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chapel. His great work is the series of frescoes in the chapel of the cathedral of Orvieto painted after 1499. In painting them he was assisted by his pupil Girolamo Genga.

Sigourney, Lydia Howard (huntley). 1701-1865. American poet, once very popular. Letters of Life, 1866.

Slgucnza j Gongora, Carlos, 1645-1700. Mexican author.

Slgwart, Christoph Von. Ph.D.. b.1880. Prof. Tubingen 1863. Logic, 1873-78, tr. 1804.

Sikcs, William Wirt, 1836-1883. U. S. Consul at Cardiff from 1876; journalist and author.—His wife, Olive (logan), b. 1841, m. 1871, is an actress and writer.

Sikhs. Sect in India, rejecting idolatry and caste distinctions, and infusing much of Buddhism and Mohammedanism into Hinduism; founded by Nanak, a Hindu, 1469-1538. They became a great military power in the 18th century; but submitted to the English 1848, when the Punjab was annexed to the British empire, and furnish ab. 14,000 soldiers to the British army.

Silage. Fodder material preserved in the fresh state in a silo by the process of Ensilage (q.v.). It usually takes also the name of the fodder so preserved: e.g., corn silage, clover silage. The former is the best silage plant in America.

Silcnus. Satyr, companion and instructor of Bacchus; gifted with the power of prophecy; represented as a fat, bald, jovial, old man, intoxicated, and often riding on an ass.

Silesia. S.e. province of Prussia; early occupied by German tribes, succeeded, as they moved w., by Slavs: joined, successively, to Moravia, Bohemia, and Poland; separated from Poland 1163, but ruled by dukes of the Piast line, who encouraged German colonies; then held by Bohemia, and thus connected with Germany. An agreement of succession, made 1587, made Prussia heir to parts of it; but Austria seized them as a lapsed fief of Bohemia, the remaining portions having previously fallen to her. This claim was resisted by Frederick II., and after the Seven Years' War (q.v.), Silesia was ceded, 1763, to Prussia. Capital Breslau. Area 15,557 sq. m.; pop., 1890, 4,224.458.

Silesia. Austrian. Duchy and crown-land in the n.e. of Moravia; province of Austrian empire. Area 1,987 sq. ni.; pop., 1890, 602.117.

Silcslus, Angelus. See Scheffler, J.

Silcx. See Silica.

Silhouette. Profile drawn in black, the shadows and extreme depths being indicated by the heightening effect of gum

or some other shining material; named from Etienne de Silhouette, 1709-1767, French Minister of Finance 1759, and noted

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Silhouette Portraits.

for reforms in the interest of economy. SilhouetU s were known to the ancients, as is shown on vases.

Silica. SiO,. Chemical compound consisting of silicon and oxygen, occurring in nature by itself in the three forms of quartz, opal, and tridymite, and in combination with various bases in the class of minerals known as silicates; made by melting sand with sodium carbonate, and treating with hydrochloric acid; insoluble in water and the ordinary acids, soluble in alkalies and hydrofluoric acid; fusible with difficulty; found in plants, straw, and eggs; used extensively in the manufacture of glass and porcelain.

Silicate Cotton. This was first made by a steam-blast on a stream of melted slag; invented by John Player, of England, as made at the present. Owing to sulphur in furnace slags, which when wetted would corrode iron, rocks are fused and treated in the same manner, 4 parts of orthoclase with 6 parts of dolomite. It is usually white, and is used as a nonconductor to prevent freezing of water pipes, cooling of steam pipes and dampness in buildings, to keep out vermin, and to prevent the spread of fire, it being non-combustible. It came into general use 1871. It occurs in nature as Pele's Hair (q.v.).

Silicates. Derivatives of silicic or. of the polysilicic acids; family of minerals, numbering several hundred species, consisting of silicon and oxygen, combined in many different proportions with aluminium, calcium, magnesium, sodium, potassium, iron, and many other chemical elements. Except sandstones and limestones, almost all the common rocks are made up to a large extent of silicates.

