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Tarnishing
Tarnish is a thin layer of corrosion that forms over copper, brass, aluminum, magnesium, neodymium and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish, although it may tarnish with oxygen over time. It often appears as a dull, gray or black film or coating over metal. Tarnish is a surface phenomenon that is self-limiting, unlike rust. Only the top few layers of the metal react, and the layer of tarnish seals protects the underlying layers from reacting. Tarnish actually preserves the underlying metal in outdoor use, and in this form is called patina. The formation of patina is necessary in applications such as copper roofing, and outdoor copper, bronze, and brass statues and fittings. Patina is the name given to tarnish on copper-based metals, while toning is a term for the type of tarnish which forms on coins. Chemistry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc Refining (metallurgy), refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes bimetallism, alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metals
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically ductile (can be drawn into wires) and malleable (they can be hammered into thin sheets). These properties are the result of the ''metallic bond'' between the atoms or molecules of the metal. A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride. In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically ductile (can be drawn into wires) and malleable (they can be hammered into thin sheets). These properties are the result of the ''metallic bond'' between the atoms or molecules of the metal. A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride. In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolfram Evaporated Crystals And 1cm3 Cube
Wolfram may refer to: * Wolfram (name) * Wolfram, an alternative name for the chemical element tungsten * Wolfram Research, a software company known for the symbolic computation program Mathematica ** Wolfram Language, the programming language used by Mathematica ** Wolfram code, a naming system for one-dimensional cellular automaton rules introduced by Stephen Wolfram * Wolfram syndrome, a genetic disorder * Wolfram, Queensland Wolfram is a former mining town within the locality of Dimbulah in the Shire of Mareeba. in Queensland, Australia, now a ghost town. Geography Wolfram is about west of Cairns and south of Thornborough. It was also known as Wolfram Camp. ..., a former mining town in Australia * The ''Wolfram'', a fictional military airship in the air combat video game '' The Sky Crawlers: Innocent Aces'' See also * {{Disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of sulfur- bearing fossil fuels. Structure and bonding SO2 is a bent molecule with ''C''2v symmetry point group. A valence bond theory approach considering just ''s'' and ''p'' orbitals would describe the bonding in terms of resonance between two resonance structures. The sulfur–oxygen bond has a bond order of 1.5. There is support for this simple approach that does not invoke ''d'' orbital participation. In terms of electron-counting formalism, the sulfur atom has an oxidation state of +4 and a formal charge of +1. Occurrence Sulfur dioxide is found on Earth and exists in very small concentrations and in the atmosphere at about 1 ppm. On other planets, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ohio Historical Society
Ohio History Connection, formerly The Ohio State Archaeological and Historical Society and Ohio Historical Society, is a nonprofit organization incorporated in 1885. Headquartered at the Ohio History Center in Columbus, Ohio, Ohio History Connection provides services to both preserve and share Ohio's history, including its prehistory, and manages over 50 museums and sites across the state. An early iteration of the organization was founded by Brigadier General Roeliff Brinkerhoff in 1875. Over its history, the organization changed its name twice, with the first occurring in 1954 when the name was shortened to Ohio Historical Society. In 2014, it was changed again to Ohio History Connection, in what members believed was a more modern and welcoming representation of the organization's image. History In its early history, Ohioans made several attempts to establish a formal historical society. On February 1, 1822, the Ohio General Assembly passed legislation creating the Historical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philadelphia Museum Of Art
The Philadelphia Museum of Art (PMoA) is an art museum originally chartered in 1876 for the Centennial Exposition in Philadelphia. The main museum building was completed in 1928 on Fairmount, a hill located at the northwest end of the Benjamin Franklin Parkway at Eakins Oval. The museum administers collections containing over 240,000 objects including major holdings of European, American and Asian origin. The various classes of artwork include sculpture, paintings, prints, drawings, photographs, armor, and decorative arts. The Philadelphia Museum of Art administers several annexes including the Rodin Museum, also located on the Benjamin Franklin Parkway, and the Ruth and Raymond G. Perelman Building, which is located across the street just north of the main building. The Perelman Building, which opened in 2007, houses more than 150,000 prints, drawings and photographs, along with 30,000 costume and textile pieces, and over 1,000 modern and contemporary design objects including fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File (tool)
A file is a tool used to remove fine amounts of material from a workpiece. It is common in woodworking, metalworking, and other similar trade and hobby tasks. Most are hand tools, made of a case hardened steel bar of rectangular, square, triangular, or round cross-section, with one or more surfaces cut with sharp, generally parallel teeth. A narrow, pointed tang is common at one end, to which a handle may be fitted.. A rasp is a form of file with distinct, individually cut teeth used for coarsely removing large amounts of material. Files have also been developed with abrasive surfaces, such as natural or synthetic diamond grains or silicon carbide, allowing removal of material that would dull or resist steel files, such as ceramic. History Early filing or rasping has prehistoric roots and grew naturally out of the blending of the twin inspirations of cutting with stone cutting tools (such as hand axes) and abrading using natural abrasives, such as well-suited types of st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Bicarbonate
Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation ( Na+) and a bicarbonate anion ( HCO3−). Sodium bicarbonate is a white solid that is crystalline, but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral natron and is found dissolved in many mineral springs. Nomenclature Because it has long been known and widely used, the salt has many different names such as baking soda, bread soda, cooking soda, and bicarbonate of soda and can often be found near baking powder in stores. The term ''baking soda'' is more common in the United States, while ''bicarbonate of soda'' is more common in Australia, United Kingdom and Ireland. and in many northern/central European countries it is called ''Na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emery Paper
Emery paper is a type of abrasive paper or sandpaper, that can be used to abrade (remove material from) surfaces or mechanically finish a surface. Operations include deburring, polishing Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material accordin ..., paint removal, corrosion removal, sizing, etc. This is accomplished by rubbing the abrasive-coated paper, with some pressure, against the object being processed. Abrasion may be performed by hand, electrically powered, or air powered equipment. Description Emery is a naturally occurring rock of impure crystalline aluminium oxide (Al2O3 mixed with oxides of silicon (e.g. SiO2), iron (Fe), and other elements and varying small percentages of clay and other silicates for example: kaolinite (Al4Si4O10(OH)8)). Smaller particles abrade smaller amou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandpaper
upright=1.35, Sheets of sandpaper with different grit sizes (40 (coarse), 80, 150, 240, 600 (fine)). Sandpaper and glasspaper are names used for a type of coated abrasive that consists of sheets of paper or cloth with abrasive material glued to one face. There are many varieties of sandpaper, with variations in the paper or backing, the material used for the grit, grit size, and the bond. In the modern manufacture of these products, sand and glass have been replaced by other abrasives such as aluminium oxide or silicon carbide. It is common to use the name of the abrasive when describing the paper, e.g. "aluminium oxide paper", or "silicon carbide paper". Sandpaper is produced in a range of grit sizes and is used to remove material from surfaces, whether to make them smoother (for example, in painting and wood finishing), to remove a layer of material (such as old paint), or sometimes to make the surface rougher (for example, as a preparation for gluing). The grit size of san ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
