The record-union., 1897-11-12
Aluminium Manufactures

Ine american Monthly Review of
Reviews tells the story of the inyen-
tion by Charles M. Hall, a graduate of
oberlin College, of the process now en-
ployed for the production of aluminium
On an extensive scale. After speaking
OF Mr.. Halfs college career and gradua-
ton, the Review writer saws:
with only the most meager euuip-
ment, without financial resources and
with little encouragement from friends
or associates. Hall now entered on a
series OF experiments which in less than
year resulted in the discovery Of what
proved to be cheap, practicable and
efficient process for the extraction of
aluminium. Hall has himself said that
his first work in this direction did not
have reference to electrolysis as the SOL
vent. At intervals during his college
course he had experimental in various
crude attempts to produce the metal by
methods which his reading on the sub
Ject had suggested. He had famliarizad d
himself with all that had been written
about aluminium, and understood thor
oughly the problem of its production.
In 1854 he spent several weeks in an
attempt to reduce the oxide of alumni
mum by carbon at a high temperature
with the aid of other reagents. Although
IN these experiments he used a blast
furnace capable of fusing platinum, he
failed to accomplish the object in view,
ana 1t was then that he turned to cleo
trolys1s as the only practicable method
1t was natural that at first he should
wish to make trial of the process then
known of producing aluminium by the
electrolysis of the double chloride He
says that he determined to follow out
this process carefully, and ii possible to
improve it. Whether or not he would
have succeeded in his efforts to perfect
this process must remain matter of
mere speculation. In October, 1885, four
months after his graduation from col
lege, he evolved an entirely new plan of
procedure. Instead of applying cleo
tricity Directly to the Chloride method
which had already been tried and found
wanting-he would endeavor to find a
stable solvent for alumina itself (the OK
idel and would then electrolyZe the pure
aluminium from the solution. 1t was,
of course, desirable that the metal
should be dissolved at a reasonably
low temperature and that the solvent
itself should be practically unaffected,
so that the oxide might be added con-
tinuously as fast as it was decompoSed
by the current. Hall believed that he
would find such solvent in the fiuoride
of calcium Chuospar), and he expert
mented with that substance; later he
tried the fluorides of magnesium, So
Gium. and potassium. He found that
all these compounds We're extremely
difficult to fuse, and that they did not,
when fused, dissolve the alumina APP
preciably. These facts he might have
inferred, perhaps from the descriptions
Of these minerals given in the books.
but nothing short Of actual experiment
and observation would satisfy him, and
he took nothing for granted. In his
search for a solvent he finally determ-
ined to test the double fuoride of
aluminium and sodium (cryolite). De-
vile, who had experimental with this
mineral thirty years before had appar-
emily never discovered that it was a
solvent, when fused, of alumina. If it
could be proven to be such solvent,
the most difficult part of the quest
seemed in fair way to be solved.
Halls first experiments with cryolite
Were not altogether satisfactory to him,
but he attributed each failure to defects
in his apparatus. He fused some cryo-
lite in clay crucible, dissolved alumina
in this path, and passed an electric cur
rent through the solution On the carbon
rod which served as the negative cleo
trode substance was deposited which
had the appearance of aluminium. but
II xyaG mt the miro metal A ,aor+;o,
of the clay from which the crucible
was made seemed to yield its silica to
the bath, and thus the product was rem
dered impure. The only way to obviate
this was to employ an insoluble lining
for the crucible. The first experiment
with carbon-lined crucible was sue
cessful. By the aid of a seven cell
Grove battery. within two hours time a
reasonable amount of aluminium of a
high degree of purity was obtained.