S I L 



S I L 



than in any of the former modes, the procefsis tedious, nor 

 can the junftures of the leaves of filver be always entirely 

 concealed. But the bell method of all is the Englifh plat- 

 ing, tor an account of which fee Plated Manufacture. 

 Aikin'sDift. 



Brafs may be filvered, by boiling it with filings of good 

 pewter and white tartar, in equal quantities. There are 

 feveral other methods of filvering, for which fee Smith's 

 Laboratory, p. 37, feq. ; alfo Handmaid to the Arts, vol. i. 

 p. 47 1, &c. Sec Gilding of Metals. 



The following is the recipe in praftice with button- 

 makers for covering the inferior kinds of plated buttons : 

 3lbs. of fulphate of zinc ; 3lb8. of common fait ; i oz. of 

 corrofive fubhmate ; and 2 oz. of muriate of filver. This 

 is made into a pulpy ilate with water, and the buttons 

 fmeared over with it. They are then expofed to a certain 

 degree of heat, which firlt caufes the furface to be covered 

 with an amalgam of filver and mercury, and then expelhng 

 the latter, which requires nearly a red heat, the copper re- 

 tains a permanent coating of filver. This is afterwards to 

 be cleaned and burnifhed, by which it acquires a filvery 

 luftre, wliich, for a time, appears like durable plating. The 

 fait and the fulphate of zinc appear to be of no other ufe 

 than to dilute and give a pulpy confidence to the mafs. 



Silvering in the cold is performed by the following com- 

 pofition : 3lbs. of cream of tartar ; 3lbs. of common fait ; 

 and I oz. of muriate of filver, which is the precipitate 

 formed by adding common fait to nitrate of filver, till no 

 more is precipitated. This compofition is made into a fimilar 

 pulp. The furface of the copper or brafs to be filvered 

 mull firlt be cleaned with diluted acid, and then made dry, 

 and kept free from greafe. The furface, being now rubbed 

 with the above pafte, will allume a white colour, by the 

 filver adhering to it. This procefs is generally employed 

 for filvering clock-faces, and the fcales of inftruments. 

 The furface fhould always be vamifiied to prevent its tar- 

 nilhing, as the filver is too thin to bear cleaning. See 

 Button. 



Silvering of Leather. See Lacquer and Japanners' 

 Gilding. 



The proceeding in filvering the leather is in all refpefts 

 the fame as when it is to have the appearance of gilding, 

 except that, inttead of the yellow varnifh, a clear colourlefs 

 one is to be ufed, where the appearance of filver is to be 

 preferved. 



The mod common varnifh for this purpofe is only parch- 

 ment fize, made warm, and laid on with a fpunge. How- 

 ever, the more hard and tranfparent the varnilhes are, and 

 the more they are of a refinous nature, the more brilliant 

 and white, :ind the more durable, will be the filvery and 

 pofiflied appearance of the filvered leather. Some, inftead 

 of the parchment fize, ufe that made of ifinglafs. 



SlLVERiMi of Mirrors, is the application of a coat- 

 ing of quickfilver to their pofterior furface, in the 

 manner briefly defcribed under the article Looking-G/it/}. 

 The management of the filvering is, in this cafe, extremely 

 fimple, and is thus detailed in Aikin's Diftionary. A per- 

 feftly flat flab of free -Hone (or fometimes of thick wood), 

 a little larger than the largeft plate, is inclofed in a fquare 

 wooden frame or box, open at the top, and with a ledge 

 rifing a few inches on three fides, and cut down even with 

 the done on the fourth. A fmall channel or gutter is cut 

 at the bottom of the wooden frame, ferving to convey the 

 wafte mercury down into a veflel below, fet to catch it. 

 The flab is alfo fixed on a centre pivot, fo that one end may 

 be raifed by wedges (and of courfe the other deprefled) at 

 pleafure, when working freely in the box. 



