<h2><SPAN name="CHAPTER_XXVII" id="CHAPTER_XXVII"></SPAN>CHAPTER XXVII</h2>
<h3>ELECTRICAL PRODUCTS—ALUMINUM.</h3>
<p>Another comparatively new article of manufacture
now produced in large quantities at
Niagara Falls is aluminum. Until within the
last few years this metal was not used to any
extent by manufacturers, because of the great
expense attending its production. Now, however,
it is produced in such quantities as to
make it about as cheap as brass, bulk for bulk.
Aluminum is a very light metal, with a color
somewhat lighter than silver; its specific
gravity being about one-third that of iron.
Aluminum is found in one of its compounds
in great quantities in nature, especially in certain
kinds of clay and in a state of silicate, as
in feldspar and its associated minerals. It is
found in great quantities in southern Georgia,
where it is mixed with the red oxide of iron
that abounds in that region. Here, it exists
as alumina, which is an oxide of aluminum.
Before it is taken to the reduction-works the
alumina is separated from all other substances.
It is a white powder, tasteless, and
not easily acted upon by acids.<span class="pagenum"><SPAN name="Page_224" id="Page_224"></SPAN></span></p>
<p>Electricity is the chief agent in the production
of metallic aluminum. The reduction
company buys this alumina, which has been
separated from the clay or ores where it is
mined. In a large room there are located a
great number of iron vats or crucibles, lined
with carbon, about two or two and one-half
feet deep, five or six feet long and four feet
wide.</p>
<p>Immediately over each vat is constructed a
metal framework, through which are inserted
a large number of carbon rods about eighteen
or twenty inches long and from two to two
and one-half inches in diameter. This framework
is electrically insulated from the iron
crucibles. The framework and the carbons
are connected with the positive conductor of
the electric current, and the vat or crucible
with the negative. These conductors are very
large, something like a foot in width and an
inch in thickness, and made of some good conductor
of electricity. They have to be very
large because they carry a current equal to
3050 horse-power. The current is one of great
volume, but very low voltage; the electromotive
force at each vat or crucible being only
about seven volts. As the process is electrolytic,
and not simply a heating process, the
direct current must be used, and therefore the
current coming from the power-house must
be transformed twice; first to bring it to a<span class="pagenum"><SPAN name="Page_225" id="Page_225"></SPAN></span>
proper voltage and secondly to change it from
an alternating to a direct current. These
iron vats or crucibles are connected up in
series, electrically, and then they are filled
with the alumina and certain other materials,
which act either as a flux or as a means of increasing
the conductivity of the mixture; just
what this substance is, is probably one of the
secrets of the process. When all of the crucibles
are filled with the mixture the current is
turned on and is kept on continuously night
and day seven days in the week. All of the
material in the different crucibles is heated to
redness, when the process of separation takes
place. The oxygen of the alumina is thrown
off as a gas, and other residuum floats to the
top of the crucible and is skimmed off.</p>
<p>Metallic aluminum in a melted state sinks
to the bottom of the crucible, where it is
dipped out from time to time with large iron
ladles and poured into sand and molded into
blocks similar to that of pig iron. From time
to time, as the metal is dipped out, fresh
alumina with the other substances are thrown
in on top of the crucible, so that the process is
continually going on, day and night, week in
and week out. The heat in the process of reducing
alumina, as we have before seen, is not
the chief factor; it simply serves to reduce the
compound to a fluid state so that the electrolytic
action can readily take place.<span class="pagenum"><SPAN name="Page_226" id="Page_226"></SPAN></span></p>
<p>Therefore it is not necessary to be brought
to a white heat, as it is in the case of the production
of carborundum, described elsewhere.</p>
<p>It was extremely interesting to observe the
wonderful magnetic effects that were produced
in iron when brought into proximity
with these enormous electrical conductors.
The voltage was so low that one could handle
them with impunity. The iron crucibles became
so magnetic that a heavy bar of iron
seven or eight feet long would cling to their
sides, so that it would be held in an upright
position. Bars of iron would cling to the conductor
at any point along its length, and, although
these conductors were carrying an
energy of over 3000 horse-power, they produced
no perceptible effect upon the human
body. The reason for this lies in the fact,
first, that the body is not made of magnetic
material, and, secondly, the pressure is so low
that the body—being a poor conductor—would
not easily allow the low-pressure current to
pass through it.</p>
<p>Aluminum is fast becoming an important
article of commerce, and it is destined to become
more and more so on account of its extreme
lightness as compared to other metals.</p>
<p>It is found to be valuable also when used
as an alloy with many of the other metals.
One of the great drawbacks to its more extensive
use lies in the fact that as yet no sat<span class="pagenum"><SPAN name="Page_227" id="Page_227"></SPAN></span>isfactory
method has been devised for soldering
it. Undoubtedly in time this difficulty
will be solved, when its use will be greatly increased.
It is estimated that in its various
compounds aluminum forms about one-twelfth
of the crust of the earth.</p>
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