Water 65 



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Soap is a substance used with water in cleaning. It is espe- 

 cially valuable for this purpose, since it will form an emulsion with 

 grease or oil. 



Alkalis are certain substances used in cleansing materials, 

 and in counteracting the effects of acids. When acids and alkalis 

 are combined they form harmless salts. 



FACT AND THOUGHT QUESTIONS 



1. Complete orally the following statements : 



(a) Water is composed of the gases . 



(b) Water covers of the earth's surface. 



(c) Three common sources of water supply are . 



2. What becomes of water that falls to the earth in a storm? 



3. How do large bodies of water affect land crops ? 



4. Name several conditions which make water unsafe for drinking. 



5. There are excellent springs at about equal distances above and below 

 a hillside farmhouse. From which spring would you advise drawing 

 the house water supply? Why? 



6. Would you expect to find a spring on the summit of the highest land in 

 your neighborhood? Why? 



7. Mention ways of sewage disposal in which water is employed. 



8. Why is the septic tank more sanitary than the cesspool? 



9. Why is good plumbing necessary to a home ? 



10. Suggest three ways in which the power of water to dissolve material 

 helps us. 



11. Where* does your town, or the nearest town, get its water supply? 



12. Why is a water tank often placed higher than the building it serves? 



13. Name certain steps that should be taken to safeguard a water supply 

 from pollution. 



14. How is artificial ice manufactured? Is such ice different from natural 

 ice? 



15. Describe three ways in which water is purified. 



16. Define (a) soap, (b) emulsion, (c) acid, (d) alkali, (e) salts. 



17. How does soap act as a cleanser? 



18. Define hard water. Define soft water. 



19. Would you rather wash clothes in hard or in soft water? Why? 



20. What causes mineral springs? Are all mineral springs valuable for 

 drinking purposes? 



PROJECTS 



1. Describe the water supply system of your town. 



2. Make a small jar of soap. Tell briefly how you did it 



