Background

Johan Gahn was born on August 19, 1745, in Ovanåker, Sweden.

Education

Gahn studied physics and chemistry at Uppsala from 1762 to 1770.

Career

When Torbern Bergman was appointed a professor of chemistry at Uppsala University 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.

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. 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.

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.

Achievements

• Johan Gahn was an eminent metallurgist who discovered manganese in 1774. With Scheele, he discovered phosphoric acid in bones and prepared phosphorus from bones. He also improved copper-smelting processes and studied technical applications of minerals, opening new branches of industry. In 1780 the College of Mining awarded Gahn its gold medal and two years King Gustavus III conferred on him the honorary title of superintendent of mines.

Membership

Gahn was a member of the Royal Swedish Academy of Sciences and of the Academy of Science in Stockholm.

Connections

colleague:

Carl Wilhelm Scheele

colleague:

Jöns Jacob Berzelius

colleague:

Torbern Bergman

References

• Dictionary of Scientific Biography