186 VERDIGRIS. 
ought to have their inner surface covered with a coat of 
tin (238). 
As copper does not, like iron, strike fire by collision, 
it has on this, as well as on some other accounts, been 
Substituted for iron in the machinery which is employed 
in gunpowder mills. It is also made into water pipes, 
and sometimes into sash frames. Under the hammer it 
is capable of being beaten into thin leaves like gold. 
Copper wire is much employed by bell-hangers and 
other artisans. The filings of this metal are used for 
giving a green colour to some kinds of artificial fire- 
works. 
Several preparations of copper are employed in me- 
dicine, some of them internally, and others externally ; 
but most of the former are violently emetic. 
Verdigris is a rust or oxide (21) of copper, usually 
prepared from that metal by corroding it with vinegar. 
There is a large manufactory of verdigris at Montpelier 
in France. The workmen place alternate strata of cop- 
per plates and husks of grapes, the latter of which 
speedily become acid and corrode the metal. The ver- 
digris, thus formed, is scraped off as it collects on the 
surface ; it is afterwards dried, and put in bags or casks 
for sale. A manufactory of verdigris has lately been 
established at Deptford, near London. 
A solution of this substance in distilled vinegar af- 
fords permanent crystals, which are improperly called 
distilled verdigris , and are made into a green paint. 
Verdigris is principally consumed by dyers in combi- 
nation with logwood, for striking a black colour. It is 
a virulent poison. 
Oxide of copper is employed for giving a beautiful 
green colour to porcelain. It also imparts the same 
colour to glass, and hence is frequently employed for 
the formation of artificial emeralds. 
Alloys of Copper. 
Of all metals that are known, copper is the most sus- 
