US1379089A

US1379089A - Production of thin metallic sheets or foils

Info

Publication number: US1379089A
Application number: US328378A
Authority: US
Inventors: Thomas A Edison
Original assignee: Individual
Current assignee: Individual
Priority date: 1919-10-04
Filing date: 1919-10-04
Publication date: 1921-05-24
Anticipated expiration: 1938-05-24

Description

T. A. EDISON.

PRODUCTION OF THIN METALLIC SHEETS 0R FOILS.

APPLICATION FILED on. 4. 1919.

1,379,089. y Patented May24, 1921.

I 2 j I J I 4 I I I 6 II/[III]!IIIIIIIIIIIIIII I, A wm plating system and an electrolytic cell em- To all whom it may concern:

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LLEWELLYN PARK, WEST ORANGE, HEW Jmm PRODUCTION OF THIN METALLIC SHEETS OB FOILS.

Specification of Letters Patent. Pat t d pl 1921 Application filed October 4, 1919. Serial No. 328,378.

until layers or coatin of nickel Be it known that I, Tnonas' A. EDISON, .0005" in thickness. 21%: plated thia:e i 1 h a citizen of the United States, and a residrums are then raised from the nickel-platdent of Llewellyn Park. in the town 0t Vest ing cells and the crane moved to the wash- Omnge county f Essex. and State of New ing tank where the cathode drums are Jersey. have invented certain new and usewashed, preferablv by spravs of water. to ful Improvements in the Production of Thin Metallic Sheets or Foils, of which the foltion which cling thereto. The above cycle lowing is a description. of operations is repeated until the desired My invention relates to the production of number (usually 250) of alternate lavers of very thin metallic sheets or foils and more copper and nickel have been plated on the particularly to the production of thin nickel cathode drums, the composite sheets then besheets designed to be used in making nickel ing stripped or removed from th th d flakes for storage batteries of the alkaline drums and cut up into verv small pieces, type: and the invention resides in an im generally about square-which are tre t, pmved process especially adapted for maked with a suitable reagent to dissolve the ing such sheets or foils and also in an electro fC10 per and produce the desired thin nickel a es.

The present invention renders the use of ployed in carrying out such process.

traveling cranes. washing tanks and difier- In Letters Patent No. 865.637 and No. 865.688 granted 936,525, granted October 12, 1909. I describe nickel in the production of the alternate processes of making metallufilms or flakes layers of copper and nickel. as described intended particularly for use in storage bat above, unnecessary, and is based on the teries of the alkaline type, and consisting discovery that alternate thin layers or films generally in electroplating upon a suitable of copper and nickel, in a condition whi h cathode thin and alternate layers or films of answers all the requirements necexary for a readily soluble metal. such as copper, and the making of nickel flakes such as are used of the desired metal. such as nickel, or coin alkaline storage batteries, may under oerbalt or cobalt-nickel alloy. The composite tain conditions, be plated on a cathode from sheet thus formed is removed from the a single electrolytic bath. Practically the cathode and cut into small portions which only labor necessary in producing composite are then treated with suitable reagents, in sheets of copper a d nickel accordance which copper is soluble. but which do not with my invention. is to remove the sa affect the nick l r cobalt, from the cathodes after they have been In apparatus at present used for carrying out the processes described in the atomsired number of alternate layers of copper said patents, a plurality of revolving cathode and nickel. drums mounted on a traveling crane are More particularly described, my invenfirst respectively and simultaneously lowtron consists in employing an electrolytic cred into the electrolyte of a plurality of cell or cells each of which comprises a comelectro-plating cells containing a copper so- 'poslte plating lution and copper anodes, where exceedingly of a strong n1ckel-plat1ng solutlom preferthin layers or films of copper are plated ably a substantially saturated solution of onto the drums. The cathode drums are nickel sulfate. and a copper-plating soluthen raised out of the copper-plating cells tion. preferably a substantially saturated and the crane is advanced to a washing tank solution of copper sulfate, and in which the where the cathodes are washed. preferably nickel-plating solution greatly predomiby spraying water thereon, to remove the nates. The bath also preferably contains a films of the copper-plating solution whichsalt of a fatty acid. preferably acetate of cling thereto. The-crane is then advanced nickel. for a purpose which will be hereinto a poi-Lion in which the drums are respecafter described. While the proportions of tively disposed above a plurality of electrothe materials in the bath may be varied conplating cells containing nickel anodes and siderably, I preferably employ these matenickel solutions. and the drums lowered into rials in the following proportions: Three said cells and allowed to remain therein hundred parts by weight of the saturated soremove the films (it the nickel-plating solu September 10. 1907. and No. entplating cells for plating the copper and formed on the latter by plating the debat-h consisting of a mixture lution of nickel sulfate, three parts by weight of the saturated solution of copper sulfate, and eighteen parts by weight of solid acetate of nickel. Disposed in the bath of each cell are a single cathode and two anodes, one of nickel and one of copper. A current of density less than that which will deposit nickel is first passed through the cell in a path which includes only the cathode, the electrolyte and the copper anode. During the passage of this current through the cell no deposit of copper will appear on the cathode for a considerable period of time providing there is no agitation of the electrolyte. If the electrolyte is ,vigorously agitated during this period, however, a thin layer of copper will be deposited on the cathode so as to completely cover the latter. This is due to the fact that the agitation of the electrolyte hastens the electrolytic action of the current on the copper solution and effects circulation of the electrolyte and therefore causes practically all of the copper freed from this solution, to gather in the vicinity of the cathode. Accordingly, as soon as the circuit is established through the cell so as to include the copper anode as described, I agitate the electrolyte and continue the agitation thereof for the greater part of the period allowed for the deposition of copper and then maintain the electrolyte quiet during the remainder of such period, preferably for about one-sixth thereof. During this time when the electrolyte is maintained quiet practically all of theremaining copper in the solution adjacent the cathode will be deposited on the latter and the solution therefore practically exhausted of copper. The

