

IRON. 



241 



How is iron 

 produced ? 



597. PRODUCTION. Iron is produced 

 from its ores, which are impure oxides, by 

 heating with lime, to remove 

 the impurity ; and at the 

 same time with coal, and 

 the gases proceeding from it, 

 to remove the oxygen. A 

 smelting furnace, such as is 

 represented in the figure, 

 being previously heated, is 

 charged with the material in 

 layers, and the heat main- 

 tained by the coal of the 

 mixture. In the upper part 

 of the furnace the materials 



are thoroughly dried. As 



they gradually settle, they 



become more thoroughly heated, and meet carbonic 

 oxide from the coal below, which robs the iron of its 

 oxygen, and converts it into particles of metal. Still 

 lower down, the lime combines with the earthy por- 

 tions of the ore, forming a liquid glass. The re- 

 duced iron thus liberated, collects, fuses, arid sinks to 

 the bottom of the furnace. Prom this point it is run 

 off into channels of sand, where it hardens into pig 

 iron. 



How is the 598. EXPLANATION. The ordinary im- 



slag formed? purities of the ore- are clay and quartz, or 



For what uses r j T. ? 



may it be em- silica. Lime has the property of forming, 

 p oye with both of these, a fusible glass, or slag, 



which floats upon the melted iron. This material is 



11 



