Il8 PROCEEDINGS OF THE COTTESWOLD CLUB 



impure water. Water as we commonly know it therefore, 

 is an aqueous solution of the various soluble materials 

 with which it has been brought into contact, and swimming 

 in and upon it is also matter living and unliving -which is 

 not capable of being actually dissolved. 



Its Natural Impurities 



The natural impurities of water then arc such as the 

 earth and the air are capable of yielding to it, and consist 

 of inorganic or mineral material, of material of organic 

 origin, of actual organisms, and of gases. As water 

 passes hurriedly over the surface of the ground, or 

 rushes down its natural channels after heavy rains, it bears 

 with it much sand and clay and such like gross material 

 diffused through it in a more or less fine state of division, 

 and giving the water a turbidity, which, however, is lost 

 by deposition of the suspended matter as soon as tran- 

 quility is restored. But limiting ourselves to what we 

 call clear water, we may find the main inorganic impurity 

 to consist of lime salts and particularly of carbonate of 

 lime, whilst magnesia and soda salts take a secondary 

 place, and silica alumina and iron occur only in very small 

 quantity ; the mineral acids in combination being chiefly 

 sulphuric hydrochloric and nitric, besides carbonic. When 

 water is brought into contact with deposits of soluble 

 salts that lie here and there in the crust of the earth, 

 relatively large quantities are sometimes taken into solu- 

 tion, and we get what is called a " mineral water." In 

 such excessive mineralization of water the salts of magnesia 

 and soda — sulphate, chloride and carbonate — are mainly 

 concerned, and iron in the form of carbonate and chloride 

 enters into solution in the creation of what are known as 

 " chalybeate waters." Sulphate of lime or gypsum is a 

 common impurity in water, being readily dissolved wher- 

 ever it occurs, but the lime in most ordinary waters is as 



