Page:The New International Encyclopædia 1st ed. v. 10.djvu/877

IRON.  with the coal measures of Ohio and Pennsylvania.

The total production of iron ores in the United States in 1901, according to the Mineral Resources, was 28,887,479 long tons. This output was distributed among the leading States as follows: Minnesota, 11,109,537 tons; Michigan, 9,654,037 tons; Alabama, 2,801,732 tons; and Pennsylvania, 1,040,684 tons. The imports for the same year were 966,950 tons, more than one-half of which came from Cuba.

. The iron ores of Great Britain include siderite, limonite, and hematite. The Cleveland district is the most important, and produces siderite averaging 30 to 40 per cent. in iron from deposits in the coal measures. Limonite is mined in Lincolnshire, Northamptonshire, and Leicestershire, and hematite in Lancashire and Cumberland. As the domestic supply of ore is insufficient, large quantities are imported from Spain, Sweden, Greece, and other countries. Germany has iron-mines in Alsace-Lorraine, Westphalia, and Hesse-Nassau, and the Grand Duchy of Luxemburg is noted for its iron. The ores are mostly limonites and hematites, and carry from 30 to 50 per cent. of iron. France, Spain, Sweden, Austria-Hungary, and Russia complete the list of the important producers. Canada has given much attention in recent years to the development of her iron industry, with results that promise well for the future. Large blast-furnaces and steel-works were completed in 1901, which utilize hematite and magnetite ores from Newfoundland, Nova Scotia, and Ontario.  IRON,. The pseudonym of (q.v.).  IRON AND STEEL,. In some cases the ores of iron can at once be treated in the blast-furnace without preparation of any kind. In all cases the preliminary treatment must be simple and cheap, in order to be commercially practicable. The common methods of preparing iron ore for the blast-furnace are the following: Sorting and sizing consists in roughly separating the ore from the barren rock and other fragmentary impurities, and then grading it into lumps of similar size to promote regularity in smelting. Washing consists in removing clay and other earthy matter from the ore by means of water; both hand washing and mechanical washers are employed. Magnetic concentration consists in passing naturally fine ores, or ores made fine by crushing, through so-called separators, in which the ore is drawn from the non-ferrous gangue by means of magnetized drums or other mechanism. Weathering consists in stacking the ore in heaps to remove shale and sulphur, which crumble or wash away under the action of the elements. Calcination consists in treating the ores to drive off volatile matters, usually water, carbon dioxide, sulphur, and carbonaceous matter, or to oxidize the ore. Calcination may be accomplished by washing the ore in open heaps or by heating it in calcining kilns. Sometimes a combination of two or more of the methods of preparation previously described is employed.

. As stated under, cast iron was first produced in Germany. Previous to about 1350 the highest temperatures obtainable in the blast-furnace had been barely sufficient to produce a pasty bloom of iron which then had to be hammered to remove the cinder and forged into shape. During the early part of the fourteenth century, however, German iron-makers, in their endeavors to reduce the cost of manufacture, began to build blast-furnaces of gradually increasing size, from which, by allowing the metal to remain longer in contact with the fuel, iron was obtained in a molten condition capable of being readily cast into any desired shape. At once the founding of iron became an important art. It was not long, however, before the fact was established that by further treatment the cast iron would be transformed into wrought iron. To-day the production of cast iron in the blast-furnace is the first step in the manufacture of iron and steel.

With the discovery of cast iron and the introduction of its manufacture into England, the British iron trade, which had lain dormant, began to revive, and at the end of the sixteenth century it had assumed very considerable proportions. At first charcoal was the fuel used in the blast-furnace, and this fact resulted in such depletion of the timber-supply that several acts of Parliament were passed between 1558 and 1584 restricting the number and position of iron-works and prohibiting the construction of new works in certain districts. A decline in iron manufacture was the natural result.

Naturally, also, attention was turned to the possibility of some substitute for charcoal. This was discovered about 1619 by Dud Dudley, who produced coke from pit coal, and successfully used it for smelting iron in the blast-furnace. The substitute did not gain favor, for various reasons, which it is needless to mention further than to say that they were not lack of success in the use of coke.

During all of the seventeenth century charcoal remained the almost universal fuel for blast-furnaces. These furnaces were small and widely scattered: they had a capacity of about 20 tons of cast iron per week each, were built of