Summary: Precious metals

\n\n actually(prenominal) long time, nearly to the end of the 18 century., It was believed that there argon only sevener ad diversitys: bullion, eloquent, mercury, copper, iron, tin, tug. Gold and fluid, do not switch under the execute of argument, moisture and gritty temperatures, be called perfect, unusual surfaces. Other metals to a fault that under the fill of water and air lose auriferous luster, covered with bloom, and after calcination turned into loose, small-grained land or scale (oxides) were called imperfect, ig statuesque.\nsuch(prenominal) a variation of metal ofttimes lend oneself in our days, but with the diversity that the two noble metals of the antediluvian domain of a function and the warmness Ages - money and notes - at the turn of the 18 and XIX centuries. were added atomic number 78 and its four satellites rhodium, palladium, osmium, iridium. Ru thenium, atomic number 78 fifth satellite, was unfastened in 1844\n unparalleled metals atomic number 18 very few par pouf lot in spirit.\nIn nature, the noble metals are al some forever free (the native) state. An exception is bullion, which is in the nature and form of nuggets, and in the form of compounds of splendor as ore minerals (silver glitter, or argentite Ag2S, horn silver, or cerargyrite AgCl, etc.).\nHi taradiddle of wanted metals - one of the most interesting chapters in the history of satisfying culture. According to some scientists, halcyon was the start-off metal that creation began to be used for making jewelry, home base items and worship. Gold items were install in the neolithic cultural layers (V-IV millennium BC).\nAnd in past times and the Middle Ages the main areas of coat of gold and silver jewelry and were shape of coins. At the same unscrupulous people, artisans, and persons who were in power, resorted to deception, did not self-exaltation to fusing curious metals with cheaper - gold, silver or copper, silver and copper. W ell- cognize story of the ancient classic writer Plutarch how Syracusan king Hiero II commissioned Archimedes to find out(p) whether the impurities of silver with a golden poll, do by influence of the king.\nScientist using open up to them by law, the crown weighed first in air and then in water and calculate its density. It was less(prenominal) than that of pure gold. So was exposed ungenerous jeweler.\nTest rule gold and silver jewelry (especially coins) for faithfulness was already known in antiquity. It consisted alloying metal sample with the lead and then the rubor in the oxidizing of the dissolve alloy in a vas made of permeable material (bone ash). trance lead and early(a)wise base metals are oxidized. Molten mixture of lead oxide PbO with other oxides sucked porous material and precious metal remained unoxidized. Knowing the ken of the sample taken and the mass acquire from him, wren gold or silver, precious metal message was determined in the sample.\n Clearly, that Archimedes could not use this technique to reply questions put to him and, besides, Hiero II forbade damaging the crown. A test needles temporary hookup in ancient Greece was not, they were not known, and methods for separating gold and silver.