Fossils. 169 



Platma is a noble metal of a white co- 

 lour ; for which reason some called it 

 white gold. In Europe it is known only 

 since the middle of the present century, 

 and brought to us in small irregularly-fig- 

 ured grains, but which are impure, and 

 mostly contaminated with iron. Pure 

 platina exceeds all other metals, even gold 

 In specific gravity, which is found to reach 

 21,061. It is ductile and malleable ; its 

 hardness and tenacity are greater than 

 those of gold, and it admits of being 

 welded. 



Silver is a noble metal, of a white color 

 whose specific gravity is variable from 

 1O,474 to 10,542 ; it is very malleable 

 and ductile, and of a moderate hardness. 

 It fuses in a heat of less intensity than is 

 required by gold ; it is fixed in fire, and is 

 not affected by water nor air, remaining 

 in both unaltered ; but by sulphureous 

 vapours it is very soon tarnished. 



Mercury, or quicksilver is a base metal 

 of a white colour. Its specific gravity is 

 upon an average 13,674 it is the most 

 fusible of all known metals, and continues 

 in the fluid state even in the cold temper- 

 ature of our winters j it congeals only at 



