EXERCISE No. 59 

 FREEZING AND THAWING 



Object : To show the effect of freezing and thawing upon 

 soil structure. 



Material : Clay soil and a mixing board. 



Method : Take a big handful of clay, wet it, mix it well, 

 and mould it into a ball with the hands. Prepare a second 

 ball of clay in the same manner, adding the same quantity 

 of water to an equal weight of clay. Expose the second ball 

 of clay to alternate freezing and thawing about ten times. 

 Keep the first ball in a frozen condition. At the end of a 

 week allow both balls to thaw out. 



Conclusion: Compare their structures. What has hap- 

 pened? Tell the reason. 



