Part 14 (2/2)

In the past few years the United States has jumped from an insignificant position in the production of iron and steel to the first rank among the iron-producing countries. This great advance is due to the fortunate geographic position of the iron ore and the coal, and also to the discovery of the Bessemer process of making steel.

In general it is more economical to s.h.i.+p the ore to the coal than _vice versa_. The position of the steel-making plant is largely determined by the cost of moving the c.o.ke and ore, together with that of getting the steel to the place of use. Formerly, iron manufacture in the United States was not profitable unless the coal, ore, and limestone[46] were very near to one another.

These conditions still obtain in the southern Appalachian mineral fields; the ore and the coal are at no great distance apart, and a great iron-making industry, in which Birmingham and Bessemer form the princ.i.p.al centre, has grown into existence. For the greater part the coal is c.o.ked; and in this form less than a ton[47] is sufficient to make a ton of pig-iron. The smelteries and rolling-mills are built at places where the materials are most conveniently hauled.

In the past few years the iron and steel industry which formerly centred about the navigable waters at the head of the Ohio River, has undergone a readjustment. Rolling-mills and smelteries exist at Pittsburg and vicinity, and at Youngstown, New Castle, and other nearby localities, but greater steel-making plants have been built along the south sh.o.r.es of Lakes Michigan and Erie, all of which have come about because of reasons that are purely geographic.

Immense deposits of excellent hemat.i.te ore in the old mountain-ranges near Lake Superior have recently become available. For the greater part the ore is very easily quarried. In many instances it is taken out of the quarry or pit by steam-shovels which dump it into self-discharging hopper-cars. Thence the ore is carried on a down grade to the nearest s.h.i.+pping-port on the lake. There it is dumped into huge bunkers built at the docks, and from these it slides down chutes into the holds of the steam-barges. A 6,000-ton barge is loaded in less than two hours; a car is unloaded in a few seconds.

[Ill.u.s.tration: MOVEMENT OF IRON ORE]

Water transportation is very cheap compared with railway transportation, even when the road is built and equipped as an ore-hauling road. The ore is therefore carried a distance varying from one thousand to one thousand five hundred miles for less than it could be loaded, on cars hauled one-tenth that distance by rail, and unloaded.

[Ill.u.s.tration: STEEL MANUFACTURE--ORE DOCKS]

At the south sh.o.r.e of Lake Erie, the ore meets the c.o.ke from western Pennsylvania and coal from the Ohio coal-fields, and as a result new centres of iron and steel manufacture have grown up along this line of ”least resistance.” The ore is unloaded at the docks by means of mechanical scoops and shovels. So cheaply and quickly is it mined and transported that it is delivered to the smelteries at a cost varying from $1.75 to $3.25 per ton.

[Ill.u.s.tration: LAKE SUPERIOR IRON ORE FIELDS]

There are three forms in which iron is used--cast iron, wrought iron, and steel. Cast iron is crystalline and brittle. The product as it comes from the blast furnace is called pig-iron. In making such commodities as stoves, and articles that do not require great strength, the pig-iron is again melted and cast into moulds which give them the required shape.

Cast iron contains from one to five per cent. of carbon.

Wrought iron is malleable, ductile, and very flexible; when pure it is also very soft. It is prepared by melting pig-iron in furnaces having such a shape that the molten metal can be stirred or ”puddled” in contact with the air. By this means the carbon is burnt out, and while still at a white heat the pasty iron is kneaded or ”wrought,” in order to expel other impurities.

Steel is a form of iron which is thought to contain a chemical compound of iron with carbon. It is stronger than iron and finer in grain.

Formerly, steel was made by packing bars of pure iron in charcoal powder, the whole being enclosed in clay retorts that were heated to whiteness for about three days. The product obtained by this method is known as cementation steel. It is still used in the manufacture of cutlery, tools, and fine machinery; it is likewise very expensive. In smelting certain ores it is easy to burn out the carbon in open furnaces, and ”open-hearth” steel is an important factor.

Just about the beginning of the Civil War, when the railways of the United States were taxed beyond their capacity to carry the produce of the country, it became apparent that something more durable than iron must be used for rails. The locomotives, then weighing from twenty-five to thirty-five tons each, were too light to haul the freight offered the roads; they were also too heavy for the rails, which split at the ends and frayed at the edges.

[Ill.u.s.tration: IRON AND STEEL]

The Bessemer process of making steel was the result of the demand for a better and a cheaper method. By this process, the iron is put into a ”converter” along with certain Swedish or Cuban ores to give the product hardness. A hot blast is then forced into the converter which not only melts the ma.s.s but burns out the excess of carbon as well. The color of the flame indicates the moment when the conversion to steel is accomplished.

In 1860, before the establishment of the Bessemer process, steel commanded a price of about one hundred and twenty-five dollars per ton; at the beginning of the twentieth century steel billets were about eighteen dollars per ton. In western Europe and the United States there are used about three hundred pounds of iron and steel per capita; in South America the rate of consumption is about fifteen pounds; in Asia (j.a.pan excepted) it is probably less than three pounds.

The economic results of low-priced steel are very far-reaching. Steam boilers of steel carry a pressure of more than two hundred and fifty pounds to each square inch of surface--about four times as great as in the iron boilers formerly used. Locomotives of eighty tons draw the fast pa.s.senger trains at a speed of sixty miles an hour. Ponderous compounding engines weighing one hundred and twenty tons haul ninety or more steel freight cars that carry each a load of 100,000 pounds. The iron rails formerly in use weighed about forty pounds per yard; now steel rails of one hundred pounds per yard are employed on most trunk lines.

In the large commercial buildings steel girders have entirely supplanted timber, while in nearly all modern buildings of more than six stories in height, the frame is constructed of Bessemer steel. Indeed, a steel-framed building of twenty-five stories has greater stability than a brick or stone building of six. Such a structure as the ”Flatiron Building” in New York or the Masonic Temple in Chicago would have been impossible without Bessemer steel.

In ocean commerce cheap steel has worked even a greater revolution. In 1860, a vessel of 4,000 tons displacement was thought to be almost up to the limit. The Oceanic of the White Star Line has a displacement of about twenty-eight thousand five hundred tons. This is nearly equalled by the measurement of half a dozen other liners, and is exceeded by the freighters built by Mr. J.J. Hill for the China trade.

[Ill.u.s.tration: _From a copyrighted photograph by C.L. Ritzmann, N.Y._

STEEL MANUFACTURE

THE FULLER (FLATIRON) BUILDING, NEW YORK CITY]

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