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considered as similar to that of fulminating gold: it probably consists of oxide of silver and ammonia, the elements being united by affinities so nicely balanced, that the slightest external force subverts them, and causes new combinations: the oxygen of the oxide unites with the hydrogen of the ammonia, and forms watery vapor; the nitrogen must assume the elastic form, and the augmentation of elasticity in these products, by the caloric suddenly extricated, may be the cause of the detonation. A fulminating silver totally different from that above described, is frequently sold as an object of amusement: it is enclosed between the folds of a card cut in two lengthwise, the powder being placed at one end, and the other being notched, that it may be distinguished: if it be taken by the notched end, and the other be held over the flame of a candle, it soon detonates with a sharp sound and violent flame; the card is torn and changed brown, and the part in contact with the composition is covered with a slight metallic coating of a grayish-white color. This compound is formed in the following manner: Into a pint tumbler, or other glass vessel, is introduced 100 grains of dry nitrate of silver, over which is poured one ounce of alcohol, and the same quantity of smoking nitric acid. The mixture of the alcohol and nitric acid occasions much heat and effervescence in the liquid: if this is so violent as to overflow the vessel, cold alcohol is added in small portions to abate the ebullition: in a few minutes the liquor becomes turbid, and a very heavy, white, crystalline powder falls down, which is separated by the filter, and thoroughly washed with tepid water: before being fully dry, it should be separated into parcels of ten or twenty grains, which portions, when thoroughly dried at a distance from the fire, present the following properties: The substance is white and crystalline; the light changes its color to a dark brown; when heated, it explodes with great violence. It explodes also by percussion and friction, and the contact of sulphuric acid. When put into dry chlorine gas, it explodes with a loud report. So powerful is this powder in its explosions, that no persons but chemists should venture upon its manufacture, or presume to experiment with it. The most painful accidents have repeatedly occurred with it, in the hands of the inexperienced and the careless. It is composed of oxide of silver 14.75, and of a peculiar acid, called the fulminic, 5.25. (For some

ac

count of fulminic acid, see Prunt Acid.)

Silver Ores.-There are five important ores of silver, viz.-1. Native silver; 2. vitreous silver (or silver glance); 3. black silver; 4. red silver; 5. horn silver.-Notive silver is occasionally found crystallized in the following shapes, viz.-the cube, octahedron, tetrahedron, rhombic dodecahedron, trapezohedron, and sixsided tables. The cube is the primitive form; but it more often occurs in dentiform, filiform, and capillary shapes; also reticulated, arborescent, and in plates: likewise in plates, formed in fissures, and in superficial coatings; cleavage none; fracture hackly; lustre metallic; color silver-white, more or less subject to tarnish; streak shining; ductile; hardness between gypsum and calcareous spar; specific gravity, 10.47. Native silver has been distinguished into common and auriferous native silver: the former consists of silver alloyed with a small proportion of antimony, arsenic, iron, &c.; the latter frequently contains fifty per cent. of gold. Native silver occurs principally in veins, traversing gneiss, clay-slate, and other primitive and transition rocks. There are but few countries in which it is found in any considerable quantity. Among these are the mining districts of Saxony and Bohemia, also Norway and Siberia, but particularly Mexico and Peru.Vitreous silver presents itself crystallized in cubes, octahedrons, and rhombic dodecahedrons. Its primitive form is the cube. It also occurs in reticulated, arborescent, dentiform and capillary shapes; also massive and impalpable; fracture imperfect, and small conchoidal, uneven; lustre metallic, subject to tarnish; color blackish lead-gray; streak shining; malleable; hardness about that of gypsum; specific gravity 7.19. It consists of silver 85.0, sulphur 15.0. It is easily fusible before the blow-pipe, and intumesces; but it gives a globule of silver by a continuation of the blast. It has been hitherto found almost exclusively in veins, along with ores of lead, antimony and zinc. It occurs in Saxony, Bohemia, Hungary, Mexico and Peru. It is an important species for the extraction of silver.Black silver has for its primitive form a right rhombic prism of 100° 0'. The crystals, however, are not often observed; but it is more frequently in granular masses; fracture imperfect conchoidal, uneven; lustre metallic; color iron-black; streak unchanged; sectile; hardness about that of gypsum; specific gravity 6.2. It consists of

