ACTION OF SALTS. 107 



to, much of which has been anticipated. Lime is a 

 general term, it includes all forms of calcareous mat- 

 ter. It is the lime, the base of the salts^ which acts, 

 and that always as lime, no matter how it is appli- 

 ed ; whether as marble, as marl, shells, air slacked 

 lime, bones or plaster. In a more restricted and 

 usual acceptation of the term, lime refers only to 

 that which has been burned, or stone lime. Its ac- 

 tion is threefold, each distinct, first, as a neutralizer, 

 secondly, a decomposer — thirdly, a converter. 



1st. Wherever free acids exist in soil, lime acts 

 as a neutralizer. It has been asserted, on undoubt- 

 ed authority, that occasionally free phosphoric, muri- 

 atic, geic, acetic and malic acids exist in soil. 



2d. Soil may contain abundant geates, particular- 

 ly geate of alumiua, the least of all demanded by 

 plants. Long formed and sun-baked, they are 

 scarcely acted on by rain or dew, and are almost 

 useless. Here, lime, by decomposing these earthy 

 and metallic geates, forms a combination which in 

 its nascent state, is readily dissolved. If the car- 

 bonate of lime, acts better than the hydrate, it is 

 because, following a well known law, double decom- 

 position is easier than single. If any acid geine ex- 

 ists in the soil, or any free acids, carbonic acid is 



