67 



E.rpei'hiuid No. 9. 



A STUDY OK THE KATE OF RISE OF CAPILLARY WATER J X SOILS. 



Use soils Nos. 1, 2, 3, 4, and 5 in tiiis experiment. Place a cheese-cloth disk in 

 the bottom of each tube (fig. 18) to prevent the escape of soil grains. Use the com- 

 pacting machine to fill the tubes, all(5\ving the weight to drop twice from the 12-inch 

 mark after each mea.«ure of soil. Weigh the filled tubes carefully and place them in 

 the frame with the lower ends standing in about 1 inch of distilled water, which 



should be maintained at constant level. 

 As the water rises by capillaritj- into the 

 soil the tubes will increase in weight. 

 Weigh the tubes carefully each day for 

 one week, noting the daily increase in 

 each tube and also the total increase 

 for each tube for the period. 



Experiment Xo. 10. 



TO TEST THE ADHESIVENESS OF SOILS. 



In this experiment soils Nos. 1, 2, 3, 

 and 4 will l»e used. The adhesiveness 

 will be determined bv measuring the 



Fig. 18.— Measuring capillarity in soils. 



force reciuired to overcome the molecular attraction in a column of moist soil 1 

 square inch in cross secti(jn. 



Weigh out roughly 150 grams of soil Xo. 1 and ISO grams each of Nos. 2, 3, and 4. 



Determine the force required to start the empty movable cage (a) by running sand 

 from the rul^ber tube (h) into the tin pan (r) until the weight is sufficient to cause 

 the cage to move (fig. 19). See to it that the cages are clean and the bearings clean 

 and oiled. The weight of the pan plus the sand it contains represents the force 

 required to overcome the friction of the empty cage, and should be deducted from 

 the total breaking force in each subsequent test of soil. 



Empty the weighed sample of soil upon the "mixing board" and add a small 

 quantity of water. 3Iix soil and water thoroughly by hand Avorking. P^lnough 

 water should be added to bring the soil to its maximum adhesiveness. 



Pack the roll of mud thus formed into the mold, holding the cages together firmly; 

 then with the spatula scrape off the top level with the upper edge of the mold. 

 Attach the pan to the hook at the end of the wire. Pour sand into the pan in a 

 constant stream until the weight is sufficient to separate the cages and break the soil 

 column. Weigh the pan with the sand it contains and deduct therefrom the weight 

 required to overcome the friction of the empty cage. The result represents the adhe- 

 sive strength of a column of moist soil 1 square inch in cross section. 



