years, it is obvious that even
very large and frequently repeated doses are not likely to produce any
great accumulation of that substance. In point of fact, analyses of
overlimed soils have proved that the lime does not exceed the ordinary
quantity found in fertile land. The explanation of the phenomenon is
probably to be found in the rapid decomposition of organic matter by the
lime, and its escape as carbonic acid, by which the soil is left in that
curious porous condition so well known in practice. The cure for
overliming is found to be the employment of such means as consolidate
the soil, such as eating off with sheep, rolling, or laying down to
permanent pasture.

The immediate effect of lime on the vegetation of the land to which it
is applied is very striking. It immediately destroys all sorts of moss,
makes a tender herbage spring up, and eradicates a number of weeds. It
improves the quantity and quality of most crops, and causes them to
arrive more rapidly at maturity. The extent to which it produces these
effects is dependent on the form in which it is applied. When the lime
is used hot, that is, immediately after it has been slaked, they are
produced most rapidly and effectually; but if it has been so long
exposed to the air as to absorb much of the carbonic acid it lost in
burning, and has got into what is commonly called the mild state, it
operates more slowly; and when it is applied as chalk, marl, or pounded
limestone, its action is still more tardy. Various circumstances, which
must depend upon very different considerations, must necessarily
influence the farmer in the selection of one or other of these different
forms of lime; but on the whole, it will be found that the greatest
advantages are on the side of the well-burned and freshly slaked lime.
The consideration of all the minutiae to be attended to, however, would
carry us far beyond the limits of this work, and trench to some extent
on the subject of practical agriculture.

Various kinds of refuse matters containing lime have been used in
agriculture, but they are generally inferior to good lime, and not
generally more economical. The most important of these is gas lime, or
lime which has been used for purifying coal gas. In going through this
process it absorbs carbonic acid from the gas, and consequently passes
back, more or less, completely into the form of carbonate of lime. But
it also takes up sulphur, which remains in it in the form of s