plating circuit through the copper anode,

the electrolyte and the cathode is then broken and another circuit established in a path which includes the nickel anode, the electrolyte and the cathode, through which a current of high density is passed. A coating of nickel of the desired thickness, namely, about .0005", will now be plated on the cathode in a comparatively short time, and this nickel will be practically free from copper, the amount of copper deposited with the nickl being so very small as hot to efi'ect the brightness and smoothness of the nickel deposited. This would not be the case if the copper were not practically exhausted from the solution adjacent the cathode and if the solution contained such an amount of copper, that copper would immediately be deposited without agitation of the electrolyte uponthe establishment of the depositing circuit through the copper anode, electrolyte and cathode. The circuit through the nickel anode, electrolyte and cathode is now broken, and the cycle of o erations above described is repeated until t e desired num-' ber of alternate layers of cop i er'and nickel are plated onto the cathode. he composite sheet formed on the cathode may then be removed and treated as hereinbefore described to obtain thin films or flakes of nickel. The cathode employed in my improved cell is preferably formed of copper and previous to the mounting-thereofin the cell, is preferably ro'vided with an extremel thin surface ayer or film of selenide 0% copper in order to facilitate the stripping or removal of the composite sheet plated thereon, as described in my ending application Serial No. 308,821 filed une 21, 1919, and entitled Electro-plating.

The densities of the copper-plating and nickel-plating currents ma be varied considerably as may also the time for performing the complete cycle of depositin one layer of copper and one layer of nicke the division of this time into periods respecwhich will effect deposition of nickel, and a nickel-plating current having a density about twenty-five times that of the copperplating current.

The presence of the acetate of nickel in the electrolyte effects the deposition of substantiall pure, malleable nickel on the cathode w ien the ath of the plating current is through the nickel anode, electrolyte and the cathode, as described in my en ing application Serial No. 324,291 file September 18, 1919, and entitled Production of: nickel.

In order that my invention ma be more clearly understood, attention is the drawing accompanying and forming a part of this specification and in which V Figure 1 is a diagrammatic view, partly in section, of an electrolytic plating system in accordance with my invention, the agitator for the cell shown being omitted;

Fig. 2 is a plan view of the cell shown in Fig. 1 and one form of means for agitating the electrolyte of the cell; and

"Fig. 3 is a sectional view taken on line 33 of Fig. 2.