Silicic Acids. These are numerous. All may be regarded as derived from normal silicic acid, Si(OH)4. The simplest form is H^SiO,, made by decomposing a silicate in solution with dilute hydrochloric acid. When the solution is evaporated to dryness, the residue is no longer soluble. Disilicic acid, H^Si,05, is derived from two molecules of the ordinary form by abstracting one molecule of water; trisilicic acid, H»Si,Oio, from three molecules of the ordinary acid by abstracting two molecules of water. Other trisilicic acids are derived in a similar way. Many minerals are derivatives of some form of silicic acid.

Silicide of Carlton. See Cakborundum.

Silicifled Wood. Wood in which the organic matter has been removed and its place taken by silica, usually in the form of agate (agatized wood), or of opal. Tree trunks, three or four feet in diameter or more, have been found in considerable quantity in the silicifled condition in Arizona and elsewhere. When polished, these masses exhibit a beautiful variety of colors. See Petrified Wood.

Silicic. Short form of the fruit called a silique, found in

Peppergrass, Shepherd's Purse, and other plants of the Mustard family.

Silicon. Si. At.wt. 28.4, sp. gr. 2.49, sp. ht. .167, Valence IV.; discovered by Berzelius 1823. Next to oxygen it is the 1392

SILICON BBOnOFOBH-SI LOAM

chief constituent of the earth's crust, probably one-fourth. It occurs in crystallized and amorphous forms. The former may be made by fusing potassium fluosilicate with sodium and zinc. As a brown amorphous powder, it is obtained by passing the vapor of silicon tetrachloride over heated sodium. Amorphous silicon is not dissolved by sulphuric or nitric acids, but is readily soluble in hydrofluoric acid and potassium hydroxide.

Silicon Bromoform. SiHBr,. Colorless liquid, spontaneously inflammable in the air; bpt. 115°-117° C; sp. gr. 2.7; formed by treating silicon chloroform with hydrobromic acid; analogous to bromoform, CHBr,.

Silicon Carbide. SiC. Transparent, rhombic tablets, of brilliant luster, not soluble in the common acids; decomposed by fusion with caustic alkalies; hardness 9.5, sp. gr. 8.22; made by treating silica with carbon at a temperature of ab. 3,500°C.; used for polishing purposes and for the manufacture of polishing apparatus. See Carborundum.

Silicon Chloroform. SiHCU. Colorless, mobile, fuming liquid of a strong odor, very inflammable and unstable; so called on account of its compositional resemblance to chloroform.

Silicon Hexabromide. Si,Br„. Liquid boiling at 240° C. It forms a white substance with water, and is made by the action of bromine upon silicon hexiodide dissolved in carbon disulphide.

Silicon Hexachlorldc. SiaCl„. Colorless, mobile, fuming liquid; bpt. 146°-148°C. It solidifies at 14° to large white leaf-like crystals. It is made by passing the tetrachloride over • fused silicon.

Silicon Ilexiodiile. 8i,I,. Colorless, doubly refracting prisms or rhombohedra; nipt. 250° C. (in vacuum); made by heating the tetraiodide with finely divided silver to 290°-300°C.

Silicon Hydride. 8iH4. Colorless gas, made by treating a compound of magnesium and silicon with hydrochloric acid. Prepared in this way. it takes fire in the air.

Silicon Iodoform. Si III,. Colorless, strongly refractive liquid; bpt. 220° C. sp. gr. 3.36; made by passing hydriodic acid gas over heated silicon.

Silicon Tclrabromide. SiBr4. Colorless, fuming liquid; bpt. 149° C, sp. gr. 2.81; made by heating the elements together.

Silicon Tetrachloride. SiCl4. Acrid, fuming, colorless liquid, made by passing chlorine over a strongly heated mixture of silica and charcoal; decomposed by water.

Silicon Tetrafliioride. SiF,. Strongly fuming, colorless gas of a pungent odor, made by treating calcium fluoride and silica with sulphuric acid.

Silicon Tetraiodide. Sil,. Colorless, transparent, regular octahedra, isomorphous with carbon tetraiodide; mpt. 120.5° C, bpt. 290° C; made by passing iodine vapors over heated silicon.

