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CHAPTER XVI 

 METALS 



ALUMINIUM. This is a comparatively new metal. It was 

 not until 1886, after repeated experiments and discoveries 

 by distinguished scientists of various nationalities, that an 

 English chemist found a method by which it could be prepared 

 cheaply in sufficiently large quantities for use in commerce. 



Aluminium is obtained from various sources, but chiefly 

 from clay, and of all the clays which contain it, bauxite yields 

 the largest quantities. Ten miles north-east of Aries, in the 

 Rhone Valley, is the village of Les Baux, and the particular 

 kind of clay from which aluminium is now obtained was first 

 found there ; hence this clay is now called bauxite. 



After the bauxite has been purified it is mixed with molten 

 cryolite. 1 The mixture is then electrolysed, when the melted 

 aluminium sinks to the bottom of the vessel and is drawn off. 

 Hence aluminium extraction works are usually situated near 

 waterfalls, so that electricity may be generated easily. 



Aluminium has many valuable qualities, chief among which 

 is its lightness : it is four times lighter than silver. It is not 

 very tenacious, however, and therefore when strength as well 

 as lightness is required, alloys of it instead of the pure metal 

 are employed. 



These alloys are used in the construction of parts of torpedo 

 boats, and air-ships, and submarines, and motor-cars, and 

 for all parts of ordinary ships where it is desirable to save 

 weight. 



Besides lightness, aluminium has other valuable qualities. 

 It does not corrode with acid, nor tarnish in dry air, and it is 

 a good conductor of heat. For these reasons it is very suitable 

 for making surgical instruments, and chemical apparatus, and 

 cooking utensils. But none of these should be washed in 



1 The only place in the world in which this mineral is being worked is 

 Ivigtut in Greenland. The deposit is owned by a Danish company. 



