246 



ON THE CHEMICAL CONSTITUENTS OF SOILS. 



Silica with fine siliceous sand 



Alumina 



Peroxide and protoxide of iron 



Peroxide of manganese . 



Lime .... 



Magnesia 



Potash, principally combined with silica 



Soda .... 



Phosphoric acid ... 



Sulphuric acid . 



Chlorine • . . . 



Humus, soluble in alkalies 



Humus .... 



Carbonic acid, combined with lime 



Nitrogenous organic matter 



100-000 100-000 * 



In the preceding part of the chapter we have in- 

 serted a number of analyses of various soils, as well 

 as the conclusions deduced from them, by means of 

 which the farmer may be enabled to ascertain the 

 manures best adapted for each variety of soil. By 

 inspecting the analyses of the sterile soils, it will be 

 apparent that it is in the power of chemistry to point 

 out the causes of their sterility. The general cause 

 which conduces to the sterility of soils is either the 

 absence of certain constituents indispensable for the 

 growth of plants, or the presence of others, which 



* Soil from Chelmsford, Massachusetts, on the Merrimack river, 



which has produced a large crop of wheat for 20 years, with only one 



failure, analyzed by Dr. Dana. 100 parts contain : — 



Soluble geine ..... 3.9228 



Insoluble " . . . . . 2-6142 



Sulphate of lime ..... -7060 

 Phosphate of '* . . . . -9082 



Silicates (silica, alumina, iron &c.) . • . 91-8485 



No trace of carbonate of lime, or of alkaline salts, could be discovered. 

 Soil from Maine, analyzed by Dr. Jackson, has produced 48 bushels 



of wheat per acre. 



Water . . . . . . 5-0 



Vegetable matter .... 17-5 



Silica ...... 54-2 



Alumina ..... 106 



Subphosphate of alumina . . . .3-0 



Peroxide of iron .... 7-0 



Oxide of manganese . . . . , 1*0 



Carbonate of lime . . . . 1"5 



99-8 

 From Hitchcock's Final Report^ p. 29. 



