- Calamine brass
Calamine brass is
brassproduced by a particular alloying technique using calamine, a zinc ore, rather than metallic zinc. Calamine brass was produced using proportions of two-sevenths fine copper, four-sevenths calamine, and one-seventh shruff (old plate brass). Calamine brass was the first type of brass produced, probably starting during the 1st millennium BC, and was not replaced in Europeby other brass manufactures until the 18th century (it is likely that Indian brass manufacturers had developed more advanced techniques some centuries earlier).
Brass is an alloy of
copperand zinc, and when it was first developed, methods for producing metallic zinc were unknown. Metallurgists wishing to produce brass thus used calamine (actually a mixture of the virtually indistinguishable zinc ores smithsoniteand hemimorphite) as the zinc component of brass. The resulting brasses, produced by heating a mixture of copper and calamine to a high temperature for several hours (allowing zinc vaporto distill from the ores and permeate the metallic copper), contained a significant amount of slagmaterial resulting from the non-zinc components of calamine. The use of ore rather than metallic zinc also made it difficult to accurately produce the desired final proportion of copper to zinc. This process is known as cementation.
The mineral calamine takes its name from La Calamine in
Belgium. That area was the source of much of the medieval brass of northern Europe. Brass production was introduced to England in 1587 when several members of the Company of Mineral and Battery Worksobtained a licence from the company (within whose monopoly it was) at built brass works at Isleworth. However a decade later the company obstructed the owners from mining calamine.
New brass works were built by
Jacob Momma, a German immigrant in 1649 at Esher, probably using Swedish copper. After the passing of the Mines Royal Act in 1689, further works were built near Bristol, where brass production became a major industry in the 18th century. [cite book
publisher=David & Charles |year=1973 |isbn=0715360655 ] [cite web
title=A Short History of Baptist Mills Brass Works - Part One: The Early Years, 1700 - 1720
accessdate=2005-08-03] Later brass production sites in England included Cheadle and
Calamine brass was slowly phased out as zinc
smeltingtechniques were developed in Europe, which produced metallic zinc more suitable for brass production than calamine. However, the conversion away from calamine brass manufacture was slow; a British patentwas awarded to William Champion in 1738, but the alloying of metallic zinc and copper to produce brass was not patented until 1781 (by James Emerson), and calamine brass mills persisted in South Walesuntil as late as 1858. The slow diffusion of this technology was probably the result of economic factors.
title=A Brief Review of the Development of the Copper, Zinc and Brass Industries in Great Britain from AD 1500 to 1900
title=A History of Metallurgy
last=Tylecote |first=R. F.
edition=2nd edn |year=1991 |pages=84
last=Donald |first=M. B.
chapter=Copper, Zinc and Brass Production
title=The Industrial Revolution in Metals
coauthors=R. F. Tylecote (eds.)
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