Improvements in the Method of and Apparatus for Depositing Metals by Electro-deposition.
Year: 1890

page_text: Date of Application. 10th June, 1890-Accepted. 6th Dec., 1890
COMPLETE SPECIFICATION.
Improvements in the Method of and Apparatus for Depositing
Metals by Electro-deposition.
I, GEORGE HENRY FELT, of 244 West 135th Street City and State of New York,
United States of America 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:
The first part of my invention relates to method for the electro-deposition of metals.
and has particular reference to the electro-deposition of the metal known as aluminium.
The invention consists, broadly, in adding to the liquid, which surrounds the kathode
of a galvanic battery, clay, as free as possible from impurities, preferably in con-
junction with a weak solution of nitrate of mercury. In carrying out my process, I
prefer to employ a special form of battery, which will be described hereinafter; but
the particular structure of the cell, as given below, is not a necessity, but is chosen as
being well suited to the particular work which has to be performed. I find in practice
that the clay which I put into the liquid surrounding the kathode is decomposed in
and by the action of the acid and the battery, and that if the proper facilities are
present, the aluminium, which is set free, can be collected in forin of a deposit upon
some metal which can afterwards be either removed by acids or combined with the
aluminium to form an alloy. I provide the proper facilities, by employing metallic
screens for separating the silica and by securing the presence of free mercury which
combines with the metal of the screens and the aluminium, thereby securing a deposit
of the last named metal.
I will now proceed to describe the particular form of battery cell which prefer,
and the arrangement and character of the solution which I have found to work well
in practice. But I do not wish to confine myself to the particular form, or to the
particular elements or ingredients recited in the Specification which follows.
I sustain one liquid of my battery in a removable receptacle formed of bond or
parchment paper.
I prefer to use this substance because I find in practice that it
offers little or no perceptible resistance to the passage of the current through the cell,
while at the same time it keeps the liquids from intermingling. This property I find
very useful and important for my purposes.
Some distance below the top, the jar is reduced in size so as to form an interior
ledge on which the bond paper diaphragm constituting the receptacle for one of the
liquids is supported. The portion of the jar above the ledge forins a chamber within
which the diaphragm is contained. The upper part of the diaphragm is pressed
against the inner surface of the chamber, by a hoop or ring of hickory or other
elastic material, between which and the diaphragm is a band of water-proof paper, or
similar material to provide an additional safeguard against the mixing of the liquids
by reason of their creeping up the sides and over the edges of the diaphragm. The
band referred to effectually prevents such creeping, and insulates the liquids. The
band and hoop also help to give the necessary stiffness for rendering it possible and
easy to remove the diaphragm and its contents. By a special coupling arrangement,
which will be described hereinafter, I am able to preserve the continuity of the band
all around the vessel without leaving an opening at the joint.
Below the ledge referred to is a chamber of considerable size, and below that
another of still smaller diameter. On the ledge which divides the last named
chambers, I support perforated metallic plates or sheets of wire netting, and press
them down into contact with the negative electrode in the lowermost chamber.
In setting up my battery, my kathode, consisting preferably of a bunch of copper
plates joined together so as to present as much surface as possible to the action of the

page_text: liquid, is placed in the lowest chamber and an insulated wire is carried from it along
the walls of the jar and out at the top. The perforated plates or sheets of wire
netting are then put into place on the lower ledge and pressed and held down by an
elastic hoop say of hickory. After this an exciting liquid, preferably consisting of a
sulphuric acid solution is poured in until it passes slightly above the top of the middle
chamber. The diaphragm is then set in and the hickory hoop inserted with the band
of a waterproof paper between the two. The pouring in of the upper liquid say
sulphate of zinc, and the insertion of the anode, which is preferably of zinc in the
form of a circular grate having a grooved upper surface for containing mercury to
keep the electrode amalgamated, completes the process. One or more tubes between
the diaphragm and the wall of the jar for assisting in the replenishing of the liquid
in the lower chamber and for admitting of the escape of gas therefrom may be added,
though they are not absolutely essential.
I have illustrated my invention in the accompanying sheets of drawings
whereon: 11
Fig. 1. is a vertical section of a battery cell constructed in accordance with my
invention.
