Mr. H. L. Pattinson on Smelting Lead Ore, 8$c. 175 



REDUCING OF LITHARGE. 



The reduction of Litharge into Lead is an easy process, and, in the 

 great way, is very expeditiously performed, in a reverberatory furnace 

 almost exactly similar to the roasting furnace already described, except 

 that its bed or bottom, instead of being flat, is made to slope towards 

 an opening in the side, through which the reduced Lead is conveyed, 

 by means of a cast-iron channel, into a pot, to be finally made into pigs 

 for sale. The inside of a roasting furnace is generally made somewhat 

 elliptical, about 6 feet long, and 5\ broad, and a furnace of this size, 

 worked by three men, at 8-hours shifts each, is capable of reducing, 

 without difficulty, all the Lead oxydized in two refining furnaces, each 

 working six tests, or 24 fodders per week. After the reducing furnace 

 has been properly heated, the process is commenced by covering its 

 bottom with a stratum of coal, which taking fire, very soon forms a 

 mass of ignited fuel some inches in thickness. Upon this the charge 

 of Litharge mixed up with a small quantity of fresh Coal, is thrown, and 

 a furnace of the size mentioned, will hold from two to three tons. The 

 reduction goes on rapidly, and the furnace is supplied, from time to 

 time, with fresh Litharge, until the quantity added is such as will pro- 

 duce from 4 to 5 fodders of Lead ; the charge is then suffered to run 

 down, with the addition of fresh Coal, to promote the reduction, as it 

 seems to be required. At the end of nine or ten hours, the whole of 

 the Litharge is reduced, and, at the bottom of the furnace, there re- 

 mains only a portion of slag, called Litharge Slag, which is raked out 

 while still hot to prepare for the next charge. 



This Litharge Slag is formed by the vitrification of the earthy matter 

 contained in the Coal used in reduction, and, as a small quantity of 

 Lead is unavoidably united with it, it is afterwards worked over in the 

 slag-hearth with black slag, in the same way as the test bottoms, yield- 

 ing what is called Litharge Slag Lead, which, like Test-bottom Lead, 

 is of inferior quality and contains little Silver. It is of importance that 

 the best Coal should be used to mix with the Litharge, in order that 

 the slag formed may be as little as possible. The Coal required for 



vol. n. u u 



