GEINE. 65 



and manganese, will therefore in soil, immediate- 

 ly seize upon any soluble geine, and forming com- 

 pounds with it, detain it there. The air and water 

 will have now little action upon it. 



113. But supposing that none of these elements 

 (112) are present in soil, the fact stated (1 10) shows 

 that all soluble geine, or solution of extract in water, 

 soon passes to a mixture of soluble and insoluble, 

 forming a dark brown powder. This is thus with- 

 drawn, deep in the soil, from the immediate action 

 of the air, and undergoes no further change. It 

 may remain unchanged an indefinite time. If plough- 

 ed up, exposed any how to the action of air or 

 moisture, it again becomes partly soluble in water, 

 and exhibits its former characters, viz : great affinity 

 for earths and metallic oxides. In this state it is 



VEGETABLE MOULD. 



114. Vegetable mould then, is a mixture of the 

 organic, and inorganic elements of soil. It is a com- 

 pound of soluble geine, with earths and metals, mix- 

 ed with soluble and insoluble geine. It is a chemi- 

 cal compound of organic with inorganic parts of soil, 

 mixed with a large portion of free organic matter. 



115. The inorganic elements of mould are, 1st. 

 Those which already had existed in plants, combined 

 with vegetable acids. These last, by decomposition 



6* 



