first, the earthy
matters and extraneous metals, by forming them into oxides by
calcination: these are subsequently obtained as waste products in the
form of slag; while the copper is left in combination with sulphur,
which is then dispelled at one operation. According to Mr Vivian,
copper undergoes eight, and sometimes nine, distinct operations in its
progress from the ore to the ingot; and these consist of alternate
calcinations and fusions, extending over a period of from 100 to 120
hours. As, however, some of these are simple repetitions, we may, for
convenience' sake, illustrate the process under its three most
important steps.

1. _Calcination of the Ore._--Having arranged a proper mixture of ores
in the yard, it is weighed out in boxes to the calcining-men. This is
drawn up an inclined plane over the tops of the furnaces, and from
thence emptied through hoppers, 3-1/2 to 4-1/2 tons at a time, into
the large calcining furnace. Here it is roasted for a period ranging
from twelve to twenty-four hours, after which it is drawn into the
ash-pit, where it remains to cool. In this state, the ore is a black,
amorphous substance, and is termed _calcined ore_. The object of this
process is to oxidise the extraneous metals, and also to reduce the
quantity of sulphur, by driving it off in the form of vapour. It is,
therefore, in this and the analogous processes of roasting, that the
sulphurous and arsenous vapours are so profusely given off.

We stood upon one occasion beside a furnace, when the charge was in
the act of being withdrawn; but we took especial care never to do the
like again. The sensation resembled what one might expect to feel on
holding a lighted lucifer-match under each nostril. It is surprising
how the workmen stand it. For the greater part of their lives, these
poor Welshmen exist habitually in an atmosphere so charged with the
above-mentioned abominable gases, that it is difficult to understand
from whence their lungs receive the necessary supply of pure
oxygen.[6] Sulphurous acid, we may add, is the predominant smell in a
copper-work; but arsenic acid, hydrofluoric acid, and even
arseniuretted hydrogen, are not at all unfrequent.

2. _Melting the Calcined Ore._--This is a totally different operation
from the last: in place of roasting, it is one of fusion. The calcined
ore is put into the furnace much in the same manner as before; a
quantity of the slag from a subsequent process is added to assist in