Document jNEGEkyD0zd4r49LMg7ZDgmZk

G.E. Jo h n s o n I'l.AXT M,\.NAOKU from A Ea s t Ch ic a g o ,In d ia n a December 17th, 1937 I'l.ANTK : Fa s t Ch ic a g o , !n l >. AKKO.N.OMIO '*1-. Frederick Laist, Vice-President, International Smeltg. and Refg. Co., Room 1720 - 25 Broadway, New York, N. Y. Dear Mr. Laist:- I acknowledge receipt of your letter of December 13th addressed to Mr. Johnson, enclosing copy of a letter from Mr. McCarthy and a copy of the application, Serial No. 178,352, for Method of Producing White Lead. We note that this application was filed on December 6th, 1937. Thanking you, I remain Youra very truly Superintendent. RGB/e cc-Mr.F.O.Case PNYC00008515 INTERNATIONAL SMELTING & REFINING COMPANY 26 BROADWAY FREDERICK LAIST VICE'PRESIOINT Ne w Yo r k Leceaber 13, 1337. Ur. G. 2. Johnao::, Hrneper, / .. Internstioisi cceiti-ij. It-fl:;! : Company, Lead Scfiri-ij. leper tseat. East Caic0, Indiana. - Dearer. Johnsoni '. \ I ca sendlnp you bbreith'ojy or lettor fror- Sr. McCarthy In shioi: jo-.i ni.ll -'.eta 11.at the patent Fpplicaticr. of losers. Johnaoa, doFinn and 7~.ox, Jr., covirlr.? the aothod of producing i.ldte lord vran Tiled oa Lccccler 6, 1957 under Serial isueber 178,352. - . One copy of the explication as Tiled la enclosed herewith. Tours very truly, C Enel. ,'P i. ect Kr. ?. $ Case ----------- PNYC00008516 N11457.01 Wil l ia m H. Da v is ARBI B Ma XVIK - *fcTi De a n S. Eb mo k d s Fr a n k E. Ba r r o w s W. Br o w n Mo r t o n Me r t o n W. Sa o e Wil l is H Ta y l o r .Jr . Er n e s t H Me r c h a n t Ge o r o e E. Mid d l e t o n Mo r r is D. Ja c k s o n R.Mo r t o n Ad a ms Ra y mo n d F Ad a ms Le s l ie B Yo u n g Da n ie l V. Ma h o n e y Ra y mo n d B Ca n f ie l d Ba l d w in Gu il d Amb r o s e A Ar n o l d S. Ho w e l l Br o w n , Jr . Lo u is D. Fo r w a r d H. St a n l e y Ma n s t t e l d Ge o r o e E.Fa it h f u l l Do n a l F. Mc Ca r t h y Jo h n Bo x ie Jo h n T. Fa r l e y Cu r t Vo n Bo e t t ic h e r . Ja me s B. Ch r is t ie Ja me s W. La is t Cy r u s S. Ha p o o o d Ro o er T. Mc Le a n Ha r o l d A.Tr a v e r Ke n n e t h H. Mu r r a y Ha r r y E. Do w n e r Ca r l E. Rin o Pe n n ie , Da v is , Ma r v in a n d Ed mo n d s Co u n s e l l o r s a t La w 165 Br o a d w a y Ne w Yo r k Wa s h in o t o n Of f ic e s Na t io n a l Pr e s s Bu il d in o December 9, 1937. D4947 Mr. Frederick Laist, Vice President International Smelting & Refining Co., 25 Broadway, Room 1720, New York, New York. g d .v ,,, CO UN S E Dear Mr. Laist: We have been advised that the application of Gunnard E. Johnson, Reginald G. Bowman and William J. Knox, Jr. for United States patent, covering improvements in the Method of Producing White Lead, was received in the Patent Office on December 6, 1937 and has been given Serial Number 178,352. Two copies of the application as filed are enclosed herewith. Very truly yours, Enclosures. PNYC00008517 N11457.02 O 7 ' I \/s' t _'j i - U--N--I-T--E--D---S--T--A-T--E-S=5Pr=A-T-E--N--T---A'--P-P--L--I-C--A-T--I-O--N- '' GUNNARD E. JOHNSON.' REGINALD C. Bo'vrMAN and wj.jji.xAia ,, . ANOX.JI. -for- n-'.n METHOD OF PRODUCING WHITE LEAD t 1 r' SERIAL NUMBER 178,552 PECEMHER~6 '1937*" A , { > ; " i - PNYC0000fl5ia N11457.03 iI I This invention relates to the production of white lead-and has for an objeot the provision of oertaln improve ments in prooesses for producing white lead,. liore parti cularly, the invention contemplates the provision of certain improvements in prooesses for producing white lead by electrolysis. e trv . "fhe present-day oommarolal '>'>'106"" producing white lead eleotrolytically is carried out in a so-called bi-fluid cell having a lead anode and an iron cathode separated by a porous diaphragm. The anode is surrounded by an electrolyte (the anolyte) containing sodium aoetate and a very small amount of sodium carbonate. The cathode is surrounded by an eleotrolyte (the oatholyte) containing sodium aoetate and a relatively large amount of sodium carbonate. Eaoh eleotrolyte is maintained in rapid circu lation about its electrode. The circulation system of the two eleotrolytes are entirely independent and no communica tion exists' between the oatholyte and anolyte in the cell except through the diaphragm in the oell. In praotice, a small amount