Referring to the drawing, reference character C represents one form of electroplating cell in accordance with my invention, consisting of a suitable container 1, a cathode 2, a pair of

copper anodes

3, 3 respectively disposed closely adjacent and at either side of the cathode 2, and a pair of nickel anodes 4, 4 respectively disposed at either side of the cathode 2 and beyondthe

copper anodes

3, 3. The cathode 2,

copper anodes

3, 3 and nickel anodes 4, 4 may be supported in the electrollyte 5 of the cell in any suitable manner. .iach of the copper anodes 3 is provided with numerous perforations 6'extendirected topurposes which will M for actuating the means for effecting agitation of the electrolyte, are preferably automatic'ally controlled by any suitable commutating device. As shown in the drawn this commutating device comprises a sha A of conducting material driven at a slow and constant speed from any suitable source of power, such as a finely regulated electric motor (notshown), three commutator disks 7', 8 and 9 m unted on the shaft A to rotate therewith and brushes cotiperating with said disks. The disks 7, 8 and 9 are respectively provided with peripheral portions 10, 11 and 12 of insulating material, the remainder of these disks being formed of conducting material. Each of the disks 7 and 8 is grounded to the shaft A, and these disks are therefore in electrical connection, this connection being represented on the drawing by conductor A; while the disk 9 is insulated from said shaft and therefore from the disks 7 and 8 as by means of a sleeve 13, formed of any suitable non-conducting material, surrounding the shaft and extending through the disk 9and the hub 14 thereof. Brushes 15, 16 and 17 respectively bear "011 the peripheries of the disks 7, 8 and 9,

and a brush 18 bears on the periphery of the hub 14 of the disk 9. Conductors 19 and 20 leading from any suitable source (not shown), are respectively directly connected to the cathode 2 and the shaft A, The brush 15 is electrically connected by means of a conductor 21 and branches leading fromthe latter to the nickel anodes 4, 4. The brush 1.6 is connected by a conductor 22 to one terminal of a suitable resistance 23, the other terminal of the resistance being connected by a conductor 21 and branches leading from the latter, to the

copper anodes

3, 3. Reference characters 25 and 26 represent conductors leadin from any suitable source (not shown), for supplying current to the agitator motor M. The brushes 17 and 18 are included in the motor circuit, being respectively directly connected to the conductor 25 and to a branch 27 of the latter which leads to one of the motor brushes. The shaft A is constantly driven in the direction indicated by the arrows in Fig. 1, at such a'rate as to make one complete rotation during the period allowed for performing the complete cycle of electroplating one layer of copper and one layer of nickel on the cathode 2. Preferably, the insulation 10 extends threefourths the way around the periphery of disk 7, the insulation 11 extends around that fourth of the periphery of disk 8 corresponding to the portion of the peripherypf disk 7 not formed of insulation and the in-,

sulation 12, starting at a point 1 inthe pe:

riphery of disk 9 corresponding to the point D. where the insulation 11 on disk 8 begins and to the point D where the insulation 10 on disk 7 ends (with reference to the direction indicated by the arrows) extends threeeighths of the way around the periphery of disk 9. The conductor 20 will therefore of shaft A, the conductor 20 will be electrically connected to conductor 22 through shaft A, disk 8 and brush 16. Conductor 25 will alsobe electrically connected to the .branch conductor 27 through brushes 17 and 18 and disk 9, during the five-ei hths of the period of each rotation of shaft equal to the first five-sixths of the period'of con nection of conductor 20. to brush 16 through shaft A and disk 8.

The motor M may actuate any suitable means for agitating the electrolyte in the cell C during the first and major part of the time of the passage of the copper depositing current through the cell; As

U-shaped frame 30 and at its other end to a crank pin 35 carried by a disk 36. The disk 36 is mounted on a shaft 37 which is driven by suitable reducing gearing, such as a worm 38 and worm wheel 39, from the motor M.

During the period in each cycle when the conductor 20 is electrically connected to conductor 22, a copper plating current will pass through the cell in the following path: from the source of current through the conductor 20, shaft A, disk 8, brush 16, conductor 22,

resistance 23, conductor 24, to the

copper anodes

3, 3, then through the electrolyte 5, cathode 2 and conductor 19 back to the source. During the first five-sixths of this period, the circuit of the agitator motor M will also be closed, the path of this circuit being as follows: from the source of current through the conductor 25, brush 18, disk 9,

