36 



PROPERTIES OF ELEMENTS OF SOIL. 



CHAPTER III. 



PROPERTIES, AND CHEMICAL ACTION 

 OF THE ELEMENTS OF SOIL. 



62. The alkaline bases of the silicates, have 

 common properties, which are, 



1st. Alkaline. Whatever may be our idea of the 

 effect of an alkali, as exhibited by potash or soda, 

 the same in kind, but in degree less, is exhibited by 

 lime, magnesia, and alumina. Placing potash as the 

 type of alkaline power, the same power, in a de- 

 creasing order is found in lime, magnesia, and alum- 

 ina. 



2d. They are, most of them, soluble in water. 

 Potash stands here also first, and the solubility de- 

 creases in lime, magnesia, and totally disappears in 

 alumina. This may have some connection with the 

 fact, that widely diffused as it is in all soil, it is 

 very seldom found in plants. 



3d. They exhibit great affinity for carbonic acid. 

 The order of affinity is potash, soda, lime, magne- 

 sia ; alumina, if it possesses it at all, exhibits it only 



