ON THE CHEMICAL CONSTITUENTS OF SOILS. 217 



mean that which is below the former, and out of 

 reach of the ordinary plough. 



CHEMICAL COMPOSITION OF CERTAIN SOILS, ACCORDING TO 



ANALYSIS. 



1. Surface-soil (A) a good loamy soil, from the 

 1 vicinity of Gandersheim. It is remarkable for pro- 

 ducing uncommonly fine red clover when manured 



^with gypsum. (B) is an analysis of the subsoil. 

 100 parts contain ; — 



(A) (B) 



Silica, with fine siliceous sand . . 91-331 93-883 



Alumina 1-344 1-944 



Peroxide of iron, with a little protoxide 1-562 2 226 



Peroxide of manganese . . . 0-082 0-320 

 Magnesia and silica, in combination with 



sulphuric acid and humus . . . 0*800 0720 

 Magnesia, with silica and humic acid 



combined . . . . . 0-440 0-340 



Potash, in combination with silica . 0-156 0-105 

 Soda, principally in combination with 



silica, and a little as common salt . 0-066 0-060 



Phosphoric acid 0-098 0190 



Sulphuric acid in combination with lime 0111 0*012 



Chlorine (in common salt) . . 0012 0-012 



Humus, with traces of azotized matter . 4100 0184 



100-000 100000 



An inspection of the above analyses will show 

 that the soil contains a very small proportion of salts 

 of sulphuric acid, — a circumstance which accounts 

 for the favorable action of gypsum upon it. 



2. The surface-soil (A) is a fine-grained loamy 

 soil from Gandersheim, distinguished for the re- 

 markably large crops of beans, peas, tares, &c., 

 which it produces when manured with gypsum. (B) 

 is the analysis of the subsoil. 100 parts contain: — 



(A) (B) 



Silica, with fine siliceous sand . . 90221 92-324" 



Alumina 2106 2 262 



Peroxide and protoxide of iron . . 3951 2 914 

 Peroxide of manganese . . . 0-960 2960 

 Lime, principally combined with phos- 

 phoric acid and humus . . . 0539 0-532 



19 



