CAST IRON. As stated under IRON. east iron was first produced in Germany. Previous to about 1330 the highest temperatures obtainable in the blast-furnace had been barely sufficient to pro duce 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 in creasing 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 impor tant art. It was not long, however, before the fact was established that by further treatment the cast iron would be transformed in to wrought iron. To-day the produc tion of cast iron in the blast-furnace is the first step in the manufacture of iron and steel.
With the discov ery of east iron and the introduc tion of its manu facture into Eng land, the British iron trade, which had lain dormant, began to revive, and at the end of the sixteenth cen tury it bad as sumed very con siderable propor tions. At first charcoal was the fuel used in the blast-furnace, and this fact resulted in such depletion of the timber-sup ply that several acts of Parliament were passed be tween 1558 and 1584 restrict ing the number and posi tion of iron-works and prohibiting the construc tion of new works in certain districts. A de cline 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 east iron per week each, were built of mason ry, and the blast was supplied by bellows oper ated by water-pomer. In 1713 Ahraham Darby,
of 'on !brook !tale, in revived the use of coke fuel for blast-furnaces, and after much labor succeeded about 1740 in making a success of it. The use of coke now spread rap and this, with the development of the steam engine for blowing purpose's and for supplying power to mills and forges, gave an enormous impetus to iron manufacture.
No further improvement in blast-furnace prac tice occurred until 1825, when .1. B. Neilson. an Englishman, brought forward a proposition to heat the air for the blast. The great ly increased output which resulted from the use of the hut blast set On foot a series of improvements in blast-furnace construction. These improvements took the form of increased dimensions and ca pacity of the furnace and of the use of an in creased number of the stove for heat ing the blast. air was improved, more efficient and powerful blowing, engines were employed, apparatus fur hoisting the ores, fluxes, and fuel, and for charging, them into the furnace were introduced. and a great variety of minor im provi meats we re made. Until 1880 British fur naces led the world in size and output; hut about this time American iron-makers began to take the lead in these respects. and have main tained it ever since. A few figures selected at random will show the progress of growth in blast-turnace dimensions, capacity, and output: IS55 to 1861, height 30 feet, capacity 2000 cubic feet, output 200 tons weekly; 1882 to IS85, height 70 feet, capacity 8200 cubic feet, out put SOO tons weekly; to 1895, height 90 feet, capacity 18,201) cubic feet. output 2500 tons weekly; 1900, height 100 feet, capacity 24.000 cubic feet. output ti00 tons every 24 hours. At this point it may be noted that the first iron furnace in America was a bloomery erected in Virginia in 1010, and the first blast-furnace with a forced blast was built about 1714 in the same State. Shortly after the Revolutionary War numbers of charcoal-furnaces were working. From this time on the growth of iron and steel manufacture in America was rapid, until in 1890 the United States took lirst place among the iron•working nations the world.