104: ACTION OF CARBONATES IN SOIL. 



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, prepared by nature, to dissolve the earthy con- 

 stituents of soil, rendering them so soluble, that they become 

 fit for food, or constituents of plants. 



2d. The free alkalies, produced as has been described by 

 the influence of carbonic acid, and carbonates, 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 converting vege- 

 table fibre into geine. This eflect has long been known to 

 be produced by potash and lime. These hasten decay ; and 

 next in power to lime, in this singular process, is alumina, 

 then oxide of iron, in passing from a lower to a higher state 

 of oxidation. 



137. This remarkable process, this power, energy, func- 

 tion, influence, property, called by whatsoever name it may 

 be, which is thus exerted, by the elements of silicates upon 

 vegetable fibre, and insoluble geine ; and the power of 

 developing acid properties in that principle, is intimately 

 connected with the action of growing plants upon soil. The 

 joint effect of organic and inorganic elements of soil and 

 plants may be better understood by adverting to the proba- 

 ble cause of this property of earths, alkalies and oxides ; 

 though in the present state of science, this cause may be 

 apprehended only by giving it a name, which arranges only 



