1892-9:J.] NOTES on the amalgamation process. 363 



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40 to 54 pounds. The stamping is proceeded with, the ore being damped 

 from time to time to prevent loss by ejection ; the ore is then passed 

 through brass sieves, and that portion coarser than sand is returned 

 to the stamps. It is then conveyed to a mill, the running stone of which 

 is kept in a box and nothing but the admission funnel being left open. 

 The mill stones were made of porphyry. The ore being ground fine 

 enough was taken to the furnace to be roa.sted. 1 he furnaces appar- 

 ently were modified, double-hearthed reverbatories as far as I can 

 gather from the description. When the furnace was at the proper 

 temperature, about 30 quintals was spread evenly over the hearth and 

 the required amount of salt and lime — the amount required being 

 previously determined by assay — was spread over, then the whole 

 turned with crooks and rakes until thoroughly mixed ; the process 

 then proceeded as calcination in double-hearth roasting furnaces of 

 to-day. If during the calcination the material clagged, grinding and 

 sifting were again resorted to. '1 he ore was then, if properly calcined, 

 conveyed to the boilers or amalgamators constructed according to the 

 "recommendation" of Alonzo Barba, the stirring apparatus being put 

 in motion by the crank of a water wheel and a horizontal rack with cogs, 

 which being properly fixed in a groove by cross-bars, slid backwards and 

 forwards on brass rollers and casters, the cogs of the rack catching in 

 the perpendicular trundle and spindle of the stirrers which turned round 

 twice by a three and a half (3I ft.) foot motion of the sliding rack. The 

 stirrers were circular segments corresponding with the sides and bottom 

 of the boiler. The ore was mixed with sufficient water to make it fluid 

 and the amount of mercury required being, gauged from appearance ; if 

 the ore was light and voluminous more mercury was required than if it 

 was heavy and compact, the presence of antimony or lead in the ore 

 necessitating an excess of mercury to provide for the neutralizing effect of 

 these metals on the mercury. The residuum or tailings were then washed 

 in tubs provided with stirrers. The amalgam was then freed from 

 excess of mercury by compressing small portions in the hand at a time, 

 as the deerskin was considered too expensive a process. The distillation 

 was then performed " per descensum " in iron pots ; the under one stand- 

 ing up to the middle in cold running water, which passed under the 

 hearth, the upper part appearing about two (2") -inches above it. The 

 amalgam made into balls and placed in an iron cullender fixed to an 

 iron tripod was set in the bottom pot, covered on the inside with a coarse 

 cloth. The upper pot was then inverted on the lower one and luted ; 

 fire then being put about it the mercury was sublimed and condensed in 

 the bottom pot kept cool by the water ; a strong red heat being kept up 



