Eng., xiv, 5io.)--T~he ores to be treated are complex sulphides, Broken Hill slime, and mixed sulphides of lead, zinc, copper, and iron, which have hitherto but little commercial value. The furnace has carbon electrodes, one in the bed and the other removable through the roof, and the smelting is affected by resistance with low voltage currents. The capacity of the furnace is 3 tons; its rate 2.8 tons of roasted ore per 23 hours at a horse-power of 35 ° . The charge consists of roasted ore,

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... or anthracite dust and flux, and the yield is crude spelter, zinc-lead powder, :afterwards recharged, silver-bearing lead, a copper iron matter containing zinc and silver, and slag containing a little lead. Tests were run for a period of 27~ days at Trollhattan, in which were smelted 518 tons of Broken Hill slime, 19 tons of calamine, 22~ tons of zinc-lead powder, and the products were I6i tons of crude zinc, 2~ tons of lead, 36 tons of powder, and 17 tons of lead, which had leaked through the porous material of the furnace, and 9 tons of zinc-silverlead skimmings. This means 64 per cent. of the zinc, 74 per cent. of the lead, and 46 per cent. of the sliver.. It is believed the yield can be made to reach 75 per cent. of the zinc, 80 per cent. of the lead, and 80 per cent. of the silver; and on this basis the profit would be about $7.5 ° per ton of slime, with slime at $14.15 per ton at Broken Hill, freight $I1.25, cost Of treatment $7.60, and electric heat at Trollhattan costing $7.50 per horse-power year, and the cost of calcination at Tyse at $3.50 per horse-power year.