THE GROWTH OF METALLURUGY
The Growth of MetallurgyAfter the seven metals of antiquity: gold, silver, copper, mercury, tin , iron and lead, the next metal to be discovered was Arsenic in the 13th century by Albertus Magnus. Arsenicus (arsenious oxide) when heated with twice its weight of soap became metallic. By 1641 arsenious oxide was being reduced by charcoal. Arsenic is steel gray, very brittle and crystalline; it tarnishes in air and when heated rapidly forms arsenious oxide with the odor of garlic. Arsenic compounds are poisonous. The symbol As is taken from the latin arsenicum. Arsenic was used in bronzing and improving the sphericity of shot. The most common mineral is Mispickel or Arsenopyrite (FeSAs) from which arsenic sublimes upon heating.
The next metal to be isolated was antimony. Stibium or antimony sulphide was roasted in an iron pot to form antimony. Agricola reported this technique in 1560. Antimony whose name comes from the Greek "anti plus monos"- a metal not found alone, has as its symbol Sb from the latin stibium. It is an extremely brittle flaky metal. Antimony and its compounds are highly toxic. Initial uses were as an alloy for lead as it increased hardness. Stibnite is the most common ore. It was commonly roasted to form the oxide and reduced by carbon.
By 1595,bismuth was produced by reduction of the oxide with carbon , however, it was not until 1753 when bismuth was classified as an element. Zinc was known to the Chinese in 1400; however , it was not until 1738 , when William Champion patented the zinc distillation process, that zinc came into common use. Before Champion's process, zinc, which was imported from China, was known as Indian Tin or Pewter. A Chinese text from 1637 stated the method of production was to heat a mixture of calamine (zinc oxide) and charcoal in an earthenware pot . The zinc was recovered as an incrustation on the inside of the pot. In 1781 zinc was added to liquid copper to make brass. This method of brass manufacture soon became dominant.
One other metal was discovered in the 1500's in Mexico by the Spaniards. This metal was platinum. Although not 100% pure, it was the first metal to be discovered and sourced from the "New World". The property which brought this metal to the prospectors attention was its lack of reactivity with known reagents. Early use of platinum was banned because it was used as a blank for coins which were subsequently gold coated, proving that the early metallurgists understood not only density but also economics. Although, platinum was known to the western world, it was not until the 1800's that platinum became widely used.
Several other metals were isolated during the 1700's. These were Cobalt, Nickel, Manganese, Molybdenum, Tungsten, Tellurium, Beryllium , Chromium, Uranium, Zirconium and Yttrium . Only laboratory specimens were produced and all were reduced by carbon with the exception of tungsten which became the first metal to be reduced by hydrogen.
The next metal to be isolated was antimony. Stibium or antimony sulphide was roasted in an iron pot to form antimony. Agricola reported this technique in 1560. Antimony whose name comes from the Greek "anti plus monos"- a metal not found alone, has as its symbol Sb from the latin stibium. It is an extremely brittle flaky metal. Antimony and its compounds are highly toxic. Initial uses were as an alloy for lead as it increased hardness. Stibnite is the most common ore. It was commonly roasted to form the oxide and reduced by carbon.
By 1595,bismuth was produced by reduction of the oxide with carbon , however, it was not until 1753 when bismuth was classified as an element. Zinc was known to the Chinese in 1400; however , it was not until 1738 , when William Champion patented the zinc distillation process, that zinc came into common use. Before Champion's process, zinc, which was imported from China, was known as Indian Tin or Pewter. A Chinese text from 1637 stated the method of production was to heat a mixture of calamine (zinc oxide) and charcoal in an earthenware pot . The zinc was recovered as an incrustation on the inside of the pot. In 1781 zinc was added to liquid copper to make brass. This method of brass manufacture soon became dominant.
One other metal was discovered in the 1500's in Mexico by the Spaniards. This metal was platinum. Although not 100% pure, it was the first metal to be discovered and sourced from the "New World". The property which brought this metal to the prospectors attention was its lack of reactivity with known reagents. Early use of platinum was banned because it was used as a blank for coins which were subsequently gold coated, proving that the early metallurgists understood not only density but also economics. Although, platinum was known to the western world, it was not until the 1800's that platinum became widely used.
