104 IRON. 



forms the ore called finnabar. The greatest quan- 

 tity of it is found in Spain and South America. 



When acted on by heat and air for a long time, 

 it absorbs oxygen, and is converted into a red 

 oxide called formerly precipitate per se : and when 

 the heat is increased, the oxygen is given out, and 

 the mercury re-assumes its metallic appearance. 

 When it is agitated long in air, it is converted into 

 the black occidcy which contains a smaller propor- 

 tion of oxygen than the red oxide. It is the black' 

 oxide which is employed in mercurial ointment. 

 Mercury is acted on by the acids, forming salts of 

 mercury. It also unites to chlorine (oxymuriatic 

 acid,) in two proportions, forming calomel and cor- 

 rosive sublimate. 



Mercury when triturated with sulphur, com- 

 bines readily into a black compound called ethiops 

 mineral ; when united to a larger proportion of 

 sulphur, it forms the beautiful pigment called 

 cinnabar. 



Mercury combines with several of the metals, 

 forming soft alloys called amalgams. The amal- 

 gam with tin is used for mirrors : that with zinc is 

 employed in electrical machines. 



IRON. 



ISIo metal is so universally diffused throughout 

 nature as iron. It is never found in the earth in 

 the metallic state, but is always procured from 

 ores. 



Iron is of a bluish-grey colour. It is very duc- 

 tile, for it may be drawn into wire as fine as 

 human hair. It is also very malleable, and pos- 



