[35] “Sir Henry Bessemer: an Autobiography.” Offices of Engineering, 36 Bedford St., Strand, London, 1905. 16 shillings.
Soon afterward Bessemer’s attention was directed to the bronze powders sold at high prices to printers and decorators. These powders were produced by hand in Germany by processes so laborious as to make the cost enormous. Examining the material with a powerful microscope Bessemer was convinced that he could dispense with hand labor, and turn out a powder of equal quality at nominal expense. His machinery for this purpose proved a success and laid the foundation of his fortune; unpatented and worked in secret for thirty-five years, it yielded him a huge profit indispensable for the costly experiments he had ever in hand. Naturally enough his fame as a man of ingenuity was promptly noised abroad, and his talents were next invoked for a much-needed improvement of sugar-cane milling. The moment that Bessemer saw a cane-mill at work he placed his finger on the chief cause of its wastefulness. He noticed that the cane was squeezed between two rollers for only a second, a period so short that the cane at once re-expanded and re-absorbed much juice. He forthwith designed a press, on much the same principle as a hydraulic press, which subjected the cane to severe pressure for two and a half minutes, until every drop of juice had left the fibres, almost doubling the output of the old machinery. For success in this task Bessemer declares himself indebted to a golden ignorance. He says: “I had an immense advantage over many others dealing with the problem under consideration, inasmuch as I had no fixed ideas derived from long-established practice to control and bias my mind, and did not suffer from the too-general belief that whatever is, is right. Hence I could, without check or restraint, look the question steadily in the face, weigh without prejudice or preconceived notions, all the pros and cons, and strike out fearlessly in an absolutely new direction if thought desirable.”
But in his case ignorance in one field was joined to knowledge in many another field, and there he found weapons wherewith to surmount an old difficulty at a quarter never assaulted before. He continues: “The first bundle of canes I ever saw had not arrived from Madeira a week before I had settled in my own mind certain fundamental principles, which I believed must govern all attempts to get practically the whole juice from the cane; but, of course, there were many circumstances that rendered it necessary to modify first principles, having reference to cost of construction, lightness for easy transit across country, freedom from necessity for repairs, and the like.”
Copyright, London Stereoscopic Co.
The Late SIR HENRY BESSEMER
of London.
Bessemer’s Steel Process.
In the supreme effort of his life Bessemer once more held himself a debtor to his ignorance, to the fact that his mind was unworn by routine and ruttiness. Referring to his attempt to make a cheap metal stronger than cast iron for guns, he says: “My knowledge of iron metallurgy was at that time very limited, and consisted only of such facts as an engineer must necessarily observe in the foundry or smith’s shop; but this was in one sense an advantage to me, for I had nothing to unlearn. My mind was open and free to receive any new impressions, without having to struggle against the bias which a life-long practice of routine cannot fail more or less to create.”
Now appears the genius of the man, showing that if his brain was unoccupied by rules-of-thumb it was full to overflowing with original and sound ideas. He goes on to say: “A little reflection, assisted by a good deal of practical knowledge of copper and its alloys, made me reject all these from the first, and look to iron or some of its combinations, as the only material suitable for heavy ordnance.” Of fascinating interest is the great inventor’s story of how step by step he arrived at his final success. After reciting his preliminary experiments, in an endeavor to remove carbon from pig iron so as to make malleable iron and steel, he says:
“On my return from the Ruelle gun-foundry I resumed my experiments with the open-hearth furnace, when some pieces of pig iron on one side of the bath attracted my attention by remaining unmelted in the great heat of the furnace, and I turned on a little more air through the fire-bridge with the intention of increasing the combustion. On again opening the furnace door, after an interval of half an hour, these two pieces of pig still remained unfused. I then took an iron bar, with the intention of pushing them into the bath, when I discovered that they were merely shells of decarburized iron, showing that atmospheric air alone was capable of wholly decarburizing grey pig iron, and converting it into malleable iron without puddling or any other manipulation. Thus a new direction was given to my thoughts, and after due deliberation I became convinced that if air could be brought into contact with a sufficiently extensive surface of molten crude iron, it would rapidly convert it into malleable iron. Without loss of time I had some fire-clay crucibles made with dome-shaped perforated covers, and also with some fire-clay blow-pipes, which I joined on to a three-foot length of one-inch gas pipe, the opposite end of which was attached by a piece of rubber tubing to a fixed blast pipe. This elastic connection permitted of the blow pipe being easily introduced into and withdrawn from the crucible which, in effect, formed a converter. About ten pounds of molten grey pig iron half filled the crucible, and thirty minutes’ blowing was found to convert this metal into soft malleable iron. Here at least one great fact was demonstrated, namely, the absolute decarburization of molten crude iron without any manipulation, but not without fuel, for had not a very high temperature been kept up in the air furnace all the time this quiet blowing for thirty minutes was going on, it would have resulted in the solidification of the metal in the crucible long before complete carburization had been effected. Hence arose the all-important question: Can sufficient internal heat be produced by the introduction of atmospheric air to retain the fluidity of the metal until it is wholly carburized in a vessel not externally heated? This I determined to try without delay, and I fitted up a larger blast-cylinder in connection with a 20 horse-power engine which I had daily at work. I also erected an ordinary founder’s cupola, capable of melting half a ton of pig iron. Then came the question of the best form and size for the experimental converter. I had very few data to guide me in this, as the crucible converter was hidden from view in the furnace during the blow. I found, however, that slag was produced during the process, and escaped through holes in the lid. Owing to this, I constructed a very simple form of cylindrical converter, about four feet in interior height, sufficiently tall and capacious, I believed, to prevent anything but a few sparks and heated gases from escaping through a central hole made in the flat top of the vessel for that purpose. This converter had six horizontal tuyères arranged around the lower part of it; these were connected by six adjustable branch pipes, deriving their supply of air from an annular rectangular chamber, extending around the converter.