CftEMISTRY OF SOIL. 27 



SECOND DIVISION. 



Alkaline — Potash. 

 Soda. 

 Lime. 

 Magnesia. 

 Alumina. 

 Iron. 

 Manganese. 



2d.-Urets. Carbon, -| United ^ ^ 



bulphur, I bases of division 2d 



Phosphorus, r , ass ls(> 

 bmcon, J 



3d. — Salts. Urets, with oxygen form acids, and 

 these, with division 2d, class 1st, form salts. The 

 silicates are truly salts, but are distinguished not on- 

 ly by their stony, earthy appearance, but by their 

 great insolubility in water. 



Carbonate of lime is a salt, with the insolubility, 

 and earthy character of the silicates, but in agricul- 

 ture it acts only as a salt, and will be treated of as 

 such, and not as a rock formation. (14.) 



46. The terms, salts, urets, silicates, may need a 

 further explanation. Pearlashes and vinegar are 

 well known substances. One is an alkali, the other 

 an acid. Pearlash, has the alkaline properties of a 

 bitter, burning taste, the power of changing vegetar 

 ble blues to green, and pinks to blues. Vinegar has 

 the acid property of sour taste ? of causing a hissing 



