heated by passing it through great steel cylinders as high as the furnace. The fuel used is nothing more than the gases which come out at the top of the furnace. 8 The slag is so much lighter than iron that when the ore is melted the slag floats on top just as oil floats on water, and can be drained out of the furnace through a higher opening than that through which the iron flows. The slag tap is open most of the time, but the iron tap is opened only once in about six hours. It is a magnificent sight when a furnace is "tapped" and the stream of iron drawn off. 9 Imagine a great shed, dark and gloomy, with many workmen hurrying about to make ready for what is to come. The floor is of sand and slopes down from the furnace. Through the center of this floor runs a long ditch straight from the furnace to the end of the shed. Opening from it on both sides are many smaller ditches; and connecting with these are little gravelike depressions two or three feet long and as close together as can be. These are called "pigs." 10 When the time has come, the workmen gather about the furnace, and with a long bar they drill into the hard-baked clay of the tapping hole. Suddenly it breaks, and with a rush and a roar the crimson flood of molten iron gushes out. It flows down the trench into the ditches, then into the pigs, till their whole pattern. is marked out in glowing iron. Now the blast begins to drive great beautiful sparks through the tapping hole. This means that the molten iron is exhausted. The blast is turned off, and the "mud-gun" is brought into position and shoots balls of clay into the tapping hole to close it for another melting, or "drive." The crimson pigs become rose-red, darken, and turn gray. The men play streams of water over them and the building is filled with vapor. As soon as the pigs are cool enough, they are carted away and piled up outside the building. 11 In some iron works molds of pressed steel carried on an endless chain are used instead of sand floors. The chain carries them past the mouth of a trough full of melted iron. They are filled, borne under water to be cooled, and then dropped upon cars. A first-class machine can make twenty pigs a minute. 12 Most of the iron made in blast furnaces is turned into steel. Steel has been made for centuries, but until a few years ago the process was slow and costly. A workman's steel tools were treasures, and a good jackknife was a valuable article. Railroads were using iron rails. They soon wore out, but at the suggestion to use steel, the presidents of the roads would have exclaimed, "Steel, indeed! We might as well use silver!" Trains needed to be longer and heavier, but iron rails and bridges could not stand the strain. Land in cities was becoming more valuable; higher buildings were needed, but stone was too expensive. Everywhere there was a call for a metal that should be strong and cheap. Iron was plentiful, but steel was dear. 13 A cheaper method of making iron into steel was needed; and whenever there is pressing need of an invention, it is almost sure to come. Before long, what is known as the "Bessemer process" was invented. One great difficulty in the manufacture of steel was to leave just the right amount of carbon in the iron. Bessemer simply took it all out, and then put back exactly what was needed. Molten iron, tons and tons of it, is run into an immense pear-shaped vessel called a "converter.' Fierce blasts of air are forced in from below. These unite with the carbon and destroy it. 990 There is a roar, a clatter, and a clang. Terrible flames of glowing red shoot up. Suddenly they change from red to yellow, then to white; and this is the signal that the carbon has been burned out. The enormously heavy converter is so perfectly poised that a child can move it. The workmen now tilt it and drop in whatever carbon is needed. The molten steel is poured into square molds, forming masses called "blooms," and is carried away. More iron is put into the converter, and the work begins again. 14 The Bessemer process makes enormous masses of steel and makes it very cheaply; but it has one fault - it is too quick. The converter roars away for a few minutes, till the carbon and other impurities are burned out; and the men have no control over the operation. In what is called the "open-hearth" process, pig iron, scrap iron, and ore are melted together with whatever other substances may be needed to make the particular kind of steel desired. This process takes much longer than the Bessemer, but it can be controlled. Open-hearth steel is more homogeneous,° that is, more nearly alike all the way through, - and is better for some purposes, while for others the Bessemer is preferred. 15 Steel is hard and strong, but it has two faults. A steel bar will stand a very heavy blow and not break, but if it is struck gently many thousand times, it sometimes crystallizes and may snap. A steel rail may carry a train for years and then may crystallize and break and cause a wreck. Inventors are at work discovering alloys to prevent this crystallization. The second fault of steel is that it rusts and loses its strength. That is why an iron bridge or fence must be kept painted to protect it from the moisture in the air. 16 If all the iron that is in use should suddenly disappear, did you ever think what would happen? Houses, churches, skyscrapers, and bridges would fall to the ground. Railroad trains, automobiles, and carriages would become heaps of rubbish. Ships would fall apart and become only scattered planks floating on the surface of the water. Clocks and watches would become empty cases. There would be no machines for manufacturing or for agriculture, not even a spade to dig a garden. Everybody would be out of work. To see how it would seem, try for an hour to use nothing. that is of iron or has been made by using iron. alloy 15 (ǎ loi'), a mixture of metals into tiny crystals Bessemer 13 (běs' è mer), an Eng lish engineer carbon 13 (kär' bon), a substance Catalan (kǎt' à lăn), oldest way of making iron coke (kōk), substance like coal converter 13 (kon vûr' tẽr), the ves sel used in the Bessemer process crystallize 15 (kris' tăl iz), change 14 (hō' mo je' ně us), the same throughout meteoric 5 (mē' tẽ ŏr' ik), from a meteor, or falling star meteorite 5 (mē' té or it'), a stony substance that falls from the sky open-hearth 14 (härth), a way to make steel I. Are there traces of iron in your community? 2. Explain what rust is. 3. How have beds of iron ore been formed? 4. What attracts iron? 5. Describe a meteorite. 6. Why was the "Catalan method" so costly? 7. How is iron made to-day? 8. How do they get the slag and the iron out? Picture the scene. 9. What is the difference between iron and steel? 10. How does the "Bessemer process" differ from the "open-hearth process"? What are the advantages and disadvantages of each? II. Give instances to show the faults of steel. How do we try to prevent these? 12. Make up in class an outline in which you give the topic of each paragraph. Write it on the board. 13. Conversation and discussion: Prove that "everybody would be out of work" in your community if iron were taken out of the world. 14. Memorize section 1 or 16 as a declamation on "The Everyday Uses of Iron." 15. Get from the library Parton's Captains of Industry and find out how Sir Henry Bessemer invented his process. PAST AND OUR COUNTRY PRESENT COLUMBUS AND THE SAILORS When Columbus lived, people thought that the earth was flat. They believed the Atlantic Ocean to be filled with monsters large enough to devour their ships, and with fearful waterfalls over which their frail vessels would plunge to destruction. Columbus had to fight these foolish beliefs in order to get men to sail with him. He felt sure that the earth was round. He believed that by sailing westward he would find a "short cut" to India. The French people have always admired courage. Here a French writer, Lamartine, pays tribute to courage of spirit which is even greater than physical courage. As you read, look for the various ways in which Columbus showed his greatness? 1 HEN Columbus left the Canaries to pass with his three small ships into the unknown seas, the eruptions of Tenerife° lit up the heavens and were reflected in the sea. This cast terror into the minds of his seamen. They thought that it was the flaming sword of the angel who expelled the first man from Eden, and who now was trying to drive back in anger those who were seeking entrance to the forbidden and unknown seas and lands. But the admiral passed from ship to ship explaining to his men, in a simple way, the action of volcanoes, so that the sailors were no longer afraid. |