Silvering

“ I have had silver-leaf, and it seemed as thin as gold-leaf.
Tut. It is nearly so. That is used for silvering, as gold-leaf is for gilding. It is common, too, to cover metals with a thin coating of silver which is called plating.
Har. The child’s saucepan is silvered over on the inside. What is that for?
Tut. To prevent the victuals from getting any taint from the metal of the saucepan; for silver is not capable of being corroded or dissolved by any of the liquids used for food, as iron and copper are. ”

“ The charging, the workman’s term for silvering. This operation consists in placing the silver leaves on the heated piece, and fixing them to its surface by burnishers of steel, of various forms. The workman begins by applying the leaves double. Should any part darken in the heating, it must be cleared up by the scratch-brush.
The silverer always works two pieces at once; so that he may heat the one, while burnishing the other. After applying two silver leaves, he must heat up the piece to the same degree as at first, and he then fixes on with the burnisher four additional leaves of silver ”

“ How silver is purified and made brilliant. Take a part of silver and an equal weight of lead; place in a furnace, and keep up the melting until the lead has just been consumed; repeat the operation several times until it becomes brilliant.
27. coloring in Silver.
For silvering objects of copper: tin in sticks, 2 drachmas; mercury, 4 drachmas; earth of Chios, 2 drachmas. Melt the tin, throw on the crushed earth, then the mercury, and stir with an iron and fashion into globules. ”

“ Silvering face down is in some respects less convenient but does free the operator from the very serious trouble of the heavy sediment which is deposited from the rather strong silver solution. This is the essential difficulty of the Brashear process in silvering face up. The trouble may be remedied by very gentle swabbing of the surface under the liquid with absorbent cotton, from the time when the silver coating begins fairly to form until it is completed. ”

“ As the quantity of beading used is often very considerable, the labour of silvering by means of a soldering iron would be too great, and therefore the plated or silvered beading is prepared from metal silvered in the sheet. ”

“ When it is remembered that though the process of silvering is an easy operation to perform, yet it is a delicate chemical one, in which good results are best obtained when several good conditions all meet together, this is not to be wondered at, but it is certain the instructions given above will reduce the chances of failure to a minimum, and imperfect results will be rare. The silver usually lasts a long time. ”

“ To the former class belongs the native metal, which is usually more or less alloyed with gold, and sometimes with other metals, as above remarked. The occurrence of gold and silver in variable natural alloy is so general that they may almost be said to constitute but one mineral species, ranging from silver with a slight trace of gold to gold with a slight trace of silver. Native silver is found in masses and in arborescent and filiform shapes in veins of quartz, calcite, &c., or as segregations accompanying other silver ores. ”

“ A small quantity of iron, chromium, cobalt, or nickel imparts great hardness to silver. Steel may be made to retain about 1/500 of its weight of silver, which is said to improve its quality; the alloy is called silver-steel. Combined with mercury, silver forms a most brilliant amalgam for mirrors. An alloy of 20 to 30 parts of silver with 30 of nickel and 50 of copper is said to be equal in all respects to the ordinary standard silver, which is 9 parts of silver with 1 of copper. Small coins have been made in Switzerland of an alloy of silver and copper with 10 per cent. ”

“ When they conceive that all the silver has incorporated with the mercury, the mixed mass, or cuerpo, is carried to a basin or pond, into which a small stream of water is introduced to wash it, much in the same way as I shall afterwards describe the manner in which they wash gold, only that as the silver-ore is reduced to a fine mud without stones, it is stirred by an Indian with his feet, to dissolve it thoroughly, and loosen the silver. ”

“ Pure silver is often found in or near iron ores and the dark brown zinc blende. The Colorado silver lodes are porous at the surface and colored more or less red or green. Any rock suspected of containing silver should be powdered and dissolved in nitric acid.{90} Pour off the liquid and add to it a solution of salt. If a white powder falls to the bottom which upon exposure turns black, there is silver in it. Silver mines increase in value as in depth, whereas gold diminishes as we descend. ”

