356

APPENDIX.

hundred grains gave of siliceous sand of different degreesof fineness about—

Grains.

280

Of finely divided matter, which appeared in the

form of clay -----

-

104

Loss in water - - - - -

-

16

400

The 104 grains of finely-divided matter

contained

Of carbonate of lime - - - -

-

18

Oxyde of iron.

-

n

Loss by incineration, most probably from

vegetable

decomposing matter ...

-

17

Remainder principally silex and alumine. There was noindication of gypsum or phosphate of lime.

This analysis accounts, not unsatisfactorily, for two atleast of the phenomena in the foregoing experiments—namely, the great activity of gypsum, and the inutility ofpeat-ashes. The soil, containing in itself no gypsum, re-ceives from the application of that mineral an accession ofactive power which it wanted; and having already morethan a necessary share of iron in its composition, it be-comes, by the addition of peat-ashes, supersaturated withthat which in certain proportions is an invigorating stimu-lant, but when too abundant, operates as a poison.

Two sets of experiments, and with the same proportionof manures, were tried, on a soil of a very different nature,with buck-wheat and turnips. As my object in thesetwo sets of experiments was to try the intrinsic effects of