Metals That Build New Worlds 181 



roofs. Its weather-resistant qualities make it economical in 

 the long run. 



Lead, not a rare or precious metal, is proving worth its 

 weight in gold in alloys replacing copper for roofing and 

 flashings. Plentiful silicon (used in silicon steel for springs and 

 electromagnets) replaces scarce tin in bronze. 



Uncommon Metals 



Several other metals, hardly mentioned outside of text- 

 books, have been put to work by metallurgists. Tantalum was 

 used in incandescent lamps until replaced by tungsten. Now it 

 is used to make electronic tubes for radios and Radar equip- 

 ment. Indium, a silverlike metal softer than lead, is finding 

 wide uses as a wartime substitute for tin. Small quantities of 

 selenium and tellurium are added to steel, copper, and copper- 

 rich alloys to make them more easily sawed and cut. Selenium 

 and tellurium also make lead more resistant to corrosion as 

 well as stronger and tougher. 



Lithium, the lightest of the metallic elements, is used in 

 silver solder for brazing tungsten-copper electrical contacts. 

 The adding of small amounts of lithium improves iron and 

 copper used for casting. Osmium, the heaviest metal known, 

 is employed in secret war-industry processes. It has been used 

 in peacetime to produce hard alloys for tipping gold pens. 

 Molybdenum, already mentioned, has taken over so many 

 jobs in the past two years that people have forgotten that it, 

 too, was one of the metals so long "buried in textbooks." 



Beryllium the Magic Metal 



Beryllium, a third lighter than aluminum and harder than 

 steel, deserves special mention again (we have already touched 

 upon it in the chapter on automobiles). It was identified in 



