200 



MOVEMENTS OF SALTS IN THE SOIL 



of soil thus prepared was about eight inches in height, and 

 4\ inches in diameter. The neck of the funnel was connected 

 by a cork and tube with a flask placed beneath. The flask 

 was then connected with a filter-pump, so that a diminished 

 pressure was produced in the flask and in the mass of soil 

 above it. Distilled water was next gently poured on the 

 surface of the soil, the supply of water being steadily main- 

 tained so that the surface was always supersaturated. One 

 great advantage of the connexion with the pump was that 

 the air in the soil was removed as the water descended through 

 it ; when no pump is used, the air is apt to escape upwards 

 through the wet soil, the mass consequently becomes broken, 

 and the displacing action of the water is disturbed. 



In 25 hours the whole column of soil had become saturated, 

 and dropping into the flask commenced. The drainage water 

 was collected in several portions, and the quantity of chlorine 

 and nitric acid in each portion was ascertained. The results 

 are shown in Table XXXH. 



TABLE XXXII 



COMPOSITION OF DRAINAGE WATER OBTAINED BY PERCOLATION 

 THROUGH A PREVIOUSLY DRY SOIL 



