141 



III. 



INORGANIC CHEMISTRY. 



CHAPTER I. 



What is oxy- 

 gen 



METALLOIDS. 

 OXYGEN. 



329. DESCRIPTION. Oxygen is a trans- 

 parent and colorless gas, a little heavier than 

 the atmosphere. It is much the most 

 abundant substance in nature. One fourth 



of the air, one-ninth of the ocean, and, probably, half 



of the solid earth, is oxygen. 

 330 . PREPAR- 

 ATION. Gase- 



ous oxygen is expelled from 



many substances, which 



contain it, by the simple 



agency of heat, Chlorate 



of potassa, and black oxide 



of manganese, are such 



substances. 



Give the com- 331. Mix equal quantities of these ma- 



phte process, terials, and heat half a tea-spoonful of the 



How is oxygen 

 prepared ? 



