A very extensive manufacture of iron articles is now carried on at Birmingham, Sheffield, and other places, which, although they are cast from fluid metal, arc nevertheless malleable. This property is derived from two causes ; first, the pigs are prepared from the rich and pure iron ores of Cumberland ; and the metal thus obtained, is combined with but a small quantity of carbon, so as nearly to resemble steel in colour, hat•dness, and the brilliancy of its fracture ; and it has in consequence been designated by some manufacturers run steel. An infinite variety of articles, including nails, saddler's ironmongery, (and particularly such goods as after wards receive another metallic coat, as those which are plated upon Teel,) are cast from this metal. The castings thus pro duced arc exceedingly brittle ; but this property is entirely destroyed by a process termed annealing, in which the metal is deprived of the carbon to which its previous fusibility was owing, and is in consequence brought to that state of wrought iron requiring only the operations of the shingling forge and rollers to give it a laminated and fibrous texture. Nails made by this process may he drawn out longer, and bent backwards and forwards, without breaking. The metal is, however, not so strong or tough as hammered and rolled iron ; the discovery of the process is nevertheless of great value. as many excellent articles are produced in consequence, which would not without it be made at double the cost. The discoverer of this mode of converting cast-iron goods into malleable, was Mr. Samuel Lucas of Sheffield.
A description of iron was introduced a short time since, under the name of corrugated iron, which has already met with great success, and promises to be very extensively used. It is called corrugated from its grooved or wrinkly appear ance, produced by putting the sheets between rollers having grooved peripheries. Sheet-iron thus prepared, acquires a strength and stiffiniss much beyond its ordinary strength, and adapts it for purposes flu• which the common sheet-iron is found insufficient. Corrugated iron has been much used for roofs of railway stations, and works of a similar kind.
Formerly, large quantities of iron were imported from Russia and Sweden. and previously to the discovery in 1785 by Mr. Curt, of the methods of puddling and rolling or shingling iron, this country imported 70,000 tons of this metal, a vast, quantity, considering the state of our manu factures at that time. So much, however, has our own wrought iron been improved in the manufiicture, that it may now be considered fully equal to the Swedish. As a proof of this, the Admiralty, East India Company, and other public departments, now contract for British iron only. See STEEL.
r. Jessop, of the Butterlev Works, estimated the annual produce in Great Britain (exclusive of Ireland) in 1840, at 1,396.400 tons ; and the quantity of coal used for smelting that quantity was 4,877,000 tons, besides 2,000,000 tons for converting into wrought iron.
At the late meeting of the British Association at Cam bridge, Mr. Watt read a report on the iron trade in Scotland, from which it appears. that, at the present moment, there are extensive new iron works erecting in Scotland, especially in Ayrshire and in 1Zenfrewshire. At several of the old works, considerable additions are being made to the mimber of furnaces now at work. The increase in the minim] quan tity of pig-iron smelted in that country in April, 1845, amounts to 37.4 per cent. ; and there is every appearance that, betbre another ', ear expires, a similar increase will be made in the amount of iron produced in Scotland. Sir J. Guest,' of Dowlars Works, in evidence before the import Duties Committee, 1840, stated, that the iron made at the beginning of this century amounted to 150,000 tons.—In 1806, 253,000.-1n 1823, 452,000.—In 1825, 5S1,000.—lu 1S28, 703,000.—In 1835, 1,000,000.—In 1836, 1,000,000 —In 1840, 1,500,000. We may remark, that the manufac ture of malleable iron is vet but in its infancy in Scotland, although making rapid strides towards an important position. There are five establishments; and the present make may be computed at about 900 tons per week, or 50,000 tons per annum. For superior finish, toughness, and uniffirmity, it will stand comparison with either English or Welsh iron.