126 



THE ROYAL SOCIETY OF CANADA 



To obtain the capillary lift produced by a soil under a pressure 

 greater than one atmosphere we used the apparatus shown in Fig. 2, 

 The apparatus was set up as in Fig. 1. It was then placed in a large 

 glass tube closed at the lower end by a solid rubber stopper and at the 

 upper end by a stopper with two holes. A continuous stream of air 

 was forced into the glass tube through one hole. It passed out 

 through the other and into the pressure gauge. The clip of the pressure 

 gauge was so adjusted that although air passed out continuously a 



yACUUM CAUCEL 



LAROt C1AS$ TUBL— 



Figure 3. Apparatus used to measure the capillary lift produced by a soil under 

 a pressure less than one atmosphere. 



certain pressure greater than one atmosphere was maintained in the 

 apparatus. 



Thus water evaporated from the surface of the soil and the capillary 

 lift was produced, under a pressure greater than one atmosphere. 



To measure the capillary lift produced by the clay under a pressure 

 less than one atmosphere we used the apparatus shown in Fig. 3. This 

 apparatus is similar to that used in Fig. 2, except that air was drawn 

 through the large glass tube by means of a filter pump. The clip 

 was so adjusted that although air passed in continuously, a certain 

 pressure, less than one atmosphere, was maintained in the large glass 

 tube. 



Thus water evaporated from the soil and the capillary lift was 

 produced, under a pressure less than one atmosphere. 



