For sampling the Vezin apparatus is used, cutting out one-fifth in each of three passes, crushing intervening, the sample from the third machine being 1/625 of the original ore; after further comminution of sample in a coffee-mill grinder, it is cut down further by hand, using a riffle. The final sample is bucked down to pass an 80-mesh sieve, but gold ores are put through a 120-mesh. The steps in the smelting process are as follows: Roasting the poorer ores in reverberatory furnaces and in Brückner cylinders. Smelting raw and roasted ores, mixed, in water-jacketed blast furnaces, for work-lead and lead-copper matte, the latter containing 15 per cent. lead and 10 to 12 per cent. copper. Roasting the ground matte, containing 22 per cent. of sulphur, down to ¾ per cent. in reverberatory furnaces. Smelting the roasted matte together with acid flux in the blast furnace for a matte with 45 per cent. copper and 12 per cent. lead. Only the pyritic ores are roasted in Brückner furnaces, the lead ores and matte being roasted in reverberatory furnaces. Each of the 20 Brückner furnaces, which constitute one battery, roasts 8 to 12 tons of ore in 24 hours down to 5½ to 6 per cent. sulphur, with a coal consumption of two tons. The charge weighs 24 tons. The furnaces make one turn in 40 minutes. To increase the draft and the output, steam at 40 lb. pressure is blown in through a pipe; this has, however, resulted in increasing the quantity of flue dust to 10 to 15 per cent. of the ore charged. Ten furnaces are attended by one workman with one assistant, working in eight-hour shifts. For firing and withdrawing the charge five men are required. The gases from the Brückners and reverberatory furnaces pass into a dust-flue 14 × 14 ft. in section and 600 ft. long, built of brickwork, with concrete vault; in the stack (225 ft. high, 20 ft. diameter) they unite with the shaft-furnace gases, the temperature of which is only 60 deg. There are 12 reverberatory furnaces with hearths 60 ft. long and 16 ft. broad. They roast 14 tons of ore (or 13 tons of matte) in 24 hours down to 3½ to 4 per cent. sulphur, consuming 32 to 34 per cent. of coal figured on the weight of the charge. There are 12 working doors on each side. The small coal (from Rock Springs, Wyoming), which is burnt on flat grates, contains 5 per cent. ash and 3 to 5 per cent. moisture. The roasted product is dumped through an opening in the hearth, ordinarily kept closed with an iron plate, into cars which are raised by electricity on a self-acting inclined plane. Their content is then tipped over into a chute and cooled by sprinkling with water. From here the roasted matte is conveyed to the blast furnace in 30-ton cars. The roasted ore is tipped into the ore-bins.