of Na2C03, not exceeding about .05, is added to the anolyte before plaoing the eleotrolytlc cells in operation. When the current is turned on, the lead dissolves from the surface of the anode and is immediately preoipitated as white lead at a slight distanoe from the anode surface. The precipitate is carried down through the oell by the descending current of anolyte in a thick cloud without depositing on the anode surface. Hydrogen and the hydroxide ions are liberated at the cathode. The hydroxide and carbonate ions of the hydrolyzed sodium oarbonate (HagCOg) of the oatholyte I -1- % migrate through the diaphragm toward the anode, replenishing j the anions removed from the anolyte by precipitation of the lead ions. By this electrolytic migration, the electro chemical equivalent amount of anions required to precipitate the lead cations as they are dissolved at the anode are j transported to the anolyte. Slight traces of carbonate can be detected in the anolyte but it is entirely free of | j dissolved lead salts. However, there is no sodium oarbonatei (HagCOg) present in the solution film in oontact with the anode. The foregoing outlines the major reaction. In practice, in order to replenish and conserve chemicals and to restore j the loss in volume of eatholyte due to decomposition of water! at the cathode, evaporation and mechanical losses, anolyte is added to the oetholyte in a small continuous stream. This introduces sodium acetate into the eatholyte whioh is jalso acted upon by the current, the acetate ions replacing a jpart of the hydroxide and oerbonate ions that migrate to the j anolyte. This is compensated for by permitting a oertain j amount of seepage of eatholyte Into anolyte through the diaphragm. The seepage is controlled by selecting a diaphragm fabric of the desired porosity for a given hydrostatio solution head of eatholyte of a selected composition i j in the cathode compartment. The addition of relatively j I small amounts of anolyte to eatholyte and eatholyte to j anolyte permits adjusting the sodium concentration of the | two electrolytes and the conservation of obemioals, since I all make-up solution can then be added to the anolyte in the form of filtrate from the filters. All anolyte in the filter oekes is replaced by water by a oounter current wash- -2- 1 ing operation and returned to the anolyte circulation system] In addition, wash water filtrate ia also returned as re quired to replenish the losses enumerated above. As the volume of solutions transferred between the two electrolytes is very small the anolyte as previously stated is essentially free of the reacting salts and they are only brought into the zone where the white lead is preoipitated in electro chemical equivalent amounts, there is never an excess present to alter the reaotion or influence the size of the partiole. The white lead which is removed continuously from the cell by the circulation of the anolyte, is removed from the anolyte by settling and filtering. The filter pulp is washed, dried, ground and air floated, and is then barrelled in a dry pulverulent form. The clear anolyte is recirculated through the cell. The composition of the anolyte during its passage through the cell remains unchanged except for a small in crease in the acetate concentration. This ia controlled by i i dilution with wash water from the filter. The oatholyte ia depleted in carbonate ions and a small percent of acetate ions, and enriched in hydroxide ions during its passage through the cathode oompartment of the oell. The excess of hydrate ions is neutralized and the loss in carbonate ions restored by passing the oatholyte through carbonation towers, in whioh a stream of descending solution passes through a rising stream of C02 gas from a coke burning boiler. The acetate loss is replenished as noted by running a small stream of anolyte into the oatholyte after it is discharged from the oella. -3- PNYC00008521 In the United States patent to Ralph U. Harrington, No. 1,308,948, it is recognized that the cbaraoter and quality of the white lead produot may be controlled by regulating the amount of carbon dioxide supplied to the catholyte, and it is further recognized that in order to obtain rapid carbon dioxide absorption and at the same time avoid