ABSOIIPTIVK POWER OP THE SOIL. 343 



is diminished or even destroyed by burning o)' calcination. 

 Peters, experimenting on this point, obtained the follow- 

 ing results : 



Potash absorbed from solution of chloride of potassium by 

 unburned burned 



Vegetable mould, 0.2515 0.0303 



Loam, 0.1S41 0.1200 



The Cause of the Absorptive Power of Soils for 



Bases when combined with chlorine, sul])huric, and nitric 

 acids, has been the subject of several extensive investiga- 

 tions. Way, in his papers already referred to, was led to 

 conclude that the quality in question belongs to some pe- 

 culiar compound or compounds that are associated with 

 the clayey or impalpable portion of the soil. That these 

 bodies were compounds of the bases of the soil with 

 silica, was a most probable and legitimate hypothesis, 

 which he at once sought to test by experiment. 



Various natural silicates, feldspars, and others, and some 

 artificial preparations, were examined, but found to be 

 destitute of action. Finally, a silicate of alumina and 

 Boda containing water was prepared, which possessed ab- 

 soi'ptive properties. 



To produce this compound, pure alumina was dissolved 

 in solution of caustic soda on the one hand, and pure silica 

 in the same solution on the other. On mingling the two 

 liquids, a white precipitate separated, which, when washed 

 from soluble matters and dried at 212°, had the following 

 composition * : 



Silica, .46.1 



Alumina, 26.1 



Soda, 15.8 



Water, 12.0 



100.0 



* Way gives the composition of the anhydrous salt, and says it contained, 

 dried at 212% about 12 per cent of water. In the above statement this water is in- 

 cluded, since it is obviously an essc'ntial ingredient. 



