Year: 1887

page_text: Date of Application, 5th Dec., 1887
Complete Specification Left, 7th Sept.. 1888
Complete Specification Accepted, 12th Oct.. 1888
I, ALBERT BERWICK CUNNINGHAM, of New Barnet, in the County of Hertford,
Gentleman, do hereby declare the nature of this invention to be as follows:-
:-
My invention chiefly relates to the production of metallic aluminium from substances
containing the same, and comprises the improvements hereinafter described.
According to my said invention 1 sometimes provide a bath of molten lead with
which I alloy metallic sodium.
The aluminium containing substance which is preferably in the form of a chloride
or fluoride of aluminium is immersed in the molten bath.
When the chloride or fluoride is immersed, volatization takes place, the fumes as
they rise through the bath being caught and reduced before they have time to escape.
The metal thus obtained having a very low specific gravity and having little or no
affinity for lead rises to the surface whence it may be skimmed off and afterwards
separated from any adhering lead by cupulation or any other convenient means.
After the removal of the aluminium has taken place the bath is replenished with
the amount of lead skimmed off and is recharged with sufficient sodium to produce
the required alloy.
It will thus be understood that the process is practically continuous.
In some cases, instead of introducing the aluminium compound into the molten
bath, I reduce the aluminium compound itself to a molten state and then add thereto
a sufficient quantity of the alloy to effect the reduction of the aluminium.
As the gravity of the said alloy is sufficient to cause it to sink through the
aluminium compound, the use of mechanical means for effecting the submersion will
be unnecessary.
Instead of using an alloy of lead and sodium I can substitute for the lead, metals
which combine with aluminium. By this means the aluminium as it is extracted at
once forms an alloy with the metal of the bath.
Dated the 5th day of December 1887
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant,

page_text: Aluminium Alloys.
I, ALBERT BERWICK CUNNINGHAM of New Barnet, in the County of Herts,
Gentleman, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
In the manfacture of aluminium by means of metallic sodium or other metals of
alkalies or alkaline earths, in order to obtain a good result it is indispensable to
intimately and completely mix the sodium or other decomposing metal with the
aluminium compound to be decomposed.
To effect this complete mixture is, however, somewhat difficult, as the sodium having
a smaller specific gravity than the aluminium compound has the tendency to remain on
the surface of the bath if it is thrown upon it, or to rush forthwith to the surface if
it is submerged, where it will burn on exposure to air or will evaporate if oxygen is
not present.
In either of these cases a great loss of sodium results and in order to prevent this
disadvantage I first alloy the sodium with metallic lead by introducing the metallic
sodium into a bath of molten lead thus forming an alloy of lead and sodium and then
pouring the same into moulds in order to cool it suddenly before the sodium has time
to burn away.
I then proceed to use the alloy in the following manner, that is to say :-I first
melt the aluminium compound, proferably cryolite, together with a flux in a rever-
beratory furnace and when all is well fused I add the quantity of sodium-lead alloy
required for the decomposition. The alloy sinks immediately to the bottom of the
bath and melts there. The sodium which is, so to say, ballasted by the lead cannot
rush immediately to the surface, but is gradually liberated and in rising through the
bath of the aluminium compound is completely taken up by the remaining constituents
of the latter after it has separated a corresponding quantity of metallic aluminium.
The reaction being completed, the contents of the furnace are tapped into a mould
where they are allowed to cool.
The product thus obtained consists of the slag on the surface, the lead containing a
small quantity of sodium and aluminium at the bottom, and between the aluminium
containing a small quantity of lead.
Instead of allowing the molten mass to cool, in most cases I prefer to skim or draw
off the slag and then the aluminium.
The small amount of lead contained in the aluminium is easily got rid of either by
cupellation or by keeping the metal for some time in a molten state in a deep vessel,
whereupon the lead will collect at the bottom, owing to its relatively high specific.
gravity as to the aluminium, as the lead does not form a real alloy with aluminium,
being merely mechanically mixed therewith.

page_text: The trifling amount of aluminium and sodium contained in the lead is of no con-
sequence, as the lead is used over and over again after having been each time alloyed
anew with sodium.
I also use the process hereinbefore described for the manufacture of aluminium
alloys.
In this case I apply, instead of lead, a metal which combines with the sodium and is
also capable of forming an alloy with aluminium.
Such metal or metals are first converted into a sodium alloy, in the same way as the
lead-sodium alloy above described.
If this sodium alloy is subsequently used for the decomposition of the aluminium
compound, the separated aluminium is found united with the other metal or metals of
the sodium alloy.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I wish it understood that, although
in describing the above processes I have for convenience used sodium as an example
of the metals of the alkalies and alkaline earths, I claim the use of any of these classes
of metals for the manufacture of aluminium according to my processes hereinbefore
described, that is to say, I claim :—
First. In the manufacture of aluminium, the employment as a decomposing agent
of sodium or other metal of alkali or alkaline earth alloyed with lead, substantially as,
and for the purposes, described.
Second. In the manufacture of aluminium alloys, the method of uniting the metal
or metals desired to be alloyed with aluminium with the sodium or other decomposing
metal, substantially as, and for the purpose, described.
1000
7th day of September 1888.
cu ULTS FU
A. B. CUNNINGHAM.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.