276 



GENERAL SCIENCE 



and determine from this the loss for the periods of time mentioned above. 

 Turn on the faucet so that a very slight stream runs. Try several different 

 streams, from slow dripping to a stream the size of a pencil. 



I IG. 175. What part of this faucet must be renewed whenever there is a 

 leak? What causes the water to run from the pipe? 



Sources of Fresh Water. Fresh water may be obtained from: 



1. Rain water. 



2. Lakes and rivers. 



3. Springs and shallow wells. 



4. Artesian wells. 



Not all water which looks clear may be considered pure. Shallow 

 wells and springs may often contain surface water which has been 

 contaminated. Sparkling spring water may be very unsafe to drink. 

 Artesian well 'water, however, is usually pure, since the water comes 

 from such a great depth in the earth that it cannot be affected by 

 animal contamination. Such water usually contains a great many 

 mineral compounds. 



