ON THE CHEMICAL CONSTITUENTS OF SOILS. 223 



SOILS OF HEATHS. 



11. Soil of a heath converted into arable land, in 

 the vicinity of Brunswick. It is naturally sterile, 



but produces good crops when manured with lime, 

 marl, cow-dung, or the ashes of the heaths which 

 grow upon it. 



Silica, and coarse siliceous sand . . 71*504 



Alumina ..... 0*780 



Protoxide and peroxide of iron, principally com- 

 bined with humus . . . 0*420 

 Peroxide of manganese, idem . . . 0*220 

 Lime, idem .... 0*J 34 

 Magnesia, idem ..... 0032 

 Potash and soda principally as silicates . 0*058 



Phosphoric acid, (principally as phosphate of iron) 0*115 

 Sulphuric acid (in gypsum) . . . 0*018 

 Chlorine (in common salt) . . . 0014 



Humus soluble in alkalies . , . 9*820 



Humus, with vegetable remains . . 14*975 



Resinous matters .... 1*910 



100000 



Ashes of the soil of the heath, before being con- 

 verted into arable land: — 



Silica, with siliceous sand . , . 92*641 

 Alumina . . . . . 1*352 

 Oxides of iron and manganese . . 2.324 

 Lime, in combination with sulphuric and phos- 

 phoric acids ..... 0*929 

 Magnesia, combined with sulphuric acid . 0*283 

 Potash and soda (principally as sulphates and 



phosphates) ..... 0*564 



Phosphoric acid, combined with lime . 0250 



Sulphuric acid, with potash, soda, and lime , 1*620 



Chlorine in common salt . . . 0*037 



100.000 



12. Surface-soil of a fine-grained loam, from the 

 vicinity of Brunswick. It is remarkable from the 

 circumstance, that not a single year passes in which 

 corn plants are cultivated upon it without the stem 

 of the plants being attacked by rust. Even the 

 grain is covered with a yellow rust, and is much 

 shrunk. 100 parts of the soil contain: — 



Silica and fine siliceous sand . . 87 859 



Alumina ..... 2652 



Peroxide of iron with a large proportion of protoxide 5* 132 



