20 ELEMENTS OF AGRICULTURE 



and trash; but much of the rain soaks down into the 

 soil and comes out again in springs and wells. The 

 rain water in passing through the soil dissolves many 

 substances which it takes with it when it comes from 

 the soil. Mineral springs result when the water has 

 dissolved much of the salts or other mineral matter in 

 the soil. A water that has dissolved in it a large quan- 

 tity of certain minerals is a hard water. A soft 

 avater is one almost free from any dissolved matter 

 When water dissolves substances and carries them from 

 the soil it is said to lea.ch the soil. The salts and 

 other substances which water dissolves in its passage 

 through the soil are carried by the water until it reaches 

 some sea or lake. Here the salts remain; for when 

 water evaporates it carries nothing with it, the salts and 

 other impurities being left behind.. Rain water, you 

 know, is very pure and soft. So rivers are constantly 

 pouring salts of various kinds into the sea, and as none 

 comes out again the sea is becoming more salty every 

 day. This change, however, is very slow; for seas and 

 oceans, you must remember, are very large bodies of 

 water, and it takes a vast quantity of salt to affect them. 



17. Rain as a Robber. — Judging by the way it be- 

 haves to the soil, rain water must be considered a great 

 robber, and when farmers are careless and give it a 

 good chance, it will undoubtedly rob the soil of much 

 that is valuable. If allowed it will also cut great gullies 

 in exposed fields, wash away bridges and roads, and 

 even take away crops from the fields. But where the 

 rain does all this mischief it is usually the fault of the 



