-40 Chemical Changes in the Soil. [July, 



generates carbonic acid in the soil, favors vegetation by supplying 

 plants with food by the decomposition of the comminated rocks. 



But we may go still farther, and speak of the solubility of car- 

 bonate of lime and carbonate of magnesia in water holding in so- 

 lution carbonic acid, substances which are difficult of solution in 

 pure water The importance of all these substances to all vege- 

 tables without exception renders it a matter of considerable impor- 

 tance to furnish a supply of carbonic acid water for the sole pur- 

 pose, were there no other, of effecting the solution of silica, lime 

 and magnesia. 



One of the means by which this important result may be brought 

 about is by the use of almost any organic matter, as peat, and 

 other manures of a similar kind. By decomposition they furnish 

 as one of their products of change, carbonic acid, which is readily 

 soluble in w^ater, and which may in this state of solution be ab- 

 sorbed by plants, or may exert its solvent powers upon the various 

 elements composing the soil. Supplying then the soil with de- 

 composing organic matter, and several important results follow; 

 the rocks are dissolved and the plants may be supplied with the 

 necessary carbon, ammonia and other essential inorganic matter. 

 In all these chemical changes there is much to admire, and much 

 which is calculated to gratify an inquiring mind. See the beau- 

 tiful as well as useful changes which are effected by the agency 

 of iron, which in the soil is always in a state of oxydation. If it 

 is in its highest state of oxydation, then the organic matter in the 

 soil, in consequence of its affinity for oxygen, takes one atom of 

 it and reduces it to its lowest state of oxydation, or to a protoxide. 

 This change being effected, it is not possible for it to remain at 

 rest in this state, but it must immediately seize upon the water of 

 the soil and take an atom of oxygen from it, by which change 

 hydrogen is freed or set at liberty, and which at the moment of 

 its freedom takes to itself the nitrogen of the atmosphere of the 

 soil and forms ammonia. If in nature there are wiser or better 

 adaptations, we know not where they are to be found. The 

 farmer, then, when he turns over the sod, or in any way breaks the 

 soil, or when he commits the seed to the bosom of the earth, has 

 before him not one lesson only replete with wisdom, but many, 

 and to which the finger of Deity points. With what propriety 

 may he stop, and as he withholds his hand from its accustomed 

 work, inquire why is all this. Amidst the complicated arrange- 

 ments of nature, it is his privilege to learn wisdom, and he who is 

 in their midst and performs his labors, and is the daily witness of 

 those results, and remains insensible to their teaching, proves 

 himself a fit companion of the undevout astronomer. 



The complex nature of the rocky strata increases the facility 

 with which carbonic acid decomposes them, for in all cases the 



