110 
Brass . 
per : cover it with charcoal : to two parts of copper by 
weight, add, tightly folded up in paper, one part of admix- 
ture of equal weights of potash and arsenic fused to- 
gether ; putting in the arsenic when the potash is quite 
hot. As soon as you have thrust this to the bottom of 
the melted copper with a stick, cover the crucible quick- 
ly, and lute the sides of the cover. In a quarter of an hour, 
the mixture may be poured out. It will be hard, white, 
and very brittle. Where the latter quality does not spoil 
It, this alloy may be used, as a substitute for silver. Per- 
haps brass thus treated with arsenic, might be used to 
good purpose. T. C. 
Plating .— This is confined to the covering of copper 
or brass, the metals usually employed for this purpose* 
with a plate of solid silver. The other methods of cover- 
ing copper or brass with a still thinner coating of silver* 
is called Silvering . 
Plating is thus performed. An ingot or bar of copper, 
previously well hammered to increase its ductility, and 
neatly cleaned and planished, is covered with a very thin 
coating of pounded and finely-sifted glass of borax :• upon 
this, is laid a plate of silver from one-tenth to one- six- 
teenth part of the weight of the copper, according to the 
proposed value of the plated goods. The plate of silver 
is very nearly but not quite so large as the bar of copper. 
The silver is also planished, so that previous to the ope- 
ration, the under surface of the silver and the upper sur- 
face of the copper may touch nearly in all their parts. 
The silver being laid on the copper, previously strewed 
verv thinly with the sifted borax, a few blows with a harm 
mer or mallet are given, to bring the surfaces still more 
into contact. The silver is then bound to the copper by 
iron wire drawn tight. The edges are also covered with 
powdered and moistened glass of bora x so as to cement 
the silver, when heated, to the copper. They are th$n ex- 
