156 LABORATORY LESSONS IN GENERAL SCIENCE 



enough to stand above the surfaces. Shake all well, let 

 settle fully, and then drain off the water into separate dishes. 

 Measure the amount of such drainage in each case. Ex- 

 plain any marked difference. 



4. Put into a test tube a half inch of soil that apparently 

 is dry, and heat it gently. Watch closely for any evidences of 

 moisture in the tube as the heating is continued, and explain. 



Examine some soil that feels and looks moist. Just where 

 in the soil is this water, and how is it held in place? 



5. Weigh out several grams of apparently dry soil in an 

 evaporating dish. Heat it gently, stirring all the time, and 



FIG. 70. Rise of soil water by capillarity. 



be careful not to char or cause other change in it than to 

 drive off any water in the sample. Weigh anew, and calcu- 

 late the per cent of loss of moisture from the soil when dried. 



6. Let pieces of cheesecloth be tied over the small ends 

 of three student-lamp chimneys, and have one chimney 

 filled with sand, one with loam, and one with silt. Have 

 the contents of the chimneys made compact by jarring. 



