rom whole bones is slow and troublesome, as it
requires a long time for the effect to diffuse itself through the whole
mass of a large bone. When it is made in this way, the bones should be
_dry_, and the acid should be diluted in many times its bulk of water,
and should be applied to the bones (which may be placed in a suitable
cask, with a spiggot at the bottom), in quantities sufficient to cover
them, about once in ten days; and at the end of that time, one half of
the liquid should be drawn off by the spiggot. This liquid is a solution
of super-phosphate of lime, containing sulphate of lime, and may be
applied to the soil in a liquid form, or through the medium of a compost
heap. The object of using so much water is to prevent an incrustation of
sulphate of lime on the surfaces of the bones, this must be removed by
stirring the mass, which allows the next application of acid to act
directly on the phosphate remaining. The amount of acid required is
about 50 or 60 lbs. to each 100 lbs. of bones. The gelatine will remain
after the phosphate is all dissolved, and may be composted with muck, or
plowed under the soil, where it will form ammonia.

[May less water be employed in making super-phosphate from
bone dust or crushed bones?]

_Bone dust_, or _crushed bones_, may be much more easily changed to the
desired condition, as the surface exposed is much greater, and the acid
can act more generally throughout the whole mass. The amount of acid
required is the same as in the other case, but it may be used
_stronger_, two or three times its bulk of water being sufficient, if
the bones are finely ground or crushed--more or less water should be
used according to the fineness of the bones. The time occupied will also
be much less, and the result of the operation will be in better
condition for manure.

Bones may be made fine enough for this operation, either by grinding,
etc., or by boiling under pressure, as previously described; indeed, by
whatever method bones are pulverized, they should always be treated with
sulphuric acid before being applied to the soil, as this will more than
double their value for immediate use.

Bone-black is chiefly used by manufacturers of super-phosphate of lime,
who treat it with acid the same as has been directed above, only that
they grind the black very finely before applying the acid.

[What other forms of bones may be used in making
super-phosphate of lime?

Why is super-phosphate of