silver poplar: see willow.

silver nitrate, chemical compound, AgNO₃, a colorless crystalline material that is very soluble in water. The most important compound of silver, it is used in the preparation of silver salts for photography, in chemical analysis, in silver plating, in inks and hair dyes, and to silver mirrors. It is used in medicine in the treatment of eye infections and gonorrhea. Fused silver nitrate is also called lunar caustic. Taken internally silver nitrate is a poison. It is prepared by reaction of nitric acid with silver, and purified by recrystallization. It is darkened by sunlight or contact with organic matter such as the skin.

silver chloride, chemical compound, AgCl, a white cubic crystalline solid. It is nearly insoluble in water but is soluble in a water solution of ammonia, potassium cyanide, or sodium thiosulfate ("hypo"). On exposure to light it becomes a deep grayish blue due to its decomposition into metallic silver and atomic chlorine. This light-sensitive behavior is the basis of photographic processes (see photography, still). Since silver bromide, AgBr, and silver iodide, AgI, react similarly, all three of these silver halide salts are used in making photographic films and plates. Both the bromide and iodide are less soluble in water and more sensitive to light than the chloride. The bromide forms light yellow cubic crystals; the iodide forms yellow hexagonal or yellow-orange cubic crystals, depending on the temperature. Besides use in photography, silver chloride is used in silver plating, and silver iodide is used for seeding clouds. The chloride, bromide, and iodide occur naturally as the minerals cerargyrite, bromyrite, and iodyrite, respectively. Silver fluoride, AgF, forms colorless cubic crystals; it is much more soluble in water than the other silver halides.

silver, metallic chemical element; symbol Ag [Lat. argentum]; at. no. 47; at. wt. 107.8682; m.p. 961.93°C;; b.p. 2,212°C;; sp. gr. 10.5 at 20°C;; valence +1 or +2. Pure silver is nearly white, lustrous, soft, very ductile, malleable, and an excellent conductor of heat and electricity. In many of its properties it resembles copper and gold, the elements above and below it in Group 11 of the periodic table. It is not a chemically active metal, being considerably below hydrogen in the electromotive series (see metal). It is, however, attacked by nitric acid (forming the nitrate) and by hot concentrated sulfuric acid. Silver is almost always monovalent in its compounds, but an oxide, a fluoride, and a sulfide of divalent silver are known. It does not oxidize in air but reacts with the hydrogen sulfide present in the air, forming silver sulfide (tarnish). Silver nitrate is the most important compound. Silver chloride, bromide, and iodide are used in still photography because of their sensitivity to light. Solutions of certain protein complexes containing silver are used as antiseptics. A mirror can be made by coating glass with metallic silver derived from the reaction of a solution of a silver ammonia complex with an organic reducing agent such as formaldehyde. Although silver can be found uncombined in nature, most silver used today is obtained from its ores. Among these the most important are argentite or silver glance (silver sulfide), which is found associated with other metal sulfides, e.g., galena; horn silver or cerargyrite (silver chloride); two ores composed of silver and antimony (in different proportions) called pyrargyrite (or ruby silver ore) and stephanite; and another ore composed of silver and arsenic sulfides called proustite. Mexico, the United States (Idaho, Montana, Arizona, Colorado, Utah, Nevada, California, New Mexico, and Texas), the former USSR, Peru, Australia, and Canada are the leading producers. The metal is prepared in various ways depending upon the nature of its occurrence; the greatest quantity is obtained in connection with the refining of lead and copper. It is separated from lead by the Parkes process, which is based upon the fact that silver is soluble in molten zinc whereas lead is not. The cyanide process has largely replaced an amalgam process in which silver is dissolved in mercury. Some of the silver produced today is used, as in the past, in making coins (see coin; money; bimetallism). Large quantities are used for silver utensils and jewelry, and in plating tableware electrolytically from a solution of sodium silver cyanide. Alloys of silver with copper, in which the copper adds hardness, are important. Coin silver is an alloy consisting of 90% silver and 10% copper. Sterling silver contains 92.5% silver and 7.5% copper. Silver alloys are used in dental amalgams and for electrical contacts. Silver was one of the first metals to be used by humans (see silverwork).

free silver, in U.S. history, term designating the political movement for the unlimited coinage of silver.

