On the Chemical Properties of Soils. 11 



Consequently *189 grains of ammonia were removed from 

 every 1000 grains of solution, or 2*646 grains from the whole 

 solution ; 1000 grains of soil therefore absorbed *7543 grains of 

 ammonia. 



Fourth Experiment, on Sterile Sandy Land. 



100 parts of the soil, dried at 212 Fahr., contains : 



Oxide of iron and a little water of combination .. 



Oxides of iron and alumina 



Carbonate of lime 



Alkalies and magnesia 



Phosphoric acid 



Sulphuric acid 



Soluble silica 



Insoluble siliceous matter (sand) 



100-00 



It will be seen that this soil hardly contains any lime and 

 abounds in sand. It contains a good deal of organic matter, 

 but very little clay, which will be seen by the subjoined me- 

 chanical analysis : 



Organic matter 5'36 



Clay 4-57 



Lime *25 



Sand . .... 89-82 



100-00 



3500 grains of this soil were mixed with 14,000 grains of am- 

 monia solution and left to settle for three days, when the follow- 

 ing results were obtained : 



Before contact with soil 1000 grains of ammonia 



solution contained *332 



After contact with soil 1000 grains contained . . . . '063 



269 



Consequently '269 grains were removed from every 1000 grains 



of solution, or 3*766 grains from whole solution. 



1000 grains of soil therefore absorbed 1*076 grains of ammonia. 



In a second experiment, in which the ammonia was deter- 

 mined by a standard solution of test-acid, in the same manner 

 as in the first experiment, 1000 grains of soil were found to 

 have absorbed 1*136 grains of ammonia. 



In both experiments the solution, after remaining in contact 

 with the sandy soil, had a deep yellow colour. The caustic 

 ammonia evidently dissolved a good deal of the organic matter of 

 the soil. The ulmic and humic acids in the soil, in uniting with 

 ammonia, form salts, which are soluble in water, and of a brown 

 colour. A brown coloured solution thus indicates that some 



