Although the first iron furnace in America was built in 1619, in Virginia, and the first blast furnace with forced blast dates from 1714, nevertheless the iron and steel business did not assume a large magnitude in the United States until the building of the Edgar Thompson fur naces in Pittsburgh, the first of which was blown in in 1879. In these furnaces American skill showed the world how to triple the weekly output and to cut the fuel cost in two. That is, while the best English and Scotch furnaces in 188() produced from 400 to 800 tons of pig iron per week and required two tons of coke for one ton of pig, the Edgar Thompson furnaces between 1880 and 1885 produced from 2,000 to 2,500 tons per week and used only one ton of coke to one ton of pig. The coke in some cases fell as low as 1,882 pounds per ton of output. The ore used contained about 62 per cent of iron and the volume of air reached 25,000 cubic feet per minute, at a temperature of 1,000° to 1,100° F.
While we thus see that the modern steel industry is of such recent date, yet the inven tions of the processes now used mainly, viz., the Bessemer (1856) and open-hearth (1861), for making steel were relatively of long standing, and the gradual improvements in the processes themselves, their mechanical details and costs, and the. gradual education of the large users of metals to employ steel in place of wrought iron and cast iron, gradually led up to the enormous demands of the last 30 years, to which the American manufacturers have re sponded so energetically.
Henry Bessemer was of a distinctly in ventive turn of mind and had many useful in ventions to his credit before he turned his at tention to steelmaking. He gave considerable attention to the manufacture of projectiles during the Crimean War. The cast iron can non of this time were seen to be unsuitable for Bessemer's powerful projectile's and he, therefore set about producing not only the pro jectiles, but a better material for making large guns. After many trials and discouragements he succeeded in producing steel from cast iron by blowing air through it to oxidize the im purities. His first experiments were performed in a crucible, and this being successful his next idea was to use several crucibles fed by a com mon air pipe. Later he adopted a large sta tionary converter about three feet in diameter and seven feet high and used 700-pound charges. The results were most astonishing, for Bessemer found that by the simple method of blowing air into fluid cast iron that the highest temperature then known in the arts was produced. The first formal announcement of his invention was made at the British Asso ciation for the Advancement of Science in 1856, the title of his paper being The Manu facture of Malleable Iron and Steel Without Fuel.' Great excitement followed the reading of this paper and the process was tried in many parts of England, but in many cases the results were anything but satisfactory. The
steel produced was red short and cold short. The cause of the trouble was soon found to lie in the use of very impure pig irons running high in sulphur and phosphorus. The first converters were lined with acid or silicious materials, and little or no sulphur or phos phorus was eliminated. As long ago as 1856 Dr. Collyer writing of the effects of phosphorus and sulphur said: uThe former I consider most pernicious of all. I would suggest, with due deference, that a stream of finely pulver ized anhydrate of lime be forced at a given time with the compressed air into the incan descent mass of iron. The lime having a great affinity for silica and phosphorus would form a silicate and phosphate of lime and be thrown off with the slag. By this contrivance I can not conceive but that the phosphorus would be entirely got rid of.° Here we see the Bessemer') process clearly anticipated many years before it was actually successfully worked out and adopted (1871). The irregularity men tioned above was overcome by the use of se lected pig irons, low in sulphur and phosphorus, and by the important discovery of Robert Mushet, viz., the addition of manganese to the metal in the ladle after the blow. The steel in the converter after the blow is dead soft, being nearly carbonless, and contains a good deal of dissolved oxide of iron, beside rather high sulphur and phosphorus. The addition of speigeleisen or ferro-manganese corrects all of these troubles. It adds a certain amount of carbon to the steel, thereby increasing its strength and hardness; it deoxidizes the over blown metal and the residual manganese com bines chemically with phosphorus and sulphur, some of the sulphide and phosphide being eliminated in the slag, and the rest being ren dered relatively harmless by reason of its com bining directly with the manganese. After these chemical difficulties with the process had been overcome, Bessemer and others turned their at tention to the mechanical side of the question and produced the converter mounted on an axis, so that the vessel could be rotated or tipped down and the air-inlets or tuyeres could be thus brought either above or below the surface of the metal in the converter. This improve ment rendered the charging or discharging of the metal much easier. Bessemer was more fortu nate than all the other inventors previously mentioned in that he made a vast fortune out of his invention. As a matter of fact his• in vention was so complete in every way that the process stands to-day exactly as he originated it, excepting for minor details. Somewhat less than half of all the steel now produced is made in the Bessemer converters. What the inven tion of Bessemer steel meant to the world will be seen from a few illustrations.