Jof the tf/e ofArt'ifis, MamtfaBurers, &c. t^^ 



*his purpofe a folution of mercury in nitrous acid {aquafortis), 

 t)r what the workmen call quickfilver vyater, is applied to tlie 

 parts intended to be gilded : the acid, by a ftronger affinity, 

 feizcs on a portion of the iron, and depofits in the place of it 

 a thin coating of merciirv, which will not rclufe a union 

 afterwards with the gold amalgam that may be applied ; but 

 by this procefs the furface of the metal is injured by the ni- 

 trous acid, and the union of the mercury is very flight, lo 

 that a bright and durable gilding cannot be obtained. 



Gliding ivith Ainalgam and Sulphate of Copper. 



Sometimes a folulion of fulphate of copper {blue vitriol) is 

 applied, with a canul's hair pencil, to the parts of the ftct-1 

 intended to be gilt. Cv a chemical aftion cxaftly fimilar to 

 what wc have dofcribed as taking place when a folution of 

 nitrate of mercurv is employed, a thin coating of copper is 

 precipitated on tlje metal. Copper having an affinitv for 

 mercury, a kind of union may by this means be effected be- 

 tween the amalgam and the iron or fteel, as the cafe may be. 



In whichever of thefe ways the amalgam be brought into 

 union with the lied, the furface is inj'.ired by the action of 

 the acid employed, and flill a heat fulFicient to volatilize the 

 mercury nioft be afterwards cm))loycd. Mofl: artifts, there- 

 fore, follow the firfl procefs, that of applving gold leaf, and 

 burnifliing it down on the article while hot ; which, though 

 a laborious procefs, is attended with lc.*3 rifk of the furface 

 being injured. 



An Improved Proofs for gilding Ir^.n or ^teel. 

 This procefs, which is lefs known among artifts than if 

 defervcs to be, may prove ufeful to thofe who have oceallon 

 to gild iron or Heel. The firft part of the procefs confilla in 

 pouring over a folution of gold in nitro-rauriatic acid {aqud 

 regia) about twice as much a-.lher, which mull be done with 

 caution, and in a large veflfel. Thefe liquids m-dt then be 

 fliaken together: as foon as the mixture is at rell, the aether 

 will be feen to feparatc itfelf from the nitro-muriatic acid, 

 and to float on the furface. The nitro-muriatic acid becomes 

 more tranfparent, and the ;Etber darker than they were be- 

 fore ; the reafon of which is, that the aether has taken the gold 

 from the acid. The whole mixture is then to be poured into a 

 glafs funnel, the lower aperture of wlyeh is fmall j but this 

 aperture mull not be opened till the fluids have completely 

 feparated themfelves from each other. It is then to be 

 opened ; by w hich means' the liquid which ha:? taken the 

 lowed place by its greater gravity, viz. the nitro-mutiatic 

 acid, will run off; after which the aperture is to be llmt, and 

 ' Vol. XI. K ihs 



