ACTION OF SALTS. 101 



is the presence of organic matter, or geine in the soil. 

 It is the want of a principle like that which has 

 been stated, which has led to a waste of time and 

 money, in applying mineral manures, to worn out 

 barren soil. Whereas, the principle (145) leads to 

 the application of both salts and geine. The salts 

 alone, would be useless. Their first* eflect -in eiiher 

 case, would be the same on silicates, ;.fyufc with geifrfc^ 

 this action, like fermentation, goes on, begetting new 

 salts ; without it, this action ceases after the first 

 chemical changes have occurred. In the first case, 

 it goes on. In the second, it stops. 



155. Salts without geine, act only on silicates of 

 the soil. If now, these silicates contain any portion 

 of aqueous rock, (1 1) they usually contain also, dis- 

 tinct traces of organic matter. This matter is due 

 for the most part, to the geine, held in solution in the 

 water, from which the rocks were deposited. It is 

 certainly within the bounds, not only of a chemical 

 possibility, but of a high degree of probability, that 

 the carbon under the influence of growing plants, 

 may unite with oxygen or hydrogen, that is, with 

 the elements of water, and form thus food for plants. 

 Hence, on such soil, the mere application of salts, or 

 of mineral manures, may produce, yea, and does 

 produce marked and wonderful effects. This would 

 9* 



