The bessemer process

I well remember how anxiously I awaited the blowing of the first 7-cwt. charge of pig iron. I had engaged an ironfounder's furnace attendant to manage the cupola and the melting of the charge. When his metal was nearly all melted, he came to me, and said hurriedly: "Where be going to put the metal, maister?" I said: "I want you to run it by a gutter into that little furnace," pointing to the converter, "from which you have just raked out all the fuel, and then I shall blow cold air through it to make it hot." The man looked at me in a way in which surprise and pity for my ignorance seemed curiously blended, as he said: "It will soon be all of a lump." Notwithstanding this prediction, the metal was run in, and I awaited with much impatience the result. The first element attacked by the atmospheric oxygen is the silicon, generally present in pig iron to the extent of 1 1/2 to 2 per cent.; it is the white metallic substance of which flint is the acid silicate. Its combustion furnishes a great deal of heat; but it is very undemonstrative, a few sparks and hot gases only indicating the fact that something is going quietly on. But after an interval of ten or twelve minutes, when the carbon contained in grey pig iron to the extent of about 3 per cent. is seized on by the oxygen, a voluminous white flame is produced, which rushes out of the openings provided for its escape from the upper chamber, and brilliantly illuminates the whole space around. This chamber proved a perfect cure for the rush of slags and metal from the upper central opening of the first converter. I watched with some anxiety for the expected cessation of the flame as the carbon gradually burnt out. It took place almost suddenly, and thus indicated the entire decarburisation of the metal. The furnace was then tapped, when out rushed a limpid stream of incandescent malleable iron, almost too brilliant for the eye to rest upon; it was allowed to flow vertically into the parallel undivided ingot mould. Then came the question, would the ingot shrink enough, and the cold iron mould expand enough, to allow the ingot to be pushed out? An interval of eight or ten minutes was allowed, and then, on the application of hydraulic force to the ram, the ingot rose entirely out of the mould, and stood there ready for removal.

This is all very simple now that it has been accomplished, and many of my readers may, from their intimate knowledge of this subject, have felt impatient at its mere recital. But it is, nevertheless, impossible for me to convey to them any adequate idea of what were my feelings when I saw this incandescent mass rise slowly from the mould: the first large prism of cast malleable iron that the eye of man had ever rested on. This was no mere laboratory experiment. In one compact mass we had as much metal as could be produced by two puddlers and their two assistants, working arduously for hours with an expenditure of much fuel. We had obtained a pure, homogeneous 10-in. ingot as the result of thirty minutes' blowing, wholly unaccompanied by skilled labour or the employment of fuel; while the outcome of the puddlers' labour would have been ten or a dozen impure, shapeless puddle-balls, saturated with scoria and other impurities, and withal so feebly coherent, as to be utterly incapable of being rendered, by any known means, as cohesive as the metal that had risen from the mould. No wonder, then, that I gazed with delight on the first-born of the many thousands of the square ingots that now come into existence every day. Indeed, at the date I am writing (1897), the world's present production of Bessemer steel, if cast into ingots 10 in. square and 30 in. in length, weighing 7 cwt. each, would make over 90,000 such ingots in every working day of the year.

I had now incontrovertible evidence of the all-important fact that molten pig iron could, without the employment of any combustible matter, except that which it contained, be raised in the space of half an hour to a temperature previously unknown in the manufacturing arts, while it was simultaneously deprived of its carbon and silicon, wholly without skilled manipulation. What all this meant, what a perfect revolution it threatened in every iron-making district in the world, was fully grasped by the mind as I gazed motionless on that glowing ingot, the mere contemplation of which almost overwhelmed me for the time, notwithstanding that I had for weeks looked forward to that moment with a full knowledge that it meant an immense success, or a crushing failure of all my hopes and aspirations. I soon, however, felt a strong desire to test the quality of the metal, but I had no appliances to hammer or roll such a formidable mass; indeed,