AT FREIBERG. 



415 



of tlio battery ; so that load of the required percentage is always on hand to fill up any kettle. In order to compre- 

 hend this more clearly, let us suppose the battery to consist of the kettles A B C J) K M, and let 3 = capacity of 

 each kettle. 



Assume that lead of a known percentage of silver is introduced into the middle kettle of the battery (G). Then 

 3 of crystals go to II and 1 of mother liquor to F. Each of these is filled with lead of a richness corresponding to 

 that of its contents, and the process is continued by allowing F and II to crystallize, whereby 2 from F are transferred 

 to the now empty kettle G, and 1 to E. From II, 2 are carried to I and 1 to G, which is just filled from the two 

 kettles next to it. This is continued, the number of kettles increasing until lead of the required silver-percentage in 

 one end, and of the necessary purity at the other, is obtained. In the above diagram the numbers between two 

 dashes represent thirds of lead which have to be added from lead at hand to fdl a kettle, but are not transferred 

 from any other kettle. The § of a kettlo which are carried as crystals to the right, are indicated by dotted lines 

 ending in arrow heads ; the full lines ending in arrow heads lead to the one-thirds, or the richer mother liquor. 



2. Two-thirds System witii Iktkmediatb Crystals. 



By this system § of the contents of the first kettlo are transferred to the neighboring kettle to the right, as before, 

 in the form of crystals, but after this is done the remaining mother liquor is treated in the same way ; the first two- 

 thirds of the ono original third ( 5 ) being transferred as crystals to the first kettle to the left, and the remainder J being 

 ladled, as the mother liquor, into the second kettle to the loft, as thus : 



B 



D 



E 



F 



G 



II 



K 



It will be observed that each of these kettles represents a certain percentage of silver. The next to the last ket- 

 tle on the " rich lead" side is crystallized, without intermediate crystals. During the process a button is obtained 

 from each kettle, for analysis, in order to ascertain exactly how the concentration is.proceeding. At every kettle there 

 are employed two workmen who complote two crystallizations. One lireiuan attends to firing the furnaces of the 

 battery under direction of the foreman. 



