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Method of Culture, — They are all readily increafed by 

 parting the roots, and planting them out in the autumn or 

 fpring, where they are to remain in the borders and clumps. 

 They may alfo be raifed by planting the flips in the fame 

 manner : they (hould be afterwards managed as the perennial 

 fun-flower. They are durable in the root, but decay an- 

 nually in the flalk. 



They afford a good variety and effeft among other pe- 

 rennial plants in the fummer feafon, when put out in a 

 proper manner. 



SiLPHiuM, in Ancient Geography, a country of Libya, 

 which took its name from the plant. It commenced eaft- 

 ward towards Aziris and the ifle of Platxa, and extended 

 weftward as far as the Syrtis. 



SILSTADT, in Geography, a town of Germany, in the 

 eounty of Wernigerode ; 3 miles N.E. of Wernigerode. 



SILVA, a river of Ruffia, which runs into the Kama, 

 near the town of Silva, in the government of Perm. — Alfo, 

 a river of RufTia, which runs into the Tchufovaia, 16 miles 

 N.E. of Perm. — Alfo, a town of Ruflia, in the government 

 of Perm ; 12 miles N.W. of Solikainfk. 



Silva Plana, a town of Switzerland, in the bifhopric 

 of Coire ; 16 miles W.N.W. of Bormio. 



SILVANEZ, a town of France, in the department of 

 the Aveiron ; 9 miles S. of St. Afrique. 



SILVELLA, a town of Italy, in the department of 

 the Upper Po ; 3 miles E.N.E. of Cremona. 



SILVER, a river of the King's county, Ireland, which 

 rifes on the north-weil fide of the Sliebh-Bloom mountains, 

 and takes a northerly direftion. It has this name in Beau- 

 fort's and Arrowfmith's maps, but is called the Frankford 

 river by Mr. Longfield, in Jiis report to the Bog commif- 

 fioners, from the fmall town of Frankford, which it paffes. 

 Mr. Longfield reprefents it as capable of being eafily made 

 navigable for canal boats, and alfo of being made to contri- 

 bute to the drainage of the vafl bogs between which it flows. 

 In one part of its courfe, a little before it joins the Brufna, 

 the Macartney aqueduft, a part of the Grand Canal, paffes 

 over it. 



Silver, in the Arts, ManufaEiares and Commerce, and 

 in Domejiic Economy, is a white malleable metal, fufceptiblc 

 of a fine polifh. In Chemifiry, it is a fimple inflammable 

 body. 



It is fometimes found in the native ftate, but more fre- 

 quently combined with antimony, arfenic, or fulphur ; 

 forming the varieties of filver-ores ; with which we Ihall 

 begin, and then proceed to the aflay and analyfis, phyfical 

 properties, and chemical properties of filver. 



Silver-ores contain that metal either native, or alloyed 

 ■with other metals, or mineralized by fulphur, and fome- 

 times with the muriatic acid, the fulphuric acid, and in one 

 rare inflaiice v/ith the carbonic acid. 



Silver-ores principally occur in the rocks which have been 

 denomiiialed primary and tranfition rocks, and rarely in 

 fecondary rocks ; but many rich argentiferous lead-ores 

 occur in alpine hme ftone and fecondary ftrata. The ores 

 of filver are accompanied by calcareous fpar and fulphate of 

 barytes, and fometimes with quartz, horn-llone, jafper, and 

 fluor fpar. It has been remarked, that the warmer regions 

 of the globe afford the greatelt quantity of gold, but the 

 richetl repolitories of filver are fituated either in high lati- 

 tudes or in elevated regions. The moft celebrated filver- 

 mines of Europe are in Sweden and Norway, at no great 

 diftance from the polar regions ; and thofe which are in 

 warmer latitudes, are almoft all fituated near the furamits 

 of alpine mountains commonly covered with fnow, as at 

 AUeraont in France, and the mines of Mexico and Peru, in 



the centre of the Cordilleras. Silver never oecuri, like 

 gold, in alluvial foil, or the fands of rivers. After the 

 mineralogical defcription of the ores, we fhall give a (hort 

 account of the principal repofitories of filver at prefent 

 known. 