SilicoMkelcta. Sub-class of Radiolaria, including the orders Peripyl.ea, Monopyl^ea, and Ph^eodaria (q.v.).

Siliculo§a. Order of the Linnaean class Tetradynamia, including those cruciferous plants which bear short round pods called silicles.

Silique. Two-valved, capsular fruit, each valve having a parietal placenta, from which the valves break away wiien mature, as in many plants of the Mustard family.

Sillquosa?. Order of the Linnaaan class Tetradynamia, including those cruciferous plants which bear elongated, slender pods called siliques.

Sllistrla. Town of Bulgaria on the Danube; besieged in

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sians 1854 and many times assaulted in vain. June 15th the garrison assumed the offensive, crossed the river, defeated the Russians, destroyed the siege works, and raised the siege. Its principal redoubt was ordered to be destroyed by the Congress of Berlin, 1878. Pop., 1893, 11,710.

Siliu§ Itallcus, 25-101. Latin epic poet, Consul 69. His Puniea, in 17 books, describing the second Punic war, is extant. His meter is good, but the work is too close an imitation of Virgil and Homer to claim much originality.

Silk. Fine, lustrous fiber produced by the larvae of certain moths, the best by the Silkworm (see BOMBYCINA), an annual, and a native of China. The moth is white, about 1 in. long, and lays many eggs, as large as mustard seeds. About six weeks after hatching the worm begins to spin the cocoon, which is completed in a week. The worm is 8} in. long, of a cream color, and feeds on white-mulberry leaves. The silk is produced by the two glands opening in the underlip. The cocoon is egg-shaped, and about li in. long. An equal number of male and female cocoons are selected for breeding, the latter being the larger, and placed in a room ab. 70° F., when the moth develops, lavs its eggs, and dies. The diseases of the silkworm are muscadine, due to a fungus, and pebrine and flacherie, due to bacteria; they have entailed great losses on silk growers. Pasteur suggested remedies, which have been largely efficacious. The remainder of the cocoons are placed in hot water or an oven to kill the chrysalis. The fiber is as fine as jlxs in. diameter, each cocoon yielding ab. 300 yds. The outer floss silk is separated, the cocoons floated in hot water and the silk reeled off, 2 to6 cocoons being run into one thread. The cocoons yield ab. 10 per cent of raw silk. The raw silk contains up to 25 per cent of gum. which is removed by boiling with soap. The silk is used in the raw and in the boiled state, several threads being twisted into one. It is dyed in the thread, or in the piece after weaving. The fabrics are often loaded with tannic acid and metallic salts in the dyeing to increase their weight. The world's annual production of raw silk is estimated at 30.000,000 lbs., China and Japan furnishing onehalf, Italy one-third, and France, the Levant and India the balance. The annual silk manufactures of the world are valued at $320,000,000, of which $120,000,000 are by France, $80,000,000 by the U. S.. Switzerland and Germany each $20,000,000, and England $5,000,000; Japan also largely manufactures. In 1896 there was imported into the U. S. silk manufactures valued at $26,652,768, and unmanufactured silk valued at $26,753,428. The price of raw silk in New York, Jan. 1898, was from $2.25 to $4.50 per lb. Good silk, rated as No. 1, was from $3.50 for Japanese to $3.90 for Piedmont, Italian.

Silk. In Botany, long styles of the flowers in an ear of maize.

Silk-Cotton Trees. Of the Mallow family, of the genera Bombax, Pachira and Eriodendron, natives of tropical Asia and America, bearing very large flowers and seeds provided with long, silky hairs.

Sllkweed. See Milkweed.

Silkwor m. See Bombycina.

Silkworm Out. Material prepared in Italy and Sicily, and used by anglers for dressing the hook end of a fishingline. The worms, about to begin spinning, are immersed in vinegar for ab.12 hours, when they are pulled apart, exposing two transparent yellowish-green cords, which are stretched on a board to dry.

SHI. In Mining, horizontal piece of timber laid to support the vertical or inclined legs of a set of timbers.

Sill,Edward Rowland, 1841-1887. Prof. Univ. Cal. 1874-82; poet.

