NICKEL. 117 



found native, but oftener combined with sulphur. 

 The sulphuret of arsenic is called orpiment. 



Arsenic is frequently mixed in metallic ores, 

 and is driven off by heat. It is known by its pecu- 

 liar smell, like garlic. 



The colour of metallic arsenic is grey; it is very 

 brittle. It soon loses its metallic lustre in the air, 

 and becomes black. The oxides of arsenic have 

 acid properties. There are two: the white oxide 

 of arsenic is called arsenious acid. It is highly 

 poisonous. It is soluble in water. It reddens 

 vegetable blues. It is of a white colour, is semi- 

 transparent, and brittle. Its taste is acrid, with a 

 nauseous sweetness. The best way of getting rid 

 of its action as a poison, when taken into the sto- 

 mach, is to produce vomiting and purging. 



Arsenic acid is a white deliquescent substance, of 

 a sour taste, obtained by distilling nitric acid off 

 metallic arsenic. It forms salts with several of the 

 metals. Arseniate of iron crystallizes in cubes of 

 a green colour. The arseniates of copper are 

 among the most beautiful minerals. The alloys of 

 arsenic with some of the metals are used for some 

 purposes. It is mixed with lead to assist its 

 granulation in making small shot. It is also used 

 in making flint glass, and in calico-printing. 



NICKEL. 



Nickel is a rare metal. It is white, much resem- 

 bling silver*, and possesses, like iron, the magnetic 

 property. It is not easily fused, and it is malleable. 

 It is rather softer than iron, and soon tarnishes in the 

 air. It is found native, and combined with arsenic. 



Nickel dissolves in the acids, and its salts are 

 distinguished by their fine green colour. 



I 3 



