EXERCISE A-17. 



A STUDY OF " WARM " AND " COLD " 

 SOILS. 



Equipment: Dry loam soil; two thermometers; two 

 flower pots or quart cans; a beaker or tumbler. 



Method: (a) Tie a piece of muslin cloth around the 

 bulb of one thermometer and suspend it over a tumbler 

 with the lower end of the cloth dipping into the water, 

 but the bulb one inch above the surface. Suspend the 

 other thermometer in the air near the tumbler. At the 

 end of ten minutes read both thermometers and take the 

 temperature of the water. Record as follows: 



Why is the temperature of the wet bulb lower than that 

 of the air or water? 



(b) Fill two flower pots with the dry soil and add 

 sufficient water to one to thoroughly wet the soil. Insert 

 the bulb of one thermometer to the depth of one-half inch 

 into the wet soil and the other to the same depth into the 

 dry soil. Make a reading of both thermometers at the end 

 of fifteen minutes. 



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