:^78 ANALYSES OF SOILS. 



detect mica in the rock. The condition of the Hamilton group enables it to resist the action 

 of the weather, and hence it is common for it to appear in mural precipices or in well 

 exposed outcrops. A more important change, however, remains to be noticed ; it is the 

 disappearance of lime and magnesia, or rather a very perceptible diminution of both. It 

 is not supposed that any rock is entirely destitute of either of these elements, yet it is not 

 uncommon that it is diminished so far as to influence the growth of the cereals, as well as 

 of maize. The consideration of the Hamilton group will be deferred for jhe present. 



The soil derived from the red shale may be distinguished from the succeeding green 

 shales by its red color. Where it is unmixed, and consists wholly of the matter of the 

 rock, it is frequently a heavy tenacious clay ; and usually it has more tenacity, and is 

 more compact than the soils from the rocks below or above. Its composition indicates the 

 relation it bears to the wheat culture, and the confidence which may be placed in it as to 

 returns for many years in succession. It furnishes the phosphates of alumina and iron, and 

 the carbonates of lime and magnesia. We have already hinted that it may be improved 

 by employing the broken down rock ; a plan, which, if systematically pursued, would 

 forever prevent its deterioration. This opinion is justified by experience in a few instances. 



Soil of the green shales. 



We notice this product of the rocks next succeeding in the ascending order, though its 

 characters, when its components are taken into consideration, are much the same as the 

 soil of the red shale. Its color, however, is quite different, and it is less compact ; and 

 these shales, we believe, never produce a stiff clay, but the soil has a good body, and can 

 never be ranked among the light soils. The standard specimen of this soil yields, on 

 analysis, 



Water of absorption 5*16 



Silex... 35 '54 



Carbonate of lime 2*50 



Mag^nesia 1"50 



Sulphate of lime 0-50 



Peroxide of iron and alumina 4*87 



Phosphate of alumina 0'06 



50-13 



Two hundred grains, submitted to the action of cold water for a few days, gave, of 



Soluble matter 1 "34 



Organic matter - I'OO 



Saline matter 0-34 



Another specimen, from the vicinity of the Green lakes near Manlius centre in Onondaga 

 county, gave 



