(1694–1768) Swedish chemist
Brandt was the son of an ironworker and former apothecary in Riddarhyta, Sweden, and from an early age he helped his father with metallurgical experiments. He studied medicine and chemistry at Leiden, and gained his MD at Rheims in 1726. He was later made warden of the Stockholm mint (1730), and professor of chemistry at the University of Uppsala.
In 1733 he systematically investigated arsenic and its compounds. He invented the classification of semimetals (now called metalloids), in which he included arsenic, bismuth, antimony, mercury, and zinc.
In 1735 Brandt postulated that the blue color of the ore known as smalt was due to the presence of an unknown metal or semimetal. He named this ‘cobalt rex’ from the Old Teutonic ‘kobold’, originally meaning ‘demon’, later applied to the ‘false ores’ that did not yield metals under the traditional processes. In 1742 Brandt isolated cobalt, and found it was magnetic and alloyed readily with iron. His results were confirmed in 1780 by Torbern Bergman, who first obtained fairly pure cobalt.
Brandt also, in 1748, experimented with the dissolution of gold in hot concentrated acid, and with its precipitation from solution. These experiments clarified some of the alleged transmutations of silver into gold. Indeed, Brandt devoted his later years to exposing fraudulent transmutations of metals into gold, and it was said of him that no chemist did more to combat alchemy.
Subjects: Science and Mathematics.