196 § 107. ANALYSIS OF SOILS AND EOCKS. 



3. To determine the ease with which water perco- 

 lates through the soil, construct a zinc box about 25 cm. 

 high and 3 cm. square, with a funnel-like bottom; put 

 some cotton in the bottom, so as to close up the throat 

 of the funnel, and fill the narrow tube, and extend out a 

 little at the mouth of the latter. Fill the funnel above 

 the cotton with coarse quartz sand, moisten the cotton 

 and sand with water, and weigh the apparatus ; then 

 carefully fill the box with the properly prepared earth, 

 putting in small quantities at a time, and tapping the box 

 on the table after each portion is added ; when the box is 

 filled to within 9 cm. of the top, weigh the whole again ; 

 then, just saturate the soil by carefully pouring on water 

 in small quantities at a time, until it appears at the 

 bottom ; when it has ceased to drop through, weigh the 

 box and its contents again, and the result may be used 

 to confirm that obtained before for the water-holding 

 power of the soil. 



Now carefully fill the box with Avater to within 1 cm. 

 of the top without disturbing the surface of the soil, 

 cover with a glass plate, and observe how long a time is 

 required for 50 c.c. of water to pass tlirough. If the 

 operation is repeated, by filling the box with water again, 

 after the first quantity has passed through, it will be 

 found that a somewhat longer time is i-equired ; three 

 such tests may be made, and the mean of the three re- 

 sults taken. 



4. To determine the rapidity with which water will 

 move upwards in the soil, fill a glass tube about 80 cm. 

 high and 1.5-2 cm. in diameter, graduated in cubic cen- 

 timetres, and closed at its lower end with a piece of fine 

 linen that is tied over the end, with the air-dried soil, tap- 

 ping the tube gently on the table while filling it ; then 

 immerse the lower end of the tube in water 3-4 mm. 

 deep, and observe how long a time is required for the 

 Avater to rise to a height of 70 or 80 cm., or how high 



