WATER AND ITS EVERYDAY USES 



PROBLEM I. WHAT IS WATER? 



Those of you who live where snow falls in winter have 

 had the experience of a cold rain changing first to sleet 



and then to snow. 

 You have at some 

 time brought ice and 

 snow into the house 

 and seen it change 

 back to water. Per- 

 haps you have placed 

 it in a vessel over 

 the fire and watched 

 it pass off into the 

 air as steam. You 



What kind of changes are taking place here? have all seen water 

 How do you know ? . ,-, ,, 



in the three states 



solid, liquid, and gas. But in all of these conditions, 

 its molecules are still made up of the same elements. 



How Scientists Found Out the Composition of Water. 

 Water is so common it seems absurd at first to ask, " What 

 is water?" And yet if any one asked you the question, 

 what would you answer? Is water an element? Is 

 it a compound? Does it contain several things mixed 

 together? The chemist has at his command several 

 methods by which he can solve such a problem as this. 

 As long ago as 1784, Henry Cavendish burned hydrogen 

 in oxygen and produced a liquid. This liquid he found 

 had all the properties of water and in fact was water. 

 Sixteen years later, two chemists, Nicholson and Carlisle, 

 reversed the process of Cavendish. They began with 

 water, and by using electrical energy tore the molecules 

 apart and produced hydrogen and oxygen. This process 

 is reproduced now in thousands of schoolrooms every 

 year. The process is called electrolysis of water and is 



