20 Account of the Gold and Silver Mines of Hungary. 
with the other ores. But the smaller pieces are separated by 
putting them in sieves, which are repeatedly plunged into water. 
The water penetrates from below; and as the displaced fragments 
of ore again subside, the heaviest and generally the richest fall 
to the bottom. This being several times repeated, the sorters 
are enabled to make a tolerably accurate division, by removing 
with a shovel the upper half, that which remains being retained 
as valuable. 
The greater part of the ores at Schemnitz contain a large 
proportion of lead, some copper, with sulphur, arsenic, and other 
minerals, and a small proportion only of silver. These are 
smelted in the furnaces, which are erected upon the spot; but 
those which contain a large proportion of silver are taken to the 
silver furnaces at Kremnitz. 
The works which I visited near Schemnitz are denominated 
lead fernaces, although their object is not to obtain the lead, ex- 
cept in combination with the silver and gold, and as a means of 
procuring these precious metals. 
The ores, having: by the operations of the pochwerk been se- 
parated from a large part of their earthy impurities, are roasted, 
in order to drive off the arsenic, sulphur, and other volatile mat- 
ters. This is done either in open furnaces, in which it is piled 
in alternate layers with wood, or in reverberatory furnaces,. in 
which only a moderate degree of heat is kept up. This roasted 
ore is then removed to a blast furnace, the bellows of which are 
worked by water. It is here mixed in layers with charcoal and 
various slags and scoria of former processes, all of which con- 
tain more or less lead, and contribute to the easy and perfect fu- 
sion of the ores. ‘The heat in the furnace having by the con- 
stant working of the beilows been greatly raised; at the end of a 
given period, if the process is found to be perfected, an opening 
is made in the lowest part or eye of the furnace, by piercing a 
stopper made of clay and charcoal powder, with which the aper- 
ture had been closed when the furnace was charged. Through 
this opening, the liquefied metal, which had collected in the bot- 
toin of the furnace, runs into a circular cavity, or bed formed of 
charcoal and clay. This fluid metal consists of the lead, to which 
the silver and the gold, if any, have a strong attraction, and are 
intimately united ; aud of copper and any other metallic sub- 
stance, such as iron, that may have been combined with the ores, 
and have not been oxidated in the furnace. As the lead con- 
taining the silver remains fluid at a much lower temperature 
than copper; the latter separates with the other impurities, and 
quickly forms a porous crust, or slag, upon the surface, which is 
removed by tongs as soon as it acquires the thickness of half an 
inch. This is repeated till these crusts cease to collect, when 
the 
