WESTERN DISTRICT. 
289 
The Onondaga limestone forms another terrace above the preceding. The soil is porous, 
and bears good corn and wheat, but does not differ essentially from that of the Pentamerus 
limestone. It is composed of 
Water of absorption_ 0-50 
Organic matter__ 4*85 
Silicates___ 85*50 
Peroxide of iron_ 4*62 
Carbonate of lime_ 0*62 
Alumina_ 3*30 
Magnesia_ trace. 
Loss. 0*61 
100*00 
The composition of the Onondaga limestone has been given. It contains a trace of 
phosphate of lime, and two per cent of magnesia; but as it is a hard rock, one which 
resists decomposition, it slowly furnishes food for vegetables. 
The shales of the Salt group frequently give more magnesia than lime. A specimen 
taken from the farm of Mr. Geddes, of Fairmount, gave 
Water_ 4*75 
Organic matter. 6*20 
Silicates__ 75*62 
Carbonate of lime_ 0*50 
Magnesia. 2*15 
Alumina and iron__ 10*34 
99*56 
This arises from the fact that magnesia exists in all the shales and thin-bedded limestones, 
from the red marl up to the pentamerus limestone, varying from two to eighteen per cent; 
and as it is less soluble than carbonate of lime, it is retained in the soil when the lime 
would disappear. 
An uncultivated soil near Clyde, upon the Salt group, gave, on analysis, 
Water of absorption__ 4*00 
Vegetable matter. 6*50 
Silicates_ 78*82 
Peroxide of iron and alumina_ 4*69 
Carbonate of lime. 3*71 
Magnesia_ 1*75 
Phosphate of alumina_ 0*24 
99*71 
The two following specimens of soil were taken from the farm of Mr. Ira Hopkins, of 
Mentz, Cayuga county. The Salt group lies below, but the surrounding region contains 
J Agricultural Report.] 37 
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