

CHAPTER XVII 

 METALS USED IN THE HOME 



The value and source of metals. If you examine a sky- 

 scraper which is being built, you will see that its framework 

 is metal ; if you examine the new railroad coaches and Pull- 

 mans which traverse the country, you will see that they, too, 

 are metal. Metal wires carry our telephone and telegraph 

 messages; metal tracks guide our trolley cars and railroad 

 engines ; metal pipes convey water and gas from reservoir to 

 consumer ; metal stoves cook our food and metal utensils hold 

 it; metal coins serve as money. Metals are among the 

 most important substances known, and in proportion as man has 

 used them, in just that proportion has civilization advanced. 

 As long as stone and wood implements and utensils served man's 

 needs, he remained savage, or at most, semicivilized. 



Metals are obtained from ores. Sometimes metals such as 

 copper and gold are found in the earth as metals, and can be 

 mined directly and put into use. More often they exist in com- 

 bination with other substances. Tin, for example, does not 

 occur in the earth as tin, but it occurs in combination with 

 oxygen as tin oxide. Tin oxide is mined and the metal tin is 

 then extracted from it. Lead does not occur in the earth as 

 lead, but in combination with sulphur as lead sulphide. Lead 

 sulphide is mined and the lead is then extracted from it. 

 Minerals rich in metals are called ore. 



Iron is always obtained from iron ore by smelting, that is, 

 by heating. When broken iron ore, coal, and limestone are 

 heated together in a blast furnace (Fig. 62) the iron melts and 



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