STEEL, EVOLUTION OF STEEL MAKING PROCESSES. In prehistoric times the earth's inhabitants fashioned their im plements from flint. After a time, as the result of observation or chance, primi tive men discovered that metals, such as copper and lead, could be obtained from certain earths or ores, and it was not long until they found that copper could be made harder by the addition of a little iron, arsenic or tin. That they ever actually hard ened copper, in the sense that we harden steel for tools, is extremely improbable.
It is not easy to say whether the Bronze Age preceded the Iron Age or not, and if it did, by what period. Flint instruments and weapons are almost imperishable, bronze is very endur ing, while iron rusts, and if buried in a damp place is wholly converted into hydrated oxide or carbonate of iron, soluble in waters contain ing much organic matter. For this reason iron relics of great age are scarce, while flint and bronze fill the museums. However, in certain ruins of the Swiss lake dwellings all three sorts of implements were found, flint, bronze and iron.
The use of iron is frequently mentioned in the early books of the Old Testament. The Egyptians were familiar with it at least 4,000 years ago. The Assyrians probably knew how to obtain iron from its ores and how to fashion it into saws, chisels, etc., at a still earlier date than the Egyptians. The various ages known as the Stone, Bronze and Iron ages are not fixed periods in the world's history, but are periods in the history and development of individual tribes and nations. For example, while at a period, say 1000 }Lc., the Egyptians and As syrians were making swords of iron (and a cross-cut two-handed saw of this period is in the British Museum) the Bronze Age existed in southern Europe, while in the northern and western Europe wood and stone implements were in general use. In India, China and Japan there is abundant evidence of the manu facture and use of iron at a very early period. In •this very day there are tribes in central Africa which have but attained the degree of skill which we picture in our minds when the eIron Agee is mentioned. They are making iron in a most primitive fashion and their methods may be the identical ones used thou sands of years ago by the Assyrians. Their metallurgical skill is by not means slight, for they know how to smelt ores in a little cupola blown by a hand bellows, and to employ the right fluxes to obtain a product of remarkably good analysis. They use charcoal as fuel and the chunks of metal which' they obtain by first smelting are sold to smiths who refine them still further by a sort of puddling process, and a tool made by this means gave, according to Bellamy and Harbord, the following excellent analysis : Carbon, 1.02; silicon, .026; sulphur, .006; phosphorus, .012; manganese, trace. There are evidences in Belgium of ancient iron workings dating from the Roman occupa tion, and they were famous armorers through many centuries. The skilled workmen of this
country emigrated especially to England and Sweden and were the founders of the fine steel industries in those countries. Those who emigrated were the Walloon Belgians, and the exodus became so great that at one time it was stopped by law.
During the time of the Norman Conquest and the Tudors, the manufacture of iron in Great Britain was an insignificant industry, and the chief supplies were imported from Bel gium, and from Belgium came the invention which gave a great impulse to the iron and steel business, viz., the invention of the blast fur nace. Prior to this invention iron was pro duced direct from ore in a crude form of hearth, the product being wrought iron or steel, which was obtained in a solid or pasty condi tion far from homogeneous in composition, and when large or intricate forms were desired they were made from these crude materials by laborious welding and forging methods. With the invention of larger and improved blast fur naces by the Belgians it was found that prac tically a new metal, fused cast iron, was at the disposal of the early metallurgist. Cast iron was made in Sussex as early as 1350, and the art of iron founding gradually grew and flour ished in England and on the Continent until in 1543 cast-iron cannon were made in and in 1595 these were made as heavy as three tons each. But cast iron was not only used for foundry purposes, for it was argued that if by one application of the purifying influence of fire the crude metal had been prepared from the ores, the second application of the same agency might convert it into a malleable prod uct, and wrought iron was subsequently pro duced in small fineries, and from that day to this the blast furnace has been the first step in the manufacture of iron and steel. Much of this early wrought iron was delightfully low in sulphur and some other impurities, but at that time no means were known of reducing the. phosphorus, and the amount of this element present in the product was due to the chance selection of the ore. There were no chemists in those days to say whether the iron contained phosphorus or not, and practical experience with the product in use was the only way of de termining the merits of ores from various sources. It was soon discovered that wrought iron by long heating in contact with carbon ab sorbed some of that element and was thus con verted into or ((blister steel.° Blister steel when piled, welded and forged be comes *shear steel, and if shear steel is piled, welded and forged the product is known as *double By this piling and welding operation, the carbon which is highest in the outer portions of the cemented bar becomes more uniformly distributed throughout the mass of steel. In 1781 Bergman, of Upsala, pointed out that it was carbon which determines the difference between wrought iron, steel and cast iron.