IRON 



3059 



IRON 



cast iron. They are made by remelting pig 

 iron and pouring it into specially-shaped molds. 

 Cast iron is not malleable; that is, if you 

 hammer it you will break it. Its softness is 

 due to carbon and silicon, its brittleness prin- 

 cipally to phosphorus and sulphur. In 1915 an 



IRON AND STEEL SEEN THROUGH THE 

 MAGNIFYING GLASS 



Fig. 1. Soft, or low-carbon, steel. The light 

 spaces are iron ; the dark, combined iron and 

 carbon, called pearlite. 



Fig. 2. Pearlite, which resembles mother-of- 

 pearl, is formed of alternate plates of iron and 

 carbide less than 1^5,000 of an inch thick. 



Fig. 3. Steel with too much sulphur. The lines 

 and spots between the grains of iron are iron sul- 

 phide, which melts more easily than iron and 

 makes the steel brittle when heated. 



Fig. 4. Cast iron. Breaks are liable to occur 

 along the black lines, which are plates of graph- 

 ite. The mottled areas are iron and phosphorus 

 and carbon ; the white are iron crystals. 



oil-burning cupola, or melting furnace, which 

 produces iron with less sulphur, was adopted 

 by a few manufacturers. 



Wrought Iron. Iron which can be hammered 

 into shape as a blacksmith hammers a horse- 

 shoe is wrought iron. It contains very little 

 carbon. The metal lump made in the ancient 

 clay furnace was wrought iron, which requires 

 less heat than cast iron. 



Nowadays it is much cheaper to make 

 wrought iron from pig iron than directly from 

 -he ore. While the pigs are in the long horizon- 

 al furnace called a puddling furnace, the charge 

 s stirred through a small door, with a sort of 

 ice. When most of the carbon and other im- 

 purities have been burned off a pasty mass of 

 ron results. This is broken into balls of one 

 or two hundred pounds and put through a 



squeezer, which crushes out most of the inter- 

 mingling slag and welds the grains of iron to- 

 gether. The metal is then rolled into bars, cut 

 in pieces, piled, heated and rolled again several 

 times. Wrought iron may also be made from 

 scraps of cast iron and steel. 



A piece of wrought iron can be welded to 

 another piece without solder, an operation im- 

 possible with any other metal but steel or 

 platinum. Its principal value is for bars, bolts 

 and plates. 



Slag, far from being useless waste, is an ex- 

 cellent material for ballasting railroad tracks 

 and makes a good basis for concrete. When it 

 contains considerable phosphorus it is em- 

 ployed as a fertilizer. 



Steel, which is intermediate between cast 

 iron and wrought iron in the amount of carbon 

 contained and is stronger than either, is fully 

 dealt with in the article under that title. 



Sources of Iron Ore. The United States 

 normally produces from thirty to forty per cent 

 of the world's iron ore, or about 55,000,000 

 gross tons. The War of the Nations caused a 

 decrease in the European output, but ordinarily 

 Germany is second to the United States, with 

 a production half as great. France, which was 

 fifth in 1906 with 8,000,000 tons, ranked third 

 in 1913, with 21,000,000 tons. The United 

 Kingdom mines about 16,000,000, Spain 9,000,- 

 000, Sweden 7,000,000 and Austria-Hungary 

 5,000,000 tons. Cuba and Newfoundland, with 

 over 1,000,000 tons each, rank second and third 

 in North America, while Canada's production 

 is sometimes 300,000 tons. 



In present production the greatest iron ore 

 district of the world is in the Mesaba range of 

 Minnesota. Together with the other mines of 

 the Lake Superior region it sometimes produces 

 nearly ninety per cent of a year's American 

 output. The United States Steel Company, the 

 so-called "steel trust," has its ore properties 

 in this district, but within the last few years 

 some of the large steel companies of the East- 

 ern coast have been importing their ores from 

 Chile through the Panama Canal, and from 

 Cuba. 



To be worked in the ordinary manner ores 

 must contain at least forty per cent iron. 

 Those of the Lake Superior region yield on the 

 average about fifty-five per cent. There are 

 several methods of preparing ore when it is 

 below the requirement. It may be washed to 

 drive out the minerals of different weight; or 

 weathered, that is exposed to the air, to free 

 it of certain chemicals ; or roasted, for the same 