Origins of the Movement

Free silver became a popular issue soon after the Panic of 1873, and it was a major issue in the next quarter century. The hard times of 1873-78 stimulated advocacy of cheap money, and the Greenback party nominated presidential candidates several times and flourished in local elections, especially in 1876 and 1878. The market price of silver fell rapidly after 1873, because of American and European demonetization of silver and because of increases in mine production. Inflationists failed to secure paper-money expansion and turned to silver, believing its free coinage would serve their purpose as well as greenbacks so long as a silver dollar was worth intrinsically less than a gold dollar. Silver-mining interests also wanted silver coinage to aid their business.

Political Ferment and Legislative Compromise

The demands for unlimited silver coinage led to the passage (1878) of a compromise measure, the Bland-Allison Act, over President Hayes's veto. The act provided for definitely limited coinage at a ratio of 16 to 1 with gold, but its provisions were insufficient to halt the decline of silver prices, or to increase the circulation of money. Meanwhile, sectional lines over money were becoming sharply drawn. The financial interests in the East favored sound money and the gold standard. The indebted agrarian classes of the South and West demanded inflation, to ease debt burdens in the face of falling prices of farm products. Their demands were reinforced by Western silver-mining interests.

As the prosperity of the early 1880s vanished, demands arose again for free silver. By 1890 the political strength of the silver advocates, especially in the West, was so great that the Sherman Silver Purchase Act, another compromise, was passed, to replace the Bland-Allison Act and to provide for increased government purchases of silver. The West's discontent was further emphasized by the rise of the Populist party, with demands including free silver. The silver advocates were no longer content with compromise measures and were displeased by the 1892 presidential candidacy of Grover Cleveland, a supporter of the gold standard. Many silver Democrats deserted Cleveland to support James B. Weaver, the Populist candidate. This coalition of silverites and Populists was able to gain control of half a dozen Western states.

Advocates of free silver were enraged when the Panic of 1893 brought repeal of the Sherman Silver Purchase Act. By the middle of his second term, Cleveland's Western and Southern opponents had captured the Democratic party. Publication of Coin's Financial School, by William Hope Harvey (1894), made many converts to free silver by presenting the complicated money question in easily understood terms.

Decline of the Movement

In 1896 free silver became the major issue of a presidential campaign when William Jennings Bryan made it the chief plank of his platform. McKinley's victory over Bryan then and again in 1900, coupled with increased gold supplies and returning prosperity, minimized free silver as a political issue. Yet the silver bloc, partly inspired by Nevada silver interests, continued to be active and secured legislation mandating heavy U.S. Treasury purchases of silver under Franklin Delano Roosevelt. The decreasing supply of silver in the 1960s led the U.S. Treasury to end its use in coins and to sell its surplus stock of silver in 1970.

Silver, Abba Hillel, 1893-1963, American rabbi and Zionist leader, b. Lithuania. He was taken to the United States in 1902. Educated at the Univ. of Cincinnati (B.A., 1915) and Hebrew Union College, Cincinnati, he became rabbi of the The Temple, Cleveland, in 1917. He was cochairman of the American Zionist Emergency Council during World War II and chairman of the American section of the Jewish Agency for Palestine, and he thus played a part in the founding of the state of Israel. He was the author of several books, including Democratic Impulse and Jewish History (1928), Vision and Victory (1949), and A History of Messianic Speculation in Israel (1959).

Silver Springs, mineral spring, N central Fla., source of the Silver River. The limestone spring, one of the world's largest and most famous, has a basin 80 ft (24 m) deep and 300 ft (91 m) wide. The water temperature is 72°F; (22°C;) throughout the year. The extreme clearness of the water is due to the filtration of rainwater through the porous soil and substrata. Silver Springs remains a tourist attraction; a great variety of aquatic life may be seen through glass-bottomed boats. The Spanish explorer Hernando De Soto was probably the first European to visit the spring (1539). The town of Silver Springs is nearby.

Silver Spring, uninc. city (1990 pop. 76,046), Montgomery co., W central Md., a residential suburb of Washington, D.C. It is a major suburban office center and has a large naval ordnance laboratory, several research laboratories (for the development of defense materials and of electronic and prosthetic equipment), and a plant that makes precision instruments.

Silver Purchase Act: see Sherman Silver Purchase Act.