[blocks in formation]

93.00

Before the blow-pipe, upon charcoal, it yields a dark-colored metallic globule, which may be reduced with saltpetre. It is found in silver veins along with other ores of silver. It occurs chiefly in Saxony, Bohemia and Hungary, in Mexico and Peru. It is a valuable ore for the extraction of silver.-Red silver. The primitive form of this species is an obtuse rhomboid of 109° 28'. Its secondary forms are six-sided prisms, variously truncated and acuminated, and an equiangular double six-sided pyramid; cleavage parallel with the sides of the primitive form, pretty distinct; fracture conchoidal; lustre adamantine; color iron-black to cochineal-red; semi-transparent to opaque; sectile; hardness about that of gypsum; specific gravity 5.84. The crystals are very liable to occur twin-shaped. Red silver is often found massive, granular, and even impalpable. It consists of

Silver,.
Antimony,
Sulphur,

58.949

22.846

65.50 found in the upper parts of veins in clay-
10.00 slate, but occurs also in beds, generally
5.00 along with other ores of silver, or with
12.00 iron-ochre. It is not abundant in Euro-
.50 pean countries, but occurs in large masses
in Mexico and Peru. It is used for ex-
tracting silver.-Such are the ores of sil-
ver which are properly so called, and
from which silver is chiefly extracted.
Besides these, however, argentiferous sul-
phurets of lead and copper are sometimes
smelted for the small proportion of this
precious metal which they contain. We
have now to allude to the methods em-
ployed in obtaining the silver from its
various ores. These are two in number,
smelting and amalgamation. The former
is founded on the great affinity of silver
for lead, which, when fused with silver,
acts as a solvent, and extracts it from its
union with baser metals. The silver is
afterwards separated from the lead by the
well-known process of cupellation, which
consists in exposing the alloy to a stream
of atmospheric air, by which the lead is
converted into an oxide or litharge, while
the silver remains untouched. The latter
method depends upon the property of
mercury to dissolve silver without the aid
of heat. The first is called the dry, the
last, the wet way of treating silver ores.
One or the other process is employed, ac-
cording to the nature of the ores.
ores which are treated in the wet way
are usually those which consist princi-
pally of argentiferous sulphuret of lead.
The first thing to be done, by this meth-
od, is to pulverize and roast the ore in a
furnace, to expel the sulphur. When
the well or crucible is full of metal, it is
tapped and run off. It is now ready for
the process of refining, or cupellation.
For this purpose, a reverberatory furnace
is employed, the lower part of which is
covered with wood ashes and clay, so as
to form a cupel. On one side of the fur-
nace there is a hole for the exit of the
litharge; and on the opposite side is an-
other for the admission of air to the sur-
face of the metal, which is introduced
through an aperture above, to which a
cover is adapted. After the lead is melt-
ed and brought to a red heat, the blast of
air is admitted, and the scoria, as it col-
lects, is removed. When the litharge is
formed, the heat is increased, and the
quantity becomes greater, and is with-
drawn through the opening in the fur-
nace. At the same time, some lead is
volatilized. Towards the end of the pro-
cess, the litharge which comes off contains
a small quantity of silver, and is therefore

16.609

It decrepitates before the blow-pipe upon charcoal, melts, and emits fumes of sulphur and antimony, after which it yields a globule of silver. Red silver is confined to a small number of localities, and occurs in veins along with other ores of silver, galena and blende. It is found in the metallic veins near Freiberg, also at Marienberg, Annaberg, Schneeberg, and Johanngeorgenstadt in Saxony; likewise in Bohemia, Hungary, Dauphiny, and Norway; but is much more abundant in Mexico and Peru. It is a valuable ore for silver.-Horn silver has the cube for its primitive form, in which shape it frequently occurs, as also in acicular fibres; cleavage none; fracture more or less perfect conchoidal; lustre resinous, passing into adamantine; color pearl-gray, passing into lavender-blue, and some shade of green; the color becomes brown on being exposed to light; streak shining; translucent; sectile; hardness about that of tale; specific gravity 5.5. It occurs also in crusts and granular masses. It consists of silver 76.0, oxygen 7.6, and muriatic acid 16.4. It is fusible in the flame of a candle, and emits fumes of muriatic acid. Horn silver is most frequently

