Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 4, 1802).djvu/91

71&#93; SIL frora their oommunicatlotis, and from foreign authorities, the in- quisitive reader will consult the 2d, 4th, 5th, and 7th vols, of the So- ciety's " TransaBions" &c. in which the various expedients prac- tised by silk-cultivators in this country, are fully related. — Some pi'a£tical remarks likewise occur in Mr. BERtEZEN's " Thoughts on the different kinds of Food given to Silk-W07ms," &c. (8vo. pp. 47, Is. Bew, 1789); a treatise worthy of perusal. SILVER, one of the whitest of the perfeft metals, is found iu various parts of the globe, bolh in a native .state, and alloyed with other ores. The purest silver is imported by the Spaniards, from Potosi, in South America ; and, though the lead-mines of England contairt a uortion of this valuable ore, yet it w^so inconsiderable as not to defray the expence of separating it from lead. In point of malleability, silver is somewhat inferior to gold ; but it is much harder than the latter. If, however, both metals be melted to- gether, they readily combine, with- out materiall)'^ diminishing their du6tility : hence, such alloy is ge- nerally employed for gold coinage. Silver acquires hardness by ham- mering, and is therefore (when alloyed with a certain proportion of copper), not only used for coining money, but likewise in the ma- Ijufafture of spoons, goblets, and other articles of plate. — Being, however, a6ted upon, in a pe- culiar manner, by sulphureous vapours, the surface of silver, if exposed to the air, easily becomes tarnished, and assumes a dark- brown colour. Various powders have^ therefore, been contrived. S 1 L [71 . 'XV'ith a view to restore plate to its original lustre ; but, as most of these compounds are apt to scratch, and injure the substance of such expensive utensils, we recommend the following preparation : lake one ounce of red calx of vitriol fcrociis martisj and two ounces of calcined chalk; let both ingredients be pulverized, and passed through the finest sieve. This composition may be applied, either in a dry state, or, if the silver be unusually tarnished, the powder may pre- viously be moistened with spirit of wine, in order to produce the de- sired eifedt with greater expedition. I'his precious metal is, likewise, advantageously employed in phar- macy. When dissolved in the ni- tric acid, it forms the nitrate of silver ; and, though a niost viru- lent medicine, it has been giveh with great success, to persons sub- jetSt to epileptic fits ; in doses of a quartcrof agrain, taken three times in the course of the day. It is far- ther useful externally, as a caustic, for consuming warts, and similar excrescences, not less than for pre- venting the growth of fungous tiesh in ulcers ; but, in all these cases, it ought, on account of its deleterious qualities, to be directed by the pro- fession. Silver pays, on importation, a duly of 2s. lOd.,'^; and, for home consumption, 4s. ld|. per ounce troy : its price, in the market, va- ries from 5s. 3d. to 5s.lOd. per oz. SILVER-WEED, Wild Tan- SEY, or GoosE-ORASS, Poteritilla. Anserina, L. a British perennial plant, growing on the sides of paths and roads, and in low pastur. s j flowering in June and July.—*. Gunner observes, that the Scotch and Irish, in times of scarcity^ convert the roots of this vegetable F 4 ~int«