Silver has been used for the beginning of our era decorations and cards. Excavations show that already 4000-3500 BC. silver was separated from lead on islands in the Aegean and Anatolia. Silver was often associated with the moon, the sea and various deities. The alchemy was used for silver symbol of a crescent and alchemists called Luna. Metal mercury was thought that it was some kind of silver. In some languages, there is still the name that mercury like quicksilver in English or mercury (meaning alive silver) in older Dutch. Much later turned out to be two completely different elements. The name Silver leads through the Old High German silbar of the Germanic root * seluƀra-. One suspects that it is a loan word that from Asia Minor or even further afield comes here. In Latin it is called Silver argentum, where silver symbol Ag owes. There are at least fourteen languages in which the same word is used for silver and money. Well known examples are the Spanish and French plata argent. Until well into the 20th century coinage of silver and gold, the main payment of humanity. Today we see the use of silver only on commemorative coins and other collector coins and medals. Silver is a widely used material in the applied arts for the production of reliefs, busts, reliquaries, baptismal shells and other liturgical vessels, candlesticks, tobacco and snuff boxes, coffee pots, silverware and other ornamental and utensils. Sterling Silver (alloy with very high silver content) by goldsmiths is widely used for the manufacture of jewelry. Silver bracelets, necklaces and earrings are already known from antiquity. In the 18th century, silver shoe buckles in fashion. A charm bracelet is almost always made of silver. Silver is also used to redeem items made of inferior metals. Silver leaf, consisting of thin slices of silver, is used for decoration, for example in the painting (icons), or gold in the manufacture of leather. A special application of silver leaf is vark (or varakh), India in the popular use to decorate cakes with very thin layers of pure silver. For levels of very high quality silver is suitable because it possesses good light reflecting properties. But usually uses aluminum because it is much cheaper. The good electrical conductivity of silver makes it a very suitable material in electrical and electronic products. In circuits is silver (or silver alloy) used to connect components to each other. For longer connections silver too expensive. As a silver catalyst is used in the industry for example for the production of formaldehyde and ethylene oxide. In dentistry, silver is now no longer used because, while it is relatively easy to make the correct shape, but still has some toxic properties. Because of its disinfectant properties, silver is now also used again to purify drinking water or pure love. Especially for small quantities of water (up to 100 liters) is silver (as silver nitrate), easier to dose and apply than chlorine. In medicine, colloidal silver was once used as an antibiotic, alternative medicine, this happens still. In the laboratory lot of silver nitrate applied as a reagent in chloride provisions, including by precipitation. In addition, the insoluble silver chloride is formed. Silver is used as the silver halides in the photography. Finely atomised silver iodide is used to make rain and to reduce fog around airports. Namely, silver iodide allows for the aggregation of small water droplets which form the cloud. Silver is a metal that is easy to work a little harder than gold and has a white sheen. Silver has the best of all metal electrical conductivity and the lowest contact resistance, better than copper and gold. Gold, by contrast, used more often because it does not corrode. In addition, silver conductive of all metals heat the best and has the highest optical reflectivity (at least as far as the visible light, ultraviolet light reflects the bad). Silver halides are sensitive to light. The metal is stable in pure air and pure water, but when exposed to ozone or hydrogen sulfide discolors it. In the event that silver with sulfur or compounds thereof comes into contact a black layer is formed of silver sulphide.
Mother of pearl is part of the shell of the mollusc. The material is used in many cultures utensils or art. Almost all of the shells comprise a number of superimposed layers, each with its own function, and of which the pearlescent layer is one of them. The thickness of the different layers varies per week group of animals. In most groups, the pearly layer one of the thinner layers the shell exists, some is low (almost) absent, there are also groups where the shell consists mainly of the nacre layer. The pearlescent layer is always located on the inside of the shell, where it is (as well as the rest of the shell) are secreted by epithelial cells of the mantle tissue of the animal. Apart from the provision of strength is the main purpose of smoothing of the inside of the shell. A second function is to defend the animals against parasites and harmful waste. When the animal by a parasite attacked or if it is irritated by an external object that can not eject the animal, what the process is in operation, and the object is included in successive layers of nacre. This process can continue without interruption until the shellfish late life. Usually, such an object is located between the animal and the shell. In such cases, the shell on the spot will only exhibit a thickening: the object is included in the shell itself. Less common is the subject is not on this site and will develop an entirely loose pearl. Pearlescent is made up of hexagonal platelets aragonite (calcium carbonate (CaCO3)) containing 10 to 20 microns wide and 0.5 microns thick. They are placed parallel in a continuous, thin layer. The layers are separated from each other by sheets of organic matrices which are composed of elastic biopolymers, such as chitin, lustrine and silk-like proteins. This mix makes the material strong and resilient, which is also due to the adhesion caused by the "masonry structure" of the pictures. This constantly recurring pattern greatly increases the hardness, whereby it can almost match to silicon. The iridescent appearance of mother of pearl is due to the fact that the thickness of the aragonite platelets is about 0.5 microns, which is comparable to the wavelength of visible light. This results in constructive and destructive interference of light at different wavelengths, so that the various colors of light to be reflected at different angles which looks at the mother of pearl.
Mother of Pearls