Evening capital. (Annapolis, Md.) 1884-1910, 1891-07-02
PRICE ONE CENT
whs. I. steel.


Steel has been defined as any kind Of
iron which when heated to redneSs and
suddenly plunged into cold water be-
comes hard; and every kind Of mallea-
Bile or flexible iron that can be hardened
by that process is steel. But this def
milton, says An Occasional Contributor
in the Mechanical NetrS. is not applica-
Bile 70 the steel of mild quality now
made for many mechanical uses. One
of the requisites for this mild steel ia that
it will not harden after being heated co
a cherry red and plunged into water. To
include all the kinds of steel now used in
agricultural and mechanical the better
definition OF steel will be malleable iron
combined with a percentage of carbon.
Chemically considered, steel occupies a
half way position between wrought and
cast iron. wrought iron being simply iron
almost entirely free from carbon, while
steel that is to be tempered contains 10
II per cent of carbon.
The reason why this very slight change
In the chemical construction should pro.
duce such wonderful results in the prop
critics of iron and steel is as yet an un.
solved mystery. We know that bar OF
iron converted into steel becomes more
granular or open, and while it loses 10
some extent its toughness, IL gains, in.
stead, elasticity, greater strength, and
closeness of fiber.
Blister steel is made by heating bars Of
iron packed in charcoal in a furnace for
a period of from six to 10 days. When
the metal is withdrawn the bars are
found TO be of crystalline texture, and
have blistered surface-hence the name.
Cast steel was formerly made OF blister
steel broken into fragments, melted in
crucibles, and cast into ingots; but the
modern practice is TO charge the cruel.
bles with pieces of good Swedish or
American bar iron, adding charcoal and
black oxide of manganese. The heat of
the furnace soon seals the lid of the cru
chile, and the melting iron absorbs car
bon from the fumes of the charcoal, thus
shortening the tedious process Of making
~blister" bar The cast steel is rolled or
hammered from the ingot TO any desired
bar, sheet, or plate.
The chief characteristic of steel con.
sists in its capability of being hardened
and tempered, and when exposed 10 heat
it takes on in succession the following
coloH:
1. A faint yellow. which indicates a
proper temper for lancets or small cut
tiers that require the finest edge, with but
little strength of metal.
2. A pale yellow, which indicates the
temper for razors and surgical instru-
ments.
3. Full yellow for pen knives, etc. with
increased toughness.
4. Brown, with purple spots--that be.
ing for axes and carpenters tools.
8. Bright blue, for swords and watch
springs.
8. Full blue, for fine saws, daggers,
etc.
z. Dark blue, for large saws or instru.
ments that may be sharpened with file.
The above colors are based on steel
suitable for the requirements. A piece
of steel suitable for razors, lancets, ETC.,
would not take the color indicated for
large saws, as that quality of steel is but
little above the blister" quality. The
finer steel is, the less heat il viii temper
at, requiring a lower temper Of color.
Recently there have been some valuable
discoveries in tempering, welding, aud
restoring steel, both from burnt or low
grade.