preoipitation of white lead on the anode, it is necessary to maintain the catholyte as compared with the anolyte reiati*^/ strongly alkaline. V.'e discovered that the composition of the white lead produced varies direotly with the HCO3 ion or bioarbonate oontent of the anolyte. Our investigations have indicated that the white lead formation is represented by the following reaotion equation: 3Pb (CgHgO 2) 2 + 4NagCO>5 2H20 " PbC03*Pb(0H)2 2NaHC03 6HaC2n302. The composition of the basic lead salt precipitated i varies with the pH value of the solution in which it is formed. It will be apparent, therefore, that if only sodium oarbonate {Na2C03> and lead acetate (Pb(C2H3o2)2) were supplied to the solution, the sodium bicarbonate {NaHCOg oontent would progressively inorease and the ratio of HCO3 to OH ions in the resulting precipitated lead salt would increase until finally only PbC03 would ba produoed. In other words the carbon dioxide (C02) content of the precipitated white lead bears a direct relation to the sodium bicarbonate (NaHCOs) concentration of the anolyte. This has been found to be true in actual operation. In order to control tbB composition of the white lead produced, therefore, it is neoessary to control the NaHC03 oontent of the anolyte. Our discovery of the effect of the H003 ion or bicarbonate oontent of the anolyte on the composition of the white lead produced is described in our United States patent No, 1,845,713, dated February 16, 1932 which oovers control of the bicarbonate content of the anolyte by main taining a uniform and deficient carbonation of the oatholyte and adding an acid or a bicarbonate to the anolyte. Our aforementioned patent alBO points out that it is desirable that the oarbonate salt content of the anolyte be kept low --much lower than is required in order to avoid formation of white lead incrustations on the anodein order to permit washing the white lead free of these salts in the finishing of the white lead separated from the anolyte. This is important in the commercial production of white lead by the electrolytic method, since the presence of any considerable amount of alkali metal carbonate in the white lead product renders it unfit for use as paint pigment Te have found that the difficulty in washing the white lead sufficiently free of adsorbed salts increases with increas ing concentration of carbonate salt in the anolyte to a point at which it is practically impossible to eliminate them. This may be explained by adsorption of the salts in the white lead particles, but it seems more probable that a reaotion may occur as follows: 2(2PbC03*Pb(0H)g) Na2C03 NaflC03 3NaPb2(C03)20H + HgO whereby the oarbonate salt becomes chemically combined and therefore very difficult or impossible to remove. Our present invention provides for control of the bioarbonate content of the anolyte by means of exoeBS r -> oarbonatlon of the oatholyte and theaddlti^on .ta \br of an alkali metal hydroxide. The alkali metal hydroxide may1 be added to the anolyte In any suitable manner as, Tor exam ple, by dissolving the hydroxide in the anolyte outside the cell, by adding a preformed solution of the hydroxide to the anolyte outside the cell, or by adding catholyte high in hydroxide (after electrolysis and prior to oarbonatlon) to the anolyte outside the cell. The solution of hydroxide for addition to the anolyte may be formed by employing as solvent the filtrate normally employed as make-up solution. The in vention permits simplification of the oarbonatlon operation and provides a simple method of maintaining a supply of anolyte of the proper concentration with respect to bi carbonate. Instead of controlling the oarbonatlon operation to completely or partially neutralize the oatholyte solution from the oell (depleted in carbonate ion and high in hydroxide) and, in the case of the partially neutralized catholyte, adding an aoid or bicarbonate to the anolyte to compensate for the incomplete neutralization, the carbonation operation may be permitted to proceed to the point at whioh excess oarbonatlon is effected without the necessity for exercising extreme oaution to secure exaot neutraliza tion or accurate deficient oarbonatlon. The Invention simplifies the process also by eliminating the necessity for exact control of addition of oatholyte to anolyte by electrolysis and by seepage through the diaphragm to meet changes in operating conditions. The composition of anolyte thus harmfully altered can be adjusted readily by the method of the invention. In the preferred method of the invention, the oarbonatlon operation is so controlled 31 as to effeot substantially uniform and exoess oarbonatlon of -6- PNYC00008524 r -r<j we vqqjpjou ., -<y-S^.