Native Jiher, Argent natlf of Haiiy, pofleffes the charac- 

 ters of filver extrafted from other filver-ores, but is gene- 

 rally lefs malleable. The colour is pure white, but the 

 furface is commonly tarnifhed, and is of a yellowifh-brown 

 or greyifh-black. Native filver occurs cryftallized in 

 cubes and oAohedrons ; the cryftals are fmall, and 3re often 

 aggregated, forming beautiful ramifications ; the branches 

 fometimes crofs each other in a redangular direction, and 

 are reticulated. It is fometimes in leaves and fometimes 

 capillary, and when the filaments are much entangled, it 

 becomes nearly compatl. Native filver is alfo found ia 

 fhapelefs malles of confiderable fize. In the )'ear 1750, 

 there was found in the famous mine of Hemraels Furfl, near 

 Freyberg, in Saxony, a mafs of native filver, which 

 weighed one hundred weight and a quarter; in 1771 an 

 equally large mafs was found. It is alfo mentioned by 

 Albini, in his " MeifTnifche Berg Arconicke," p. 30, " that 

 at Schneeberg, in 1478, a rich filver vein was difcovered ; 

 and fo large a block of native filver cut out, that duke 

 Albert of Saxony defcended into the mine, and ufed this 

 large block as a table to dine upon. It was fmelted into 

 four hundred centners of filver: a centner is 1 10 lbs." 

 ( Jamefon's Mineralogy. ) Native filver is fufible into a 

 globule, which is not altered by a continuance of the heat ; 

 it is fcarcely ever pure : the metals with which it is alloyed 

 are commonly gold, copper or arfenic, and iron. Native 

 filver alloyed with gold is rare ; its colour is intermediate 

 between filver-white and brafs-yellow ; it often contains a 

 confiderable proportion of gold. The ftones which form 

 the matrix of native filver in the mine are very numerous ; 

 it fometimes appears to be infiltrated into the fiflurcs, fome- 

 times to vegetate on the furface, and in other inftancea to 

 be intimately combined with the fubllance of the ftone. 

 It is found in almoft all the filver-mines that are worked 

 in Europe or America ; but the mafies difcovered in 

 America are not fo large as fome which have been found 

 in Europe. The pacos, a moil abundant ore in Peru and 

 Mexico, confiits of minute particles of native filver, inter- 

 mixed with brown oxyd of iron ; but the particles are too 

 fmall to be feen without a lens, and bear but a very fmall 

 proportion to the mafs. Silver rarely occurs in detached 

 grains, like gold or platina. 



Antlmonlal fdver-ore is compofcd of filver combined with 

 antimony, without any other iubilancc. Its colour is tin- 

 white ; It has a Ihining metallic lultre, which is often tar- 

 nifhed fuperficially reddifh or yellowifh. It is diftinguifhed 

 from native filver by its biittlenefs, being fcarcely malleable: 

 the ftrufture is lamellar. It is commonly found cryftalhzed 

 in four-fidcd and fix-iidcd prifm?, having the fides deeply 

 ftriated : its fpecific gravity is from 9.4 to 9.8. It melta 

 eafily before the blowpipe, giving a white fmoke from the 

 oxyd of antimony, and leaving a globule of filver. Its 

 conftituent parts arc from .76 to .84 filver, and from 16 to 

 24 of antimony. Antimonial filver is rare, particularly 

 the regular cryllallizations of it. It occurs in veins with 

 calcareous fpar and fulphate of barytes, and is accompanied 

 by galena and native filver. The foliated llrufture of anti- 

 monial filver diftinguifhes it from white cobalt-ore, which 

 has a granular itrudture j it differs alfo from arfenical pyrite.s, 

 both by its if rufture and foftnefs ; the latter is extremely 

 hard. Antimonial filver yields to the knife. 



Arfenical Jiher-ore is harder than the former fpecies ; ita 



ftrufture 