Figs. 2. and 3. are respectively details of the positive and negative electrodes.
Fig. 4. is a detailed perspective of the water-proof band.
Fig. 5. is a vertical section of a modified form of battery cell and-
Fig. 6. is a detail view of the positive electrode of the cell Fig. 5.
On the drawings the reference letters wherever repeated indicate similar or like
parts.
Referring to Figs. 1. 2. 3. and 4 of the drawings by letters,
A. is a jar, made of some good insulating material, preferably glass. B. is the
upper chamber of the jar. C. the middle & D the lower chamber. In the chamber D
is the negative electrode E.shown more particularly at Fig. 3 which consists of a
series of leaves or plates e, e, preferably of copper, joined centrally and bent out, as
shown, so as to present as much surface as possible to the exciting liquid F. The
extremities of the plates or leaves are so bent as to press against the sides of the jar
and hold the electrodes firmly in place. Their top extends slightly above, or at least,
as high as the top of the ledge which separates the middle and lower chambers. The
liquid which surrounds the negative electrode, is preferably a sulphuric acid solution.
It fills the lower chamber and also the chamber C. extending slightly beyond the
same, as will presently appear. At the top of the chamber D is a ledge or shoulder c
on which is supported one or more (in this instance two) perforated metallic plates or
sheets of wire netting G. The wire netting or its equivalent, when of copper, as I
prefer, for battery purposes, forms practically an extension of the kathode. A hoop J
of hickory holds the plates G against the top of the copper plates which form the
body of the kathode.
In the upper chamber B is contained a diaphragm H preferably of bond or parch-
ment paper. This diaphragm is formed into a receptacle, the walls of which rest
against the inner surface, of the chamber B. Within the rim of the diaphragm is a
band of some waterproof substance, such as stiff waterproof paper, which is
pressed against the diaphragm by an elastic hoop or ring L, say of hickory. From
Figure 4 it will be seen that the band is slitted at 's and that one end is folded longi-
tudinally in a double fold and passed through the slit. The folds are afterwards
removed and then laid endwise along the body of the band, the other end being left
long enough to pass around and cover the joint at the slit.
At R is shown the positive electrode in the shape of a circular grooved grate, the
grooves of which are filled with mercury.
I find that the application of mercury in this way is quite sufficient to amalgamate
the entire surface of the zinc below the liquid. The binding posts K, of which I
have shown-four,.are for obvious reasons, arranged far enough from the edge of the
grate to escape touching any part of the receptacle.-.
M is a tube which passes down between the diaphragm H and the inner wall of
the jar. This tube can be used in supplying the lower liquid either in the first

page_text: instance or when it has run low. In general, however, the filling is accomplished by
the process already described and when the liquids are to be changed, the upper
receptacle, with its contents, is removed, and the jar emptied. After which the
re-filling takes place by precisely the same process. The tube or tubes may do service
in permitting the escape
of the gases set free in the lower and middle chambers by
the decomposition at the lower electrode.
When the receptacle H is put into place, the liquid below is forced up along the
side about as high as the top of the liquid within the diaphragmn. Thus the pressure
of the liquids is about equal on both sides of the diaphragm.
An insulated wire N passes from the lower electrode up through the jar traversing
the lower liquid and passing next to the wall of the jar outside the diaphragm.
When it is desired to use the apparatus for the electro deposition of aluminium I
also place on the metallic plates or sheets G a vessel O having a perforated top and
filled or partially filled with mercury.
And on the same plates I place clay P, which is to be subjected to decomposition
for the purpose of yielding up its aluminium.
Moreover, to the exciting liquid in the lower and middle chambers, I add a very
weak solution of nitrate of mercury.
When carrying out my aluminium process I find that the clay becomes disintegrated
and decomposed by the action of the battery, the silica falling through the meshes of
the wire netting to the bottom of the lower chamber. On the other hand, the
aluminium forms an amalgam with the mercury of the nitrate and combines with
that and with the metal of the wire netting, so that I obtain practically a combination
of aluminium with the netting with mercury as the binding agent.
