LABORATORY PRACTICE 227 



tap the walls of the cylinder with the wood rod, distributing 

 the tapping over the whole length of the cylinder. The 

 tapping should not be severe enough to batter the walls of 

 the cylinder. 



6. After the settling has ceased, carefully brush the 

 threading of the top section, carefully vaseline at the base, 

 and add two empty sections. 



7. Introduce water into the top of cylinder, being care- 

 ful to keep the upper sections nearly full of water, until 

 water begins to percolate from the bottom. 



8. Place a piece of cheese-cloth, or some other covering, 

 over the top of the cylinder and allow to stand 48 hours. 



9. At the end of 48 hours, carefully and quickly separate 

 the sections by unscrewing ; carefully wipe vaseline from 

 joints. 



10. Place each section in a dry tared tray, numbered to 

 correspond with the number of the section. 



11. Carefully weigh each tray with contents and care- 

 fully record weight. 



12. Dry to constant weight and weigh and record 

 weight of each tray and contents. 



13. Remove, carefully wipe and weigh each section, and 

 carefully record its weight. 



14. From the data thus obtained determine : 



(a) The weight of dry soil in each section. 



(b) The weight of water contained in each section before 

 drying. 



(c) The percentage of water in each section. (The per- 

 centage is obtained by dividing the water lost in drying 

 by the dry weight of soil.) 



15. Plot curve of distribution of water in the column 

 of soil in the cylinder at the end of 48 hours after satura- 

 tion. 