“ When the rock has been separated from the amalgam by a washing operation, the quicksilver is recovered by distillation in an iron retort, and the remaining crude retort-silver melted into bars and shipped to a refinery, which removes the impurities, the leading one of which is copper. A silver ore is either free-milling or refractory, that is, the silver mineral is readily amalgamated or it is not. In free-milling ore the silver is present either in the native state, or as chloride or as simple sulphide. ”

“ We are informed that a mass of capillary native silver was found, in veins traversing the blue-coloured limestone of Isla, one of the Western Islands of Scotland. Great quantities of silver are extracted from lead. There was lately melted in one refining house in London 50,000l. worth of this metal, from lead of the Beralston mines in Devonshire.
Different methods are employed, in different countries, to extract silver from its ore. In Mexico and Peru the mineral is pounded, roasted, washed, and then mixed with mercury in vessels filled with water ”

“ Fine silver, with a small proportion of alloy, is largely used by all nations for purposes of coinage. It amalgamates with nearly all the metals, but is principally used in alloys suitable to the watchmaker’s and silversmith’s art. The purchasable price of fine silver for manufacturing purposes, which in 1884 was 4s. 8d. is now, 1921, 3s. per ounce, troy weight, varying however in value according to the total amounts purchased; for which see refiners' and assayers' charge lists, to be procured at the offices of any bullion dealer. ”

“ Navaho Silverware. Of equal interest is the making of silverware by the Navaho peshlikai, or silversmith, whose primitive forge is in the first room entered at the Hopi House.
Fondness for Silver. The innate desire of a primitive people for personal adornment early led the pueblo Indians to a use of metal. When the Spaniards and Mexicans came among them, the iron, brass and copper of the conquerors were soon added to the dried seeds, shell beads, pieces of turquoise and coral they had hitherto used. But silver has ever been their favorite metallic ornament. ”

“ Subsequently, I received a boulder specimen from the shores of Lake Huron, containing veins of native silver. Part of the metal had been detached. I submitted these specimens to the Lyceum of Natural History at New York, in 1825. The following remarks are taken from their annals.
Mineralogical and Chemical Characters.—By examining this mineral, it will be perceived to possess the color, lustre, malleability, and other obvious characters of native silver. It is so soft as to be easily cut by the knife; and in a state of purity which permits it to spread under the hammer. ”

“ Our standard silver is composed of somewhat more than 121⁄4 parts of pure metal and one part of copper; and the metal of this standard is used, both for silver plate, and in the coinage. The mark or stamp which is given to it at Goldsmiths’ Hall is similar to that which has been explained for sterling gold.
After platina (226) and gold (227) , silver is considered the most unchangeable of all metals. The air does not easily act upon its surface in such manner as to injure it ”

“ Metalliferous products containing silver arise in many operations; the chief products which may yield silver economically are copper and lead mattes, burnt argentiferous pyrites and certain drosses and scums. Argentiferous ores consist of silver-bearing base-metal minerals and gangue. ”

“ In essence, thus, there are only three techniques of forming silver into an article of desired shape: casting the molten metal in a properly shaped mold; hammering an ingot into the shape desired; and building the desired shape from smaller pieces soldered together. Wire produced on the drawing bench might be one of these smaller elements. Filing is considered to be a finishing rather than a forming process.
These forming and working processes, as they would have been used by an eighteenth-century silversmith, will be described in more detail in a moment. ”

“ The metals most usually associated with silver in the native alloy, are gold, copper, arsenic, and iron. At Andreasberg and Guadalcanal it is alloyed with about 5 per cent. of arsenic. The auriferous native silver is the rarest; it has a brass-yellow colour.
2. Antimonial silver.—This rare ore is yellowish-blue; destitute of malleability; even very brittle; spec. grav. 9·5. It melts before the blowpipe, and affords white fumes of oxide of antimony; being readily distinguished from arsenical iron, and arsenical cobalt, by its lamellar fracture. ”

