70 THE ROYAL SOCIETY OF CANADA 



It was found that (1) the pressures were greater when the soil 

 had been shaken with ammonia than when it had been shaken without 

 ammonia; (2) the minimum effective quantity of ammonia was 10 

 drops with 30 g. of subsoil and 150 c.c. of water; (3) the minimum 

 effective time of shaking was 2 hours; (4) greater pressures were ob- 

 tained when the soil had been boiled to expel ammonia than when 

 it had not been boiled. 



A mechanical analysis of the clay subsoil gave the following results: 



Clay 68-8% 



Silt 19-3% 



Very fine sand 11 -9% 



Fine sand 0-0% 



Coarse sand • 0% 



Part of the clay consisted of extremely fine particles which, on long 

 standing in water, assumed a jelly-like appearance, that is, part of 

 the clay was colloidal in nature. 



Measurin g Tube 



Rubti'frr Sfo pper 



Soil Solution 



Fig 1 



HOW THE APPARATUS WAS SET UP. 



The apparatus used in the first, third and fourth tests was ar- 

 ranged as shown in Fig. 1 , that used in the remaining tests was arranged 

 as shown in Fig. 2. 



