be kept well painted.

_Impression wax for vents._

Beeswax 4 parts.
Tallow 2 parts.
Charcoal, finely powdered 1 part.

Melt the beeswax and tallow, and stir in the charcoal.

_Paper parchment._

Immerse unsized paper for a few seconds in sulphuric acid, diluted
with half its volume of water at about 60 deg.; wash it well in cold
water, then immerse it in a weak solution of caustic ammonia, and
again wash.

It absorbs water, and becomes soft and pliable like animal parchment,
but is water-proof. It is not affected by boiling water, is
indestructible by most acids, and is not diminished in strength by
wetting. It has about 2/3 the strength of animal parchment when dry;
the thinner kinds make capital tracing-paper, which takes ink readily.

_Cement for the above._

Cheese--fresh, without salt, if possible 3 parts.
Quicklime 1 part.

Wash the cheese thoroughly three or four times in boiling water, and
grind the materials on a stone and muller, adding cold water until it
is of the consistency of honey.

_Composition for lining the interior of rifle-shells._

Soap--common yellow, not salt-water soap 16 ounces.
Tallow 7 ounces.
Rosin 7 ounces.

The tallow should be melted first, then melt and add the rosin, and
lastly the soap, bringing the mass to a heat that will make it _very_
fluid.

The shells having been first thoroughly cleaned, fill them about
one-third full of the composition, roll them slowly so as to spread
the mixture over the whole interior surface, and then pour off the
residue. This coating should be about one-tenth (0.1) of an inch in
thickness, except at the bottom of the shell, where it should be about
three-quarters of an inch thick. To obtain these thicknesses, the
operation of coating should be performed twice; then pour into the
shell enough of the composition to produce the desired thickness at
the bottom, the shell standing on its base. After the composition is
perfectly cool, immerse the shell in hot water at as high a
temperature as the composition will stand without "running"--about 170
degrees. This second heating of the composition in the bath toughens
it, and causes it to adhere more closely to the shell.

APPENDIX.

A. ALLOWANCE TABLE OF