49 



PRACTICE 24 

 A Study of tiie Capillary Power of Soils. 

 The capillary power of soils is influenced by several factors, the 

 most important of these being the physical composition, texture and 

 compactness of the soil. In field soils all of these are changed by con- 

 tinuous cropping and capillary action is therefore altered. Of these 

 factors, physical composition is most important. 

 The soils selected are as follows: 



1. Peat. 



2. Sod, preferably an old blue grass pasture. 



3. Heavily cropped soil as near (2) as possible so that the type of 

 soil will be the same. 



4. Clay. 



5. Silt. 



6. Loam. 



7. Loess. 



8. Sand that will pass a 100 mesh sieve but not a 120. 



9. Sand that will pass an 80 mesh sieve but not a 100. 



10. Sand that will pass a 60 mesh sieve but not an 80. 



11. Sand that will pass a 48 mesh sieve but not a 60. 



12. Sand that will pass a 20 mesh sieve but not a 40. 



13. Sand and clay equal parts by weight. 



14. Loess and clay equal parts by weight. 



15. Loess and sand equal parts by weight. 



16. Loess with 10 per cent of well ground peat. 



17. Sand with 10 per cent of well ground peat. 



18. Clay with 10 per cent of well ground peat. 



19. Silt and 5 per cent peat. 



20. Silt and 10 per cent peat. 



21. Silt and 15 per cent peat. 



22. Silt and 20 per cent peat. 



23. Silt and 35 per cent peat. 



24. Silt and 50 per cent peat. 



One end of the large glasstubes is closed by means of a piece of 

 muslin firmly tied on. These tubes are then filled with the finely 

 pulverized and sifted air-dried soils. Great care must be exercised 

 in filling these tubes so as not to separate the coarse and 

 fine particles. This may best be accomplished by holding the tube 

 vertically during the process of Ailing. When the tubes are filled, 

 the soil is compacted slightly by letting each tube drop 4 times, a 

 distance of 4 inches upon a book. The tubes are now placed in the 

 supporting frames in such a manner that the ends shall dip one half 

 inch beneath the surface of the water contained in the tray. The 

 water should be turned in all trays at the same time. The exper- 

 iment is now ready for observation and the data to be obtained at 

 each reading is the total hight to which the water has risen. The 

 readings are to be taken as nearly as possible at the intervals stated 

 below and tabulated. 



