Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1893-09-14
ALUMINIUM.
Some Interesting Facts About This Popu
lar White Metal.


lar White Metal.
N. Y. Evening Telegram.
Aluminium is the highest of the COM
mercial metals, given bulk of it being
only one-third as heavy as q correspond
ing bulk Of iron. The color of alumi-
mum is almost the same as that of
silver, though instead of the dead white
of silver aluminium has q delicate
purple tint.
Attempts are now being made to
change the color of aluminium. There
are reasons for the belief that many
varying colors can be successfully i'm
| parted to the metal without additions
which will considerably vary its chemi-
cal composition Or interfere with valu-
able properties. This field is an open
/ one and offers valuable rewards to the
successful Investigators. The purity of
commercial aluminium varies from "a to
09.75 per cent. The resistance of this
metal to oxidation is one of its marked
qualities, In pure state it does not
tarnlsh from the influence OF the
weather to any degree. 1t is found to
withstand the action Of organic secre-
tons better than silver and is little acted
upon by salt water,
The hardness Of ALUMINIUM varies &C.
cording to its purity, the purest metal
being the softest. The ordinary COM
mercial aluminium is about as hard as
copper. Aluminium hardens remark
ably when it is being worked either on
the forge or in the rolls. By reason of
this phenomenon the metal may be
turned out rigid in finish and shape
where the soft annealed metal would be
too weak to answer the purpose. This
is especially true with aluminium con-
tanning few per cent of some metal as
a hardener. Castings require a large
amount of alloy metal in order to in
crease their hardness; but when these
castings are drop-forge6 or hammered
the metal becomes as hard and as rigid
as hard.drawn brass.
| The impurities most commonly found
in aluminium are silicon and iron. Sill
con in aluminium exists in two forms,
one seemingly combined with alumni.
mum, as combined carbon exists in pig
| iron, and the other as an allotropic
graphitoidal modification. For many
purposes the pure aluminium can
not be so advantageously used as that
containing three per cent or four per
cent of impurities, as the pure alumni
| mum is soft and not so strong as the less
pure. 1t is only where extreme malle-
ability, ductility, sonorousness and nom
| corrodibility are required that the purest
metal should be used. For some pur-
poses, however, small amounts of other
metal are advantageously added to pro-
duce hardness, rigidity and strength
constituents that will not detract from
the lightness of the metal aud will not
affect the non -corrodibility so much as
either silicon or iron.
A sheet of aluminium IL inches square
and one inch thick weighs 1403 pounds;
a bar OF aluminium one inch square and
IL inches long will weigh LII pounds,
and bar of aluminium one inch in d.
aneter and IL inches long will weigh
OBS pounds.
The weight of given bulk of alumni.
mum being /, iron is 80 times as heavy,
copper is 3.6 times as heavy, nickel 3.5
times as heavy, silver times as heavy,
lead 4.S times as heavy, gold ~ times
as heavy, and platinum SO times as
heavy.
In malleability aluminium is preceded
only by gold and silver, and in ductility
by gold, platinum, iron, soft steel and
copper. Under transverse tests pure
aluminium is not very rigid, although
the metal will bend nearly double be.
fore breaking, while cast iron will crack
before the detection has become at all
| large