brush 17, branch conductor 27, through the motor to the conductor 26 and back'to the sourcej When the circuit of motor M is thus closed, the motor will, of course, effect 112- ciprocation of the frame 30 and thereby agitation of the electrolyte. The resistance 23 is such that the copper plating current passing through the cell will be of a density just below that which is suflicient to plate nickel. This current is also insuflicient in density to efi'ect the plating of copper on the cathode for a considerable period, provided the electrolyte is maintained quiet. However, due to the agitation of the electrolyte during the first and major part of the period allowed for plating copper, as just described, a thin film of copper is deposited on the cathode. Moreover, at the end of this periodthe elec-. trolyte adjacent the cathode will be practically exhausted of copper, as described above. During the period in each cycle, when the conductor 20 is electrically connected to conductor 21. a nickel plating current of comparatively high density will pass through the cell in the following path: from the source of current through conductor 20, shaft A, disk 7, brush 15, conductor 21, to the nickel anodes 4, 4, then through the electrolyte 5, cathode 2 and conductor 19 back to the source. During this period a film or coating of nickel substantially .0005

inch in thickness will be deposited on the cathode-2, as described above. The operation of the system is continued until the desired number of alternate-layers of copper and nickel are plated onto the-cathode. The composite sheet thus formed is then removed or stripped from the cathode and cut into pieces of the desired size, which are suitably treated to dissolve out the copper and produce the thin nickel flakes, as above described.

The

copper anodes

3, 3 are of such quality and made of such size and surface area as to be nearly one hundred percent. eflicient, whereby the percentage of copper in the electrolyte is maintained substantially constant for a long period. The provision of the perforations 6 in the

copper anodes

3, 3 increases the effective surface area of these anodes and also facilitates the circulation of the electrolyte and therefore the action of the cell during the plating of both the coppeer and the nickel.

It is to be understood that-my invention i subject to numerous modifications and is limited only as defined by the terms of the appended claims.

Having now described my invention. what I claim and desire to protect by Letters Patent is as follows 1. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprising a bath containing solutions of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in passing a current through the cell in a path including one of said anodes, the electrolyte and the cathode,

which current has a density less than that which will deposit metal of which the other anode is composed, then breaking the circuit of said current and passing a current of comparatively high density through the cell in a path including said other anode, the electrolyte and the cathode, substantially as described.

. 2. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprising a bath containing solutions of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in passing a current through the cell in a path including one of said anodes, the electrolyte and the cathode, which current has a density less than that which will deposit metal of which the other anode is composed, agitating the electrolyte during the passage of said current through the cell, then breakingthe circuit of said current and passing a current of comparatively high density through the cell in a path including said other anode, the electrolyte and the cathode, substantially as described.

3. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprisin a bath containing solutions of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in passing a current through the cell in a path including one of said anodes, the electrolyte and the cathode, which current has a density less than that which will deposit metal of which the other anode is composed, agitating the electrolyte for only a part of the period during which said current is passed through the cell,then breaking the circuit of said current and passing a current of comparatively high density through the cell in a ath including said other anode, the electro yte and the cathode, substantially as described.

4. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprising a bath containing solutions of a salt of each of such metals, and

two anodes respectively formed of such metals and a cathode dlsposed In said bath, Wl'llCll consist-s 1n P3581110 a current through the cell in a path inclilding one of said,

anodes, theelectrolyte and the cathode. which current has a density less than that which will deposit metal of which the other anode is composed, agitating the electrolyte for the first and greater part of the period during which said current is passed through the cell and maintaining the electrolyte quiet during the remainder of said period, then breaking the circuit of said current and passing a current of comparatively high a ing said other anode, the elec density through the cell in a ath includtrdlyte and the cathode, substantially as described.

5. The process of electro-plating alternate layers of two difierent metals in an electro: lytic cell comprising a bath .containing solutions of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in passing a current through the cell in a path including one of said ,anodes, the electrolyte and the cathode,

which current has a density less than .that which will deposit metal of which the other anode is composed, then breaking the circuit of said current and passing a current of comparatively high density through the-- cell in a path including said other anode, the electrolyte andthe cathode, then breaking the circuit of said last mentioned current, and repeating the foregoing steps until the desired number of alternate layers of said two metals are plated on the cathode,

substantially as described.

6. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprising a bath containing solutions-of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in assing a current through the cell in a pat including one of said anodes, the electrolyte and the cathode, which current has a density less than that which will deposit metal of which the other anode is composed, agitating the electrolyte during the passage of said current through the cell, then breaking the circuit of said current and passing a current of comparatively high density through the cell in a path including said other anode, the electrolyte and the cathode, then breaking the circuit of said last mentioned current, and repeating the foregoing steps until the desired number of alternate layers of said two metals are plated on'the cathode, substantially as described. A

7. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprising a bath containing solutions of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in passing a current through the cell in a path including one of said anodes, the electrolyte and the cathode, which current has a density less than that which will deposit metal of which'the other h gh de si y hr gh the cell in a path in cluding said other anode, the electrolyte and the cathode, then breaking the circuit of said last mentioned current, and repeating the foregoing steps until the desired number of alternate layers of said two metals are plated on the cathode, substantially as described.

8. The process of electro-plating alternate layers of two different metals in an electrolytic cell comprising a bath containing solutions of a salt of each of such metals, and two anodes respectively formed of such metals and a cathode disposed in said bath, which consists in, passing a current through the cell in a path including one of said anodes, the electrolyte and the cathode, which current has a density less the other anode is composed, agitating the electrolyte for the first and greater part of the period during which said current is passed through the cell and maintaining the electrolyte quiet during the remainder of said period, then breaking the circuit of said I current and passing a current of comparatively high density through the cell in a' path including said other anode, the electrolyte and the cathode, then breaking the circuit of said last mentioned current, and repeating the foregoing steps until the desired number of alternate layers of said two metals are plated on the cathode, substantially as described. 1

9. In an electro-plating system, an electrolytic cell comprising a bath containingsolutions of salts of two metals to be plated, two anodes respectively formed of said two metals and a cathode disposed in said bath, and means for alternately effecting passage of current through said cell in two paths respectively including one of said anodes,

the electrolyte and the cathode and the other ,of said anodes, the electrolyte and the cathode, substantially as described.

10. In anelectro-plating system, an electrolytic cell comprising a bath containing solutions of salts of two metals to be plated, two anodes respectively formed of said two metals and a cathode disposed in said bath,

- and means automatically operative to effect passage of current through said cell alternately in two paths respectively including one of said anodes, the electrolyte and the cathode and the other of said anodes, the electrolyte and the cathode, substantially as described.

11. In an elcctro-plating system, an electrolytic cell comprising a bath containing solutions of salts of two metals to be plated, two anodes respectively formed of said two metals and a cathode disposed in said bath, means automatically operative to effect passage of current through said cell alternately in two P h r wt vely in luding e of said anodes, the electrolyte and the cathode and the other of said anodes, the electrolyte and the cathode, and means whereby the electrolyte is agitated during only a. part of the period of each passage of current through the cell in the path including one of said anodes, substantially as described.'

12. In an electro-plating system, an electrotytic cell comprising a bath containing solutions of salts of two metals to be plated, two anodes respectively formed of said two metals and a cathode disposed in said bath, means automatically operative to effect passage of current through said cell alternately in two paths respectively including one of said anodes, the electrolyte and the cathode and the other of ,said anodes, the electrolyte and the cathode, and means whereby the electrolyte is agitated during only the first and greater portion of the period of the passage of current through the cell in. the path including one of said anodes, sub stantially as described.

13. In an electro-plating system, an electrolytic cell comprising a bath containing solutions of a copper salt and a nickel salt, two anodes respectively formed of copper and nickel and a cathode disposed in said bath, the bath being weak in the solution of the copper salt and comparatively strong in the solution of the nickel salt, and means for alternately effecting the passage of a current of low density through the cell in a path including the copper anode, the electrolyte and the cathode and the passage of a current of comparatively high density through the cell in a path including the nickel anode, the electrolyte and the cathode, substantially as described.

14. In an electro-plating system, an electrolytic cell comprising a bath containing solutions of a copper salt and a nickel salt, two anodes respectively formed of copper and nickel and a cathode disposed in said bath, the bath being weak in the solution of the copper salt and comparatively strong in the solutionof the nickel salt, and means for alternately. efiecting the passage of a current of a density less than that which will deposit nickel through the cell in a path including the copper anode, the electrolyte and the cathode and the passage of a current of comparatively high density through the cell in a path including the nickel anode, the electrolyte and the cathode, substantially as described. 15. .In an electro-plating system, an electrolytic cell comprising a bath containing solutions of a copper salt and a nickel salt, two anodes respectively formed of copper and nickel and a cathode disposed in said bath, the bath being weak in the solution of the copper salt and comparatively strong in the solution of the nickel salt, means 91" alternately effecting the passage of a current through the cell in a circuit including the copper anode, the electrolyte and the cathode, said current being of such low density that unless the electrolyte is agitated, no copper will be plated on the'cathode for a considerable period after said circuit is made, and the passage of a current of comparatively high density through the cell in a path including the nickel anode, the electrolyte and the cathode, and means whereby the electrolyte is agitated during each passage of the current of low density through the cell, substantially as described.

