The nature of copper is such that when it is " dried " it becomes ash
coloured, and since this copper contains silver, it is smelted again in the
blast furnaces.23
I have described sufficiently the method by which exhausted liquation
cakes are " dried " ; now I will speak of the method by which they are made
into copper after they have been " dried." These cakes, in order that
they may recover the appearance of copper which they have to some extent
lost, are melted in four furnaces, which are placed against the second long
wall in the part of the building between the second and third transverse
walls. This space is sixty-three feet and two palms long, and since each of
