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On Smelting of Lead. 279 



is smelted in reverberatitig furnaces: this kind of smelting 

 is distingnishecl from the oilier bv the name of cupola smelt- 

 ing: each of these mtthocls has its advocates. 



The superiority of either depends much on local circum- 

 stances, and, perhaps, also on the skill of the workmen. 



Ore-hearth smelting shall be first described. — To render 

 the description intelligible, it will be necessary to commence 

 with a description of the hearth. 



Fig. 1, (Plate VIII.) is a sketch of the hearth : it is con- 

 structed principally of pieces of cast iron, which are called 

 generally iron sstones or metal stones; each different casting 

 has a distinguishing name: they are the (<7) pan, (/») back, 

 {c) pipe-stone, ('/) spark-stone, {e) bearers, (/) keys, (g) 

 fore-stone, and the (//) work-stone. 



The hearth is erected under a spacious chimney, and nearly 

 in the centre; one side of it is called the water-side, being 

 near the wafer wheel, which urges the bellows ; the opposite 

 is called the land side. 



Figs. 2 and 3 are plans and sections of the ore hearth: the 

 same ieitcrs in the different figures are placed to the same 

 parts. — (/) the floor of the smclting-house, {k) the back of 

 the chimnev, {1} the front of the chimney, (m) the founda- 

 tion on which the hearth is constructed: it is built of rough 

 masonry, and levelled and run in at the lop with thin mor- 

 tar or grout ; the pan or bottom of the hearth is laid steadily 

 in mortar on this bed: upon the posterior part of the pan 

 is placed the back, its face being even with the inner edge 

 of the pan. 



The work-stone is next arranged ; its upper edge three or 

 four inches from the anterior part of the pan, and parallel 

 with the back ; the bearers are placed on the sides of the 

 pan, one end of each butting against the back, the other 

 ends restini'' on the upper edge of the work-stone. Two thin 

 pieces of stone, (about half an inch thick,) generally slaty 

 sandstone, are laid on the back, and on these is planed the 

 pipe-st(jne, the inner face of which overhangs the back near 

 an inch. The keys are set on the bearers, their faces even 

 w ith them ; two pieces of brick are set on edge on the bearers, 

 next to the keys, and on these, a few inches from the keys, 

 rests the fore-stone; the spark-stone laid on the pipe-stone 

 completes the hearth. 



Before laving the foundation, a large flat stone (//) called 

 the cheek-btone is fixed firmly in the ground, and determines 

 the extent of the lan<l-?ide of the hearth ; the spaces between 

 the water- side, the back of the chinmey, and the cheek- 

 etone are filled up with pieces of sand-stone, bricks, or old 

 S 4 iron- 