The

surplus metal is separated, and a compound remains in the sack, consisting of six parts of mercury and one of silver. This amalgam is subjected to the action. of heat in a distilling furnace, by whicta the mercury is sublimated, and the silver remains. Silver is also sometimes separated from copper by the process of diquation. The eliquation is effected by means of lead, which, possessing a greater affinity for silver than for copper, combines with the former, when brought into fusion with the alloy, and forms a new metallic compound. The argentiferous lead, thus obtained, is subjected to the usual processes of cupellation, and the coarse copper, from which the silver has been separated, is refined.—We shall now take notice of the mines of silver in different parts of the world, which furush the silver of commerce. Those of Mexico and South America are incomparably more important than those of all the rest of the world. Mexico alone has above three thousand mines, or excavations for silver ores, which produced annually, during the last ten years of the seventeenth century, about $4,000,000. The mines of Guanaxuato yielded nearly one quarter of this amount; while the singe mine of Valenciana, situated in the same district, has afforded, for years together, during the last thirty years, between one and two million dollars. Nor are the ores of Mexico, for the most part, rich in sil

kept separate from the rest. After the whole of the litharge is removed, and the surface of the metal in the furnace becomes bright, a quantity of water is poured on it, to keep it from spirting, which it is apt to do when congealing. The metal thus obtained is subjected to a similar operation for about five hours, in a smaller furnace, and at a higher temperature, by which it is completely freed from the lead. With respect to the other method of reduction or separation-amalgamation-the following is an outline of the more important steps, of which it consists. The ores best adapted to this process are native silver and vitreous silver. The first operation that requires description is the selection of the ores to form a proper mixture, with reference to the quantity of silver and sulphur they contain. It has been observed that the amalgamation process succeeds best when the silver produce is about seventy-five ounces to the ton of ore; at the same time, regard being had to the quantity of sulphur present, which is ascertained from the quantity of sulphuret in the ore, previously learned by an assay in the crucible. The sulphur is got rid of, by adding to the mixture of raw ore ten per cent. of common salt, by which, during the furnace operation, the sulphur becomes acidified, and the acid thus formed, uniting with the base of the salt, forms sulphate of soda; whilst the muriatic acid, thus set free, combines with the silver; but the rich produce of that country ver in the ore, that was not in the metallic state, and forms muriate of silver. In this state, the ore is subjected to various mechanical operations, with riddles, mills and sieves, until it is reduced to an impalpable powder. It is then submitted to the action of mercury. This operation is performed in barrels, which are arranged so as to revolve on their axes. The mixture or charge in each barrel consists of sifted calcined ore, mercury, metallic iron, and water, in certain proportions. The ore is composed of sulphate of soda, muriate of silver, and other metals and earthy matters. By the process of amalgamation, the barrels being made to revolve during a period of sixteen or eighteen hours, the muriate of silver becomes decomposed by the action of the iron on its acid; and the silver, thus reduced to the metallic state, combines with the mercury, forming what is termed amalgam, whilst the sulphate of soda, the muriate of iron, and other salts, become dissolved in the water. The silver combined with mercury is then filtered, by which the

has depended upon their abundance, and the facility with which they have been explored. In Peru, the annual produce of this metal was formerly as great as $2,000,000; the major part of which was furnished by the mines of Tasco, of Chota, and of Huantajaya. Chile affords $150,000 per annum. Buenos Ayres contains the celebrated mines of Potos, discovered in 1545, and which have produced, according to the estimate of Humboldt, from the time of their discovery, the enormous amount of $1,150,000,000. These mines have diminished in value of late, though they still rank next to those of Guanaxuato. The celebrated mines of Kongsberg, in Norway, once so rich in native silver, have now become in a great measure exhausted. They are estimated to have produced above $20,000,000 since they were opened in 1623. The most important silver mines of Europe at pres ent, are those of Saxony, Hungary, ani the Hartz. The annual produce of Saxony is about $250,000; while those of the Hartz and of Hungary are each about the

same. Within the last sixteen years there has been a great increase in the produce of silver from the Russian mines. According to a communication from baron Humboldt, made since his return from Asia, to the editor of Poffendorf's Annalen, it appears that the annual produce of the mines of precious metals of Europe and Asiatic Russia amounts to 25,500 marcs of gold, and 292,000 marcs of silver; of which 76,500 of silver and 22,000 of gold are supplied from the Russian empire. The value of all this silver is about $2,353,000. The present annual produce of all the silver mines in the world is probably within $20,000,000. SILVER FISH. (See Gold Fish.)

