220 
very small, only 2.1 per cent.; and hence, together with the 
absence of calcareous earths, the "deafness," pulverulent 
state, or want of cohesion of these unchalked soils. The 
calcareous matter added by the operation of " chalking'* 
may seem small in quantity, being 3j% per cent. (carb. lime 
2j% + 1 magnes. = 3.9 — io==^-io gain), but there is also 
added by chalking l^^o pe^" cent, of alumina, although it seems 
difficult to explain how this quantity could have been added ; 
for the chalk at Hessle Cliff only contains per cent, of it. 
In the present state of our knowledge respecting the ingre- 
dients which constitute fertility, it would be premature to 
state the quantity of calcareous earths the w^old soils should 
contain, to produce fertility ; neither do we think it possible 
to state, from chemical analysis, which should be chalked, or 
which do not require that operation. For if one of the 
magnesian limestone soils, probably the most fertile upon the 
whole formation between Worksop and the river Aire, be 
compared with the imchalked soil of Riplingham, it will be 
found exceedingly similar in the ingredients which it con- 
tains : the unchalked soil of Riplingham contains 2-}q of alu- 
mina, that of the magnesian limestone 2x% per cent., that of 
Riplingham per cent, of carb. lime, while that of the 
limestone contains l^^ per cent, of lime (not carbonate); so 
that if a calcareous soil containing so small a portion of lime 
as per cent, be pre-eminently fertile, it becomes exceed- 
ingly difficult to predicate whether the addition of so small 
a quantity of that earth would afford the increased produc- 
tiveness. As a further corroboration of this opinion, the 
chalk soils of Neswick do contain 2 per cent, of calcareous 
matter, and yet the author of the paper in the Transactions 
of the Society states " that although the corn crops may be 
permitted to follow each in their turn without variation, 
" yet the green or alternate crops seem by certain natural 
" laws to deteriorate, if recurring so frequently as once in 
