Gahn, Johan Gottlieb

(b. Ovanåker, Sweden, 19 August 1745; d. Falun, Sweden, 8 December 1818)

mineralogy, chemistry.

Gahn studied physics and chemistry at Uppsala from 1762 to 1770. When Torbern Bergman was appointed professor of chemistry there in 1767, Gahn became his laboratory assistant. After passing in 1770 the examination for mining engineer, he worked at the College of Mining, where he was assigned the task of applying new and more scientific methods to the copper smelting processes at the Falun mine in the Kopparberg district. For four years he worked exclusively with copper smelting, introducing important improvements and solving many technical problems. Above all, he modernized the methods for using the by-products of the smelting process, among them sulfur, iron sulfate, red pigment, copper mastic, and copper precipitate. Gahn performed his chemical research in a well-equipped laboratory that he installed at his own expense in his garden at Falun.

Although he seldom took the time to write down his observations and published almost nothing, rumors of Gahn’s extensive chemical and technical abilities spread beyond Sweden; Falun became a mecca for scholars, factory owners, and industrialists seeking advice and guidance in technical problems. “Gahn is building in Sweden a real center for everything that happens in the technical field. The country still lacks a Polytechnic Institute where new ideas can be tried out and from which innovations and projects can emanate. Gahn supplies that” (Johann F. L. Hausman, Reise durch Skandinavien in den Jahren 1806 und 1807 [Leipzig, 1811–1818]). Such merit did not remain unnoticed. In 1780 the College of Mining awarded Gahn its gold medal and two years later informed King Gustavus III of the improvements and growth that Gahn’s work had brought to the refining of copper. On this basis the king conferred on him in 1782 the honorary title of superintendent of mines and in 1784 authorization as associate member at the College of Mining. In the same year he was elected member of the Academy of Science in Stockholm.

It was of great importance to contemporary Swedish chemistry that Scheele, who worked in the pharmacy Uplands Wapen in Uppsala from 1770 to 1775, was introduced by Gahn to Torbern Bergman. Gahn collaborated in the work of both of these men; and Bergman, who in many cases benefited from Gahn’s experimental ability, emphasized this both in his letters and published works. For instance, he mentions, concerning the mineral pyrolusite, that he himself had doubted that it contained any metal but that Gahn was the first to reduce the mineral and to discover, in 1774, the pure metal later named manganese.

Gahn shared a friendship and an exchange of ideas with Scheele that were fruitful for the work of both. Unfortunately, their correspondence provides no information about Gahn’s contributions; although Gahn conscientiously preserved Scheele’s letters during the 1770’s, Scheele was so indifferent towards preserving his correspondence from Gahn that only a few writings saved at random still exist. Scheele’s letters reveal that he often solicited and received valuable explanations for his experiments with pyrolusite and barium sulfate. It is interesting that Scheele thanks Gahn especially for the suggestion of an important study concerning what is now called solid-state reactivity.

Gahn was a capable chemical experimenter, but Scheele was his unchallenged superior in everything except blowpipe analysis, in which Gahn was unsurpassed. It is therefore not surprising that the possibility of conceptual cross-fertilization that existed here would materialize. A conversation with Scheele in the spring of 1770 concerning his research with inorganic substances in animal bones, the so-called animal earth, provided the incentive for Gahn to study this material more carefully; he was then able to show, with the aid of the blowpipe, the presence of phosphorus. This observation later led to Scheele’s method of obtaining phosphorus from animal bones.

Preserved letters indicate that—at least in the first part of the 1770’s—Gahn was the trusted friend for whose opinion Scheele first sent his scientific articles.

Gahn also worked with J. J. Berzelius. Among other things they were both financially and scientifically interested in a sulfuric acid factory near Gripsholm. Berzelius tried unsuccessfully to persuade Gahn to go to Stockholm, but ultimately he traveled to Falun to meet Gahn in the summers of 1813–1816. The two friends explored the area’s rich mineral deposits and, as Berzelius wrote, “a number of entirely new minerals were discovered . . . and analysed at the time in Ghan’s excellently equipped laboratory” (Jöns Jacob Berzelius Autobiographical Notes, trans. by Olof Larsell [Baltimore, 1934], p. 91).

BIBLIOGRAPHY

I. Original Works. Gahn’s works include Några anmärkningar i svenska bergs-lagfarenheten om författningar till befrämjande av god hushållning vid järnhyttor (Uppsala, 1770), his doctoral diss.; “Yttrande över Kommerskollegii fråga om någon ljusare och gladare färg än rödfärg,” in Kongliga Vetenskaps Academiens nya Handlingar, 25 (1804), 289–301; and Underrättelse om upställningen och nyttjandet af herr assessor J. G. Gahns förbättrade appareil för vattens aererande med tabell (Uppsala, 1804).

The principal part of Gahn’s literary remains is kept in the library of the Royal Institute of Technology. Certain parts of his correspondence are preserved in the archives of the Nordic Museum and in the National Record Office. The important letters from Scheele and Bergman as well as Gahn’s correspondence with Berzelius are to be found in the library of the Royal Academy of Science. Gahn’s correspondence with Berzelius is in Jac. Berzelius brev, H. G. Söderbaum, ed., IX (Stockholm, 1922). The 38 surviving letters from Gahn to Bergman (1768–1778) are in the university library of Uppsala.

II. Secondary Liteature. On Gahn and his work, see J. A. Almquist, Bergskollegium och bergslagsstaterna (Stockholm, 1909); J. G. Anrep, Svenska slägtboken, 3 vols. (Stockholm, 1871–1875); J. Berzelius, Själfbiografiska anteckningar (Stockholm, 1901), and in the trans. by Olof Larsell, Jöns Jacob Berzelius Autobiographical Notes (Baltimore, 1934); B. Boethius, Grycksbo 1382–1940 (Stockholm, 1942); U. Boklund, “När Gahn upptäckte Scheele på Lokks apotek,” in Lychnos (1959), 217–222; Hans Järta, Åminnelse-Tal öfver . . . Herr Joh. Gottl. Gahn . . . hållet inför Kongl. Vetenskaps-Academien den 8 October 1831 (Stockholm, 1832); AB Ferrolegeringar (publisher), Av meteorernas ätt. En krönika om mangan . . . (Stockholm, 1962); S. Lindroth, Gruvbrytning och kopparhantering vid Stora Kopparberget . . ., II (Stockholm, 1955); and C. Sahlin, “Johan Gottlieb Gahns laboratorium och samlingar,” in Blad för bergshanteringens vänner, 16 (1919–1921). See also J. E. Jorpes, Jac. Berzelius, His Life and Work (Stockholm, 1966).

Uno Boklund