Lead . 
213 
The lead to be refined is exposed to the action of heat 
and air upon a cupel or test, composed of a mixture of 
bone and fern ashes, in a reverberatory furnace ; the de- 
scription of which, with the different manipulations, are 
follows : 
The refining furnace is composed of good solid mason* 
ry, bound together with iron bolts. It differs very little 
in its construction from the common reverberatory fur- 
nace, except the bottom, which is perforated to receive the 
test or cupel. 
Fig. 1, plate I, of the refining furnace is a perspective view 
of the furnace with its iron work ; a the teazing hole, b aper- 
ture by which the test is supplied with lead, c an arch or 
dome over the feeding hole, communicating with the furnace 
stack by a flue, d area or space where the test is taken in 
and out the furnace, ee two strong iron bars to support 
the test when in its place, f cast iron pot set in masonry, the 
flue passing into the stack of the furnace, g the stack, p 
the ash pit, q an iron bar to slide the ladle on when feeding 
the test. 
Fig. 2, a perpendicular section of the furnace showing 
the test i, supported in its place under the opening of the 
bottom of the furnace by the two wedges rr ; k aperture 
for the nozzle of the bellows, s fire bar resting on the 
bearers. 
Fig. 3, plan of the interior of the furnace ; l part of 
the bellows, hh flues from the body of the furnace to the 
stack. 
The same letters in the different plans are meant to de- 
note the same parts, in the next plate. 
Plate II, fig. 1, plan of the iron frame into which the 
mixture of bone and fern ashes is rammed to form the test. 
This frame is something larger than the elliptical hole iri 
the bottom of the furnace. 
