[lynde-dtjpré] 



CAPILLARY LIFT OF SOILS 



125 



capillary lift of the soil constituents fell between the calculated limits 

 in all cases except that of clay. The lowest calculated lift for clay is 

 2118 cms. or about 70 feet, but the observed lift was only 817 cms. 

 or about 26-8 feet. 



From these results we concluded that, with the apparatus arranged 

 as above, the pressure of the atmosphere limits the capillary lift which 

 can be observed. 



To test this conclusion we decided to measure the capillary lifts 

 produced, under pressures equal to, greater than and less than one 

 atmosphere, by a soil the calculated lift of which is greater than the 

 length of water column supported by one atmosphere. We reasoned 

 that, if it is the pressure of the atmosphere which limits the capillary 

 lift observed, then with a pressure greater than one atmosphere we 

 should obtain a greater lift, and with a pressure less than one atmosphere 

 we should obtain a less lift, then we obtain when the pressure is one 

 atmosphere. 



Experiments 



We carried out experiments of this nature with the soil constituent, 

 clay, mentioned in Part II. The lowest calculated capillary lift for 

 this soil is 2118 cms. 



Apparatus. — To obtain the lift under a pressure of one atmosphere 

 the apparatus was set up as shown in Fig. 1. 



FROM AIR PUMP 



lARGC CLASS TUBL- 



MtRCURV CUP 



Figure 2. Apparatus used to measure the capillary lift produced by a soil under 

 a pressure greater than one atmosphere. 



