SILVER. When pure and planished, silver is the brightest of the metals. Its specific gravity in the ingot is 10.47 ; but, when condensed under the hammer or in the coining press, It becomes 10.6. It melts at a bright red heat, a temperature estimated by some as equal to 1280° Fehr., and by others to Wedgewood. It is exceedingly malleable and ductile ; afford ing leaves not more than of an inch thick, and wire far finer than a hu man hair.
Its tenacity is, to that of gold and pla tinum, as the numbers 19, 15, and 26i; so that it has an intermediate strength between these two metals. Pure atmos pheric air does not affect silver, but that of houses impregnated with sulphureted hydrogen, soon tarnishes it with a film of brown sulphuret. It is distinguished chemically from sold and platinum by its ready solubility m nitric add, and from almost all other metals, by its saline solu tions affording a curdy precipitate with a most minute quantity of sea salt, or any soluble chloride.
Silver occurs under many forms in na ture :— 1. Nistive silver possesses the greater part of the above properties ; yet, on ac count of its being more or less alloyed with other metals, it differs a little in malleability, lustre, density, &c. It oc curs crystallized in wedge-form octa hedrons, in cubes, and cubo-octahedrons; or in dendritic shapes, and arboreseences, resulting from minute crystals implanted upon ouch other. But more usually it presents itself in small grains without determinable form, or in amorphous masses of various magnitude.
The gangues (mineral matrices) of na tive silver are so numerous, that it may be said to occur in all kinds of rocks. At one time it appears as if filtered into their fissures, at another ns having vegetated on their surface, and at a third, as if im pasted in their substance. Such varieties are met with principally in the mines of Peru and Mexico.
The native metal is found in almost all the silver mines now worked; but espe cially in that of Kongsberg in Norway ; at Schlangenberg in Siberia, in a sulphate of barytes ; at Allginont, in a ferruginous day, &e.
The metals most usually associated with silver in the native alloy are gold, copper, arsenic, and iron. At Andreas berg and Guadalcanal it is alloyed with about 5 per cent. of arsenic. The auri ferous native silver is the rarest ; it has a brass-yellow color.
2. Antimonial silver.—This rare ore is yellowish-blue ; destitute of malleability; even very brittle ; spec. gran. 9.5. It melts before the blowpipe, and affords white plumes of oxide of antimony. It consists of from 76 to 84 of silver, and from 24 to 16 of antimony.
3. Mired antimoniol silver.—At the blowpipe it emits a garlic smell. Its con stituents are, silver 16, iron 44, arsenic 35, antimony 4. It occurs at Andreas berg.
4. Sulphuret of silver.—This is an opaque substance, of a dark-gray or leaden hue; slightly malleable, and easily cut with a knife, when it betrays a me tallic lustre. The silver is easily sepa rated by the blowpipe. It consists of, 18 of sulphur to 89 of silver, by experiment. Its spec. gray. is 6.9. It occurs crystal lized in most silver mines, but especially in those of Freyberg, Bohemia, Schem nitzin, Hungary, and Mexico.
5. Red sulphuret of silver ; silver glance. —Its spec. gray. is 5.7. It contains from 84 to 86 of silver.
6. Suiphureted giver, with bismuth.— Its constituents are lead 85, bismuth 27, silver 15, sulphur 16, with a little iron and copper. It is rare.
7. Antimoniated suyniuret of silver, the red silver of many mineralogists, is an ore remarkable for its lustre, color, and the variety of its forms. It is friable, easily scraped by the knife, and affords a powder of a lively crimson red. Its color in mass is brilliant red, dark red, or even metallic reddish-black. It crystallizes in a variety of forms. Its constituents are— silver from 56 to 62; antimony from 16 to 20; sulphur from 11 to 14; and oxy gen from 8 to 10. The antimony, in the state of a purple oxide in this ore, is its coloring principle. It is found in the mines of Freyberg, Sainte-Marie-aux Mines, and Guadalcanal.