COPPER. 
513 
posing them to the fumes of zinc. The leaves are 
afterwards beaten as thin as leaf-gold, and, like that 
substance, put into books of paper in order to be 
used for the common kinds of gilding. The parings 
or shreds of copper-leaf, after they have been ground 
to a powder on a marble slab, are used to cover 
figures and other ornaments, so as to give them the 
appearance of real bronze. 
Copper, like other metals, in a melted state is 
remarkably impatient of moisture, and explodes 
with the most dreadful violence if a little w ater 
should unhappily get to the bottom of a mould in a 
foundery. Cramer mentions a melancholy instance 
of its violent effects in a brass-foundery in Wind- 
mill-street, near Moor-fields, where, it seems, several 
persons of quality attended to observe the casting 
of two large brass cannon at a time. The heat of 
the metal of the first gun drove so much damp into 
the mould of the second, which was near it, that as 
soon as the metal was let in, it blew up with the 
greatest violence, tearing up the ground some feet 
deep, breaking down the furnace, untiling the 
house, killing many of the spectators on the spot 
with the streams of melted metal, and scalding many 
others in a most miserable manner. 
Copper is soluble, more or less, in all acids, and 
likewise in alkalis. Even pure water, if suffered to 
stand long in copper vessels, extracts enough to ac- 
quire a disagreeable coppery taste. It is a fact 
well known, though somewhat singular, that fluids 
2 L 
VOL. III. 
