SILVERING, in the arta, consists in covering the surfaces of substances with a thin coating of silver; either for the purpose of beauty, silver being so much more handsome than the inferior me tals; or, on account of its superior whole someness, compared with copper, brass, or lead, for culinary purposes, it resisting the corroding power of vinegar and other weak acids. The metals that are usually covered with silver are, copper and brass, and sometimes iron, and there are three distinct modes of performing the operation. 1. Silvering, by amalgama tion, is thus performed: to a solution of nitrated silver add some plates of cop per, which will throw down the silver in its metallic state, and very finely divided scrape it from the surface of the copper, wash it well and dry it. Of this powder take half an ounce, of common salt and sal ammoniac two ounces, and of corro sive sublimate one drachm, rub them well together, and make them into a paste with a little water. Then take the vessel to be silvered, and clean it by means of a little very dilute aquafortis, or by scouring it with a mixture of com mon salt and tartar. When it is perfect ly clean, rub it with the above-mention ed paste till it is entirety covered with a white metallic coating ; this coating is an amalgam produced by the decomposition of the corrosive sublimate, by means of the copper, to the surface of which it ap plies very closely and expeditiously. The copper, being thus silvered over, is to he washed, dried, and afterwards heated nearly red, in order to drive off the mer cury; the silver remains behind, adher ing firmly to the copper, and capable of being highly polished. 2. Silvering by tuna cornea. Prepare the Iona cornea in the usual manner, by pouring a solution of common salt into nitrate of silver, RS long as any precipitation takes place, and boiling the mixture ; the white curdy matter, thus obtained, is to he mixed with three parts of good pearl ash, one part of washed whiting, and somewhat more than one part of com mon salt. The surface of the brass, be. ing cleared from scratches, is to be rub bed with a piece of old list and rotten stone, to remove any grease, and then is to be moistened with salt and water ; a little of the composition being now rub bed on with the finger, the surface of the metal' will presently he covered with silver. Then wash-it well, rub it dry
with soft rag, and, as the coat of silver is extremely thin, cover it with transpa rent varnish, to preserve it from tarnish. This kind of silvering is very imperfect, and is only used for the faces of clocks, the scales of barometers, and similar ob jects. 3. Silvering by silver in substance. There are three ways of performing this. The first is, by mixing together twenty grains of silver, precipitated by copper, two drachms of tartar, two drachms of common salt, and half a drachm of alum ; this composition being rubbed on a per fectly clean surface of copper or brass will cover it with a thin coating of silver, which may afterwards be polished with a piece of' soft leather. A still better way is that which is called French plating, which consists in burnishing down upon the surface of the copper successive layers of leaf-silver to any required thick ness. In this the silver has much more solidity than in any of the former, but the process is tedious, and the junctures of the leaves of silver cannot always be entirely concealed. The English method of plating (in those works to which it is applicable) appears to be the best of all. It is thus performed; one of the surfaces of an ingot of copper is rendered quite smooth and clean, and is sprinkled over with glass of borax ; upon this is laid a plate of fine silver, about one-twelfth of the weight of the copper, and the two are carefully bound together by wire ; the mass is now exposed to a full red heat, which melts the borax, and causes the silver to adhere to the copper ; the ingot is now passed through a rolling press, and formed into a plate ; both the silver and copper extending uniformly during the whole process, at the conclu sion of which, the two metals are inse parably fixed to each; other. See Aikin's " Dictionary."