224 
are strictly sandy soils, containintj 97 per cent, of sand,* 
and many fields might be termed " blow away" sands. There 
is little doubt that by the addition of the Kimmeridge clay 
many of these lighter soils would be permanently improved, 
and as it lies contin^uous to them on the whole rano^e from 
north to south, it could be applied at little expense. The 
fertility of the land on the Kelloways Rock, and of part of 
the inferior oolite is amazing, considering that 97 per cent, of 
the soil is pure sand, and affords another proof of the fact 
before-mentioned. 
Lias. It becomes an exceedingly interesting inquiry to 
ascertain how the soils upon the lias soil produce suph 
excellent feeding pastures, while some of the clayey soils 
upon the New Red Sandstone formation, very similar in ex- 
ternal characters, will scarcely produce grass at all, and 
that of the most inferior description. Now it is very pro- 
bable, a priori, that as the richest natural pastures are found 
only comparatively upon a few soils, and these geologically 
distinct, that they should possess some common mechanical 
texture, or chemical ingredients, by which their fertility is 
maintained ; and although certain soils, composed of various 
constituents, may produce large crops of grain and other 
annual crops, yet they are nevertheless unfit for the produc- 
tion of the superior perennial grasses. We therefore think 
it probable that the capability of a soil to produce the 
superior grasses, may be known by an inspection of its an- 
alysis, and that it will be found that any soil which contains 
from 5 to 9 per cent, of alumina will have this power-: ' If 
there be less of alumina than 5 per cent., the soil will be too 
light and friable, — if it contain more than about 9 per cent., 
it will be too tenacious for this purpose. In Sinclair's ex- 
periments upon twelve different soils with the superior 
pasture grasses, it was found that all the plants vegetated, 
* Deposited in 3i minutes. 
