CHAPTER IV 

 NATURAL WATERS 



Pure Water or the substance made of the two elements hyd- 

 rogen and oxygen practically never occurs in Nature. Because 

 of its great solvent properties, water always dissolves certain 

 quantities of every substance with which it conies in contact. 



The purest form of natural water is rain ; however, rain water 

 is never pure, but contains varying quantities of dissolved mat- 

 ter. The quantity of dissolved substances will depend upon the 

 locality in which the rain fell. In cities and in the neighborhood 

 of factories this will be larger than in the open country. The 

 character of the substances in solution will also depend upon the 

 locality. The rain water in cities, besides containing compounds 

 of nitrogen, as ammonium nitrate, may be acid. This is due to 

 dissolved sulphuric acid, which had its origin in the sulphur di- 

 oxide produced from burning coal. In addition to these sub- 

 stances rain water contains dissolved gases. 



"When it reaches the earth the water at once begins to dissolve 

 the substances upon which it falls. In regions where the surface 

 is composed of hard, igneous rocks, the quantity of material dis- 

 solved is small, while on lime-stone soils the amount of calcium 

 carbonate that goes into solution is large. 



The water which drains away from a soil, partly finds its way 

 into the nearest creek, then to a stream or river, and finally to 

 the sea. Another portion sinks into the earth, until stopped by 

 some impervious layer of rock as shale or hard pan when it 

 accumulates and eventually finds an outlet at some lower level 

 in the form of a spring. 



The industrially important waters may be classed as folio 



1. Rain water. 



2. Ground waters furnished by 



(a) Springs, 



