[ 5'3 3 



more is absorbed out of a dilute solution, though from 

 a strong solution absolutely a larger quantity is ab* 

 sorbed The quantity of bases (and acid radicles in 

 the case of phosphates, silicates and carbonates) ab- 

 sorbed depends on various conditions: (i) the relative 

 masses of soil and the solution ; (2) temperature, less being 

 absorbed in high temperature and (3) the state of the com- 

 bination of the substance to be absorbed. For instance, more 

 Kj>O is absorbed when it is given to the soil in the form of 

 phosphate than as chloride or nitrate. The bases absorbed 

 are only slightly soluble in water, more soluble in water con- 

 taining C0 2 , and completely soluble in HC1. When a base 

 has been absorbed, it may be partially or wholly removed by 

 another base, e. g.> if a soil saturated with absorbed K 2 O, is 

 given a dose of Na 2 SO 4 solution in the above described 

 manner, part of the K 2 O will be removed, (i. e. much more 

 than if the soil had been washed only with water), and its 

 place taken by Na 2 O. If now the soil is washed with a solu- 

 tion of lime, more of the K 2 O and part of the Na 2 O will be 

 washed out and their place taken by CaO. The absorptive 

 power of soils is diminished or entirely destroyed by treat- 

 ment with HC1 or by ignition. A soil, the absorptive power 

 of which is diminished or destroyed by either of these ways 

 can get back its power if it is treated with Na 2 Co 3 or CaCoj. 

 All soils have not equal absorptive power. Speaking generally 

 the greater the absorptive power of the soil the greater is 

 its fertility. All good soils decompose to a certain limit salts 

 of potash, magnesia, soda and lime, in such a manner, that 

 the bases, and the phosphoric, silicic and carbonic acids, it 

 they are present, are retained in the soil, and nitric, hy- 

 drochloric and sulphuric acids become dissolved in the form 

 of compounds of lime, soda, magnesia &c. taken from the soil, 

 and then either taken up by roots of plants or washed away, 

 or deposited in the dry weather as an incrustation or inflores- 

 cence on the surface. Though clay loams possess the power 

 MMM 



