GILDING. ^7 



precipitate the gold from the solution by pieces of 

 copper. Lay this gold on with a strong solution 

 of borax and gum water, and it will be ready for 

 burning-in. 



Gilding Metals. 



One method of applying gold upon metals is by 

 first cleaning the metal to be gilt ; then gold leaf 

 is laid on it, which, by means of rubbing with a 

 polished blood stone, and a certain degree of heat, 

 are made to adhere. In this manner silver leaf is 

 fixed and burnished upon brass, in the making of 

 what is cdWed French plate ; and sometimes also 

 gold leaf is burnished upon copper and iron. 



Gilding hy Amalgamation is by previously 

 forming the gold into a paste, or amalgam, with 

 mercury. 



In order to obtain an amalgam of gold and 

 mercury, the gold is lirst to be reduced into thin 

 plates or grains, which are heated red-hot, and 

 thrown into mercury previously heated, till it be- 

 gins to smoke. Upon stirring the mercury with 

 an iron rod, the gold totally disappears. The pro- 

 portion of mercury to gold is generally as six or 

 eight to one. 



The method of gilding by amalgamation is 

 chiefly used for gilding copper, or an alloy of cop- 

 per with a small portion of zinc, which more 

 readily receives the amalgam, and is also prefer- 

 able, on account of its colour, which more resem- 

 bles that of gold than the colour of copper. 



When the metal to be gilt is wrought or chased, 

 it ought to be previously covered with quick-silver 

 before the amalgam is applied, that this may be 



