f27!2 filLDIXG. 



described as taking place wlien a solution of nitrate 

 of mercury is employed, a thin coating of copper 

 is precipitated on the metal. Copper having an 

 affinity for mercury, a kind of union may by this 

 means be effected between the amalgam and the 

 iron or steel, as the case may be. In whichever 

 of these ways the amalgam be brought into imion 

 with the steel, the surface is injured by the action 

 of the acid employed, and still a heat sufficient to 

 volatilize the mercury, must be afterwards used. 



Gilding of Iron by heat. — When the surface is 

 polished bright, it must be heated till it becomes 

 blue. Gold leaf is then applied to its surface, and 

 burnished down. It is then heated again, and 

 another layer of gold burnished on it. In this 

 manner three or four coats are given, according to 

 the strength of the gilding intended. This is a 

 more laborious process than the two last, but it is 

 not attended with so much risk. 



An improved process for gilding Iron or Steel. — 

 This process, which is less known among artists 

 than it deserves to be, may prove useful to those 

 who have occasion to gild iron or steel. The 

 first part of the process consists in pouring over a 

 solution of gold in nitro-muriatic acid (aqua regia) 

 about twice as much ether, which must be done 

 with caution, and in a large vessel. These liquids 

 must then be shaken together ; as soon as the 

 mixture is at rest, the ether will be seen to separate 

 itself from the nitro-muriatic acid, and to float on 

 the surface. The nitro-muriatic acid becomes 

 more transparent, and the ether darker than they 

 were before ; the reason of which is, that the 

 ether has taken the gold from the acid. The whole 

 mixture is then to be poured into a glass funnel, 

 the lower aperture of which is small j but this 