<W V-Sj..*-.**r+ Vr theoathalyt* fcqr; oeah. particulars *V of- opera&ln* eam4itlona| designed to produce a product, of; particular, ccuspoeitlaa. v - In aocordanoe with our Invention, using a bl-flnid oell with, a lead anode suspended in.an anolyte capable of yielding a solvent for the lead, e.g., sodium acetate, and j a suitable inert oathode suspended in a oatholyte containing ! | sodium carbonate and separated from the anolyte by a suitable1 diaphragm, and to whioh an exoesa of carbon dioxide (C06,,) is supplied in the oarbonation operation, the anolyte | solution is sampled and analyzed at regular intervals, say ) every hour, and its bicarbonate oontent adjusted to and , maintained at the desired figure by the addition of an alkali; metal hydroxide, as pointed out above. For example, in a cell operated at a current density of 30 amperes per square foot of oathode area and producing approximately .011 pounds of white lead per ampere . hour and operating at an anolyte displacement rate of 18 gallons per minute while maintaining uniform and excess ! oarbonation of the catholyte, the sodium bicarbonate oontent I | of the anolyte is maintained at 0.0561$ through adjustment by the addition of sodium hydroxide thereto to produoe a i j jwhite lead containing 11.60$ of carbon dioxide (CCg)* To j I produce white lead of greater or smaller COg content the i i aold carbonate oontent of the anolyte nay be increased or j decreased by the addition of lesser or greater amounts, j respectively, of sodium hydroxide. The exaot acid carbonate ; jcontent required for the production of a particular white 'lead product should be determined in each instanoe by experiment. The carbonate salt oontent of the anolyte is I i i j imaintained at not exceeding obout twenty-five one-hundredths 1 7 PNVC0C008525 of one percent, (0.25$) and preferably less then six onehundredths of one percent (0.06$). The significance of the limited oarbonate salt oonter.t of the anolyte specified nay be appreciated by comparison Kith the limitation of the carbonate salt content of the anolyte necessary to avoid troublesone precipitation of v/hlte lead on the enode in accordance with the Harrington patent. in this case the carbonate salt content of the anolyte may run as high as six tenths of one percent (0.60$), which content, however, will produoe white lead containing so much oarbonate salt that it is not feasible in oomaorolal operation to wash it sufficiently free of such salt as to produce a first grade white lead paint pigment. -8- PNt C00008526 WB CLAIM: 1. In a process of producing white lead by electrolysis in a bifluid oell involving the use of an anolyte capable under eleotrolysis of yielding a lead solvent and containing a bioarbonate and a oatholyte con taining a carbonate which is altered during the oourse of the process by removal of carbonate ion, and involving oarbonation of the oatholyte to restore uafbonate ion tharito and re-use of the regenerated oatholyte, the improvement which comprises controlling the composition of the preoipitated white lead by reference to the bioarbonate concentration in the anolyte and adjusting the bioarbonate concentration in the anolyte by controlling the oarbonation of the oatholyte and adding to the anolyte an agent oapable of establishing therein bicarbonate in the desired proportion. 2. In a process of producing white lead by eleotrolysis in a bifluid oell involving the use of an anolyte oapable under eleotrolysis of yielding a lead solvent and containing a bicarbonate and a oatholyte con taining a carbonate whioh is altered during the course of the prooess by removal of carbonate ion, and involving oarbonation of the oatholyte to restore carbonate ion there to and re-use of the regenerated oatholyte, the improvement whioh oampfiees controlling the composition of the preoipitated white lead by referenoe to the bioarbonate oonoentration in the anolyte and adjusting the bioarbonate oonoentration in the anolyte by subjecting the oatholyte to ezoesa oarbonation and incorporating in the anolyte an alkali metal hydroxide to establish therein bicarbonate in the desired proportion. 