In order to furnish a guide for the proper setting up of a cell for carrying out my
process, I will say that I may use of the free mercury in a vessel having a perforated
top, one ounce of the clay to be decomposed, five pounds; of the nitrate of mercury
solution, eight ounces, the solution being ordinary nitrate of mercury diluted with
one hundred times its weight of water. The strength of the sulphuric acid solution
around the lower electrode may vary within wide limits.
In case I use copper netting, the aluminium can be united with it by heat and
rolling to form aluminium bronze. If any other alloy of aluminium is desired, the
proper metal can be used for the netting. In any case, the arrangement should be
such that the proper proportions of both metals should be present, when the aluminium
has been deposited in such quantities as to fill and close the meshes. For aluminium
bronze I have found it advantageous to use copper netting having twelve meshes
to the square inch. In the process of heating, the mercury is dissipated. By this
process, alloys not possible by fusion-on account of different evaporating points, can
be successfully made. If pure aluminium is desired, one side of the screens can be
varnished to prevent a deposit on that side, and after the deposit on the other side,
the metal of the screens can be removed by acids, leaving the aluminium, or better
still, the screens themselves may be made of aluminium, in which case there will be
no need of any chemical treatment in order to secure the pure product.
To prevent the deposit of aluminium upon the copper electrode, I leave the surface
of the electrode comparatively dirty. When the wire netting is present, a deposit
takes place on the netting and not upon the main body of the electrode.
The cup or vessel 0 of mercury is placed on the netting to supply the waste from
the nitrate as the decomposition takes place. I have employed the same process with
success, for obtaining the precious metals from their sulphurets.
The screens G may be dispensed with and the deposit taken on the copper
electrode.
For the clay, I may substitute sulphate of aluminium or some other aluminium
compound, or may use both clay and the other compound and I may also use in
place of the nitrate of mercury any other suitable mercurial salt solution.
In Figs. 5 and 6 the battery cell is shown with the vessel O and clay P removed.
At Fig. 6 the positive electrode R is shown in the shape of a circular grooved
grate, the grooves of which are filled with mercury. It will be noted that in the

page_text: grate, Fig. 2 the inner groove is clear all round whilst in Fig. 6 the groove may be
obstructed by the cross ledges k as shown, although this is not essential.
The cell which I have shown and described is of the class in which the two
electrodes are located one above the other in the exciting liquid; but this feature is
not essential and the electrodes may be located side by side with a vertical partition
between them instead of being placed one above the other with a horizontal separating
wall.
For
A self replenishing and cheap solution may be used with the galvanic batteries.
The solution contains clay or sulphate of aluminium or some other aluminium com-
pound, from which the sulphate of aluminium in liquid form can be obtained.
example to pounds of clay add the solution of 8 ounces of sulphuric acid in
100 ounces of water. When clay is employed, the original liquid should be sulphuric
'acid more or less dilute.
This decomposes the clay into its constituent parts, the silica remaining at the
bottom and the aluminium being taken up to form the sulphate. When I use com-
mercial sulphate of aluminium, I simply place it in water and allow it to dissolve
until a saturated solution is obtained.
In carrying out the electrolytic process I add to the solution above described, a
weak solution of nitrate of mercury. In lieu of the weak solution of nitrate of
mercury heretofore mentioned I may employ the following proportions, or there-
abouts, of one ounce of mercury partially dissolved in a pound of nitric acid and
three pints of water, which have been frequently shaken together to hold the mercury
partly in mechanical suspension, and water added thereto in three times the volume
of the resultant. By this means we have a weak solution of a salt or salts of mercury
in the presence of metallic mercury.
The 8 oances of sulphuric acid hereinbefore mentioned is in excess of the amount
of acid necessary to act on the clay, the remainder being to reduce the resistance and
thus increase the electro-motive force.
This same excess of sulphuric acid is kept up by the addition of sulphuric acid
from time to time. In case the excess of acid is not entirely taken up by the clay,
clay is added from time to time as the sulphuric acid is added to take up any excess
of acid in the solution; I find that the presence of the nitrate in the solution acts not
only in such a manner as to assist in the electrolytic deposit of aluminium but also to
increase the electrical exciting capacity of the solution.
