162 



would have carried had all of the materials found been in solu- 

 tion in the soil moisture when the samples were collected. 



No chlorine or silica was included in this solution. 



The solution was passed through the samples three times in 

 quick succession and there was included in the series a sample of 

 freshly crushed granite composed of orthoclase feldspar, musco- 

 vite mica and quartz. The amounts of absorption which took 

 place are indicated in the next table. 



Absorption of salts by 8 soil types and by freshly crushed granite. 



The solution used on these samples, it will be observed, is very 

 much stronger than that used in the last series, but in these cases 

 upon samples which had been freed of much of their readily 

 water-soluble salts by repeated washing. TheJ result was the 

 throwing out of solution much larger amounts of every ingre- 

 dient present except phosphoric acid. The amount of phosphoric 

 acid present in this solution, however, was only!2 parts per mil- 

 lion more than in the one used in the guano series. 



Another remarkable relation brought out in this series is 

 that the absorption of potash from this solution by the four 

 Northern soils averages nearly double* what it does for the four 

 Southern soils, and yet for all other ingredients the Southern 

 soils have thrown out of solution more than the Northern ones 

 have, if we except sulphates, upon which they are practically 

 equal in their effects. 



