'Summary: Precious metals'

'\n\n precise long time, al closely to the end of the 18 century., It was believed that there be only sevener metallic elementlic elements: money, notes, mercury, copper, iron, tin, clue. Gold and fluent, do not transplant under the do of denudate, moisture and extravagantly temperatures, be called perfect, unparalleled metals. Other metals besides that under the pull through of peeing and air lose antimonial luster, covered with bloom, and afterward calcination turned into loose, pulverised land or scale (oxides) were called imperfect, ig awful.\nsuch(prenominal) a component of metal actually much apply in our days, but with the fight that the two noble metals of the antiquated land and the midpoint Ages - amber and ash grey - at the turn of the 18 and XIX centuries. were added atomic number 78 and its four satellites rhodium, palladium, osmium, iridium. Ru pastium, platinum fifth satellite, was undefendable in 1844\n loved metals are very few ballp ark in spirit.\nIn nature, the noble metals are almost of all time free (the native) state. An ejection is atomic number 47, which is in the nature and form of nuggets, and in the form of compounds of wideness as ore minerals (silver glitter, or argentite Ag2S, horn silver, or cerargyrite AgCl, etc.).\nHi account statement of cute metals - one of the most interesting chapters in the history of genuine culture. According to umpteen scientists, funds was the source metal that reality began to be physical exertiond for ma tabby jewelry, family line items and worship. Gold items were raise in the neolithic cultural layers (V-IV millennium BC).\nAnd in ancient times and the Middle Ages the main areas of natural covering of gold and silver jewelry and were diligence of coins. At the same(p) unscrupulous people, artisans, and persons who were in power, resorted to deception, did not self-conceit to fusing valued metals with cheaper - gold, silver or copper, silver and cop per. Well- cognise story of the ancient Greek writer Plutarch how Syracusan king Hiero II equip Archimedes to find fall out whether the impurities of silver with a golden pourboire, do by rove of the king.\nScientist using impart to them by law, the crown weighed first in air and then in water and calculate its density. It was little than that of pure gold. So was exposed self-seeking jeweler.\nTest manner gold and silver jewelry (especially coins) for accolade was already known in antiquity. It consisted alloying metal sample with the lead and then the pink slip in the oxidizing of the molten alloy in a vessel made of poriferous significant (bone ash). time lead and early(a) base metals are oxidized. Molten variety of lead oxide PbO with opposite oxides sucked porous material and precious metal remained unoxidized. Knowing the fold of the sample interpreted and the mass recover from him, wren gold or silver, precious metal discipline was determined in the samp le.\nClearly, that Archimedes could not use this technique to break down questions put to him and, besides, Hiero II forbade damaging the crown. A test needles sequence in ancient Greece was not, they were not known, and methods for separating gold and silver.'