225 
except upon the barren peat soil, but that after growing two 
years, all of them degenerated, except those having pos- 
session of two soils, viz. the rich alluvial soil and the rich 
clayey loam, the former of which contains 7, and the latter 
5 per cent, of alumina. Upon the rich sandy soil with 2 per 
cent, of alumina, the produce began to decline in the second 
and third year, while on the two soils just mentioned it in- 
creased in quantity till the fifth year, and had continued in 
the same state, with a very trifling diminution in weight, 
when he wrote, and that without the application of manure. 
There is abundant proof that the superior grasses will not 
flourish upon a soil with less alumina than 5 per cent.; for 
neither would they remain permanent on Sinclair's rich 
siliceous, which contained 2 per cent., nor on his sandy loam 
containing 3| per cent., nor on the vegetable mould, having 
4i per cent. Upon the magnesian limestone soils, as described 
by the Rev. W. Thorp, at the Doncaster meeting of the Geo- 
logical Society, feeding pastures, or superior grass land, are 
only found, upon the whole tract between the rivers Don and 
Aire and Calder, in two localities, one in the neighbourhood 
of Pontefract, the other near Skellow : all the soils analysed 
from that extensive tract of country contained less than 5 
per cent, of alumina, except that from the place near Ponte- 
fract where the excellent pastures occur, and which contained 
5.9 of that earth. Out of ten rocks examined, only one 
contained more than 5 per cent., and that from a quarry 
contiguous to the pasture land of Skellow. And the reason 
of the non-adaptation of the limestone soils to grow the 
superior perennial grasses is now for the first time explained. 
That some of the best pasture lands do only contain that 
quantity of alumina, I may mention, in addition to the two 
of Sinclair's, the excellent grazing pastures of Sir Wm. 
Cooke, adjoining the river Don below Doncaster, at Arksey, 
Bentley, &c.: these contain 6.2. In a correspondence re- 
