METALLUKGT. 163 



further description of the mechanical details of the apparatus and process, 

 which have been repeatedly described in the technical journals. 



The first operation consists in melting down 50 tons of lead in one of 

 the pots. This is then drawn off into the crystallizer, and water is turned 

 on to chill the lead, because much time would be required to cool it by radia- 

 tion. Then steam is admitted, which thoroughly stirs and at the same time 

 completely refines the melted mass. When the crystallization is completed, 

 which takes place in about one hour from the time the lead is drawn off 

 from the melting pot, about two-thirds of the mass is in the form of crystals 

 assaying 100 ounces to the ton and one-third is still melted, containing 

 about 460 ounces. This rich lead is drawn off into molds and taken to the 

 cupel furnaces. In the mean time enough lead of the value of 100 ounces 

 to the ton has been melted in the second pot, and is allowed to flow into the 

 crystallizer, where it immediately dissolves the crystals of 100-ounce lead. 

 This is now crystallized, giving 75-ounce poor lead and 150-ounce rich lead, 

 which is drawn off as before. The lead is thus crystallized until market 

 lead of about the value of one ounce to the ton is obtained. This requires 

 nine crystallizations, which give lead of approximately the subjoined values: 



LEAD FEOM THE CRYSTALLIZATION OF 220 OUNCES LEAD. 



Ounces to the ton. 



First crystallization 100 



Second crystallization 75 



Third crystallization 50 



Fourth crystallization 30 



Fifth crystallization 18 



Sixth crystallization 9 



Seventh crystallization 5 



Eighth crystallization 2. 5 



Ninth crystallization 1-25 



It is found that there is no sensible enrichment of the lead after it has 

 reached 550 ounces (less than 2 per cent). The ratio of the gold to the silver 

 in the lead from the smelting furnaces is about 1 to 32 by weight, or in value 

 about $1 gold to 82 silver. 



The use of steam in this process appears highly advantageous. The 

 stirring produced is probably more thorough than that accomplished by 



