SOLUTION AND CRYSTALLIZATION 99 



, also acts as the medium by which other important foods are 

 brought into the plant's body. 



The Soil. 



The facts brought out in the lessons immediately preceding 

 may be made to introduce a more careful study of soils. The 

 general structure of the soil, and the different kinds of soils 

 may be studied; also the relation of these to growing roots 

 and percolating water. 



In general, soil may be said to be made up of clay, sand, 

 gravel and vegetable or animal remains. All of these may be 

 present, and in different soils in varying proportions, or only one 

 or two of these may be in soil from a particular locality. 



Clay consists of very fine particles only ; and when alone, it 

 makes a compact, stiff, heavy soil that is hard to work with farm- 

 ing tools. 



Sand is composed of larger particles, and when alone, makes 

 a loose, light soil, easily worked. 



Gravel is made up of coarse particles and stones of various 

 sizes. 



Secure a portion of soil from any source, and have the pupils 

 separate the sand from the clay as follows: In a suitable vessel, 

 stir the soil up thoroly with water, and pour off the muddy water 

 into another vessel. By repeated washings all the muddy parts 

 (which are the clay) are separated from the sand and gravel. These, 

 if both are present, may be separated by a fine screen (wire 

 netting). The vessel containing the muddy water is allowed to 

 stand, until the soil settles; then the water is removed. The sedi- 

 ment is the clay. All may be dried and the proportional amounts 

 determined. 



Next study the properties of clay and sand. Placed on a 

 filter (a funnel with a cloth or filter paper), clay retains the water, 

 while sand allows it to pass rapidly thru. Note the effect of pack- 



