108 ON A METHOD OF EXTRACTING GOLD, SILVER, 
seen the coke is a em sheet of lead, with suitable 
of the residual gases, which may be con- 
a pipe to the chimney. On the perforated lead plate 
1 
The roaster should have two or three small fire place s at in- 
tervals underneath the sole, to get it to a working Sat which 
may be closed when this is attained, the flame from the reverber- 
atory furnace, mixed with a sufficient quantity of air through 
— in the flue, then supplying sufficient hea 
easter sole being heated to a dull-red hest, 2 ewt. of 
a one an nd a half inches ore soon becomes 
The last is condensed in the arsenic flue, and the two former pass 
through the combination chamber to the eee tower, and 
are there absorbed by the descending water. 
In an hour’s time the charge is pry two feet to the left, and 
a second charge of the mixture is placed in the space cleared. At 
the end of another hour the first charge is moved two feet to the 
left, the second to the space cleared, and a third is introduced, 
roaster is covered. The upper part of the roaster should be at a 
very dull red heat, whilst pas aioe si gga be sufficiently hot to 
charcoal dust, or other pretences matter is now spre vand 
the calcined residue from the first charge is turned over on. top 
of it, each charge in the roaster is moved downwards, and a 
fresh charge of mixture sithodaieeth In another hour a similar 
quantity of carbon is eon on top of — charge in the recess, 
and the second charge is turned over on top, and so on until 
= successive iietaes “of roasted vette and edrbon are in the 
rec 
The contents of the recess are then transferred to the gle 
. s e 
= 