Sill, Joshua Woodrow, U.S.A., 1831-1862. Brig.-gen. U. S. Vols.; killed at Murfreesboro.

Sillery. Village near Rheims, France, famous for its champagne. Pop. 400.

Silllman, Benjamin, M.D., LL.D., 1779-1864. Prof, of Chemistry at Yale 1802-53: founder of its museum of geology, and of the American Journal of Science and Arts, 1818; eminent as a phvsicist and geologist. Chemistry, 1830.—His son. BENJAMIN, M.D., LL.D.. 1816-1885, was Prof. Yale from 1846. co-editor Journal of Science from 1845, and author of several text-books and many monographs.

Sillimanlte. Al,Si06. Aluminium silicate, commonly found as an accessory ingredient in several kinds of metaniorphic rock; also called flbrolite.

Silo. See Ensilage and Silage.

Siloam. Fountain and pool of Jerusalem, connecting with a second pool by an aqueduct, mentioned in O. T. and

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Pool of Siloam.

a tunnel from a spring to the pool. In 1889 a second conduit was discovered 20 ft. below the ground.

Silt. Fine, impalpable mud collecting in lakes and estuaries; often all calm and gradual deposits of mud, clay, or fine sand.

Sllurcs. Ancient people, probably of a non-Aryan stock, being dark and curly-haired, inhabiting the s.e. of South Wales. They were warlike and resisted fiercely the Roman generals who invaded their territory.

Silurian. Series or system of fossiliferous rocks lying immediately below the Devonian; first studied in Wales by Murchison, who named them from the Silures. an ancient British tribe. This term has been gradually restricted, and is now applied only to Murchison's upper division, the lower being called Ordovician. See Column.

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Siluridae. See Nematognathi.

Silva, Antonio Jose Da, 1705-1739. Portuguese dramatist, b. in Brazil; burned at Lisbon, with his mother and wife, as Jews.

Silva, Jose Laurencio, 1792-1873. Venezuelan officer, prominent in the liberation of Colombia and Peru; Major-gen. 1828; exiled 1831-35; Lieut.-gen. and Sec. of War 1855.

Sllva Lifsboa, Jose Da. 1756-1835. Brazilian historian and statesman, Senator 1826.—His brother, Balthazar, 17611840, pub. Annals of Rio Janeiro, 7 vols., 1834.

Silver (argentum). Ag. At.wt. 107.92, sp. gr. 10.5, sp. ht. .057, mpt. 954° C, valence I. It unites directly with the halogens, forming insoluble compounds. Treated with hydrochloric acid, it becomes covered with a layer of the insoluble chloride. It is soluble in concentrated sulphuric acid; the best solvent is nitric acid. It is used for coins and silverware. Its salts, which are affected by light, are used in photography.

Silver, Metallurgy Of. Silver occurs most abundantly in the following ores: Native silver, Argentite, Pyrargyrite, Proustite. and Cerargyrite. Besides these there are several other ores with sulphur, arsenic, bromine, etc.; and it is also found in small amount in the ores of other metals, notably in tetrahedrite. Pure silver is white, soft, very malleable, very ductile, the best known conductor of heat and electricity. Its mpt. is 954° C.J it boils below the mpt. of platinum (1,775° O), and has been distilled; its vapor is greenish. Thin leaf is blue by transmitted light. It crystallizes usually in octahedrons. When melted, it absorbs 22 times its volume of oxygen, which it gives out suddenly when setting, producing a spitting. It does not oxidize in dry or damp air, but is easily blackened by vapors containing sulphur, forming' silver sulphide. It alloys easily with melted lead, copper, zinc, and many other metals; it dissolves in cold mercury, more easily in hot.

Three principal methods are used in treating the ores. The most usual is to smelt the silver ore together with lead ore, the lead obtained carrying all the silver. This may be accomplished in any of the ways used for treating lead ores (see Lead, Metallurgy Of). This silver-bearing lead can be desilverized by several processes. Another method is to convert the silver into chloride, then dissolve this in a salt solution, from which it is afterward precipitated. Another is to amalgamate the silver by grinding t he ore up with mercury, and distilling the mercury from the amalgam.

