INDUSTRY. INVENTION, COMMERCE 



673 



This property of iron is of the greatest value in 

 manufacturing operations. Its hardness and 

 toughness is scarcely altered by heating to red- 

 ness and cooling suddenly, forming in this re- 

 spect a striking contrast to steel and cast iron. 

 It is very malleable and ductile, and at a red 

 heat may be hammered and rolled into any 

 <ired form. By these operations, it acquires 

 fibrous texture, and increases greatly in tena- 

 ity. The presence of foreign substances modifies 

 working properties of wrought iron; thus. 

 Iphur in quantities of upwards of 0.01 per 

 it. renders it what is technically called red 

 that is, brittle and non-tenacious at a 

 ml heat. Phosphorus, if present in quantities 

 of more than 0.5 per cent., renders the iron brittle 

 at the ordinary temperature, or, as it is tech- 

 nically call< -d. cold dnirt. In dry air malleable 

 iron is unchanged, but air and moisture quickly 

 oxidize it. forming a red rust, which' in time 

 would eat through the whole mass. When 

 ited to whiteness in a current of air, malleable 

 burns with vivid scintillations, producing 

 ?tic oxide, and at a red heat decomposes 

 icous vapor; forming magnetic oxide and 

 Iving hydrogen. Cast iron, or pig iron, is 

 iron containing the highest amount of carbon. 

 There are. two kinds, viz : gray cast iron, which 

 is granular in texture and of a gray color; and 

 white cast iron, which is much whiter, has a 

 talline and somewhat conchoidal fracture, 

 is very hard and brittle. The chief differ- 

 between these two kinds of cast iron appears 

 be due to the state in which the carbon is 

 itained in them. The carbon may be re- 

 >\ -d from cast iron by heating it to the weld- 

 ing point and stirring it about in the air or with 

 oxide of iron (Puddling process), or by blowing 

 air through it in the melted state (Bessemer pro- 

 cess). In the latter operation the heat produced 

 by the combustion of the carbon is sufficient to 

 raise the temperature to such a degree, that 

 when at last the carbon is all burnt off the result- 

 ing malleable iron is still in the liquid state. 

 If these operations are stopped before all the 

 m is burnt off, steel of various qualities is 

 iced. Cast iron is the form in which the 



metal is almost invariably prepared from its ore, 

 by processes whose description would occupy too 

 much space, the reader being therefore referred 

 to works on metallurgy for further details. The 

 most important iron ores are magnetite, or mag- 

 netic iron ore, which has a black metallic luster, 

 sometimes forms mountainous masses, and con- 

 tains 72.41 per cent, of iron. Haematite red iron 

 ore, or oligistic iron, which is ferric oxide, occurs 

 either crystalline or massive, and contains 70 per 

 cent, of iron. Specular iron ore, or elba iron ore, 

 which is also a ferric oxide, and is iron gray and 

 crystalline. Brown iron ore, which is a hydrated 

 sesquioxide of iron, contains when pure 59.89 per 

 cent, of iron, and is of a compact earthy appear- 

 ance. Spathic iron ore, or sparry iron ore, a 

 native protocarbonate of iron, crystallizing in 

 masses of a light yellowish color, and containing 

 48.27 per cent, of iron. And clay iron ore, which 

 consists of haematite or spathic iron ore with clay. 

 In 1906, the production of pig iron and steel 

 in the principal producing countries of the world 

 was as follows: 



In the United States, Pennsylvania is still far 

 in advance as a producer of pig iron. Ohio, 

 Illinois, and Alabama follow in the order named. 

 Pennsylvania produces one-half of the Bessemer 

 pig iron, nearly three-fourths of the low phos- 

 phorus, nearly three-fourths of the basic, and 

 high percentages of the other grades, as well as 

 fully 50 per cent, of the cast steel and rolled iron 

 and steel products of the country. Ohio ranks 

 M-rond. Illinois third, and Now York fourth in 

 mill products. 



MIORCHANT MARINE OF THE WORLD 



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