CHAPTER III. 



CHEMISTRY OF THE SOIL. 



THE law of change, illustrated in the last 

 chapter exclusively by its influences upon the 

 sterner features of our landscape, the rocks and 

 mountains, prevails even in the soft and tender 

 layer of brown earth, which we find on the sur- 

 face of the field. Here, it is true, are less ob- 

 vious processes of chemical change, even than 

 in the instances we have been considering ; but 

 they nevertheless exist, for the whole mass of 

 vegetable mould is a body of substances con- 

 tinually decomposing and altering in nature. 

 This, therefore, also becomes an interesting sub- 

 ject of inquiry to the student of the chemistry 

 of creation. 



The soil which covers so extensive a por- 

 tion of the earth's surface consists of materials 

 which differ essentially in different localities, 

 but which may be described in general terms, 

 as comprising the following constituents the 

 disintegrated particles of rocks, sand, clay, and 

 calcareous matters, and the decomposing remains 



