waste matter must be handled. Twenty-five per
cent more ground limestone of 80% purity must be applied than would be
required in the case of an absolutely pure limestone. Any stone above
90% pure in carbonate of lime and magnesia is rated as good, but the
best stone runs from 96% to 99%.

Limestones vary greatly in ability to resist disintegration, and this
variation is a big factor in determining the agricultural value of
ground limestone that has not been reduced to a fine powder. Particles
of a hard limestone may lie inert in the soil for many years. Hardness
also affects the cost of grinding.

_A Matter of Distribution._ Nature has used various agencies in reducing
limestone for the making of soils. The stone contained its lime in
carbonate form, and when reduced to good physical condition for
distribution it helped to make highly productive land. We know that lime
carbonate does the needed work in the soil so far as correction of
acidity is concerned, but in the form of blocks of limestone it has no
particular value to the land. Burning and slaking afforded to man a
natural means of putting it into form for distribution, and it is only
within recent years that the pulverization of limestone for land has
become a business of considerable magnitude. The ground limestone used
on land continues to be in part a by-product of the preparation of
limestone for the manufacture of steel, glass, etc., and the making of
roads, the fine dust being screened out for agricultural purposes. These
sources of supply are very inadequate, and too remote from much land
that requires treatment. Large plants have been established in various
parts of the country for the purpose of crushing limestone for use on
land, and quite recently low-priced pulverizers for farm use have come
upon the market and are meeting a wide need.

_Low-Priced Pulverizers._ A serious drawback to the liming of land is
the transportation charge that must be paid where no available stone can
be found in the region. Great areas do have some beds that should be
used, and a low-priced machine for pulverizing it is the solution of the
problem. Such a machine must be durable, have ability to crush the stone
to the desired fineness and be offered at a price that does not seem
prohibitive to a farmer who would meet the demands of a small farming
community. In this way freight charges are escaped, and a long and
costly haul from a railway point is made unnecessary. The l