Brass was produced by the cementation process where copper and zinc ore are heated together until zinc vapor is produced which reacts with the copper. There is good archaeological evidence for this process and crucibles used to produce brass by cementation have been found on Roman period sites including Xanten[77] and Nidda[78] in Germany, Lyon in France[79] and at a number of sites in Britain.[80] They vary in size from tiny acorn sized to large amphorae like vessels but all have elevated levels of zinc on the interior and are lidded.
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Brass will corrode in the presence of moisture, chlorides, acetates, ammonia, and certain acids. This often happens when the copper reacts with sulfur to form a brown and eventually black surface layer of copper sulfide which, if regularly exposed to slightly acidic water such kakım urban rainwater, kişi then oxidize in air to form a patina of green-blue copper sulfate.
During the later part of first millennium BC the use of brass spread across a wide geographical area from Britain[66] and Spain[67] in the west to Iran, and India in the east.[68] This seems to have been encouraged by exports and influence from the Middle East and eastern Mediterranean where deliberate production of brass from metallic copper and zinc ores had been introduced.[69] The 4th century BC writer Theopompus, quoted by Strabo, describes how heating earth from Andeira in Turkey produced "droplets of false silver", probably metallic zinc, which could be used to turn copper into oreichalkos.
The Renaissance saw important changes to both the theory and practice of brassmaking in Europe. By the 15th century there is evidence for the renewed use of lidded cementation crucibles at Zwickau in Germany.[102] These large crucibles were capable of producing c.20Â kilo of brass.[103] There are traces of slag and pieces of maden on the interior.
The composition of brass, generally 66% copper and 34% zinc, makes it a favorable substitute for copper based jewelry, birli it exhibits greater resistance to corrosion. Brass is often used in situations in which it is important that sparks not be struck, such kakım in fittings and tools used near flammable or explosive materials.[5]
Siden bile har bodd her har de satt seg mest inn i ting, og. Die Areca Palme ist nicht giftig und kann deshalb auch problemlos in einem Haus...
"copper alloy (Scope note)". British Museum. The term copper alloy should be searched for full retrievals on objects made of bronze or brass. This is because bronze and brass have at times been used interchangeably in the old documentation, and copper alloy is the Broad Term of both.
By the first century BC brass was available in sufficient supply to use birli coinage in Phrygia and Bithynia,[72] and after the Augustan currency inkılap of 23 BC it was also used to make Romen dupondii and sestertii.
[101] Work in brass or bronze continued to be important in Benin geri and other West African traditions such kakım Cari goldweights, where the mühür was regarded as a more valuable material than in Europe. Renaissance and post-medieval Europe[edit]
This compound saf frequently been used birli a biomarker for the presence of (marine) algal matter in the environment, and is one of the ingredients for E number E499.
[70] In the 1st century BC the Greek Dioscorides seems to have recognised a link between zinc minerals and brass describing how Cadmia (zinc oxide) was found on the walls of furnaces used to heat either zinc ore or copper and explaining that it birey then be used to make brass.[71]
The keywork brassestol trä of most modern woodwinds, including wooden-bodied instruments, is also usually made of an alloy such birli nickel silver/German silver. Such alloys are stiffer and more durable than the brass used to construct the instrument bodies, but still workable with simple hand tools—a boon to quick repairs.
However, if brass is placed in contact with a more noble mühür such as silver or gold in such an environment, the brass will corrode galvanically; conversely, if brass is in contact with a less-noble metal such bey zinc or iron, the less noble maden will corrode and the brass will be protected. Lead content[edit]