274 



METALS. 



quantities, and till a recent period were considered worthless and thrown 

 aside under the name of " dry bone." In Tennessee, Claiborne county, 

 there are workable mines of the same ores. Calamine is successfully 

 worked at Friedersville, Pennsylvania. The red oxyd of zinc of Frank- 

 .lin, Nrtw Jersey, contains 75 per cent, of pure zinc, and the ore is a 

 valuable one. Blende is sufficiently abundant to be worked at the 

 Wurtzboro' lead mine, Sullivan county, N. Y. ; at Eaton and Warren 

 in New Hampshire ; at Lubec in Maine ; and at Austin's mine, Wythe 

 county, Virginia. 



The calamine and electric calamine are prepared for reduction by 

 breaking the ore into small fragments, separating the impurities as far as 

 possible, and then calcining in a reverberatory furnace. This furnace 

 differs little from that figured on a following page under Silver, except 

 that the sole is flat. The ore is frequently stirred, and after five or six 

 hours it is taken out ; by this process, water and carbonic acid are ex- 

 pelled. The prepared ore is then mixed with about one-seventh by 

 weight of charcoal, and in the English process, is reduced in large 

 crucibles. 



Figure 1, represents a vertical section of the furnace, and figure 2, 

 1 



half of a horizontal section across the line 1, 2. The oven has an arched 

 or cupola top, (a,) and contains 6 or 8 crucibles or pots, (k, k, k, h,) 



2 



placed upon the sole of the earth, (*', i, i, i.) The crucibles have a hok 



How is calamine reduced 1 



