A condition, known as argyria, results with a grayish pigmentation of the skin and mucous membranes. Silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body. Exposure to silver (metal and soluble compounds, as Ag) in air should not exceed 0.01 mg/m 3, (8-hour time-weighted average - 40 hour week). While silver itself is not considered to be toxic, most of its salts are poisonous. In recent times, however, consumption of silver has greatly exceeded the output. Silver for centuries has been used traditionally for coinage by many countries of the world. Silver nitrate, or lunar caustic, the most important silver compound, is used extensively in photography. Silver chloride has interesting optical properties as it can be made transparent it also is a cement for glass. Silver iodide is used in seeding clouds to produce rain. Silver fulminate, a powerful explosive, is sometimes formed during the silvering process. When freshly deposited, it is the best reflector of visible light known, but is rapidly tarnished and loses much of its reflectance. It is used in mirror production and may be deposited on glass or metals by chemical deposition, electrode position, or by evaporation. Silver paints are used for making printed circuits. Silver is used in making solder and brazing alloys, electrical contacts, and high capacity silver-zinc and silver-cadmium batteries. industrial consumption going into this application. Silver is of the utmost importance in photography, about 30% of the U.S. This alloy contains 92.5% silver, the remainder being copper or some other metal. Sterling silver is used for jewelry, silverware, etc. It is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulfide, or air containing sulfur. Pure silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance. It is a little harder than gold and is very ductile and malleable, being exceeded only by gold and perhaps palladium. Pure silver has a brilliant white metallic luster. Purities of 99.999+% are available commercially. Commercial fine silver contains at least 99.9% silver. Silver is also recovered during electrolytic refining of copper. are the principal silver producers in the western hemisphere. Silver occurs natively and in ores such as argentite (Ag 2S) and horn silver (AgCl) lead, lead-zinc, copper, gold, and copper-nickel ores are principal sources. Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as early as 3000 B.C. Silver has been known since ancient times. The United States monetary system was based on the silver standard from 1933 until 1968. For centuries many countries used silver for coinage.
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