Several other metals were isolated during the 1700's. These were Cobalt, Nickel, Manganese, Molybdenum, Tungsten, Tellurium, Beryllium , Chromium, Uranium, Zirconium and Yttrium . Only laboratory specimens were produced and all were reduced by carbon with the exception of tungsten which became the first metal to be reduced by hydrogen.
GOLD
Gold articles are found extensively in antiquity mainly as jewelry e.g. Bracelets, rings etc. Early gold artifacts are rarely pure and most contain significant silver contents. This led to the ancients naming another metal - electrum, which was an alloy of gold and silver, pale yellow and similar in color to amber. Therefore, early gold varied from pure through electrum to white gold. The symbol for gold is Au from the latin aurum meaning shining dawn.
Stone age man learned to fashion gold into jewelry and ornaments, learning that it could be formed into sheets and wires easily. However, its malleability, which allows it to be formed into very thin sheet (0.000005 inches), ensures that it has no utilitarian value and early uses were only decorative. As gold is a noble metal, being virtually noncorrosive and tarnish free, it served this purpose admirably.
Stone age man learned to fashion gold into jewelry and ornaments, learning that it could be formed into sheets and wires easily. However, its malleability, which allows it to be formed into very thin sheet (0.000005 inches), ensures that it has no utilitarian value and early uses were only decorative. As gold is a noble metal, being virtually noncorrosive and tarnish free, it served this purpose admirably.
The use of copper in antiquity is of more significance than gold as the first tools, implements and weapons were made from copper. From 4,000 to 6,000 BC was the Chalcolithic period which was when copper came into common use. The symbol for copper is Cu and comes from the latin cuprum meaning from the island of Cyprus. Initially copper was chipped into small pieces from the main mass. The small pieces were hammered and ground in a manner similar to the techniques used for bones and stones. However, when copper was hammered it became brittle and would easily break. The solution to this problem was to anneal the copper. This discovery was probably made when pieces were dropped in camp fires and then hammered. By 5,000 BC copper sheet was being made.
By 3600 BC the first copper smelted artifacts were found in the Nile valley and copper rings, bracelets, chisels were found. By 3000 BC weapons, tools etc. were widely found. Tools and weapons of utilitarian value were now within society, however, only kings and royalty had such tools; it would take another 500 years before they reached the peasants.
By 3600 BC the first copper smelted artifacts were found in the Nile valley and copper rings, bracelets, chisels were found. By 3000 BC weapons, tools etc. were widely found. Tools and weapons of utilitarian value were now within society, however, only kings and royalty had such tools; it would take another 500 years before they reached the peasants.
Lead is not found free in nature but Galena (lead sulfide) was used as an eye paint by the ancient Egyptians. Galena has a very metallic looking appearance and was, therefore, likely to attract the attention of early metalworkers. The production of metallic lead from its ore is relatively easy and could have been produced by reduction of Galena in a camp fire. The melting point of lead is 327 C, therefore, it would easily flow to the lowest point in the fireplace and collect. At first lead was not used widely because it was too ductile and the first uses of lead were around 3500 B.C.. Lead's use as a container and conduit was important and lead pipes bearing the insignia of Roman emperors can still be found. Lead is highly malleable, ductile and noncorrosive making it an excellent piping material. Its symbol is Pb from the latin plumbum.
Mercury was also known to the ancients and has been found in tombs dating back to 1500 and 1600 BC. Pliny, the Roman chronicler, outlined purification techniques by squeezing it through leather and also noted that it was poisonous. Mercury, also known as quicksilver, is the only metal which is liquid at room temperature. Although it can be found in its native state, it is more commonly found in such ores as calomel, livingstonite, corderite and its sulfide cinnabar. Extraction is most simply carried out by distillation as mercury compounds decompose at moderate temperatures and volatilize.
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