156 Mr. H. L. Pattinson on Smelting Lead Ore, 8$c. 



particles, the fume from the roasting furnace is conveyed into this flue, 

 where the heavy metallic portion is deposited. 



SMELTING IN THE ORE HEARTH. 



The furnace in which the roasted ore is reduced into Lead is called 

 an Ore Hearth. Its construction is almost exactly the same in all 

 smelting houses in the north of England, and seems to have undergone 

 but little alteration from a very remote period. It may be briefly de- 

 scribed as a square furnace, close on three of its sides, and open towards 

 the bottom of the fourth. Immediately in front of this opening is 

 placed a sloping cast-iron plate, the upper edge of which is four and 

 a half inches above the bottom of the furnace, forming a reservoir of 

 that depth, in which the reduced lead accumulates, and out of which 

 it flows, through a channel in the plate, into a pot below, after the re- 

 servoir becomes full. 



To construct an ore hearth, twelve pieces of cast iron are necessary, 

 (exclusive of the melting pot,^ Plate II., Figs. 1 and 3), viz. : — 



A hearth bottom, Fig. 5 and i, Figs. 1 and 3, 22 inches square, in- 

 side measure, the bottom 3 inches thick, and the sides 3 inches thick 

 and 4>h deep. In building an ore hearth, it is usual to place the hearth 

 bottom upon a layer of sand a few inches deep above the brick or stone bed. 



A workstone e, Figs. 1 and 3. This is a plate 3 feet long, by 1| 

 broad, and 21 inches thick, having a raised border an inch high on its 

 two ends and front side, with a channel o, Figs. 1 and 3, 2 inches wide, 

 and 1 deep, running diagonally across it. It is placed at a slope of 

 three or four inches from its upper to its under edge. 



Two bearers d, d, Fig. 1, being square prisms of cast iron of 6 inches a 

 side, by 26 or 28 inches in length. There is an advantage in making 

 these long, as they can be turned when worn at one end, and, as they 

 project over and rest upon the workstone, they tend to keep it firm in its 

 place. 



A backstone h, Fig. 3, upon which the bellows-pipe rests, as in the 

 figure. It is a parallelopiped 28 inches long, 6A in height, and 5 inches 

 broad. 