3. In a process of producing white lead by electrolysis in a bifluid cell involving the use of an anolyte capable under eleotrolysis of yielding a lead solvent and containing a bicarbonate and a catholyte containing a carbonate which is altered during the course of the process by removal of carbonate ion, and Involving carbonation of the oatholyte to restore oarbonate ion thereto and re-use of the regenerated catholyte, the improve meat which comprises controlling the composition of the precipitated white lead by reference to the bicarbonate concentration in the anolyte and adjusting the bicarbonate concentration in the anolyte by subjecting the catholyte to excess carbonation and adding to the anolyte sodium hydroxide to establish therein bicarbonate In the desired proportion. 4. In a process of producing white lead by eleotrolysis in a bifluid oell involving the use of an anolyte capable under electrolysis of yielding a lead solvent and containing a bicarbonate and a oatholyte containing a carbonate which is altered during the course of the prooess by removal of carbonate ion, and involving carbonation of the catholyte to restore carbonate ion ! thereto and re-use of the regenerated catholyte, the j improvement which comprises controlling the composition of : |i the precipitated white lead by reference to the bicarbonate j |! concentration in the anolyte and adjusting the bicarbonate j concentration in the anolyte by subjecting the oatholyte to i ]| excess carbonation and adding to the anolyte unoarbonated i catholyte containing sodium hydroxide to establish in the i ! anolyte bicarbonate in the desired proportion. 5. In the process of producing white lead by electrolysis in a bifluid cell in whioh the white lead is precipitated in an anolyte capable under electrolysis of yielding a lead solvent and containing bicarbonate salt the steps whioh consist in determining the bioarbonate concentra tion in the anolyte corresponding to the precipitation of white lead of the desired composition, and maintaining said bicarbonate content in the anolyte by maintaining a uniform and excess carbonation of the catholyte and adding an alkali metal hydroxide to the anolyte. 6. In the prooess of producing white lead by electrolysis in a bifluid oell in which the white lead is preoipitated in an anolyte capable under eleotrolysls of yielding a lead solvent and containing bicarbonate salt the steps which oonsist in determining the bioarbonate concentra tion in the anolyte corresponding to the preoipitation of white lead of the desired composition, and maintaining said bicarbonate content in the anolyte by maintaining a uniform and exoess carbonation of the oatholyte and adding sodium hydroxide to the anolyte. 7. In the prooess of producing white lead by electrolysis in a bifluid oell in which the white lead is precipitated in an anolyte capable under electrolysis of yielding a lead solvent and containing bicarbonate salt the steps which consist in determining the bioarbonate concentra tion in the anolyte corresponding to the preoipitation of white lead of the desired composition, and maintaining said bicarbonate content in the anolyte by maintaining a uniform and excess oarbonation of the catholyte and adding un carbonated oatholyte to the enolyte. anolyte capable under electrolysis of yielding a lead solvent and containing a carbonate and a bioarbonate and (2) a oatholyte containing a carbonate which is altered during the course of the process by removal of carbonate ion, and involving carbonation of the catholyte to restore carbonate ion thereto and re-use of the regenerated oatholyte, the improvement which comprises maintaining the carbonate concentration in the anolyte at or below a pre determined maximum, which is substantially less than the concentration resulting in objectionable deposition of white lead on the anode, and controlling the composition of the preoipitated white lead by reference to the bicarbonate concentration in the anolyte and