254 



IMPROVEMENT OF THE SOIL 



Oxide of Manganese 0.56 



Lime 0.56 



Magnesia .44 



Sulphur and loss 3.22 



where there is too much sand or silica, both clay and carbo- 

 nate of lime operate to equalize the electrical forces ; both 

 act as converters of vegetable fibre into vegetable food. 



A specimen of common blue clay from Lowell, analyzed by 

 Prof. Hitchcock, gave 



Water and organic matter 4.0 



Silica 61.52 



Alumina 20.50 



Protoxide of iron 9.82 



It will be seen by this analysis, that there is a large quan- 

 tity of protoxide of iron, and this explains further its influ- 

 ence. " Our common clays," says Dr. Dana, " contain more 

 or less of sulphuret of iron. The conversion of this into the 

 persulphate of iron, is the natural consequence of exposure ; 

 free sulphuric acid then results, which acts on any lime in 

 the soil forming sulphate of lime, or gypsum." But the most 

 important effect of the protoxide is that in passing into the 

 peroxide, it tends to induce decay in the vegetable matters, 

 which are in contact with it ; hence clay acts upon a soil 

 as an alkali, an alkaline earth, and a metallic oxide. 



Finally, clay has the property of absorbing gaseous bodies, 

 which are useful in vegetation. Liebigr attributes to it the 

 power of absorbing ammonia, from which plants derive their 

 nitrogen. Daubeny regards this power in a soil, as an in- 

 dispensable condition of fertility. 



As sand will improve a clayey or peaty soil, and clay a 

 sandy soil, it is matter of no little astonishment that New 

 England farmers have not resorted more frequently to this 

 mode of amelioration. In various parts of the country, sand 

 hills, peat swamps and clay beds, are so situated often, that 

 it would be the easiest thing in the word to transfer portions 

 of the one to the other, to the mutual improvement of all. 

 It sometimes happens, that a soil is reduced to an inipalpa- 

 ple powder when dry, and to a soft paste when wet, -while the 

 earthy and vegetable ingredients are in the right proportions 

 to ensure fertility. Such a state of the soil results from a 



