360 
hn . 
At the expiration of this period, the furnace is tapped 
by means of an iron bar, and the hot metal flows into a 
shallow pit at the foot of the furnace. When the whole 
of the metal has run out, the scoriae are drawn out of the 
furnace with a rake, and a fresh charge is immediately 
thrown in. While the metal in the pit is red-hot, it throws 
up a quantity of slag very rich in metal, which is imme- 
diately returned into the furnace, and the melted tin after 
it has become sufficiently cool, is taken out with iron lad- 
les and poured into moulds of granite, where it consoli- 
dates ; each charge, affording on an average, from four to 
live hundred weight of metal. The first scoriae are not 
entirely exhausted of metal, and are therefore transferred 
to the stamp-mill, and afterwards washed, in order to se- 
parate the richer particles, which are then mixed with the 
next parcel of roasted ore. 
The pigs of tin thus procured, are next put without any 
addition, into a small reverberatory furnace, where they 
are exposed to a very gentle heat, the purest part of the 
tin first melts as it is drawn off, forming the common grain 
tin ; the more refractory part containing a small but vari- 
able portion of copper, arsenic, and iron, is then brought 
to a state of fusion, and cast into pigs, forming the com- 
mon or ordinary tin. 
2. The stream tin- stone is not, we believe, found in any 
other part of Europe, than Cornwall, (Eng.) It differs 
from the former in its extreme purity, and absolute free- 
dom from arsenic, and in its occurring in alluvial beds. 
The largest stream -tin work is at Carn, about two miles 
to the S. E. cf Perran, not far from Redruth. It is situ- 
ated in a valley, through which flows a stream, the course 
of which has been turned, for the sake of getting at the 
treasure concealed beneath its bed. The workmen first 
dig through a stratum about fifty feet thick of clay, shells 
and black earth, in which has been found hazel nuts, the 
