n6 THE PROSPECTOR'S HANDBOOK. 



used at once than in a scorifier, the scorification process is, 

 however, the usual one for ordinary ores. 



Assay of Gold and Silver Ores by Scoriflcation : 



Charge Finely powdered ore . 50 grains. 

 ^Granulated lead 5001000 

 Borax . . 5 



Half the lead should be mixed with the powdered ore and 

 placed in the scorifier ; the other half should be spread over 

 this, and the borax on the top. The scorifier may then be 

 placed in the muffle and the door closed until fusion is 

 complete. Then the door may be partly opened and the 

 temperature raised until the surface is covered with litharge, 

 the whole time being about half an hour. The scorifier can 

 then be taken out by the tongs and the contents carefully 

 poured out into an iron cup or mould. When cool, the 

 button of lead (which contains the gold and silver) should 

 be detached from the slag, cleaned by hammering, and then, 

 in the shape of a cube, is ready for cupellation. 



If Fusion in a Crucible be desirable, the following 

 formulae are to be recommended : 



For ore, chiefly of rock 



Charge Ore . . . . 100 to 500 grains. 

 Red lead . . . . 500 

 Charcoal powder . 20 to 25 

 Carbonate of soda and borax 500 together, 



The more quartz in the ore, the more carbonate of soda 

 should be used; the more iron and other metallic bases, 



* Lead used in assaying should always be, in the first instance, 

 cupelled, in order to find out whether it contains any silver mixed with 

 it, which it usually does. The number of parts of granulated lead used 

 varies according to the nature of the ore. Comparatively pure lead can 

 be obtained by heating litharge or red lead with ^oth the weight of 

 charcoal. Even then the lead ought to be assayed for silver before 

 using it in the cupellation process. 



Character of ore. \ Parts test lead. 



Quartz. 8 



Galena. 6 



Arsenical, antimonial, iron or | 10 16 



copper pyrites ores. 



Borax. 

 th to 1. 



