34 

 PRACTICE 16 



Determination of Conductivity of Soils 



Use sand, loam, silt, clay, and peat. 



In one end of tray* place the copper vessel for the water and put 

 asbestos plates on all sides except the one adjacent to the soil. Fill 

 the tray with the soil to be tested. Place thermometers at a depth 

 of 2i inches and 1, 2, 3, 4, 5 and 6 inches from the vessel with the water 

 and apply heat to the water through the opening in the bottom of 

 the tray. Read thermometers about every five or ten minutes for 

 about one hour. Tabulate results. 



Students should work in sets of five, each student testing one 

 soil and giving data to other four for comparison. Is there any rela- 

 tion between porosity and conductivity? 



*The tray is made of galvanized iron 18 inches long by 5 inches wide and 5 inches 

 deep. At one end of the bottom is a circular opening 2 inches in diameter through 

 which heat is applied to the copper vessel containing water. This is 4" X 4" and five 

 inches deep with a lid with two holes, one for a thermometer and one for the escape of 

 steam. 



PRACTICE 16 