Sherman Silver Purchase Act, 1890, passed by the U.S. Congress to supplant the Bland-Allison Act of 1878. It not only required the U.S. government to purchase nearly twice as much silver as before, but also added substantially to the amount of money already in circulation. The Sherman Silver Purchase Act (supported by John Sherman only as a compromise with the advocates of free silver) threatened, when put into operation, to undermine the U.S. Treasury's gold reserves. After the panic of 1893 broke, President Cleveland called a special session of Congress and secured (1893) the repeal of the act.

Atomic Number:	Atomic Number: 47
Atomic Symbol:	Atomic Symbol: Ag
	Name of Element: Silver
Atomic Weight:	Atomic Weight: 107.8682
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 1

German silver, name for various alloys of copper, zinc, and nickel, sometimes also containing lead and tin. They were originally named for their silver-white color, but use of the term silver is now prohibited for alloys not containing that metal. German silver varies in composition, the percentage of the three elements ranging approximately as follows: copper, from 50% to 61.6%; zinc, from 19% to 17.2%; nickel, from 30% to 21.1%. The proportions are always specified in commercial alloys. German silver is extensively used because of its hardness, toughness, and resistance to corrosion for articles such as tableware (commonly silver plated), marine fittings, and plumbing fixtures. Because of its high electrical resistance it is used also in heating coils. It was discovered (early 19th cent.) by a German industrial chemist, E. A. Geitner.

Monetary standard under which the basic unit of currency is defined as a stated quantity of silver. It is usually characterized by the coinage and circulation of silver, unrestricted convertibility of other money into silver, and the free import and export of silver for the settlement of international obligations. No country now operates under a silver standard. In the 1870s most European countries adopted the gold standard, and by the early 1900s only China, Mexico, and a few small countries still used the silver standard. In 1873 the U.S. Treasury stopped coining silver, which led to the Free Silver Movement, but the defeat of William Jennings Bryan ended agitation for free silver in the U.S. Seealso bimetallism.

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or silver salmon

Species (Oncorhynchus kisutch) of salmon prized for food and sport that ranges from the Bering Sea to Japan and the Salinas River of Monterey Bay, Cal. It weighs about 10 lbs (4.5 kg) and is recognized by the small spots on the back and upper tail-fin lobe. Young cohos stay in freshwater for about one year before entering North Pacific waters; they mature in about three years. Some landlocked populations spend their entire lives in freshwater. Cohos were successfully transplanted in the 1970s into Lake Michigan as a game fish.

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Inorganic compound (AgNO₃), colourless, transparent crystals with a bitter, caustic, metallic taste. The most important silver compound, it is used to prepare other silver salts, to silver mirrors, and as a reagent in analysis. It is very soluble in water; dilute solutions are effective against gonococcal bacteria and may be applied to newborns' eyes to prevent blindness from gonorrhea. Ingesting silver nitrate causes violent abdominal pain and gastroenteritis.

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Ornamental, shade, and timber tree (Betula papyrifera) of the birch family, native to northern and central North America. Also called canoe birch, silver birch, or white birch, it is one of the best-known birches. The smooth, varicolored or white bark of young trees peels horizontally in thin sheets, which once were used as writing surfaces as well as for roofing, canoes, and shoes. The water-impervious bark, which burns even when wet, is a boon to campers and hikers.

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Metallic chemical element, one of the transition elements, chemical symbol Ag, atomic number 47. It is a white, lustrous precious metal, valued for its beauty. It is also valued for its electrical conductivity, which is the highest of any metal. Between copper and gold in their common group of the periodic table, it is intermediate between them in many properties. Widely distributed in nature in small amounts, as the native metal and in ores, it is usually recovered as a by-product of copper and lead production. Its use in bullion and coins was overtaken in the 1960s by demand for industrial purposes, especially photography. It is also used in printed electrical circuits, electronic conductors, and contacts. It is the catalyst for converting ethylene to ethylene oxide, the precursor of many organic chemicals. Its use in alloys in sterling (92.5percnt silver, 7.5percnt copper) and plated silverware, ornaments, and jewelry remains important; yellow gold used in jewelry is typically 25percnt silver, and gold dental alloys are about 10percnt silver. Silver dental fillings are an amalgam of silver and mercury. Silver in compounds, the most important of which is silver nitrate, has valence 1. Its chloride, bromide, and iodide are used in photography and its iodide in cloud seeding.

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