adjusting the bicarbonate oonoentration in the anolyte by controlling the carbonation of the cathdLyte and adding to the anolyte an agent capable of establishing therein bicarbonate in the desired proportion, 9. In a process of producing white lead by eleotrolysis in a bifluid cell involving the use of (1) an anolyte oapable under eleotrolysis of yielding a lead solvent and containing a carbonate and a bioarbonate and (2) a oatholyte containing a carbonate which is altered during the course of the process by removal of carbonate ion, and involving carbonation of the catholyte to restore carbonate ion thereto and re-use of the regenerated catholyte, the improvement which comprises maintaining the carbonate con centration in the anolyte at or below a predetermined maximum wbioh is substantially less than the concentration resulting in objectionable deposition of white lead on the anode, and controlling the composition of the precipitated white lead by reference to the bicarbonate concentration in j the anolyte and adjusting the bicarbonate concentration In I! j, the anolyte by subjecting the catholyte to excess oarbonaji || tion and incorporating In the anolyte an alkali metal Jj hydroxide to establish therein bicarbonate in the desired Ij proportion. li i| " i; 10. ..... ......... In a prooess of producing white lead by j electrolysis in a bifluid cell involving the use of (1) an j anolyte capable under electrolysis of yielding a lead j solvent and containing a carbonate and a bicarbonate and (2) a catholyte containing a oarbonate which is altered during the course of the prooess by removal of carbonate ion, and involving oarbonation of the catholyte to restore carbonate ion thereto and re-use of the regenerated ! catholyte, the improvement whioh comprises maintaining the carbonate concentration in the anolyte at or below a pre determined maximum which is substantially less than the j concentration resulting in objectionable deposition of white lead on the anode, and controlling the composition of the precipitated white lead by reference to the bloarbonate concentration in the anolyte end adjusting the bicarbonate concentration in the anolyte by 3ubJeoting the catholyte to excess oarbonation and adding to the anolyte sodium hydroxide to establish therein bicarbonate in the desired proportion. 11. In a process of producing white lead by electrolysis in a bifluid oell involving the use of (1) an anolyte capable under eleotrolysis of yielding a lead solvent and containing a oarbonate and a bicarbonate and (2) a catholyte containing a carbonate which is altered j during the course of the process by removal of carbonate i! lj ion, and involving oarbonation of the catholyte to restore !'ii a ii li ii PNYC00008531 T carbonate Ion thereto and re-use of the regenerated catholyte, the improvement which comprises maintaining the oarbonate concentration in the anolyte at or below a pre determined maximum whioh is substantially leas than the ooncentration resultingin objectionable deposition of white lead on the anode, and controlling tho composition of the Precipitated whits land by r-.-rs... the bicarbonate oonoentration in tho anolyte and adjusting the bicarbonate concentration in tho anolyte by subjeotlng the catholyte to excess oarbonation and adding to the anolyte unoarbonated oatholyte containing sodium hydroxide to establish in the anolyte bicarbonate in the desired proportion. 12. In a process of producing white lead by eleotrolysis in a blfluid cell involving the use of (1) an anolyte capable under eleotrolysis of yielding a lead solvent and containing a oarbonate and a bicarbonate and (2) a oatholyte containing a carbonate whioh is altered during the oourse of the process by removal of carbonate ion, and involving oarbonation of the oatholyte to restore carbonate ion thereto and re-use of the regenerated catholyte, the improvement whioh comprises maintaining the carbonate ooncentration in the anolyte at a value not exceeding about twenty-five one-hundredths of one percent (0.25$) to permit the production of a white lead product which may be freed readily of deleterious carbonate by washing, and controlling the composition of the preoipitated white lead by reference to the bicarbonate concentration in the anolyte end