846 



Handbook of Nature-Study 



covered. Constilt a watch and note how long before the water begins 

 dripping below. Do the same with the other two. Compare the results. 

 Which soil takes the water most rapidly? Which lets it through first ? 

 Which lets through the most ? How would rain affect fields of clayey soil ? 

 Of sandy soil ? Of loam ? 



Hints for teacher on Experiment No. i — Through sand the water passes 

 very rapidly — in less than a minute if the sand is coarse. It takes several 

 minutes (14 min.) to go through loam, but requires some hours to appear 

 below the clay. It requires more water to saturate clay. Care should be 

 taken to use the same amount of water on the three kinds of soil. More 

 than one application will be required for clay, since the amount of water 



Loam. Sand. Clay. 



Note that the sand has allowed the most water to drip through it, the loam next, 

 while no water has passed through the clay. 



accommodated in the chimney above the soil wiU not be sufficient to satu- 

 rate clay. 



More water will be found to have percolated through sand than through 

 loam or clay. The latter are mora retentive of moisture than is sand, 

 although absorbing rain less readily than sand. The mixture of sand and 

 clay in loam is most ideal for cultivated fields, absorbing moisture more 

 readily than clay and retaining it better than sand. 



Experiment 2 — Fill a glass tumbler with very small marbles or buckshot. 

 Pour water over them to fill the glass. Placing cheesecloth over the top of 

 the tumbler pour off all the water that easily drains away. Remove the 

 cheesecloth, and immediately examine the marbles for the film of water 

 which surrounds each one and can clearly be seen where one marble comes in 

 contact with another marble or the side of the glass. 



Hints for teacher on Experiment 2 — It is sucn a film of water as remains 

 on the marbles that on each particle of soil supplies the plant with water and 

 food. The water between the marbles has been drained off. This water 

 corresponds to that carried out of the soil by drainage; it is injurious to the 

 plant, keeping ' 'its feet too wet, ' ' and should be removed. 



