2 PROCESS FOR REFINING LEADi 



- , , The operation of refining is founded on the facility 

 It IS refined by , . , , , . . , , , % . i . • 



vitrification yvith which lead is oxidated when exposed to heat in con- 



and reduction, tact with atmospheric air, and the peculiar properties the 

 oxides of lead possess ; being easily fused, and in that state 

 oxidating and combining with most of the metals; gold, 

 silver, and platina excepted. 

 UDon a cupel The lead to be refined is exposed to the action of heat 

 in a reverbcra- and air upon a cupel or test, composed of a mixture of 

 tory furnace. \yQjyQ g^d (^^n ashes in a reverbatory furnace; the de- 

 scription of which, with the different manipulations, are 

 as follows: 

 Description of The refining furnace is composed of good solid masonry, 

 the furnace for bound together with iron bolts. It differs very little in 

 re mng ea . j^^ construction from the common reverbatory furnace, 

 except the bottom, which is perforated to receive the test 

 or cupel. 



Fig. i. Plate I. is a perspective view of the furnace 

 with its ironwork; « the tcazing hole, b aperture 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, e e two strong iron bars to support 

 the test when in its place, / 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 feed- 

 ing the test. 



Fig. 2. a perpendicular section of the furnace shewing 

 the test /, supported in its place under the opening of 

 the bottom of the furnace by the two wedges rr;k aper- 

 ture for the nozzle of the bellows, s fire bar resting on 

 the bearers. 



Fig. 3. plan of the interior of the furnace; / part of 

 the bellows, hh flues from the body of the furnace to 

 the stack. 



The same letters in the different plans are ineant to de- 

 / note the-same parts. 



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 in 

 the bottom of the furnace. 



Figs. 2 and 3. plan and section of the test; m the part 



which 



