184? COPPER. 
broken with hammers into small pieces, an operation 
which is chiefly performed by women and children. 
After this, it is piled into kilns of great length, and 
each about six feet high; from the upper parts of 
which flues are attached that communicate with what 
are called sulphur chambers. The kilns are closely 
covered ; and fires are lighted in different parts, that 
the ore may undergo the process of roasting. The 
whole mass gradually kindles, and the sulphur, which is 
combined with the "ore, is expelled in fumes, by the 
heat, and is conveyed, through the flues, to the sulphur 
chamber. This process occupies from three to ten 
months, according to the size of the kilns ; and, during 
that period, the sulphur chamber is cleared four or five 
times. When the operation is complete, or the ore is 
freed from the sulphur, it is taken to places denomi- 
nated slacking pits. It is subsequently conveyed to 
the smelting houses, where, by intense heat, the pure 
metal is drawn off in a fluid state. 
As the water, which passes through several parts of 
the Paris mine, is strongly impregnated with sulphat of 
copper (209), or copper held in solution by sulphuric 
acid (24-), the proprietors turn the course of this water 
through certain large and shallow pits, which they have 
formed for the purpose, and in each of which they 
place a quantity of iron. A decomposition here takes 
place : the iron is cprroded, and, at length, entirely 
dissolved, and the copper, in the form of a brown mud, 
falls to the bottom. One ton weight of iron, thus im- 
mersed, will produce nearly two tons of copper mud, 
each of which, when melted, will yield sixteen hundred 
weight of metal. This mode of obtaining copper is said 
to have been an accidental discovery from one of the 
workmen, several years ago, having left a shovel in the 
water, which, when afterwards taken out, appeared 
changed into copper. 
The magnitude of the above mentioned copper works 
may readily be conceived, when it is stated that the beds 
of ore are, in some places, more than sixty feet in depth ; 
