182 ADAPTATION OF MANURES. 



of most plants, and its action upon them as a manure 

 is beneficial. 



Nitrate of potash. This is a most important sub- 

 stance in hastening the growth of plants. It is 

 formed of nitric acid and potash, and is commonly 

 known as saltpetre. 



Chloride of sodium, or common salt, is found in 

 all plants. It exists in largest quantities in lands 

 which lie near the seacoast. 



Sulphate of soda has a good effect upon many 

 plants. 



Carbonate of soda in its various forms, as sesqui- 

 carbonate, bi-carbonate, and in the simple form, is 

 also beneficial. 



Phosphate of soda is another important constituent 

 of urine. 



Sulphuric acid is rarely met with in the soil, 

 except in union with other substances, forming 

 sulphates with potash, lime, soda, etc. 



These are the compounds which usually exist in 

 the soil ; but land may have an abundance of some 

 of them, while it is entirely destitute of others, or 

 of the means of producing them. This should guide 

 us in the consideration of the next division of our 

 subject. 



in. MANURES ADAPTED TO DIFFERENT SOILS. 



Accurate chemical analysis can alone ascertain the 

 exact substance which is wanting; but we doubt 



