174 BOARD OF AGRICULTURE. [Pub. Doc. 



hygiene, it is our duty to obtain for animals a supply as 

 pure as is consistent with circumstances. 



The characteristics of a pure water are absence of color, 

 taste, smell or extreme hardness. Impurities found in 

 water are of various kinds, but may be generally stated 

 to be organic or inorganic. The organic impurities are 

 small and vegetable substances in all forms, from disease- 

 producing matter to harmless vegetable growths. The in- 

 organic impurities are the salts of the metals. 



These impurities obtain entrance into the water in various 

 ways, either at its source or during its passage through 

 rivers, canals or pipes, or even after its delivery to the 

 place of consumption. The impurities obtained at this 

 origin will depend upon tke geological formation of the 

 soil in which the source is situated. If the ground is 

 charged with the products of animal excreta and refuse, 

 the "water derived from it will contain these products in 

 solution ; but it is evident that some soils or formations are 

 more impure than others, and this difference in the degree 

 of soil impurity depends upon the power the ground pos- 

 sesses of oxidizing or destroying the filth which is carried 

 into it. Where rapid destruction of this occurs, there we 

 may expect to find a purer water than in formations where 

 it does not. Moreover, the porosity of the soil, especially 

 when of great depth, will considerably assist in purifying 

 the water by acting as a natural filter. 



It is evident that in deep, porous soils, where rapid oxi- 

 dation and destruction of organic matter occur, we may 

 look for water of a pure type, and the more we depart from 

 these conditions the more impure will be the water. Again, 

 the presence of the salts of metals in great abundance in the 

 formation will affect the purity of a water ; for we find that 

 these substances, such as lime, magnesium, soda, potash, 

 iron and alumina, are very readily acted upon by the water 

 passing through the soil, and rapidly taken up in solution. 

 In gravel formations we usually expect to find a pure 

 water, particularly away from towns. Where clay exists 

 the Avater is usually impure; in alluvial formations it is 

 generally bad; iu limestone and chalk districts the water is, 