Amalgamation processes are very old, and are conducted as follows: the barrel amalgamation makes use of tight, revolving barrels. If the ore is not native silver or the chloride, it is first roasted with common salt, which converts the silver into chloride. The charge of a barrel, in Freiberg, was 1,500 lbs. of roasted ore, 300 lbs. of water, 120 lbs. of lumps of iron. The barrel was turned 12 times a minute for 2 hours, then stopped, and 300 to 500 lbs. of mercury put in, and ro

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tated again 20 times a minute for 18 hours. The barrel was then filled two-thirds full of water and turned two hours longer. The amalgam thus obtained was squeezed through canvas bags, and the pasty, rich amalgam put into retorts in which the mercury was distilled off, leaving nearly pure silver. The cost of treating an ore by this method is $10 to $20 per ton, making it profitable to treat only ores over 25 to 50 ounces of silver per ton.

The same process can be conducted more economically in iron pans, in which the finely-divided ore is ground with hot water and mercury. This is called the Washoe process, and can be operated for $5 to $7 per ton. The same principle is again employed in the more primitive Patio process, in which the preliminary grinding of the ore is done in an Arrastra (q.v.j, and the amalgamation is done by spreading the fine ore on a cemented or paved courtyard, making a mud of it, sprinkling it over with salt, and then treading it by driving mules through. After the salt is worked in, mercury and some sulphate of iron and copper are added, and trodden in. The whole working of a heap takes 15 to 45 days. The mass is then washed in tanks, the amalgam separated, squeezed through canvas bags, and distilled. This process was largely used in Mexico and Spanish-American countries from 1600 nearly to the present.

The wet processes of silver extraction depend on the fact that silver chloride, while not soluble in water, is soluble in solutions of common salt, sodium hyposulphite, copper hyposulphite, etc. If the ore is a chloride, bromide, or iodide ore, it can be treated directly. If not, it is first roasted carefully with common salt, an operation called chloridizing roasting, whereby silver chloride is formed. The ore containing the silver as chloride is then placed in tanks having false or perforated bottoms, and is washed with a strong brine (Augustin's process), or sodium hyposulphite (Patera), or calcium thiosulphate (Kiss), or hyposulphite of sodium and copper (Russell). All these solutions dissolve notable quantities of silver chloride, and are mostly precipitated by putting into them strips of copper, which throws down pure silver. Russel's process can be applied to most silver ores without preliminary chloridizing roasting, and he prefers to precipitate the silver as sulphide by adding sodium sulphide. The precipitated silver sulphide is filtered out, dried, and gently roasted in air to silver. These wet processes are in extensive use, and can treat very poor ores.

The concentration of silver in lead furnishes work-lead, which must be desilverized. The oldest method of accom

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remains. The furnaces for this operation frequently had a removable roof, as in figure. As at present conducted, this final cupellation is always preceded by a refining process, in which the lead is oxidized but is not absorbed by the hearth; a little notch in the side of the furnace allowing the melted oxides continually to flow from the furnace.

Another means of desilverizing lead is Parkes' process of stirring into it, at a red-heat, metallic zinc, and then letting the hath stand. The zinc, rising to the surface, brings all the silver with it ;is a rich alloy, while the remaining lead contains only a little zinc, and needs only to be heated a few hours in a softening furnace to be very pure. The zinc alloy is skimmed off, and heated in closed retorts provided with a condenser to catch the zinc vapors driven off. Sometimes the zinc vapors are not condensed, but allowed to burn directly to zinc oxide, which is caught in bags and used for paint. The silver in the retort is nearly pure. The use of a little aluminium in working Parkes' process is very advantageous, as it prevents oxidation of the zinc in the pot and produces richer scums. The scums are treated in Germany quite satisfactorily by electrolysis, producing a very pure electrolytic zinc and leaving rich silver residues.

In treating argentiferous copper ores, the silver accumulates in the copper-iron sulphide or matte, and is extracted by Ziervogels' process of roasting this very carefully, converting the silver almost entirely into sulphate, soluble in water, and washing it out. The silver solution is then precipitated, as by copper.

