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NATURE STUDY REVIEW [9 :3— Mar., 1913 



before. Shake and compare the suds now gotten, with the re- 

 suhs from the "hard" water. Which of the two kinds of water 

 is best adapted to washing and cleaning where soap must be used? 



3. Common sources of zvater and their impurities. — (a) 

 Secure a sample of water from a well or spring. Pass some of 

 this water through clean filter paper into a bottle. Is there any 

 solid stuff left on the filter paper? Are there any "wugglers" in 

 it? Any germs? You could find out by "planting" some of the 

 stufif on a germ culture medium. Let the water that passed 

 through the filter onto the bottle either dry away or be boiled 

 away, and see if any stufif is left on the glass surface. Where 

 was it before the water dried up? 



(b) Similarly treat water from a cistern. Compare the 



