542 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Absorption without Exchange of Bases. 



Van Beramelen shows further how soils can absorb alkalies 

 and alkaline earths from their solutions without giving other 

 bases in return. This is accomplished when the bases to be 

 absorbed are caustic, or combined with weak acids e. g., 

 hydrates, carbonates, phosphates, and borates. The bases 

 seem to be taken up by hydra ted silica in the soil, which can 

 easily combine with free bases. To explain how the silica 

 gets the bases from the acids named,Van Bemmelen assumes 

 a dissociation to take place, as set forth by Berthelot, the 

 neutral salt being split up into acid-salt and free base, which 

 latter goes to the silica. On this hypothesis a solution of 

 carbonate of potash, for instance, ought to lose its potash in 

 successive portions until half is absorbed, the other half re- 

 maining as bicarbonate. Actual experiments gave results 

 surprisingly near the theory. 



Restoration of Absorptive Power. 



By boiling soils with strong hydrochloric acid, the soluble 

 silicates would be decomposed, and more or less of their bases 

 taken away. Van Bemmelen finds that soils thus treated 

 lose most of their absorptive power. Conversely, it would 

 appear that if the bases could be restored they might absorb 

 again. It was found that such was the case. Soils thus 

 extracted and afterwards treated with carbonate of soda 

 were able to absorb considerable potash. The explanation 

 is that new basic silicates were formed with soda, which lat- 

 ter could then be exchanged for the potash. In like manner 

 it was found that a soil from which the bases had been ex- 

 tracted could absorb potash from chloride if some carbonate 

 of lime was added. 



Basic chloride of aluminum is shown to play an important 

 part in some of these reactions also {Landw. Vs. -St., xxi., 

 135; xxii., 295). 



Absorptive Powers of Different Layers of the same Soil. 



Orth, whose studies of soils are well known, and who has 

 shown very clearly the importance of knowing about the 

 lower layers as well as the surface, has been investigating 

 the absorptive powers for ammonia of different layers of the 