It is one of the most widely distributed of the metals, and has been known to man since remote antiquity. At different times, different regions have taken the lead in production. The mines of Saxony, Bohemia, and the Harz Mts. have been worked for centuries, and those of Mexico have long been celebrated for their richness. In S. America, Peru. Bolivia and Chili have been the largest producers In the U. S., prior to 1860, the amount produced was small; but during the next thirty years, the yield rapidly increased, amounting in 1892 to 63,500,000 oz., or two-fifths of the world's total production in that year. Since 1892 the amount annually produced has materially fallen.

The world's production of silver was, in 1805, 169,180.249 oz. Of this the U. S. produced 55,726,945, Mexico 46,962,738, Bolivia 21,999,966. Australasia 12,507,335, Germany 5,818.106. and the rest scattering. The U. S. coining value of silver is $1.29 per oz. U. S. coins are 900 parts silver and 100 copper, a dollar weighing 412.5 grs. (see Dollar). Sterling silver is 925 silver and 75 copper. Dec. 1897 the value of gold was $20.67, and of silver 57 cts. per oz. troy. Oct. 1, 1896, the U. S. had 437.202.141 silver dollars, of which 56.513.178 were in circulation; $75,354,781 subsidiary silver coins, of which $60,228,298 were in circulation. In 1895 there was used in the industrial arts in the U. S. 9.419,552 oz. of silver. See Assay and Coinage.

Silver, Thomas, 1813-1888. American inventor of a marine governor for engines 1854, adopted in several European navies.

Silver Ammonium. (NH,Ag)2. Deep blue liquid with metallic luster, made by the action of sodium ammonium on silver chloride.

Silver-well Tree. Small trees of the genus Mohroden

dron (Halesia), natural family Styracacece, with showy white flowers, natives of the s.e. U. S.; called Snowdrop Tree.

Silvcrfoerry. EJaagnus argentea. Shrub of the natural family Elceagnacece, with silvery leaves and fruit, native of the n.w. U. S.

Silver Rromate. AgBrOs. Tetragonal crystals, unaffected by sunlight; made by precipitating silver sulphate with potassium bromate, and crystallizing from hot water.

Silver Bromide. AgBr. Bright yellow precipitate, obtained by treating silver nitrate with a soluble bromide. It occurs native in small quantities, and is used in photography.

Silver Carbonate. Ag,CO,. Prepared from ammonium silver nitrate, it forms transparent, lemon-yellow needles, or rhombohedra, which polarize light. It blackens in light, and loses carbon dioxide at 200° C.

Silver Chlorate. AgCIO,. White, opaque, tetragonal columns; mpt. 230° C, sp. gr. 4.43; soluble in water; made by passing chlorine into water containing silver oxide in suspension.

Silver Chloride. AgCl. Occurring in nature as HornSilver (q.v.); white, curdy precipitate, obtained by adding a soluble chloride or hydrochloric acid to silver nitrate; soluble in ammonia water. Dry silver chloride absorbs 10 per cent of ammonia, forming ammonio-silver chloride, 2AgCI.3NH,. a white compound. It is decomposed by light, and is used in photography.

Silver Cyanate. AgCNO. White, anhydrous powder, sp. gr. 4.004. It blackens on heating, fuses, and takes fire. It is made by precipitating silver nitrate with, potassium cyanate.

Sliver Cyanide. AgCN. White, curdy precipitate, obtained by adding a soluble cj'anide to silver nitrate; soluble in ammonium hydroxide and in potassium cyanide solution. The solution in potassium cyanide is used for silver plating various metals with the aid of the electric current. It is not affected by sunlight.

Silver Fluoride. AgF. Extremely hygroscopic, yellowish-brown substance; sp. gr. 5.85; made by treating the oxide or carbonate with hydrofluoric acid and evaporating.

Silver Glance. Common name for Aroextite (q.v.).

Silver Grain. Wood which when split radially exhibits the sides of numerous medullary rays as shining specks or small patches.

Silver drays. Conservative Whigs, who withdrew from tlie N. Y. Convention of 1848. Many of them had gray hair.

