Brass* 
113 
corrosive sublimate of mercury, into a paste. Boil your 
copper for half an hour in alum and Tartar ; take it out, 
and rub it with this paste. Then heat it red-hot, and af- 
terward polish it. 
When buttons are stamped out of plated copper, the 
edges and backs will be coppery. To whiten them, they 
are boiled in water containing as much argol or tartar as 
it can hold, in which precipitated silver is also put. The 
backs and edges are thus whitened, in the same way that 
the brass wire of pins is tinned. 
I believe iron is plated on the same principles with cop- 
per and brass. 
I do not know that any body has yet attempted to plate 
copper with platina except Dr. Boll man* His iron plated 
with platina, is a very beautiful manufacture, and would 
prove highly useful for crucibles, and culinary vessels ; 
but I do not know that he has yet succeeded in plating 
copper with platina by lamination, in the same way as sil- 
ver is rolled on copper. But copper may be coated with 
platina by means of a mercurial amalgam, as has been 
proposed and tried on the continent of Europe. The 
process is thus. 
M* Strauss in Gehlen’s Jo urn* 20 Phih Magazine, 285. 
Take a solution of platina precipitated by sal ammoni- 
ac : wash it : dry it : expose it to a red heat in a covered 
crucible for half an hour. This may be amalgamated 
with from five to seven parts of mercury by trituration in 
warm water. (Why not use the precipitate hot ?) This 
amalgam laid over copper, unites with it, and the mercu- 
ry may be driven off by heat as in the case of silvering or 
gilding with mercury. A second coating may be applied, 
ipixed with chalk and sprinkled with water : the plate is 
again exposed to a red heat to drive away the mercury.. 
The platina may then be burnished down. 
Vot. III. 
P 
