SOLUTION 45 



Hard water is not good for washing. When you use 

 soap with hard water a dirty sediment is produced. This 

 prevents the formation of a lather, unless a good deal of 

 extra soap is used. When hard water is boiled, some of the 

 mineral matter in it is deposited on the sides and bottom of 

 the boiler or kettle. You may have noticed this formation 

 (fur} on the inside of a teakettle. It sometimes forms what 

 is known as boiler-scale on the inside of the pipes in steam- 

 boilers, and renders them useless until they have been 

 cleaned, which is an expensive process. 



River-water is usually soft, though it contains some min- 

 eral matter, and may carry a good deal of soil in suspension, 

 thus giving it a muddy appearance. Lake-water is softer 

 than well or spring water, but usually harder than river- 

 water. Rain-water is very soft, and hence is collected 

 in cisterns for use in washing. Though best for washing, 

 it is not best for drinking. It contains impurities washed 

 from the atmosphere and from roofs, and its taste is less 

 agreeable than that of other kinds of water. 



QUESTIONS 



1. What is a solution? 



2. Why do we use paint? 



3. Do fishes breathe air? Explain. 



4. Why do bubbles form in heated water before it is hot enough 



to boil? How could you prove that these were not steam 

 bubbles? 



5. What is soda-water, and why does it fizz ? 



6. What is the composition of the air? 



7. What is the difference between hard and soft water? 



8. Why does "fur" form on the inside of a teakettle? 



