7 6 



WATER IN THE HOME 



Rain water. When we think it out rain water must 

 also be very pure, for is it not condensed in somewhat the 

 same way as the drops of water we collected in the last- 

 experiment? Breathe on a cool glass. What happens? 

 The little drops of moisture have been condensed because 

 warm, moist air was suddenly cooled. Moisture in the 

 air comes from evaporation from water surfaces and from 

 all moist surfaces. Leaves give off moisture in the form of 



water vapor. An acre of 

 clover may give off from 

 500 to 750 tons of water 

 during a single season. 

 The production of one 

 pound of some plant 

 foods requires that two 

 to five tons of water be 

 taken from the soil and 

 most of this is evapo- 

 rated into the air from 

 the leaves. An acre of 

 Indian corn gives off 

 nearly a thousand tons of water in a season. When this 

 moisture in the air condenses clouds form. From clouds 

 water falls in the form of rain. 



How we get rain water. In many parts of the world 

 people drink rain water. On the islands of Bermuda, for 

 example, great cisterns are cut in solid rock to hold the 

 water, and the people of the islands depend entirely upon this 

 supply. If rain water is collected in clean cisterns or bar- 

 rels it is perfectly pure. But unfortunately the cisterns 

 and rain barrels are sometimes not clean. Roof drains and 

 gutters are allowed to become clogged with decaying vege- 



Explain this diagram. 



