INDUSTRIAL MINERALS DIAGRAM 19. 23 1 



zinc or'zinc white, which is not dangerous, can be substituted for 

 white lead. Those who work with compounds of lead should be 

 very careful to wash their hands before eating, and to change 

 their working clothes frequently, and in this way they will 

 avoid most of the dangers which are caused by the use of these 

 substances. 



Ore of antimony . The metal extracted from it is white and 

 very brilliant, with a bluish reflection. When rubbed, it emits 

 an odour somewhat resembling that of garlic. Antimony is much 

 used in medicine, and tartar emetic is composed of it. Another 

 equally important use which it serves is to make printer's type, 

 which is formed of an alloy of antimony and lead. Lead alone 

 would be too soft, and antimony alone too brittle, but when 

 mixed, a suitable alloy is obtained, which is called type- 

 metal. 



Ores of gold and silver. Silver is often mixed with lead in ores. 

 G-old is found pure in many countries, and is also found in some 

 sandy districts, and in the bed of rivers. It most frequently oc- 

 curs in fine particles called gold dust. But at other times it oc- 

 curs in large masses called nuggets. The chief use of gold and 

 silver is in the manufacture of money. But these metals 

 are not very hard, and the coins would be worn out too quickly 

 if pure metal were used. They therefore add a tenth part of 

 copper to metal for making money, which renders it much harder 

 and consequently more durable. 



Platinum. This is found in a pure state, mixed with several 

 other metals, in the Ural Mountains, in Siberia, &c. It is white 

 like silver, and completely unalterable, and the heat of the 

 strongest furnace will not melt it. These qualities make it ex- 

 ceedingly valuable for various industrial purposes, but it is only 

 lately that they have been able to obtain a sufficiently high tem- 

 perature to melt it, which is now effected by moans of 

 the oxyhydrogen blowpipe. 



Aluminium. This metal is not found pure in the bosom of the 

 earth. It is extracted by very complicated processes, from alu- 

 mina, which forms the base of clay. It is white, exceedingly 



