Georg Brandt

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Georg Brandt Born June 26, 1694
SkinnskattebergDied April 29, 1768
Stockholm
Nationality SwedishFields chemistry
mineralogyInstitutions Uppsala UniversityKnown for cobalt

Georg Brandt (June 26, 1694 – April 29, 1768), was a Swedish chemist and mineralogist who discovered cobalt (c.1735).

Brandt was born in Skinnskatteberg parish, Västmanland County. He was professor of chemistry at Uppsala University, and died in Stockholm. He was able to show that cobalt was the source of the blue color in glass, which previously had been attributed to the Bismuth found with cobalt.

About 1741 he wrote: "As there are six kinds of metals, so I have also shown with reliable experiments... that there are also six kinds of half-metals: a new half-metal, namely Cobalt regulus in addition to Mercury, Bismuth, Zinc, and the reguluses of Antimony and Arsenic". He gave six ways to distinguish Bismuth and Cobalt which were typically found in the same ores:

Bismuth fractures while Cobalt is more like a true metal.
In fusing, they do not mingle but attach about as an almond and its stone.
The regulus of Cobalt fuses with flint and fixed alkali giving a blue glass known as zaffera, sasre, or smalt. Bismuth does not.
Bismuth melts easily and if kept melted, calcinates forming a yellow powder.
Bismuth amalgamates with Mercury; the regulus of Cobalt does not at all.
Bismuth dissolved in nitric acid and with aqua regia and gives a white precipitate when put in pure water. The regulus of Cobalt needs alkalies to precipitate, and then forms dark or black precipitates.