GOLD. 99 



Platina does not tarnish on exposure to the at- 

 mosphere, and takes an excellent polish, on which 

 account it is used in making specula for telescopes. 

 It is also capable of being welded, a property only 

 possessed by it and iron. It is the heaviest of the 

 metals ; its specific gravity being nearly 22. 



Platina is readily dissolved by the nitre-muri- 

 atic acid and by chlorine, but is not acted upon 

 by any other acid. It also combines with sulphur 

 and phosphorus. 



Platina is brought to Europe in small flattened 

 grains, which, however, are not pure platina, but 

 contain a mixture also of nine other metals. Four 

 metals, osmium, iridium, rhodium, and palladium^ 

 were unknown till they were discovered in these 

 grains. 



GOLD. 



Gold is found in nature in a metallic state. It 

 is generally met with in grains called gold-dust, 

 mixed with the sands of rivers, either being carried 

 away by them from the rocks which contain it, or 

 having been deposited in ancient alluvium. It is 

 chiefly found in Africa, also in Brazil and Peru. 

 There are mines of it also in Hungary ; and it is 

 met with in quantities too small to be worth work- 

 ing, in the sands of many rivers of Europe, 



Lately some was found in the county of Wick- 

 low, in Ireland j one grain weighed 22 ounces, and 

 considerable expectations were formed ; but, not- 

 withstanding, the works were abandoned as unpro- 

 ductive. 



Gold is the heaviest of the metals except platina. 

 It is of a rich yellow colour, and not very hard 

 when pure. 



H 2 



