•When the furnace is reached to which the ore is consigned the railway cars are run onto 'car dumpers' which turn the cars over to dis charge their contents into pits from which the ore is carried by cable or tramways to stock piles, or the cars drop their contents into the furnace supply bins. From the bins, whether fed direct from cars or from stock piles, the ore is chuted to scale charging cars which feed to skip cars. These skip cars, which also re ceive the fuel and fluxing material, are ele vated to the furnace top and automatically dis charge their contents." Much progress has been made in the bene ficiation of ores including magnetic separations and agglomerations (briquetting, nodulizing and sintering) by which enormous deposits of fine ore, of ore containing much moisture, too rich in sulphur or phosphorus or too lean are now converted into excellent smelting material, with the frequent additional advantage of doing away with the cost of transportation from mine to furnace of a great weight of gangue, of moisture or of combined waters.
The rapid growth of the production of iron ores in the United States as well as some other features are shown in the following statistical tables: It will be seen that over 80 per cent of the iron ore mined in the United States are ob tained from the Lake Superior district.
It will be seen that the United States in 1890 mined more iron ore than. England and than Germany. In 1913 it mined nearly four times more ore than in 1890, nearly four times more than England whose production had re mained nearly stationary and nearly twice more than Germany. It contributed in that year 37 per cent to the world's production.
active in any one year gives no indication aS to the production of pig iron in that year. The 446 furnaces active m 1880 produced but 3,897, 000 tons of iron or 8,738 tons per furnace, while in 1913 with but 191 active furnaces the produc tion of pig iron was 31,361,000 or 164,700 Aims per furnace, a production per furnace 20 times _greater.