SILVER TREE (leucadendron argenteum); so called from the appearance of the leaves, which are lanceolate and silky. It is a large evergreen shrub, with handsome foliage, a native of the cape of Good Hope, together with the other species of the genus, and is a favorite in greenhouses. It belongs to the proteaceae, the most remarkable family of plants in the southern hemisphere, and one which contributes largely to give peculiar features to the vegetation of that portion of the globe. More than four hundred species of these plants are known, which are arranged in numerous genera. They are usually shrubs or small trees, but some attain large dimensions: the leaves are simple, entire or serrated, in most species flat, but sometimes cylindrical or threadshaped; the flowers are sometimes distinet, upon solitary foot-stalks, or in clusters, spikes, or corymbs, with bractea at the base; sometimes they are sessile, situated upon a common receptacle, surrounded with a many-leaved involucre, or are disposed in scaly cones; the color is green, yellow, or red: in short, the remarkable differences in the habit, foliage and flowers of these plants have given rise to the name of the order. The greater proportion of these plants inhabit New Holland, where they adorn large tracts of country; they are numerous, likewise, at the cape of Good Hope, but a few species only are found in the southern parts of South America. They are generally favorite green-house plants, and are not delicate with respect to cold; but their culture, in other respects, requires many precautions.

SILVERING. The application of silver leaf is made in the same way as that of gold, for which see Gilding. Copper may be silvered over, by rubbing it with the following powder:-Two drachms of

tartar, the same quantity of common salt, and half a drachm of alum, are mixed with fifteen or twenty grains of silver, precipitated from nitric acid by copper. The surface of the copper becomes white when rubbed with this powder, which may afterwards be brushed off and polished with leather. A cheap silvering is prepared as follows:-Half an ounce of silver that has been precipitated from aquafortis by the addition of copper, common salt, and muriate of ammonia, of each two ounces, and one drachm of corrosive muriate of mercury, are triturated together, and made into a paste with water; with this, copper utensils of every kind, that have been previously boiled with tartar and alum, are rubbed, after which they are made red-hot, and then polished. The intention of this process appears to be little more than to apply the silver in a state of minute division to the clean surface of the copper, and afterwards to fix it there by fusion; and, accordingly, this silvering may be effected by using the argentine precipitate, here mentioned, with borax or mercury, and causing it to adhere by fusion. The dialplates of clocks, the scales of barometers, and other similar articles, are silvered by rubbing upon them a mixture of muriate of silver, sea salt, and tartar, and afterwards carefully washing off the saline matter with water. In this operation, the silver is precipitated from the muriatic acid, which unites with part of the coppery surface. It is not durable, but may be improved by heating the article, and repeating the operation till the covering seems sufficiently thick. The silvering of pins is effected by boiling them with tin filings and tartar. Holton mirrors or globes are silvered by an amalgam, consisting of one part by weight of bismuth, half a part of lead, the same quantity of pure tin, and two parts of mercury. The solid metals are to be first mixed together by fusion, and the mercury added when the mixture is almost cold. A very gentle heat is sufficient to fuse this amalgam. In this state it is poured into a clean glass globe, intended to be silvered, by means of a paper funnel, which reaches to the bottom. At a certain temperature it will stick to the glass, which by a proper motion may thus be silvered completely, and the superfluous amalgam poured out. The appearance of these toys is varied by using glass of different colors, such as yellow, blue, or green. To silver looking-glasses, the following articles are necessary :-first, a square marble table, or smooth stone,