The flab being firft laid quite horizontal, and covered with 

 grey paper ftretched tight over it, a fheet of tin-foil, a little 

 bigger than the plate to be filvered, is fpread over it, and 

 every creafe fmoothed down carefully ; a little mercury 15 

 then laid upon it, and fpread over with a tight roll of cloth, 

 immediately after which as much mercury is poured over it 

 as will lie on the flat furface without fpilling. That part 

 of the flab which is oppofite the cut-down fide of the 

 wooden frame is then covered with parchment, and the 

 glafs plate is lifted up with care and Aid in (holding it 

 quite horizontally) over the parchment, and lodged on the 

 furface of the flab. The particular care required here is, 

 that the under furface cf the glafs fhould from the firll juft 

 dip into the furface of the mercury (fkimming it off as it 

 were), but without touching the tin-leaf in its paflagc, 

 which it might tear. By this means no bubbles of air 

 can get between the glafs and the metal, and alfo any little 

 dull or oxyd floating on the mercury is fwept off before the 

 plate without interfering. The plate being then let go, 

 finks on the tin-foil, fqueezing out the fuperfiuous mercury, 

 which palTes into the channel of the wooden frame above- 

 mentioned. The plate is then covered with a thick flannel, 

 and is loaded over the whole furface with lead or iron 

 weights, and at the fame time is tilted up a little, by which 

 dill more of the mercury is fqueezed out. It remains in this 

 fituation for a day, the dope of the done flab being gra- 

 dually increafed to favour the dripping of the mercury. 

 The plate is then very cautioufly removed, touching it only 

 by the edges and upper fide, and the under fide is found 

 uniformly covered with a foft pally amalgam, confiding of 

 the tin-leaf thoroughly foaked with the quickfilver, and 

 about the thicknefs of parchment. It is then fet up in a 

 wooden frame, and allowed to remain there for feveral 

 days, the flope of its pofition being gradually increafed, 

 till the amalgam is fufficiently hardened to adhere fo firmly 

 as not to be removed by flight fcratches, after which the 

 plate is finifhed and fit for framing. 



It is a confiderable time before the amalgam has acquired 

 its utmoll degree of hardnefs, fo that globules of mercury 

 will often drip from new mirrors fome time after they have 

 been fet up in rooms ; and violent concufTions of the air, 

 fuch as from the firing of cannon, will often detach portions 

 of the amalgam. Thefe can never be perfeftly replaced 

 by any patching, as the lines of junflion with the old amal- 

 gam will always be marked by white feams, feen when 

 looking into the glafs. See Foliating of Looiiiig-Glnjfes. 

 • Silvering of Paper. See Ch'mefe Paper. 



SILVERIUS, pope, in Biography, the fon of pope 

 Hormifdas, was placed in the pontifical chair in the year 

 536, upon the death of Agapetus. Belifarius, the famous 

 general of Judinian, having foon after taken pofieffion of 

 Rome, the emprefs Theodora refolved to take this oppor- 

 tunity of redoring Anthemius, patriarch of Condantinople, 

 and his party, who had been condemned for herefy by the 

 council of Chalcedon. She wrote to Silverius, urging him 

 to recognize Anthemius as lawful bifhop, to which he gave 

 a pofitive refufal. Upon this the emprefs made an engage- 

 ment with the deacon Vigilius, that he fhould be raifed to 

 the popedom on condition that he would anathematize the 

 council of Chalcedon, and re-admit Anthemius and his 

 party ; and (he at the fame time ient orders to Belifarius to 

 depofe Silverius. To furnidi a pretext for this aft, an 

 accufation of treafon was brought agaiud the pope, as 

 having invited the Goths to repofTefs themfelves of Rome. 

 This change was mod probably invented for the purpofe, 

 and without the fmalled foundation ; and Belifarius, without 

 afting upon it, fent for Silverius, and endeavoured by 



4 perfuafion 