Silver Hydrozoatc. AgNs. Prisms, melting at 250° C. and exploding with terrific violence; insoluble in water, decomposed by light, soluble in ammonia; similar in its proj>erties to silver chloride.

Silver lodatc. AglO,. White, crystalline substance, unaffected by light; made by the action of iodine in alcoholic solution on silver oxide.

Silver Iodide. Agl. Natural and artificial varieties form hexagonal crystals, isomorphous with greenockite (CdS). The color varies from lemon-yellow to olive-green. Sp. gr. 5.0 to 5.6: made by heating iodine and silver; acted upon by light; used in photography.

Silver Nitrate (lotar Caustic). AgNO,. Rhombic crystals, made by dissolving silver in nitric acid and evaporating the solution. Not changed in the light unless it comes into contact with organic substances, when it blackens. It disintegrates flesh, and is used by physicians to remove warts and other superfluous growths; also used as an ingredient in indelible ink.

Silver Nitrite. AgNO,. Crystallizing in needles, made by adding potassium nitrite to a concentrated silver nitrate solution; soluble with difficulty in water; used in organic syntheses.

Silver Oxide. Ap,0. Dark brown, amorphous powder, made by adding a soluble hydroxide to a silver nitrate solution. It dissolves in ammonium hydroxide, forming black crystals I of the composition A£r,G.2NHs, fulminating silver. Silver also I forms a suboxide, Ag40, and a peroxide, AgO or Ag,0B, similar I to the copper compounds.

Silver Pcrchlorate. AgCIO,. White powder, nipt. I 486° C.; made by treating silver oxide with perchloric acid.

Silver Phosphate. Ag,PO,. Yellow, insoluble compound, obtained by treating silver nitrate with a soluble phosphate.

Silver Plating. Solution of silver nitrate in water is carefully precipitated with potassium cyanide and the silver cyanide is filtered out and washed with water. It is then dissolved in a water solution of potassium cyanide, and this constitutes the plating solution. The articles to be plated are carefully cleaned and hung in the solution, being connected to the negative pole of a battery or dynamo; a plate of silver 1395

SILVER STANDARD (OlM'KlliS-SI.HOX

is also hung in the same solution and attached to the positive pole. This maintains the strength of the solution. Potassium cyanide should be added from time to time, as the solution should always have a decided odor of it. The solution should be protected from dust.

Silver Standard Countries. Bolivia, Central America, China, Colombia, Ecuador, India. Mexico, and Russia.

Silver Stiek. In the British Court, the title of the lieutenant and the standard-bearer of the corps of gentlemen-atarms; also the field officer of any of the guard regiments.

Silver Snbeliloride. Ag4Cl,?. Black or brown powder, melting to a yellow mass of silver and silver chloride; made by treating silver with a solution of cupric or mercuric chloride.

Silver Sulphate. AgaS04. Small rhombic prisms; soluble with difficulty in water; obtained by dissolving silver in sulphuric acid.

Silver Sulphide. AgaS. Regular or rhombic crystals, or amorphous powder; sp. gr. 7.1 to 7.36; made by heating silver in sulphur vapor, or by passing hydrogen sulphide into a silver salt solution. It occurs in nature as Argentite and ACANTHITE (q.v.).

Sliver Sulphite. Ag,S03. White, curdy precipitate, obtained on adding sulphurous acid to silver nitrate. It blackens when exposed to light.

Silver-Thaw. Fine rain or Scotch mist, deposited on cold objects and frozen by reason of their coldness. The ice thus formed is always clear and transparent, and gives a silvery sheen to the objects. The weight of the ice frequently breaks limbs of trees, telegraph wires, etc.

Silver-Tree. Leucodendron argenteum. Small tree of the natural family Proteacece, with lanceolate silvery leaves, native of S. Africa.

Silverweed. Potentilla anserina. Low trailing herb of the natural family Rosacere, with yellow flowers and leaves silvery-white on the lower surface, widely diffused in the n. temperate zone.

Si I vent re. Theophile Louis, 1823-1876. French critic and historian of art. Delacroix, 1864; Th. Rousseau. 1868.