“ Occurs in crystals, wax-like masses, or in crusts; when scratched shows a shining streak; becomes brown on exposure; quite soft, easily cut; a small piece placed on zinc and moistened, swells up, turns black and shows metallic silver on being pressed with a knife; dissolves in hartshorn; gravity 5.5.
Value.—An ore of silver, yielding seventy per cent.
Localities.-Found in slate with other silver ores. Lake Superior Mining Region; Austin and Comstock Lode, Nev.; Willow Springs and San Francisco districts, Eldorado Cañon, Ariz. ”

“ Silver, is found particularly in veins and beds, in primitive and transition formations; though some veins of this metal occur in secondary strata. The rocks richest in it are, gneiss, mica-slate, clay-slate, greywacke, and old alpine limestone. Localities of silver-ore itself are not numerous, at least in Europe, among secondary formations; but it occurs in combination with the ores of copper or of lead. ”

“ These riffles had to be cleaned and the blankets washed out every evening, to get their precious accumulations—and after all this eternity of trouble one third of the silver and gold in a ton of rock would find its way to the end of the troughs in the ravine at last and have to be worked over again some day. There is nothing so aggravating as silver milling. ”

“ French coinage contained 36-40ths of fine silver and 4-40ths of copper alloy, or millesimal fineness 900 parts of fine silver and 100 parts of copper per 1,000 parts of metal; the highest standard for silver wares contains 38-40ths of fine silver and 2-40ths of copper alloy, or millesimal fineness 950 parts of fine silver and 50 parts of copper per 1,000 parts of metal; the lowest French standard for silver wares contains 32-40ths of fine silver and 8-40ths of copper alloy, or millesimal fineness 800 parts of fine silver and 200 parts of copper per 1,000 parts of metal. ”

“ Silver will unite with copper in various proportions by melting the two ingredients together, and stirring them whilst in a fused state. A product will thus be formed differing physically in character from fine silver, caused by the loss of some little of the latter’s ductility and malleability; but, on the other hand, a compound will be produced harder and more elastic, which is in every sense better adapted to the manufacture and also to the durability of the articles made by the silversmith. ”

“ You have been here in Silverland—here in Nevada—two or three years, and, of course, your position on the daily press has made it necessary for you to go down in the mines and examine them carefully in detail, and therefore you know all about the silver-mining business. Now, what I want to get at is—is, well, the way the deposits of ore are made, you know. For instance. Now, as I understand it, the vein which contains the silver is sandwiched in between casings of granite, and runs along the ground, and sticks up like a curb-stone. ”

“ Having now described some of the processes in the working of silver, and alluded to the various articles which are produced by wire-drawing; raising with the hammer; stamping; spinning; chasing, &c.; we shall next direct attention to those processes which immediately come after the putting together and soldering the article; and foremost of these is polishing. We trust that the foregoing details in reference to this part of the subject will convey some idea of the art of silver-working.
Polishing is an important process With all precious metal workers. ”

“ When a sufficient number of these pieces of rich lead have been procured, so that by their respective quality, as determined by assaying, they contain in whole from 1000 to 2000 ounces of silver, they are re-melted to extract their silver, in the same furnace, but in a cupel which differs from the former in having at its bottom a depression capable of receiving at the end of the process the cake of silver. ”

“ About half of the silver production of the world comes from the dry or siliceous silver ores, which are mined solely for that metal and the associated gold; and about half of the production is obtained as a by-product in the mining of other metals, principally copper and lead. ”

“ Even with all these tools—plus forge, ingot molds, drawing bench, binding wire, and many other essentials of the craft—the silversmith was limited to six basic methods of working silver. These were casting, forging, raising, hollowing, seaming, and creasing—the principal methods still employed by hand craftsmen today.
But forging, raising, hollowing, and creasing are all hammering processes, though they differ significantly in the manipulation of the metal under the hammer. ”

“ Most silver ores are easily recognisable, and readily tested by means of the blowpipe or simple fire assay. Sometimes the silver on being tested is found to contain a considerable percentage of gold, as in the great Comstock lode in Nevada. Ore from the big Broken Hill silver lode, New South Wales, also contains an appreciable quantity of the more precious metal. A natural alloy of gold, termed electrum, contains 20 per cent. ”