well polished, and ground extremely true, with a frame round it, or a groove cut in its edges, to keep the superfluous mercury from running off; secondly, lead weights covered with cloth, to keep them from scratching the glass, from one pound weight to twelve pounds each, according to the size of the glass laid down; thirdly, rolls of tin-foil; fourthly, mercury. The artist then proceeds as follows:-the tin-foil is cut a little larger than the glass, and laid flat upon the stone, and with a straight piece of hard wood, about three inches long, stroked every way, that there may be no creases or wrinkles in it: a little mercury is then dropped upon it, and with a piece of cotton wool, or hare's foot, it is spread all over the foil; then, the marble slab being kept nearly level with the horizon, the mercury is poured all over the foil, which is covered with a fine paper; two weights are placed near its lower end, to keep the glass steady, while the artist draws the paper from between the silver-foil and the glass. This must be done with great care, so that no air-bubbles be left. After the paper is drawn out, weights are placed upon the glass to press out the superfluous mercury, and make the foil adhere. Another method is, to slide the glass over the foil without the assistance of paper. To make shell silver, silver leaf is ground with gum-water, or honey: the gum, or honey, is washed away, and the powder which remains is used with gum-water, or white of eggs, laid on with a hair pencil.

SILVESTRE DE SACY. (See Sacy.) SIMEON STYLITES. (See Stylites.) SIMOIS; a river of Troas, which rises in mount Ida, and falls into the Xanthus. It is celebrated by Homer, and most of the ancient poets, as many battles were fought in its neighborhood during the Trojan war. Modern travellers call it a small rivulet, and some have even disputed its existence. (See Scamander.)

SIMON MAGUS, or the Magician; an impostor, mentioned in the Acts of the Apostles, a native of Samaria, who pretended to be an aon of hu exalted nature, and called himself the supreme power of God. (See Gnostics.) Struck with astonishment at the miracles of the Aposties, he offered them money for their secret. (See Simony.) He then went about making proselytes, carrying with him a Tyrian courtesan, whom he represented as Helen, who had been the cause of the Trojan war, and sometimes as Minerva; calling her, at the same time, the first in telligence, or mother of all things. Other

stories are related of him, but are not well authenticated. It has also been stat that he was worshipped as a god at Rome and that his statue was erected there, with the inscription Simoni Deo sancto. His fo lowers are called Simonians. (See Her etics.)

SIMON, ST.; an ancient French family. which claims to derive its origin, through the counts of Vermandois, from Charimagne. Louis de Rouvroy, duke de St. Simon, a peer of France, known as the atthor of some very curious memoirs, was born in 1675, and died in 1755. He was employed in several diplomatic missions. and was made one of the council of regency by the notorious regent, duke of Orleans (q. v.), after whose death be retired to his estates. His memoirs remained a long time in manuscript, and were afterwards published in a mutilated form, with many suppressions. The first complete edition appeared in Pars. in 1829-30 (in 21 vols., 8vo.), under the title of Mémoires complets et authentiques du Duc de Saint Simon sur le Siecle de Louis XIV, et la Régence, publies pour in première Fois sur le Manuscrit original entièrement écrit de la Main de l'Auteur, par M le Marquis de Saint Simon.-Claude Heur, count de St. Simon, founder of the petitionphilosophical-religious sect of St. Sumonians, or of the New Christianity, wha: has recently attracted attention in Fraser. was born in 1760. We know little of h youth; but he appears to have been car tinctured with a spirit of enthusiasm, as we are told that he caused himself to be called, every morning, with the words. "Get up, count; you have great things to accomplish." He was attached to tie French auxiliary corps, which served r this country in the last years of our reolutionary war, and, soon after his retur to France, was promoted to a colonnicy Previous to the breaking out of the French revolution, the count travelled Holland and Spain; but he took no pat in the great events of 1789. He died g 1825, the last thirty-four years of his b if we may believe his own account, bay ing been devoted to the objects of bus mission, as the apostle of the New Chrs tianity. His disciples are not very car municative in regard to the history of their founder, whose reputation appears not to have been always the best in 1790, he entered into financial specia tions, for the purpose, as we are told, of raising the funds necessary to and has great projects. His partner not participatirat in his philanthropic views, St. Simon te

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