ABSORPTION OF SALTS BY SOILS. 



159 



added, 3 grams to 16 liters of solution, which also carried the 

 soluble portion of 20 grams of the guano. The soils washed by 

 percolation had the solution passed through them twice, under a 

 pressure of 30 Ibs., the time required being from 30 to 45 min- 

 utes. The other set of samples were treated exactly as though 

 they were washed in distilled water, the usual three minutes, 

 standing twenty minutes for decolorizing the solution with car- 

 bon black. 



The changes which were observed, computed as in the last 

 series, appear in the next table. 



Soluble salts absorbed by S soil types during SO to 45 minutes from 

 solution of acme guano to which potassium nitrate had been 

 added. 



This set of samples, it must be remembered, had not been 

 washed and therefore contained, before applying this solution, 

 all of the salts normal to the field condition and, if the presence 

 of those salts absorbed about the soil grains could have any influ- 

 ence on the absorption of other salts, results of a different char- 



