ABSORPTION OF SALTS BY SOILS. 



117: 



Amounts of ammonia absorbed by the same soil from solutions of 

 different strength. 



Regarding these experiments Voelcker slates that, while the 

 two stronger solutions gave up to their soils about half of their 

 ammonia, the third solution only gave up one-third, and the 

 fourth but one-fourth. Relatively larger absorptions, therefore, 

 took place from the stronger solutions. 



THE POWER OF SOILS TO RETAIN AMMONIA. 



Another series of observations was made by Voelcker to meas- 

 ure the power of a given soil to hold back the absorbed ammonia 

 against washing with water. 



He used a soil which had absorbed at the rate of 4.655 grains 

 of ammonia for each 1750 grains of soil, or 2660 parts per 

 million. This sample was washed 7 consecutive times, using 

 each time 7,000 grains of distilled water. His results appear 

 below : 



A mounts of ammonia recovered from one-fourth Ib. of soil by 7 con- 

 secutive washings with 7000 grains of water. 



