USES OF WATER 



121 



upon the amount of mineral matter that it has dissolved 

 from the ground that it has passed through. Usually 

 this mineral matter is calcium carbonate (lime) and 

 magnesium carbonate, but often- other minerals are found. 

 The ocean is said to contain traces of all the soluble ele- 

 ments, together with large quantities of the substances 

 we have named above, and common salt. Well water is 

 always hard, but of varying degrees of hardness. The 



FIG. 107. Low Lift Pump Room, Cleveland, Ohio. 

 This is the largest low lift pumping station in the United States. 



water of the streams is usually quite soft, increasing in 

 hardness as it gets farther away from its source and 

 comes in contact with more soil from which it dissolves 

 small quantities of solid matter. If hard water is boiled 

 for a short time, a white deposit will be noticed in the 

 vessel in which it was boiled. This deposit is mostly lime. 

 Is there any deposit when soft water is boiled ? 



Spring water is simply rain water that has percolated 