In practice, I always provide an excess of the clay or the solid sulphate of
aluminium so that, as the battery acts, the clay or the sulphate may be drawn upon to
form, more of the solution.
Owing to the cheapness of clay and also of commercial sulphate of aluminium, I
find that I can prepare this solution at very little cost, and maintain it for an
indefinite period with little additional expense.
By commercial sulphate of aluminium, I do not mean ordinary rock alum, which
would give an alkaline solution, but the acid sulphate which is now purchasable
under the name of sulphate of aluminium. The clay and the solid sulphate may both
be put into the same solution and in some instances I have found it advantageous to
do this. A solution of any other mercurial salt besides the nitrate would be
equivalent to the nitrate solution.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The process of obtaining aluminium, which consists in decomposing clay or
other aluminium compound by chemical and electrical action in a galvanic battery in
the presence of mercury and collecting the aluminium as an amalgam on métallic
holders, as set forth.
2. The process of obtaining aluminium which consists in adding clay or other
aluminium compound to the generating solution in a galvanic-battery, decomposing
it there by chemical and electrical action in the operation of the battery in the

page_text: presence of mercury, and collecting the solution in the form of an amalgam as set
forth.
3. The process of decomposing clay which consists in adding clay to the generating
solution of a galvanic battery and closing the battery circuit, as set forth.
4. The process of obtaining a deposit of aluminium on metal which consists in
placing the metal in the generating solution of a galvanic battery, adding clay or
other aluminium compound and a weak solution of nitrate of mercury or other
mercurial salt to the same solution and closing the battery circuit, as set forth.
5. The process of obtaining a continued deposit of aluminium on metal, which
consists in placing the metal in the generating solution of a galvanic battery, adding
clay or other aluminium compound, and a weak solution of nitrate of mercury or
other mercurial salt to the generating solution, closing the battery circuit, collecting
the aluminium in the form of an amalgam on the metal and replenishing the wasted
mercury of the nitrate, as set forth.
6. A galvanic battery having an insulating cell or jar, and a kathode of copper
plates joined centrally and bent apart at the edges, the length and arrangement of the
plates being such that their ends press against the sides of the jar and hold the
kathode in place, as set forth.
7. A galvanic battery, having a kathode of vertical copper plates joined centrally
and bent apart at the edges in combination with one or more horizontal copper plates
forming an extension of the kathode.
8. A galvanic battery, having a kathode of vertical copper plates joined centrally
and bent apart at the edges in combination with one or more perforated horizontal
copper plates forming an extension of the kathode, as set forth.
9. A galvanic battery, having a kathode of vertical copper plates joined centrally
and bent apart at the edges in combination with one or more horizontal copper plates,
and a spring holding the horizontal plates, in contact with the vertical plates, as set
forth.
10. A galvanic battery, having a jar or cell with an interior ledge or shoulder, a
diaphragm resting on the said ledge and held against the walls of the jar by a spring,
in combination with a band of waterproof material between the spring and the
diaphragm, as set forth.
11. A galvanic battery, having a diaphragmatic receptacle containing one of the
battery liquids, a spring pressing the diaphragm against the walls of the battery jar
or cell, and a band of waterproof material within the diaphragmn, as set forth.
12. The combination with a battery cup, of an interior band or lining of water-
proof material, the said band being slitted, and having one of its ends passed through
the slit and laid along the body of the band, and the other end brought around to
cover the joint at the slit, as set forth.
13. A depolarizing solution for galvanic batteries, consisting of liquid sulphate of
aluminium or other aluminium compound combined with a solution of a salt or salts
or mercury in presence of metallic mercury as set forth.
14. A depolarizing solution for galvanic batteries, consisting of liquid sulphate of
aluminium combined with a solution of a salt or salts of mercury, as set forth.
15. A self-replenishing depolarizing solution for galvanic batteries, consisting of
liquid sulphate of aluminium containing clay or other aluminium compound, as
set forth.
16. A self-replenishing depolarizing solution for galvanic batteries, consisting of
sulphuric acid containing an excess of clay, as set forth.
Dated this 7th div of June 1890
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.