CHAPTER XXI. 



IRON, NICKEL, COBALT, GOLD AND PLATINUM. 



IRON (Fe) is the most useful, the most widely diffused, and 

 next to aluminium, the most abundant of the metals. Meteoric 

 iron is nearly pure, but native iron is seldom found. Minerals in 

 great numbers contain iron; in fact there are few substances, 

 liquid or solid, that do not contain more or less of this element. 

 The most important ores of iron are the oxides and carbonates, 

 as the magnetic oxide, hematite, or sesquioxide, which consti- 

 tute the great bodies of ore found in the old rocks of New York, 

 Canada, Michigan and Missouri. Clay-ironstone, abundant in 

 the coal measures, is the carbonate of iron, FeC0 3 , mixed with 

 clay. It is the chief ore of England. 



Iron is reduced from its ores by the action of heat and fluxes 

 in a blast furnace. The steps in the process are to expel the 

 water, sulphur, carbonic acid, etc., by heat reducing the ores to 

 oxides. Next reducing the oxides to the metallic state by heat- 

 ing them with carbon, and third, the separation of the earthy 

 impurities by fusion with limestone or clay into a glass or slag, 

 and lastly the carbonizing and melting of the iron. The blast 

 furnace is charged at the top with coal, ore and flux in alternate 

 layers. The air for the support of the combustion is forced in by 

 a powerful blast. The melted iron sinks to the bottom and is 

 drawn off into molds, forming the pig iron of commerce. The 

 lighter slag is also drawn off from time to time. The resulting 

 gases are collected and used in raising the temperature of the air 

 of the blast. This iron contains from two to five per cent, of 

 carbon, is hard, crystalline and easily fusible, being generally 

 contaminated with silicon, sulphur and phosphorus. 



This pig iron is subjected to heat in the puddling furnace, 

 which oxidizes most of the impurities, finally reducing it to a 



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