274 GILDING. 



Gilding of Brass or Copper. — Fine instruments 

 of brass, in order that their surface may be kept 

 longer clean, may be gilded in the following 

 manner. 



Provide a saturated solution of gold, and having 

 evaporated it to the consistence of oil, suffer it to 

 shoot into crystals. These crystals must then be 

 dissolved in pure water, and the articles to be 

 gilded being immersed in it, are then to be washed 

 in pure water, and afterwards burnished. This 

 process may be repeated several times, till the arti- 

 cles have been well gilt. A solution of gold 

 crystals is preferred to a mere solution of gold j 

 because, in the latter, there is always a portion of 

 free acid, which will not fail to exercise more or 

 less action on the surface of the brass or copper, 

 and injure its polish. 



Grecian Gilding. — Dissolve some mercury in 

 muriatic acid (spirits of salts), which will give a 

 muriate of mercury. Mix equal parts of this and 

 sal ammoniac, and dissolve them in aqua fortis. 

 Put some gold into this, and it will dissolve. 

 When this is applied to silver, it becomes black ; 

 but by heating, it assumes the appearance of 

 gilding. 



To make Shell-Gold. 



Grind up gold-leaf with honey, in a mortar ; 

 then wash away the honey with water, and mix 

 the gold-powder with gum-water. This may be 

 applied to any article with a camel's-hair pencil, 

 in the same way as any other coloui'. 



