262 
ANALYSES OF SOILS. 
COMPONENTS. 
DUMMERSTON. 
ADDISON. 
ALBURGH. 
Carbonate of lime. 
50-08 
45-09 
53-17 
Carbonate of magnesia... 
5-40 
17-34 
2-48 
Alumina. 
28.40 
21-13 
20-95 
Peroxide of iron. 
8-12 
1-73 
6-76 
Protoxide of manganese.. 
1-50 
0-65 
1-60 
Silica . 
8-08 
16-18 
12-40 
Water. 
3-48 
The variation in composition would appear still farther by other analyses : thus, the 
silex in some of the Vermont concretions amounts to 29'08 ; the alumina varies from 7*30 
to 28 - 40 per cent; the peroxide of iron, from l - 73 to 8'81 per cent. 
Sulphate of lime, which is a common substance in the Albany clay, is not found in the 
concretions. The largest and most spherical ones seem to be formed where carbonate 
of lime is in the greatest abundance. In many instances, the same material which forms 
the claystone, forms, in the clay beds, distinct layers, in some of which silex instead of 
carbonate of lime is the predominant ingredient. The force which produces a concretion 
is closely allied to that of crystallization, for there is a tendency to build up regular sym¬ 
metrical solids. It is active in all semiconsolidated materials, as paste, mortars and clays ; 
and it always begins at a centre, and extends in the direction of the radii of a sphere. 
Paring and burning of clay soils. 
In this place the question comes up, what changes should clays be made to undergo, in 
order to become fitted for cultivation? Some maintain that the iron contained in clay is 
converted by combustion into a peroxide ; the former state of the iron being noxious, and 
the latter congenial to vegetation, or else becoming so by its relations to other elements 
existing in tire soil. Others suppose that it is the sulphuret of iron, existing in clay soil, 
which is converted into the peroxide by burning ; and that the sulphuret of iron is injurious 
to vegetation. This opinion can not be correct, unless indeed the sulphuret is of that kind 
which decomposes and forms sulphate of iron, which, in large doses, is unquestionably 
injurious to plants. We can hardly believe that sulphuret of iron is at all injurious, unless 
it is undergoing decomposition. Admitting the correctness in part of this view, still the 
mechanical effect of the burning is far more important than the chemical effect. Clay, 
as deposited, is close, impervious, or difficult to be penetrated by the roots of plants. Two 
effects follow from burning : 1st. The soil is rendered open, pervious, and penetrable ; 2. 
Some of the matters in the clay become more soluble. This is maintained by Liebig, who 
supports his view of the subject by reference to the greater solubility of argillaceous earths 
in acids after they are ignited, than before. It is true, we believe, however, that the peroxide 
of iron does exert a salutary influence on vegetation ; and this opinion is supported by the 
character of the productions of a brick red soil. This is certainly found to be a warm soil, 
there being a perceptible difference in favor of the growth of grass and grain on lands of 
this color ; and it would seem that sheep and cattle are fond of grazing upon these soils, 
and give them a preference. It appears, then, 1st, that the burning of clays of any kind 
