SOME CHEMISTRY OF EVERYDAY LIFE 201 



manner of preparation for market need not wait upon a study 

 of Chemistry. 



Iron is obtained from its oxides by an intense heating in 

 "blast" furnaces of a mixture of ore, fuel (usually coke), and 

 limestone. A reduction of the ore is accomplished by reason 

 of the chemical combination of oxygen from the iron com- 

 pound with carbon and carbon monoxide gas (CO) from the 

 fuel at the high temperatures maintained day and night in 

 the furnaces for months at a time. The supply of air re- 

 quired to furnish the oxygen necessary for the combustion 

 of the fuel is forced through pipes into the bottom of the 

 furnace as a "hot blast." This air has been heated by pass- 

 ing it through ovens kept intensely hot by burning under 

 them gases conducted through great pipes leading out from 

 the top of the covered furnace stack. A considerable part 

 of these gases is CO the same gas which forms a large per- 

 centage of illuminating gases furnished for household uses. 

 Iron set free in a liquid form in the furnace settles to the 

 bottom, and from time to time it is allowed to flow out into 

 moulds made in a bed of sand, forming when solidified the 

 "pig iron" of commerce. It contains about 5 per cent 

 of carbon together with small amounts of sulphur, phos- 

 phorus, silicon, and other substances. 



When remelted this iron can be made to take the form of 

 any mould into which it is run, and any markings on the 

 sides of the mould. (See page 92.) These castings when 

 quickly cooled are brittle, but when the cooling is continued 

 through many hours the iron becomes more or less malleable. 



Wrought iron is nearly pure iron, and results from burning 

 out of molten cast iron the carbon, sulphur, phosphorus, 

 silicon, and other substances it contains. It is tough, ductile, 

 flexible, and malleable. Steel may be made from wrought 

 iron by combining with it a certain small carefully calculated 

 per cent of carbon. 1 This amount is varied somewhat accord- 



