Inventions in the Century

by William Henry Doolittle

We have described how by Cort’s puddling process tremendous labour was imposed on the workmen in stirring the molten metal by hand with “rabbles.” A number of mechanical puddlers were invented to take the place of these hand means, but the most important invention in this direction was the revolving puddlers of Beadlestone, patented in 1857 in England, and of Heaton, Allen and Yates, in 1867-68. The most successful, however, was that of Danks of the United States in 1868-69. The Danks rotary puddler is a barrel-shaped, refractory lined vessel, having a chamber and fire grate and rotated by steam, into which pig iron formed by the ordinary blast furnaces, and then pulverised, is placed, with the fuel. Molten metal from the furnace is then run in, which together with the fuel is then subjected to a strong blast. Successive charges may be made, and at the proper time the puddler is rotated, slowly at some stages and faster at others, until the operation is completed. A much more thorough and satisfactory result in the production of a pure malleable iron is thus obtained than is possible by hand puddling.

But the greatest improvements in puddling, and in the production of steel from iron, and which have produced greater commercial results than any other inventions of the century relating to metallurgy, were the inventions of Henry Bessemer of Hertfordshire, England, from 1855 to 1860. In place of the puddling “rabbles” to stir the molten metal, or matte, as it is called, while the air blast enters to oxidise it, he first introduced the molten metal from the furnace into an immense egg-shaped vessel lined with quartzose, and hung in an inclined position on trunnions, or melted the metal in such vessel, and then dividing the air blast into streams forced with great pressure each separate stream through an opening in the bottom of the vessel into the molten mass, thus making each stream of driven air a rabble; and they together blew and lifted the white mass into a huge, surging, sun-bright fountain. The effect of this was to burn out the impurities, silicon, carbon, sulphur, and phosphorus, leaving the mass a pure soft iron. If steel was wanted a small amount of carbon, usually in the form of spiegeleisen, was introduced into the converter before the process was complete.

A. L. Holley of the United States improved the Bessemer apparatus by enabling a greater number of charges to be converted into steel within a given time.

Sir Henry Bessemer has lived to gain great fortunes by his inventions, to see them afford new fields of labour for armies of men, and to increase the riches of nations, from whom he has received deserved honours.

The Bessemer process led to renewed investigations and discoveries as to heat and its utilisation, the constituents of different metals and their decomposition, and as to the parts played by carbon, silicon, and phosphorus. The carbon introduced by the charge of pig iron in the Bessemer process was at first supposed to be necessary to produce the greatest heat, but this was found to be a mistake; and phosphorus, which had been regarded as a great enemy of iron, to be eliminated in every way, was found to be a valuable constituent, and was retained or added to make phosphorus steel.

The Bessemer process has been modified in various ways: by changing the mode of introducing the blast from the bottom of the converter to the sides thereof, and admitting the blast more slowly at certain stages; by changing the character of the pig iron and fuel to be treated; and by changing the shape and operation of the converters, making them cylindrical and rotary, for instance.

The Bessemer process is now largely used in treating copper. By this method the blowing through the molten metal of a blast of air largely removes sulphur and other impurities.

The principles of reduction by the old style furnaces and methods we have described have been revived and combined with improvements. For instance, the old Catalan style of furnace has been retained to smelt the iron, but in one method the iron is withdrawn before it is reduced completely and introduced into another furnace, where, mixed with further reducing ingredients, a better result by far is produced with less labour.

It would be a long list that would name the modern discoverers and inventors of the century in the manufacture of iron and steel. But eminent in the list, in addition to Davy and Bessemer, and others already mentioned, are Mushet, Sir L. Bell, Percy, Blomfield, Beasley, Giers and Snellus of England; Martin, Chennot, Du Motay, Pernot and Gruner of France; Lohage, Dr. C. L. Siemens and Höpfer of Germany; Prof Sarnstrom and Akerman of Sweden; Turner of Austria; and Holley, Slade, Blair, Jones, Sellers, Clapp, Griffiths and Eames of the United States.

Some of the new metals discovered in the last century have in this century been combined with iron to make harder steel. Thus we have nickel, chromium, and tungsten steel. Processes for hardening steel, as the “Harveyized” steel, have given rise to a contest between “irresistible” projectiles and “impenetrable” armour plate.