Leonhardi, Johann Gottfried

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Leonhardi, Johann Gottfried

(b. Leipzig, Saxony, 18 June 1746; d. Dresden, Saxony, 11 January 1823),

chemistry, medicine, pharmacy.

Leonhardi’s father, a physician, inspired a love of learning in his young son. After studying at home under various Leonhardi enrolled in the local lyceum, and there completed his training in the classical languages. In 1764 he entered the University of Leipzig, where in the course of his studies in philosophy and science he heard Johann Heinrich Winkler lecture on physics and Karl Wilhelm Pörner on chemistry. He began to read medicine under Christian Gottlieb Ludwig. He received his baccalaureate in 1767. Continuing his work in medicine, for which he had an “innate love,” he deliverd his “lectures for the License” in 1769 on the structure and function of the conglobate glands (that is, glands of simple structure, such as the lymphatics). He was awarded a master’s degree in 1770 and the baccalaureate in medicine the following year with a dissertation De resptionis in corpore humano praeter naturam impeditat causis atque noxis (Leipzig, 1771).

Remaining at Leipzig as Privatdozent, Leonhardi lectured on medicine and chemistry. He became extraordinary professor of medicine in 1781. In 1782 he moved to the University of Wittenberg (at that time still in Saxony) as professor of medicine; in 1791 he accepted the post of personal physician and councillor to the elector of Saxony, Friedrich Augustus III. Leonhardi was also given a seat in the Dresden public health council. Although he retained his professorship at Wittenberg, he arranged for a deputy to lecture in his place. In 1815 he became a knight of the Königliche sächsische Civil-Verdienstorden. Despite almost constant ill health during the last decade or so of his life, Leonhardi managed to continue his favorite work of editing and translating.

Leonhardi did little original research. the bulk of his writings consists of summaries, compilations, and translations. He also wrote a number of short, academic, and unoriginal medical discourses. His chief accomplishment was Chymisches Wörterbuch.... übersetzt und mit Anmerkungen und Zusätzen vermehrt, 6 pts. (leipzig, 1781-1783), his authoritative translation of Pierre-Joseph Macquer’s Dictionnaire de chimie. Leonhardi’s well-received and widely used version amounted to a new, expanded edition, approximately two and a half times the length of the original, to which Leonhardi himself contributed about 150 new articles. The abundant annotation shows him to have been in complete command of the chemical literature of his day; the references are given exactly and the commentary in the notes is clear, factual, and comprehensive. Judging by these excellent notes, Leonhardi’s primary interest appears to have been the qualitative analysis of inorganic substances, especially those of actual or potential industrial value. He followed the current controversies on the nature of combustion and the “airs” with great interest and published a summary of recent pneumatic discoveries as Aerologie (1781). The notational underbrush grows thickest in the less theoretical parts of the Dictionnaire. Like Macquer he was not a reductionist; he did not find it helpful to devise premature theories about the ultimate constituents of things. Leonhardi adhered to the phlogiston theory until the early 1790’s. Leonhardi’s was not a creative mind, but it was surely a disciplined and well-stocked one.


I. Original Works. This list contains those of Leonhardi’s works which are either (1) of special interest for chemistry or (2) not listed in the British Museum Catalogue of Printed Books or in the Index Catalogue of the Surgeon General’s Office, U.S. Army (1st ser.). The latter catalogue has a nearly complete list of Leonhardi’s medical works.

1. Observationes quasdam chemicas proponit praelec- tionesque suas aestivas... (Leipzig, 1775).

2. “Versuch einer Anleitung zu gemeinnüziger ökonomischen Prüfung der sämtlichen Gewässer in Sachsen,” in Schriften der leipziger Oekonomischen Societät,6 (1784).

3. “Chymische Untersuchung des ächten Braunschweigischen Grüns,” ibid.

4.Vinorum alborum metallici contagii suspectorum docimasiae curae repetitae et novae (Wittenberg, 1787).

5.Programma de tubarum uterinarum morbis Pauca quaedam (Wittenberg, 1788).

6. Physiologia muci primarum viarum(Wittenberg, 1789).

7.De succorum humanorum salibus dulcibus (Leipzig, 1790).

8. Letters to the editor, Crell’s Chemische Annalen (1789), pt. 2,423-424; (1790), pt.2, 126-128; (1794), pt. 1, 177-178. Translations, editions, introductions:

9. D. P. Loyard, Versuch über einen tollen Hundebiss, with notes by Leonhardi (Leipzig, 1778).

10.Herrn Peter Joseph Macquers Chymisches Wörterbush, oder allgemeine Begriffe der Chemie nach alphabetischer Ordnung, asu dem Französischen nach der zweiten Ausgabe übersetzt und mit Anmerkungen und Züsatzen vermehrt, 6 vols. (Leipzig, 1781-1783); 2nd ed., 7 vols. (Leipzig, 1788-1791); 3rd ed., prepared by J. B. Richter, 3 vols. (Leipzig, 1806-1809); separate publication of Leonhardi’s notes and additions: Neue Züsatze und Anmerkungen zu Macquers Chymischen Wörterbuch erster Ausgabe, 2 vols. (Leipzig, 1792).

11. Aerologie physico-chemicae recentioris primae linae (Leipzig, 1781); expanded and translated as Kurzer Umriss der neuern Entdekkungen über die Luftgattungen (Graz, 1783).

12. C. W. Scheeles... Chemische Abhandlung von der Luft und dem Feuer..., 2nd ed. (Leipzig, 1782), contains notes by Leonhardi which were incorporated into the Baron de Dietrich’s Supplément au Traité Chimique de l’ Air et du Feu de M. Scheele... (Paris, 1785). C.G. Kayser, Vollständiges Bücher-Lexicon (Leipzig, 1834-1838), lists a third German ed. (1788).

13. Schwedisches Apothekerbuch, translated from the 2nd (Latin) ed. and annotated by Leonhardi (Leipzig, 1782).

14. Pierre Bayen, Untersuchungen über das Zinn, und Beantwortung der Frage: Ob Man sich ohne Gefahr zu ökonomischen Gebrauche der zinneren Gefässe bedienen könne?... Aus dem Französischen übersetzt; herausgegeben und mit Anmerkungen begleitet D. Johann Gottfried Leon- hardi... (Leipzig, 1784).

15. A. F. L. Dörffurt, Abhandlung über der Kampher, mit Vorrede von J. G. Leonhardi (Wittenberg, 1793).

16. Pharmacopoea Saxonica (Dresden, 1820).

II. Secondary Litterature. See J. Ferguson,Bibliotheca chemica, II (Glasgow, 1906), 23, and the literature cited there; L. F. F. Flemming, De vita et meritis beati Joh. Gottfr. Leonhardi (Dresden, 1823)—the author was unable to locate this in preparing the above article; Michaud, Biographie universelle,XXIV, 185-186; and J. R. Partington, A History of Chemistry, III(London, 1961), 81-82, 493-494, 616-619. Leonhardi’s sketch of his early life is in A. G. Plaz, Panegyrin medicam (Leipzig, 1771), xii–xv. I am indebted to Dr. John B. Blake of the U.S. National Library of Medicine for calling this reference to my attention. For reviews of the Wörterbuch, see Annales de chimie,4 (1790), 289; 11 (1791), 204; 12 (1792), 110.

Stuart Pierson

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