104 ACTION OF SALTS. 



the base or lime, let loose by the action of the liv- 

 ing plant, acts at once, as caustic lime upon insolu- 

 ble geine, and unconverted vegetable fibre, chang- 

 ing these into soluble vegetable food ; while the car- 

 bonic acid acts immediately upon silicates, decom- 

 posing these, and upon the geates in the soil, 

 converting these into super-geates. Carbonates of 

 alkalies, as ashes, Stc, act at once. They are sol- 

 uble, their alkali acts immediately upon the geine. 

 Their carbonic acid acts upon silicates and geine. 

 Immediate and decided good effects follow their ap- 

 plication ; while carbonate of lime acts slower. It 

 often requires many years to bring out the good ef- 

 fects of carbonate of lime, and though ultimately 

 these effects, it is believed, have never failed of be- 

 ing witnessed ; yet so slowly, that its use has been 

 often condemned. The principle which is here dis- 

 cussed, may account for this apparent discrepancy. 

 Suppose a barren, worn out, exhausted soil, contain- 

 ing yet, a large portion of insoluble geine, and de- 

 cayed vegetable matter, between the state of wood 

 and insoluble geine, or even a portion of undecayed, 

 dead wood, it seems too unpromising to give it ma- 

 nure ; little of that is to be spared, and that is be- 

 stowed upon better land. If this is in a country 

 where lime is cheap, that is purchased, and freely 



