90 ACTION OF GEINE ON SOIL. 



merits has been explained, uninfluenced by tbe organ- 

 ic or geine. Referring to the properties of this element, 

 it will be recollected, that this is soluble or insoluble, 

 that it combines with alkalies, earths, and metals. 

 This element exerts a twofold action. 1st. The 

 geine combines with the potash, soda, lime, alumina, 

 magnesia, which have been let loose by the action of 

 carbonic acid, and of carbonates, and forms geic salts 

 or geates, while the carbonic acid which may be let 

 loose from any carbonate of lime, acting upon these- 

 geic salts, forms super-geates, which readily dissolve. 

 It is thus evident, that geine exerts an important and 

 powerful influence upon soil. It is the agent, pre- 

 pared by nature, to dissolve the earthy constituents 

 of soil, rendering them so soluble, that they become 

 fit for food, or constituents of plants. 



2d. The free alkalies, produced as has been de- 

 scribed by the influence of carbonic acid, and carbon- 

 ates act on geine. They render this soluble. The 

 curious and important fact, that a small quantity of 

 alkali, renders an indefinite quantity of geine soluble, 

 has been noticed (117) ; and it may now be added, 

 that probably all the alkaline earths, and oxide of 

 iron and manganese possess, this power of convert- 

 ing vegetable fibre into geine. This effect has long 

 been known to be produced by potash and lime. 



