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I remember with nostalgy when my teacher of chemistry showed us for the first time, during a lesson, the periodical system of elements and their chemical symbols, one curious colleague asked: Why that little box from the center of the table is coloured differently by it neighbours? With a misterious smile our teacher answered: ... well, it’s a long story and a short answer. Which one you would like to hear? I dont know your reply, but I will share with you the amazing incomplete story of mercury and I challenge you to read more about. As you already know, mercury’s chemical symbol is Hg and seems that there is a contradiction between the name and its symbol. Where is the connection? As my teacher told me, I looked in detail about the origin of this element and I found out more than expected. Thus, because mercury is liquid in standard conditions of temperature and pressure and its colour is silver, ancient greeks named hydor (water) argyros (silver) which in latin became hydrargyrum or argentum vivum (alive silver). That is why the symbol of this misterious chemical element is Hg. In the periodical system only 2 other elements are liquid in the same conditions mentioned above and these are: mercury (Hg) and bromine (Br). Among the elements discovered by ancients, mercury is one of them. Seems that it was known in the ancient Egypt since about 1500 B.C. Theophrastus, a greek successor of Aristotle in the Peripatetic school, in his work On stones is writing about cinnabar which is a compound of hydrargyrum (Hg) with sulphur. Dioscoride showed how mercury was obtaining from cinnabar but he was not the only one. But why the name of this element preserved as mercury and not hydrargyrum or …? The name of mercury was given during the time of alchemists after the name of god Mercury, which was equivalent to the Egyptian god Hermes. A Chinese alchemist Ko Hung (281-361) mentions how to obtain mercury from cinnabar. Thus, the classic method for the synthesis of mercury consists in the heating of cinnabar in the oven at 700°C in the presence of air, which results the metal and SO2 (because the mercury oxide that results is unstable in those conditions): HgS + O2 ? Hg + SO2
Followed by cooling mercury gas with a water condenser. Sometimes, especially in the case of small exploitation, cinnabar is heated in retorts to 700°C with lime or rasping of iron:
4HgS + 4CaO ? 4Hg + 3CaS + CaSO4
HgS + Fe ? Hg + FeS
Aristotle says that Dedal – a great artist of antiquity (over 1300 BC) – carved a wooden statue of Venus goddess, filled with mercury inside and then sunk into a bath of mercury to metallize it. He received mercury from some priests in Memphis. Phoenicians and Greeks made mercury trade that brought it from the mines in Almadén (Spain), where it was large deposits of mercury. Pliny describes the fact that some metals such as Ag and Cu floating on mercury and then dive into it and give alloys which we call amalgams namely mixture after the word Al Mulagham = mixture. An Arabian alchemist Al Idrisi left information on how to amalgamate the gold sands of Africa (XI century BC.
Agricola describes in the essay De Re Metallica five ways to extract mercury.
Significant deposits of mercury were found in Spain, Peru, Mexico, North America, Italy and are still in use.
As we can notice nowadays mercury is considered a strategical substance having a lot of utilities: from thermometers, wobbler lures, manometers, fluorescent lamps, vapour turbines, calomel electrode, batteries, mirrors, to cosmetics in mascara, in dental amalgams (with precautions), in traditional medicine, or in NMR as active nuclei through its isotopes, in silver mining and the story is not complete here …