THE HOME WATER SUPPLY 



47 



FIG. 14. The two figures on the right show the right way and the figure on the 

 left shows the wrong way to construct a well. 



DEMONSTRATION 10 



Purpose. To test the purity of drinking water. 



Apparatus. Distilled water, samples *of drinking water from 

 several sources, solution of potassium permanganate, nitric 

 acid, solution of silver nitrate, two beakers, test tubes. 



Directions. I. To test for decaying vegetable matter. 

 Pour some distilled water into a beaker. Pour the same amount 

 of drinking water into another beaker. Add to each beaker 

 one drop of potassium permanganate solution. Boil the drink- 

 ing water for a few minutes and allow it to cool. Compare the 

 colors in the two beakers. If the color of the drinking water 

 is very different from the pinkish tint. of the distilled water, 

 vegetable impurities are present. 



