Part 20 (1/2)

But there was yet one thing wanting. He had now succeeded in producing the purest malleable iron ever made, and that, too, by a quicker and less expensive process than was ever known before. But what he wanted was to make steel. The former is iron in its greatest possible purity; the latter is pure iron containing a small percentage of carbon to harden it. There has been an almost endless controversy in trying to make a definition that will fix the dividing line that separates the one metal from the other.[24]

For our present purpose, suffice it to quote the account given in a popular treatise on metallurgy, published at the time when Bessemer was in the midst of his experiments. ”Wrought iron,” it says, ”or soft iron, may contain no carbon; and if perfectly pure, would contain none, nor indeed any other impurity. This is a state to be desired and aimed at, but it has never yet been perfectly attained in practice. The best as well as the commonest foreign irons always contain more or less carbon.... Carbon may exist in iron in the ratio of 65 parts to 10,000 without a.s.suming the properties of steel. If the proportion be greater than that, and anywhere between the limits of 65 parts of carbon to 10,000 parts of iron and 2 parts of carbon to 100 of iron, the alloy a.s.sumes the properties of steel. In cast iron the carbon exceeds 2 per cent, but in appearance and properties it differs widely from the hardest steel. These properties, although we quote them, are somewhat doubtful; and the chemical const.i.tution of these three substances may, perhaps, be regarded as still undetermined.” Now, in the Bessemer converter the carbon was almost entirely consumed. In the small gun just described,[25] there were only 14 parts of carbon for 1,000,000 parts of iron. Bessemer's next difficulty was to carburize his pure iron, and thus to make it into steel. ”The wrought iron,” says Mr. I. L. Bell, ”as well as the steel made according to Sir Henry Bessemer's original plan, though a purer specimen of metal was never heard of except in the laboratory, was simply worthless. In this difficulty, a ray of scientific truth, brought to light one hundred years before, came to the rescue. Bergmann was one of the earliest philosophers who discarded all theory, and introduced into chemistry that process of a.n.a.lysis which is the indispensable antecedent of scientific system. This Swedish experimenter had ascertained the existence of manganese in the iron of that country, and connected its presence with suitability for steel purposes.” Manganese is a kind of iron exceptionally rich in carbon, and also exceptionally free from other impurities. Berzelius, Rinman, Karsten, Berthier, and other metallurgists had before now discussed its effect when combined with ordinary iron; and the French were so well aware that ferro-manganese ores were superior for steel-making purposes that they gave them the name of _mines d'acier_. So Bessemer, after many experiments, discovered a method whereby, with the use of ferro-manganese, he could make what is known as mild steel. The process of manufacture, when described by Sir Henry Bessemer at Cheltenham in 1856,[26] was so nearly complete, that only two important additions were made afterwards. One was the introduction of the ferro-manganese for the purpose of imparting to his pure liquid iron the properties of ”mild steel.” The other was an improvement in the mechanical apparatus. He found that when the air had been blown into the iron till all the carbon was expelled, the continuance of ”the blow” afterward consumed the iron at a very rapid rate, and a great loss of iron thus took place. It was therefore necessary to cease blowing at a particular moment. At first he saw no practical way by which he could prevent the metal going into the air-holes in the bottom of the vessel below the level of the liquid ma.s.s, so as to stop them up immediately on ceasing to force the air through them; for if he withdrew the pressure of air, the whole apparatus would be destroyed for a time. Here, again, his inventive genius found a remedy. He had the converter holding the molten iron mounted on an axis, which enabled him at any moment he liked to turn it round and to bring the holes above the level of the metal; whenever this was done the process of conversion or combustion ceased of itself, and the apparatus had only to be turned back again in order to resume the operation. This turning on an axis of a furnace weighing eleven tons, and containing five tons of liquid metal, at a temperature scarcely approachable, was a system entirely different from anything that had preceded it; for it he took out what he considered one of his most important patents, ”and,” he says, ”I am vain enough to believe that so long as my process lasts, the motion of the vessel containing the fluid on its axis will be retained as an absolute necessity for any form which the process may take at any future time.” The patent for this invention was taken out about four years after his original patent for the converter.

Uncle Fritz showed them a picture of this gigantic kettle, which holds this ma.s.s of molten metal and yet turns so easily.

”But,” said Helen, ”you have a model of it here, Uncle Fritz.” And she pointed to her Uncle Fritz's inkstand, which is something the shape of a fat beet-root, with the point turned up to receive the ink. Uncle Fritz nodded his approval. These inkstands, which turn over on a little brazen axis, were probably first made by some one who had seen the great eleven-ton converters.

