280 
ANALYSES OF SOILS. 
The green shales, or rock from which the above soils were derived, is composed as 
follows : 
Water of. absorption. 0*50 
Organic matter. 6*00 
Silicates___34*56 
Carbonate of lime_50*06 
Carbonate of magnesia_ 2.16 
Peroxide of iron and alumina_ 6*38 
99*66 
The inorganic salts, the sulphates of lime and magnesia, and chloride of sodium, exist 
also in the rock, but the proportion was not determined. 
The composition of the rock is eminently fitted to sustain a soil in constant fertility. 
The upper surface of the rock, when near the top of the ground, is easily broken up by 
the plow ; and its debris, being mixed with the old soil, becomes speedily a fit material 
for sustaining a vigorous growth of the cultivated vegetables. 
It is a fact worthy of a passing notice, that although gypsum abounds in the midst of the 
shales which underlie Onondaga and Cayuga counties, still it is not only wanting in the 
soil as a general rule, but is required in the practice of husbandry, and seems to produce 
effects as beneficial as in any other part of the country where it is unknown among the 
formations. This may arise partly from its solubility : it may be removed rapidly from 
the soil by solution. If this is true, it is evident that there is no danger to be apprehended 
from an accumulation of it in the soil by the ordinary use of it. Another reason why 
plaster is not found abundantly in the soil, is its change of constitution, or its change from 
a sulphate of lime to a carbonate, by means of the carbonate of ammonia contained in the 
atmosphere. This change seems to be indicated by a few experiments which have been 
made during the last five years. 
The debris about the beds of plaster consists mainly of carbonate of lime, largely mixed 
with clay in which it would seem that sulphate of lime must have existed originally. 
Thus the debris of the plaster beds from Cayuga bridge, I found composed as follows : 
Water of absorption_ 4*88 
Organic matter_ 3*00 
Silicates_41*75 
Peroxide of iron and alumina_ 8*88 
Carbonate of lime_22*20 
Carbonate of magnesia_ 19*30 
100*01 
As the debris about these beds is often rich in magnesia and carbonate of lime in a state of 
minute division, there is no doubt but the material will be as useful, applied to land, as 
the plaster itself; besides, it is not necessary that it should be transported to a plaster mill, 
as it undergoes disintegration, and becomes in a few years sufficiently fine for use. 
