SECOND BOOK. 
154 
through the soil. In the open country it is generally 
pure, but in large towns it is often unfit to drink, 
because of the impurities which it washes out of 
the air. 
4. “ When it falls on the ground much of it soaks 
in, and in time reappears in springs. But in its 
passage through the soil it either dissolves, or 
Section of Hillside. 
A, The upper part of the hill — limestone— through which the rain-water passes. 
B, The clay below, through which the water cannot pass, and upon which it flows 
to, C, The spring, or place where the water breaks forth from the hill. 
carries along with it, some of the earthy matter. If 
it passes through chalky soil it is sure to dissolve 
some of the lime, and then it becomes ‘ hard ’. As 
a rule, spring-water, although hard, is excellent for 
drinking, though not so useful for washing purposes 
as the soft rain-water. 
5 . “ Sometimes wells are dug. If these are only 
a few feet deep, the water they collect is very likely 
to contain impurities, which it gathers from the 
