SOILS AND FERTILIZERS 



with air-dry sand, with clay, with loam, and with peaty soil. Com- 

 pute the weight per cubic foot of each soil. Calculate the weight 



of water held by the 

 box. Determine the ap- 

 parent specific gravity. 



Experiment No. 7 



Influence of Color upon 

 the Temperature of 

 Soils 



Expose to the sun's 

 rays, dry clay, dry sand, 

 and moist and dry peat. 

 After two hours' expo- 

 sure take the tempera- 

 ture of each. The bulb 

 of the thermometer 



FIG. 55. Determining the Weight per Cubic Foot should be just covered 

 of Soils. vvith the soil. All of 



the observations should be made under uniform conditions. 



Experiment No. 8 . 



Movement of Air through Soils 



Fill, without compacting, a soil tube 12 inches high and 3 inches 

 in diameter with sifted loam soil. Nearly fill the outer cylinder vvith 

 water, open the stopcock, and allow the inner cylinder to sink in 

 the water, close the stopcock and connect the aspirator to the soil tube 

 with a rubber tube. Adjust the weight, 2, open the stopcock, and 

 note the time required for 5 liters of air to aspirate through the soil. 

 In like manner fill tubes with sand, gravel, peat, and clay, and deter- 

 mine the time required for 5 liters of air to be aspirated through 

 each. In filling the tubes, care should be taken that all are treated 

 alike. Repeat the experiment, using soil from your own farm loosely 



