Evening star., 1895-09-07
ADVANTAGE OF ALUMINIUM
Salt Water Does Not Affect It When Al
loysd With Nickel
Its Use In Ship Construction Opens Up
New and Endless Field
for Experiment..

lracleQ unusual alteHtlOn 10 tNdl Hieldl,
while the report of the naval experts at
Norfolk. Va, against its use on naval ves-
sells because of its corrosive tendencies. has
raised fear that 1t may lessen the chances
of the American yacht in the international
race with the Valkyre III. But James C.
Mcclure. consulting engineer of the COM
pany which supplied the Defenders alumni
mum plates, says that there need be no such
m!sgivings, because the Defenders alumi-
mum plates are alloyed with nickel, while
the plates tested by the naval officers at
Norfolk were alloyed with zinc. The for
mer, he says, are proof against corroSion,
while the latter not
The Navy Department" said Mr.. Nc
Guire to reporter for the New York Times
the other day, tested aluminium which We
furnished for ship construction. The OBJ
ject L had in view was to get the strength
and stiffness needed in ship construction,
and bent all my energies in that direction.
In order to get the requisite strength and
rigidty, we used an alloy of zinc. When
those plates were tested by the authorities
of the Navy Department at Norfolk, it was
found that they collected barnacles and
corroded. and it is from the result of those
reports that the opinion has gone abroad
that aluminium is corroded by salt water.
I'VE taen did not know that salt water
IS such enemy of zinc, but these and
other experiments taught US that when
aluminium is to be used in and around salt
water. we have got to use other alloys
than zinc. This do. The difficulty
has been overcome by using alloys of cop
per ard nickel. We had to find this out
by experimenting, and now We are not
recommending the use of any alloys which
contain zinc for use around salt water,
and the alloys we have used for marine
work which have had no zinc in them,
while they do not collect barnacles, do not
corrode to an appreciable extent
Il personally supplied the aluminium
plates for the Defender. They are made
with nickel alloy. There is no danger in
her plates at ALL far as direct corrosion
goes; the only thing to be feared is gal
vanic action between the aluminium plates
and other metals.
aluminium plates are $40 times lighter
than Tobin bronze, Of which the Vigilant
is constructed. The Defenders bottom is
of manganese bronze. which is of about the
same weight as Tobin bronze"
MIR. Mcclure exhibited two plates-one of
aluminium and the other of copper-taken
New York and West Indian ports The
copper plate was badly eorroded, while the
aluminium plate was free from rust, but
was covered with barnacies. The copper
plate was much the heavier of the two.
Both plates" said Mr.. Mcclure, were on
the same hull during the same period, so
that a comparison is instructive. During
those six months the copper plate, though
free from barnacles, lost ii 800 OF an inch
in thickness, while the thinner and lighter
aluminium plate lost 81 coo of an inch
Nearly all the European navies use
aluminium plates in the construction of war
vessels, and reports received from naval
authorities OF the old world are favorable
TO them. If aluminium was unsatisfactory
they would quickly abandon its use.
-, Aluminium. continued Mr.. MCGUIRE, "is
IKE any other metal and must be treated
Ike any other. If aluminium used in ship
construction is kept clean and painted
there will never be any trouble with it,
Mr. McGulre gave some interesting facts
concerning aluminium.
1t Is mined" he said, Sin Alabama and
Georgia, where it is usually found on high
ground in light, earthly soil. 1t is hydrated
oxide of aluminium in its crude state, and
IS known as bauXite. When the impurities
are removed, only oxide of aluminium is
left. That is put through an electric fur
ace, and the affinity which oxygen has for
aluminium is broken by the electric current
the oxygen is set free and the aluminium
is deposited. 1t is poured in its melted
state into molds, and becomes cool as soon
as ladled out
aluminium is also found in clay. Clay
oxide of aluminium. We cannot use the
clay because it is too expensive, and, be-
sides, the silicate is left behind
We expect soon to have aluminium in
competition with copper, and it will event
TALLY be used for railroad car construction
because it is so light and durable but as
yet ii is too expensive a metal for general
use. Its present value is 80 cents a pound
in ton lots. That is 81 900 ton"
Aluminium is yery ductile, and may be
rolled into sheets of .0o11 of an inch in
thickness. and beaten into leaf, the same
the best gold leaf made in Paris II
may be drawn into tubes or wires, and
spun or stamped into different shapes 1t
may he highly polished. 1t is the lightest
of commercial metals, being only one-thrd
as heavy as iron. 1t has a delicate purple
tint, but it is believed that the colors of
the metal may be varied.
Pure aluminium seldom corrodes or tar
nishes, except when exposed to damp
weather. Even salt water has little effect
the pure metal.
Aluminium melts at $50 degrees cent?
grade, or 1,16o degrees Fahrenheit, and
does not volati!ize at any temperature or
dinarily produced by the combustion of
carbon.
Pure aluminium is soft, but the CONNER
cial aluminium is as hard as copper. 1t
hardens when being worked either by
pressing, forging, rolling or stamping. Cast
ings require large amount of alloy metal,
but when they are drcp-forGed or ham,
mered the metal becomes as hard and
rigid as brass. A sheet of aluminium IL
inches square and inch thick weighs HIP
pounds A bar l inch square and u inches
long weighs 1.176 pounds. A bar l inch in
diameter and II inches long weighs .91S of
a pound.
Cast aluminium. in tension, has an equal
strength to cast iron, but under compress
sion it is weaker.
Aluminium readily unites with all metals
except lead antinory and mercury Alum
mum bronze, which is made with an alloy
of 10 or II per cent of aluminium with cop
per, is one of the densest finest grained
and strongest of known alloys. Aluminium
bronze may be worked in a lathe; the chips
cut smooth and long, and do not clog the
tool. 1t is much more rigid under trans
verse strain than gun bronze. and 1t is an
unusually safe metal under compression.
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