritative position that it has always had and is a fitting tribute to Gmelin’s skill and scholarship.

BIBLIOGRAPHY

I. Original Works. Poggendorff provides a list of Gmelin’s individual writings, in addition to those cited in the text.

II. Secondary Literature. For works about Gmelin and his life, see E. Beyer and E. H. E. Pietsch. “Leopold Gmelin—Der Mensch, sein Werk und seine Zeit,” in Berichte der Deutschen chemischen Gesselschaft, 72 (1939), 5–33; Eduard Farber, ed., Great Chemists (New York, 1961), pp. 453–463; A Ladenburg, History of Chemistry (Edinburg, 1886); Lectures on the History of the Development of Chemistry Since the Time of Lavoisier (Edinburgh, 1886). nos. 347 and 682, both works trans, by L. Dobbin: M. Nikolas, “Das Werk von Friedrich Tiedemann und Leopold Gmelin—die Entwicklung der Ernährungslehre in der ersten Hälfte des 19. Jahrhunderts,” in Gesnerus, 13 (1956), 190–214; and J. R. Partington, A History of Chemistry, vol, IV (London, 1964).

On the occasion of an anniversary celebration at the Gmelin Institute see E.H.E. Pietsch, Die Familie Gmelin und die Naturwissenschaften; Ein Ruckblick auf drei Jahrunderte (Frankfurt, 1964); and Kinder und Jugenderinnerungen der Julie G. Mayer geb. Gmelin (1817–1896). der Tochter Leopold Gmelin (Frankfurt, 1965), Also see P. Walden. “The Gmelin Dynasty,” trans. by R. E. Oesper, in Journal of Chemical Education, 31 (1954), 534–541.

Claude K. Deischer