250 SOILS, MANURES, &c. 
afterwards removed, but the earth on 
which it had been placed produced no 
plant for about a year fubfequent to its 
removal, after which the foil became 
luxuriantly rich: nor were the advan¬ 
tages confined to the narrow limits occu¬ 
pied by the wafte a files ; for in the courfe 
I ' . »• « - 
of a few years, all the adjacent parts of 
the field became enriched by the extend¬ 
ed influence of the falts ; the foil retained 
its fertility for more than thirty years, 
which by the end of that period became 
amazingly extenfive. 
The fuperficial earth of this field was 
of the peaty or moory kind, of a dark 
colour, and about fix inches deep; un¬ 
derneath was an irony clay, the metallic 
acid of which had caufed its poverty: 
but that property of the clay was con¬ 
trolled by the alkaline falts of the wafte, 
which at the fame time attrafled the 
nitrous 
I 
