CHAPTER V 



WATER 



Water is one of the common things that daily show us 

 the many ways in which matter can change its form. We 

 see it flow quietly in a stream, or dash itself to spray and 

 mist on the rocks under a waterfall. We see it float in 

 clouds above us, glisten on the grass as dew, fall as rain, 

 or hail, or in exquisite snow crystals. We see it freeze 

 to a solid, or heat to steam and vanish from sight into the 

 air. It influences our climate and affects our comfort and 

 our health. 



Water is everywhere. Not only does it cover three- 

 fourths of the earth's surface, but it is in the air about us 

 and in all living things. We ourselves are more than half 

 water. Without water, life cannot continue. For our own 

 good we must know something about water, about its 

 service to us, and about the necessity of keeping pure the 

 water that we use. 



Water is a compound of two gases hydrogen and oxygen. 

 The gases unite in the ratio of two parts of hydrogen to one part 

 of oxygen. Therefore water is known by the familiar chemical 

 formula H 2 O, in which H 2 stands for the two parts of hydrogen 

 and O for the one part of oxygen. In a pure state, water, like its 

 elements hydrogen and oxygen, is colorless, tasteless and odorless. 



Experiment to Show the Composition of Water. That 

 water is made up of these two gases, hydrogen and oxygen, may 

 be shown by the use of an instrument called an electrolysis ap- 

 paratus. This consists of two connected glass tubes each con- 

 taining a platinum plate known as a terminal, or electrode. Elec- 

 trolysis is the act of breaking up a substance into its elements by 

 means of electricity. To break up water into its elements, fill 

 the electrolysis apparatus with water made slightly acid with 

 sulphuric acid. Connect one wire of an electric storage battery 

 circuit to one terminal of the apparatus and the other wire to 

 the second terminal. If a storage battery is not at hand, two or 

 three dry cells may be used. Bubbles will start to form on the 



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