WATER 5 



its organic matter and air is extruded. This does not mean that 

 ice is pure. It is usually purer than the original water, but it 

 may contain pathogenic bacteria which freezing does not destroy. 

 It is important to bear this in mind, especially in Eastern countries 

 where large quantities of ice, often of doubtful origin, are used. 



Ice water owing to its freedom from dissolved gases is 

 unpalatable. 



Distilled water. This may be obtained from sea or fresh 

 water. In either case it is pure, but is unpalatable. Distilled water 

 as obtained on ships has often an unpleasant taste. 



THE UTILITY OF WATER FROM THE VARIOUS SOURCES. 



Because a water has a pleasant appearance and is palatable it 

 is not necessarily wholesome, for water may be contaminated with 

 sewage and yet be sparkling and pleasant to drink. Waters have 

 been classified according to their palatability and wholesomeness by 

 the Rivers Pollution Commissioners as follows : 



( Spring water, . . . ) , r 



> Very palatable. 

 Wholesome, . < Deep-well water, . ) 



' Upland surface water, . j 



; Moderately palatable. 



Suspicious, . / Stored rain water > 



I Water from cultivated land, \ 



( River water / Palatable. 



Dangerous, . J Klver water ' ( 

 I Shallow-well water, . / 



This classification must be applied with due regard to modifying 

 circumstances, and must not be taken too literally. Upland surface 

 water though usually pure may, on occasion, be badly polluted, and 

 shallow springs may yield water as dangerous as that from shallow 

 wells. The classification indicates generally what may and what 

 may not be regarded as wholesome. 



Rain water is chiefly used for washing owing to its softness. 

 In the vicinity of towns it cannot be regarded as fit for drinking 

 purposes, even if great care be taken in its collection. Surface 

 or ground water, especially from low-lying land, is always to be 

 looked upon as dangerous. 



The utility of a water is influenced considerably by the amount 

 of dissolved mineral that it holds. Waters containing much 

 mineral matter are spoken of as hard, those containing little as soft. 



HARDNESS OF WATER. 



The term " hard " describes and owes its origin to the hard 

 or harsh feeling that is obtained when soap is rubbed up with certain 



