CHAPTER XIV 



HYDROGEN 



(Hydrogen = H) 



Occurrence. Although hydrogen is found widely 

 distributed in combination with other elements, it is 

 found but rarely in the free state. It is sometimes 

 found free among the gases expelled from volcanoes, 

 in meteorites, and a trace of it is found in the air. 



Hydrogen makes up 11% of water, which covers 

 nearly three-fourths of the earth. It is found as a 

 constituent part of natural gas and the oils obtained 

 from the earth as fuel, and forms a part of all vege- 

 table and animal matter. 



Preparation. Hydrogen may be obtained either 

 from water or from any acid, of which substances it 

 forms an essential part. Water is a compound of 

 hydrogen and oxygen. If an electric current is passed 

 through water to which a small amount of acid has 

 been added, it may be separated into its component 

 parts, oxygen and hydrogen. The method commonly 

 used in the laboratory is to separate the hydrogen 

 from some acid. Some metal, as zinc or iron, is used 

 for this purpose. 



Place a few small pieces of zinc in a flask and close 



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