MINERALOGY. 



313 



This Metal h generally obtained in smaii qiiantitieSj alloj- 

 ing native platina. Native Palladium is infusible. 



H. Nickel. The specific gravity of Nickel is about nine,, 

 its colour is yellowish white, it is ductile, malleable, and 

 possesses the magnetic property, though in a less degree 

 than Iron. 



Nickel has been found combined with Iron and other sub- 

 stances, and enters into the composition of all the Meteoric 

 stones, which have fallen from the atmosphere, in this and 

 various other countries • its uses are principally contined t<? 



alloys, 



BRITTLE METALS, . 



VI. Arsenic. Specific gravity nearly eight; colour 

 bluish or greenish white ; becoming on exposure to 

 the air dark, almost black; its substance is exceedingly 

 brittle ; it occurs nearly pure, and also combined with 

 Gold, Silver, iron, Lead-, kc. 



Arsenic is one of the most active of Mineral poisons ; it is 

 of frequent occurrence ; is used in glazing porcelain, and the 

 manufacture of glass; when combined with sulpher in certain 

 proportions^ it is either the Realgar or Orpiment used by 

 Painters* Its presence may be detected by submitting it to 

 the action of heat, or striking it w ith a hammer, when it 

 gives out a garlic like smell; it is also remarkable that the 

 same appearance is produced on Silver and Steel, by the 



