aid
for good linen shreds for paper making; still, while the latter are
always preserved, the former are thrown away, although considered by
good judges to be worth forty times as much as barn-yard manure.

Old leather should not be thrown away. It decomposes very slowly, and
consequently is of but a little value; but, if put at the roots of young
trees, it will in time produce appreciable effects.

_Tanners' and curriers' refuse_, and all other animal offal, including
that of the slaughter-house, is well worth attention, as it contains
more or less of those two most important ingredients of manures,
nitrogen and phosphate of lime.

It is unnecessary to add that, in common with all other animal manures,
these substances must be either composted, or immediately plowed under
the soil. Horn piths, and horn shavings, if decomposed in compost, with
substances which ferment rapidly, make very good manure, and are worth
fully the price charged for them.

ORGANIC MANURES OF VEGETABLE ORIGIN.

_Muck_, the most important of the purely vegetable manures, has been
already sufficiently described. It should be particularly borne in mind
that, when first taken from the swamp it is often _sour_, or _cold_, but
that if exposed for a long time to the air, or if well treated with
lime, unleached ashes, the lime and salt mixture, or any other alkali,
its acids will be _neutralized_ (or overcome), and it becomes a good
application to any soil, except peat or other soils already containing
large quantities of organic matter. In applying muck to the soil (as has
been before stated), it should be made a vehicle for carrying ammoniacal
manures.

SPENT TAN BARK.

[Why is decomposed bark more fertilizing than that of decayed
wood?]

_Spent tan bark_, if previously decomposed by the use of the lime and
salt mixture, or potash, answers all the purposes of prepared muck, but
is more difficult of decomposition.

[How may bark be decomposed?

Why should tan bark be composted with an alkali?

Why is it good for mulching?

Is sawdust of any value?]

The bark of trees contains a larger proportion of inorganic matter than
the wood, and much of this, on the decomposition of the bark, becomes
available as manure. The chemical effect on the bark, of using it in
the tanning of leather, is such as to render it difficult to be rotted
by the ordinary means, but, by the use of the lime and salt mixture it
may be reduced to the finest conditi