PART IL 
NOTES ON ASSAYING GOLD, SILVER, LEAD 
AND COPPER ORES. 
GOLD AND SILVER. 
Crucible Process for the Assay of Gold and Silver Ores. 
Pass the ore through a sixty or eighty mesh sieve, 
and :— 
(a) If the ore is silicious with little or no sul- 
phides, etc., use the straight formula, as given below. 
(b) If the gangue of the ore consists of oxides, 
lime or calciti, etc., add to the charge 1% assay-ton (A. 
T.) of silica. 
(c) If the ore is a sulphide or concentrates, or if 
it contains arsenic, antimony, etc., it should be thor- 
oughly roasted. Weigh out before roasting ore 14 A. T., 
mix with an equal volume of charcoal and 1% A. T. sil- 
ica, roast in a chalk-lined frving pan at a low heat with 
continual stirring. 
GENERAL FORMULA. 
Sodium bicarbonate, 16 parts | 
Lead Flux 4 Potassium carbonate, 16 parts t 1A T 
| Borax glass, 8 parts | 
\ Flour, 4 parts ; J 
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Transfer this charge well mixed to a_ crucible 
(which should not be more than three-fourths filled), 
cover with salt and fuse in the muffle furnace at a high 