16. In an electro-plating system, an electrolytic cell comprising a bath containing solutions of a copper salt and a nickel salt, two anodes respectively formed of copper and nickel and a cathode disposed in said bath, the bath being weak in the solution of 85 the copper salt and comparatively strong in the solution of the nickel salt, means for alternately effecting the passage of a current through the cell in a circuit including the copper anode, the electrolyte and the cath-- ode, said current being of such low density that unless the electrolyte is agitated, no copper will be plated on the cathode for a considerable period after said circuit is made, and the passage of a current of comparatively high density through the cell in a path including the nickel anode, the electrolyte and the cathode, and means whereby the electrolyte is agitated during only a portion of the period of each passage of the cur- .100 rent of low density through the cell, substantially as described.

17. An electrolytic cell consisting of a bath comprising a mixture of a copperplating solution and a nickel-plating solution, and a cathode, a copper anode and a nickel anode disposed in said bath, substantially as described.

18. An electrolytic cell consisting of an electrolyte comprising a mixture of a nickelplating solution and a copper-plating solution and in which the nickel-plating solution greatly predominates, and a cathode, a nickel anode and a copper anode disposed in said bath, substantially as described.

19. An electrolytic cell consisting of a bath comprising a mixture of a substantially saturated solution of nickel sulfate and a substantially saturated solution of copper sulfate substantially in the proportion of three hundred parts by weight of nickel sulfate and three parts by weight of cop r sulfate, and a cathode, a nickel anode an a copper anode disposed in said bath, substantially as described.

20. An electrolytic cell consisting of a bath comprising a mixture of a nickel-plating solution and a cop er-plating solution and in which the nickel-plating solution greatly predominates, said bath also containing a salt of a fatty acid, and a cathode, a nickel anode and a copper anode'disposed in said bath, substantially as described.

21. An electrolytic cell consisting of a bath comprising a mixture of a substantially saturated solution of nickel sulfate and a substantially saturated solution of copper sulfate in the proportion of substantially three hundred parts by weight of nickel sulfate to three parts by weight of copper sulfate, said bath also containing substantially eighteen parts by weight of acetate of nickel, and a cathode, a nickel anode and a copper anode disposed in said bath, substantially as described. j

22. In an electro-plating system, an electrolytic cell comprising a bath containing solutions of salts of two metals to be plated,

and two anodes respectively formed of said two metals and a cathode disposed in said bath, and means automatically operative to effect passage of current through said cell alternately in two paths respectively including one of said anodes, the electrolyte and the cathode and the other of said anodes,

' the electrolyte and the cathode, and to effect in two paths respectively including the co per anode, the electrolyte and the catho e and the nickel anode, the electrolyte and the cathode, and to effect agitation of the electrolyte during each passage of current through the cell in the path including the copper anode, substantially as described.

24. An electrolytic cell consisting of a bath containing solutions 'ofsalts of two metals to be plated, and two anodes respectively formed of said two metals and a cathode disposed in said bath,- one of said anodes being disposed between the other anode and the cathode and being provided with perforations extending therethrough, substantiall as described. L

25. An e ectrolytic cell consisting of abath comprising a mixture of a copper-plating solution and a nickel-plating solution in which the nickel-plating solution greatly predominates, and a cathode, a nickel anode and a copper anode disposed in said bath,

said copper anode being provided with perforations extending therethrough, substantially as'described.

26. 'An electrolytic cell consisting of a bath comprising a mixture of a nickel-plat ing solution and a copper-plating solution,

and a cathode, a nickel anode and a copper anode disposed in said bath, said copper anode being disposed between the nickel anode and the cathode and being provided with perforations extending therethrough, substantially as described.

This specification signed September, 1919.

THOS. A. EDISON.

this 30th day of v