Mr. H. L. Pattinson on the Smelting of Lead Ore, §c. 165 



mills, a man and a boy are deemed sufficient ; the attention of one is 

 wholly given to the fire, while the other supplies coke and grey slag. 

 The length of a shift is 14 or 16 hours, during which, the quantity of 

 lead made varies from 10 to 21 cwt., according to the nature of the 

 slags. Twenty to twenty four bushels of coke are required to produce 

 one fodder of lead. The quantity of slag lead made in smelting, as may 

 be conceived, is considerably greater in poor and refractory than in rich 

 and free-running ores, but, it may be stated generally at one-thirteenth 

 of the lead yielded at the smelting hearth, so that it is usual to reckon, 

 in large transactions, 13 twelve-stone pigs of common lead, and 1 of slag 

 lead, to the fodder. 



HEARTH ENDS AND SMELTER'S FUME. 



In the operation of smelting, as already described, it happens that 

 particles of unreduced and semi-reduced ore are continually expelled 

 from the hearth, partly by the force of the blast, but principally by the 

 decriptation of the ore on the application of heat. This ore is mixed 

 with a portion of the fuel and lime made use of in smelting, all of which 

 are deposited upon the top of the smelting hearth, as mentioned in page 

 157, and are called hearth-ends. It is customary to remove the hearth- 

 ends from time to time, and deposit them in a convenient place until 

 the end of the year, or some shorter period, when they are washed to 

 get rid of the earthy matter they may contain, and the metallic portion 

 is roasted at a strong heat, until it begins to soften and cohere into 

 lumps, and afterwards smelted in the ore hearth, exactly in the same 

 way as ore undergoing that operation, for the first time, already de- 

 scribed. 



It is difficult to state what quantity of hearth-ends are produced by 

 the smelting of a given quantity of ore, but, in one instance, the hearth- 

 ends produced in smelting 9751 bings, on being roasted and reduced in 

 the ore hearth, yielded, of common lead 315cwt , and the grey slags 

 separated in this process gave, by treatment in the slag hearth, 47cwt. 

 of slag lead ; making the total quantity of lead 362cwt., which is at 

 the rate of 3cwt. 2qrs. 23lbs. from the smelting of 100 bings of ore. 



