BRONZING. 



WE have already mentioned that when a medal has been made 

 from a metal mould, protected by a little wax dissolved in turpen- 

 tine, it retains its bright copper lustre for a long time, even when 

 exposed to the air, but generally the copper medals and other objects 

 are very liable to tarnish ; for which reason it is usual to give them 

 a coating of bronze, that they may acquire a permanently agreeable 

 appearance. 



Brown Bronzes. Bronzing is effected by several very simple 

 methods, the most common of which is the following : 



Take a wine-glass of water, and add to it four or five drops of 

 nitric acid ; with this solution wet the medal (which ought to have 

 been previously well cleaned from oil or grease) and then allow it to 

 dry ; when dry impart to it a gradual and equable heat, by which 

 the surface will be darkened in proportion to the heat applied. 



Another Method. Make a thin paste pf crocus and water ; lay 

 this paste on the face of the medal, which must then be put into an 

 oven, or laid on an iron plate over a slow fire ; when the paste is 

 perfectly reduced to powder, brush it off and lay on another coating ; 

 at the same time quicken the fire, taking care that the additional 

 heat is uniform; as soon as the second application of paste is 

 thoroughly dried, brush it off. The medal being now effectually 

 secured from grease, which often occasions failures in bronzing, coat 

 it a third time, but add to the strength of the fire, and sustain the 

 heat for a considerable time : a little experience will soon enable 

 the amateur to decide when the medal may be withdrawn ; the 

 third coating being removed, the surface will present a beautiful 

 brown bronze. If the bronze is deemed too light the process can be 

 repeated. 



Another very simple method is this : after the medal is well 

 cleaned from wax or grease, by washing it in a little caustic alkali, 

 brush some black lead over the face of it, and then heat .it in the 

 same way as described for crocus, or, a thin paste of black lead may 



