ON THE CHEMICAL CONSTITUENTS OF SOILS. 



219 



Chlorine of the salt 

 Humus 



(A) 

 0-207 

 0-512 



(E) 



a trace 



0135 



100-000 100-000 



This soil produces luxuriant crops of lucern and 

 sainfoin, as well as of all other plants the roots of 

 which penetrate deeply into the ground. The rea- 

 son is apparent. The subsoil contains magnesia, 

 which is wanting in the surface-soil. 



5. Surface-soil (A) a loamy sand, from the envi- 

 rons of Brunswick. (B) analysis of the subsoil at a 

 depth of 2 feet. 100 parts contain : — 



Silica, with coarse siliceous sand 



Alumina 



Protoxide and peroxide of iron . 



Peroxide of manganese 



Lime, in combination with silica 



Magnesia in do. do. 



Potash and soda . 



Phosphate of iron 



Sulphuric acid . . ' . 



Chlorine 



Humus soluble in alkalies 



Humus insoluble in alkalies . 



This soil is characterized by its great sterility. 

 White clover could not be made to grow upon it. 

 The obvious cause of its poverty is a deficiency of 

 lime, magnesia, potash, and gypsum ; for we find 

 that the fertility of the soil was much increased by 

 manuring it with marl. The white clover, which 

 formerly had refused to grow on this soil, now grew 

 upon it with much luxuriance. The aridity of the 

 soil could not have been the cause of its sterility, 

 for the stiff nature of the subsoil on which it rested 

 prevented a deficiency of moisture. 



6. Surface-soil (A) a loamy land from the environs 

 of Brunswick. (B) the analysis of the subsoil, at a 

 depth of 2 feet. 100 parts contain : — 



Silica, with fine siliceous sand 



Alumina 



Protoxide and peroxide of iron 



(A) 

 94-998 

 0-61O 

 1080 



(B) 

 96-490 

 1-083 

 1-472 



