WHAT IS WATER? 



83 



carried out as follows : The jar has two coils or plates 

 of platinum (A and B) extending upward into some 

 water which has been made acid by having about a table- 

 spoonful of strong sulphuric acid added to half a pint 

 of water. The test tubes are each filled with this water 



drx 



cell 



dry 



cell 



switch. 



Electrolysis of water. What does this experiment show about the composition 



of water ? 



and placed over the platinum wires. The acid is used 

 to make the water conduct the electric current When 

 the current from four dry cells is sent through the water, 

 small bubbles rise from the platinum wires and collect 

 in the tops of the tubes. One gas forms twice as fast 

 as the other. If this gas is removed and lighted, it burns 

 or pops with a slight explosion. This gas has been proved 

 by experiment to be the element hydrogen. When the 

 other tube of gas is tested with the glowing end of a splint, 

 it causes the splint to burst into flame. The gas is the 

 element oxygen. These two elements have come from 

 the water because the chemist finds that there is the same 

 quantity of sulphuric acid left as he used at the beginning. 

 We may now conclude that pure water is a compound 

 made up of hydrogen (2 parts) and oxygen (1 part). 

 This is expressed in the familiar formula H 2 O. 



What Is Pure Water? Water in its purest natural 

 state is rain water. It comes from the clouds, where it is 



