ACTION OF SALTS. 109 



earths, and metallic oxides, convert geine into acid ; 

 as fast as this takes place, so fast it becomes soluble. 

 Then too, the long action of air on insoluble geine ren- 

 dering it soluble, is it not analogous to the action of 

 air on oils? Both evolve in this case, vast volumes 

 of carbonic acid, the oil becomes gelatinous and sol- 

 uble in alkali, does not a similar change occur in 

 geine ? It is possible that during the action of lime 

 on geine, a soluble substance may be produced, 

 bearing the same relation to this process that glycer- 

 ine does to saponification. These views need to be 

 followed out experimentally, and may be possibly 

 hereafter considered. 



163. In the acid soil, lime acts to eliminate car- 

 bonic acid, which then acts on silicates and geine, 

 as has been explained. All fat acids or fats and 

 oils, act in the same way upon silicates, partly by 

 their own acid properties, and partly by the evolu- 

 tion of carbonic acid gas, which is evolved during 

 their conversion into the acid state. The quantity 

 of carbonate of lime which may be applied is un- 

 limited, and the quantity of alkali depends on the 

 presence of insoluble geine. The more abundant 

 is the last, the more freely may alkalies be applied. 

 The carbonates include ashes of all kinds, and ag- 

 riculturally viewed, all kinds of lime, for the quick 

 10 