Uncle Fritz showed the children the picture in the ”Practical Magazine,”

and they spent some time together in looking over the pages of the volume for 1876.

The Bessemer process was now perfect. Nearly four years had elapsed since its conception and first application; and in addition to the necessary labor and anxiety he had experienced, no less than 20,000 had been expended in making experiments that were necessary to complete its success. It only remained to bring the process into general use.

The young people asked quite eagerly whether they could see the processes of ”conversion” anywhere, and were glad to be told that Bessemer steel is made in many parts of America. One of their young friends, who was educated at the ”Technology,” is in charge of a department at Steelton, in Pennsylvania, and they have all written letters to him.

The American steel-makers have a great variety of ores to choose from, and they have found it possible, by using different ores, to avoid the difficulties which Mr. Bessemer first met in using the ores of England.

And so far are the processes now simplified, that in many American establishments the molten iron is received liquid from the blast furnaces, and does not have to be reduced a second time in a cupola furnace, as was the iron used by Mr. Bessemer. There is no cooling, in such establishments, between the ore and the finished steel.

XIV.

THE LAST MEETING.

GOODYEAR.

When the day for the next meeting came, Uncle Fritz had a large collection of books and magazines in the little rolling racks and tables where such things are kept. But no one of them was opened.

No. The young people appeared in great strength, all at the same moment, and notified him that he was to put on his hat and his light overcoat, and go with them on what they called the first ”Alp” of the season. For there is a pretence in the little company that they are an Alpine Club, and that for eight months of the year it is their duty to climb the highest mountains near Boston.

Now, the very highest of these peaks is the summit hill of the Blue Hills, to which indeed Ma.s.sachusetts owes its name. For ”Matta” in the Algonquin tongue meant ”great,” and ”Chuset” meant ”a hill.” And a woman who was living on a little hummock near Squantum, just before Winthrop and the rest landed, was the sacred Sachem of the Ma.s.sachusetts Indians.

Hence the name of Mattachusetts Bay; and then, by euphony or bad spelling, or both, Ma.s.sachusetts.

Uncle Fritz obeyed the rabble rout, as he is apt to do. He retired for a minute to put on heavier shoes, and, when he reappeared, he took the seat of honor in the leading omnibus. And a very merry expedition they had to the summit, where, as the accurate Fergus told them, they were six hundred feet above the level of the sea. There was but little wood, and they were able to lie and sit in a large group on the ground just on the lee side of the hill, where they could look off on the endless sea.

”Whom should you have told us about, had it rained?” said Mabel Fordyce.

”Oh! you were to have had your choice. There are still left many inventors. I had looked at Mr. Parton's Life of Goodyear, and the very curious brief prepared for the court about his patents. Half of you would not be here to-day but for that ingenious and long-suffering man.”

”Should not I have come?” said Gertrude, incredulously.

”Surely not,” said Uncle Fritz, laughing. ”I saw your water-proof in your shawl-strap. I know your mamma well enough to know that you would never have been permitted to come so far from home without that aegis, or without those trig, pretty overshoes. You owe waterproof and overshoes both to the steady perseverance of Goodyear and to the loyal help of his wife and daughters. Some day you must read Mr. Webster's eulogy on him and them. Indeed, he is the American Palissy. You hear a good deal of woman's rights; but, really, modern women had no rights worth speaking of till Mr. Goodyear enabled them to go out-doors in all weathers.

”I meant we should have an afternoon with the Goodyears. Then I meant that you should know, Gertrude, where that slice of bread came from.”

”Well,” said she, ”I do not know much, but I do know that. It came out of the bread-box.”

”Very good,” said the Colonel, laughing. ”But somebody put it into the bread-box. And it is quite as well that you should know who put it in.

American girls and American boys ought to know that men's prayer for 'Daily Bread' is answered more and more largely every year. They ought to know why. Well, the great reason is that reaping and binding after the reapers, nay, that sowing the corn, and every process between sowing and harvest, has been wellnigh perfected by the American inventors. So I had wanted to give a day or two to reapers and binders, and the other machinery of harvesting. Indeed, if our winter had been as long as poor Captain Greely's was, and if you had met me every week, we should have had a new invention for each one. Here are the telephone and the telegraph. Here is the use of the electric light. Here is the sewing-machine, with all its nice details, like the b.u.t.ton-hole maker.