34 
Copper . 
termed roasting* is repeated 8 and sometimes 12 times 
before black copper can be obtained. When this appears, 
it is let off, and run into ingots, which are again exposed 
to the reverberatory till the copper is quite purified. This 
is let off and granulated by falling into water while in a 
melted state. 
Such a reverberatory may be worked by wood as well 
as coal. 
The hearth and basin (catin) may be made of sand as a- 
bove mentioned, with a thin coating of pounded and sift- 
ed glass, which when melted, unites the surface into a 
compact body. Sometimes they are made of one part by 
measure of clay, and two parts or more of charcoal dust 
with one measure of well burnt pounded brick or fire 
stone : all these are moistened, well mixed, and well 
beaten with flat wooden and iron pounders, and rammed. 
The flux is sometimes (in England) common salt, and 
sometimes broken glass, and scoria. 
Refining . — This is for the purpose of scorifying any 
iron, lead, zinc, tin, antimony or cobalt that the metal 
may contain. 
The furnace is in shape of a table 2 feet 6 inches from 
the ground, 6 feet 6 inches wide and 4 feet 6 inches deep. 
At the distance of 9 feet 3 inches from the ground, an arch 
is raised, and on this arch a chimney, and the wall against 
which the furnace is supported. At the sides of the fur- 
nace, a door- way is left, the height of a man, to clear the 
surface of the melted metal. The bottom should be as 
high as the underside of the air pipe or tuyere (tweer) and 
hollowed out by means of an iron cutting ring with a 
slanting edge, 6 feet 6 inches diameter and 9 inches deep : 
well beaten, and made smooth, and then dried by gradually 
heating it. A strong blast from a pipe of one inch diameter 
should play full on the surface of the melted metal covered 
with coals. There must be also a hole left near the tweer 
