After dressing the hide, two
strongish pieces of wood are sewn along the slit, one at each side, just
like the ironwork on each side of the mouth of a carpet-bag, and for the
same purpose, i.e. to strengthen it: a nozzle is inserted at the neck. To
use this apparatus, its mouth is opened, and pulled out; then it is
suddenly shut, by which means the bellows are made to enclose a bagful of
air; this, by pushing the mouth flat home, is ejected through the nozzle.
These bellows require no valve, and are the simplest that can be made:
they are in use throughout India. The nozzle or tube to convey the blast
may be made of a plaster of clay or loam, mixed with grass, and moulded
round a smooth pole.
Metals, to work.--Iron Ore is more easily reduced than the ore of any
other metal: it is usually sufficient to throw the ore into a
charcoal-fire and keep it there for a day or more, when the pure metal
will begin to appear.
Welding Composition for iron or steel, is made of borax 10 parts, sal
ammoniac 1 part; to be melted, run out on an iron plate, and, when cold,
pounded for use.
Cast Steel.--A mixture of 100 parts of soft iron, and two of lamp-soot,
melts as easily as ordinary steel--more easily than iron. This is a ready
way of making cast-steel where great heat cannot be obtained.
Case-hardening is the name given to a simple process, by which the
outside of iron may be turned into steel.
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