Silvia, St.. ab. 400. Of s. France; sister of Rufinus, Consul 393; supposed author of Peregrinatio ad loca sancta, pub. 1887.

Simaruoaeea*. Natural family of flowering plants, of the class Angiospermm and sub-class Dicotyledons, comprising 33 genera and ab. 110 species, mostly trees, natives of tropical and warm countries.

Simeon. Second son of the patriarch Jacob, and ancestor of one of the twelve tribes of Israel.

Simeon, Charles, 1759-1836. English Evangelical leader. Horce Homileticce, 17 vols., 1815-28; Works, 21 vols., 1832-33.

Simeon Stylites, ab.391-459. Syrian fanatic, who spent 30 years on a pillar 60 ft. high; revered as a saint and imitated by many.

Simla. Genus Anthropomorpha (q.v.) or Man-like Apes, including the Mias or Orang-tjtan (q.v.) of Sumatra and Borneo.

Simiadre (quadrumana, Pitheci, or Simoidea). Apes and Monkeys; sub-order of Primates, characterized by having the posterior limbs furnished with an opposable hallux, shorter

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front of the upper, to allow of their overlapping. The body is hairy and the tail often long and prehensile. The orbits of the eyes are shut off from the temporal fossa, and look forward. The facial angle in the adult rarely exceeds 30° (in Chrysothrix it is nearly 60"). The face is more human in appearance in the young. The pinna of the ear is rounded and human-like. They live in companies in tropical forests, with the strongest male for a leader, and feed chiefly on fruits and seeds, but also on insects, eggs and birds. The female bears one or at most two young, which it tends with great care and affection. The sections included are Arctopitheciui, Platyrhina, and Catarhina.

Similar Figures. In Geometry, those of the same form. Similar polygons have equal angles and proportional sides. Similar solids of revolution are generated by the revolution of similar figures.

Simile. Figure of speech comparing two objects by like or as; resembling metaphor, but weaker.

Simla. Town of Hindustan, on the slope of the Himalayas, 170 m. n. of Delhi; socially important as a summer resort;

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government headquarters in the hot months since ISM; settled 1819. It exports opium, fruits and shawl-wool. Altitude 7.048 ft., mean temperature 55* F. Permanent pop. ab.16,000.

Simler, Josias, 1530-1576. Prof. Zurich 1552. De Republica Helvetiorum.

Simmons, Edward Emerson, b.1852. S.A.A. 1888. American painter.

Simmons, Franklin, b.1842. American sculptor.

Simmons, James Fowler, 1795-1864. U.S. Senator from R.I. 1841-47 and 1857-62.

Simmons, Joseph Edward, LL.D.. b.1841. Pres. New York Stock Exchange 1884-86; pres. Board of Education 1886-89.

Simms, William Gilmore, 1806-1870. American novelist. Guy Rivers. 1834; 77<e Yemassee, 1835; Hist. S. Carolina, 1840; Beauchampe, 1842; Life, of Marion, 1844.

Simnel, Lambert, ab.1475-ab.1535. Yorkist claimant to the throne of England, personating Edward, Earl of Warwick: defeated at Stoke. June 16, 1487; afterward employed in the household of Henry VII.

Simon. 1. See Peter. 2. Another apostle. Zelotes, or "the Can.'Uinite," formerly of the party called Zealots.

Simon, Etienne, 1747-1809. Belgian explorer, in Brazif 1795-1804; author of books of travel and history.

Simon, Sir John. LL.D., D.C.L., b.1816. London physician and official, author of reports on sanitation. Pathology, 1850.

Simon, Jules. 1814-1896. Lecturer on Philosophv at the Sorbonne 1839-51; Deputy 1848 and 1863; opposed to'the empire; Minister of Instruction 1871-73; ed. Siecle 1874; Senator 1875. Prime Minister 1876-77; author or editor of many philosophical and political works. Natural Religion. 1856. tr. 1857.

Simon, Pedro ANTONIO, ab.1560-ab.1630. Flemish Franciscan, missionary in New Granada from ab.1590; historical writer.

Simon, Richard, 1638-1712. French theologian and Cod

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