adjusting the bicarbonate ooncentration in the anolyte by controlling the oarbonation of the catholyte and adding to the anolyte an agent capable of establishing (therein bioarhonate in the desired proportion. PNyCo0Q08532 13.. In a prooess of produoing white lead by electrolysis in a bifluld cell Involving the use of (1) an anolyte capable under electrolysis of yielding a lead solvent and containing a carbonate and a bicarbonate and (2) a catholyte containing a carbonate whioh is altered during the course of the process by removal of oarbonnte ion, and involving oarbonotion of the oatholyte to restore carbonate ion thereto and re-use of the regenerated catholyte, the improvement whioh comprises maintaining the carbonate concentration in the anolyte at a value not exceed ing about twenty-five one-hundredths of one peroent (0.25#) to permit the production of a white lead product whioh may be freed readily of deleterious carbonate by washing, and controlling the composition of the precipitated white lead by reference to the bloarbonate concentration in the anolyte and adjusting the bloarbonate concentration in the anolyte by subjecting the oatholyte to excess oarbonetion and incorpora ting in the anolyte an alkali metal hydroxide to establish I therein bicarbonate in the desired proportion. 14. In a process of produoing whito lead by eleotrolysls in a bifluid cell involving the use of (1) an anolyte oapable under electrolysis of yielding a lead solvent and containing a carbonate and a bicarbonate and (2) a oatholyte containing a carbonate whioh is altered during the course of the process by removal of carbonate ion, and involving earbonation of the catholyte to restore carbonate ion thereto and.re-use of the regenerated catholyte, the improvement whioh comprises maintaining the oarbonate con centration In the anolyte at a value not exceeding about twenty-five one-hundredths of one peroent (0.25#) to permit the production of a white lead product whioh may be freed readily of deleterious carbonate by washing, and controlling the composition of the precipitated white lead by reference to the bicarbonate concentration in the onolyte and odjusting the bicarbonate concentration in the anolyte by nubjeotlng the catholyte to excess carbonation and adding to the onolyte sodium hydroxide to establish therein bicerbonate in the desired proportion. IP In - "rooesa of producing white lead by eleotrolysis in a bifluid cell involving the use of (1) an anolyte capable under eleotrolysis of yielding a lead acavent and containing a carbonate and a bicarbonate end (2) a catholyte containing a carbonate which is altered during the oourae of the process by removal of carbonate ion, and involving carbonation of the catholyte to restore carbonate ion thereto and re-use of the regenerated catholyte, the improvement which comprises maintaining the oerbonate oonoentratlon in the snolyte et a value not exceeding about twenty-five one-hundredths of one percent (0.25$) to permit the production of a white lead product wMob may be freed readily of deleterious oarbonate by washing, and controlling the composition of the preoipitated white lead by reference to the bicarbonate concentration in the enolyte end adjusting the bicarbonate concentration in.the anolyte by subjecting the catholyte to excess carbonation and adding to the enolyte unoorbonated catholyte containing sodium hydroxide to establish in the anolyte bicarbonate in the desired proportion. 16. In a process of producing white lead by electrolysis in a bifluid cell involving the use of (1) an anolyte capable under eleotrolysis of yielding a lead solvent and containing a oarbonate and a bloarbonate and (2) a oatholyte containing a carbonate whioh is altered during the oourae of the process by removal of carbonate ion, and ; ~"r involving oarbonatlon of the oatholyte to restore oarbonata Ion thereto and re-use of the regenerated oatholyta, the improvement whioh comprises maintaining the oarbonata oonoentration in the anolyte at a value less then six onehundredths of one peroant (0.06) to permit the production of a white lead produot whioh may be freed readily of *tXete~<''ne carbonate by washing, end controlling the composition of the preolpitated white lead by reference to the bloarbonate oonoentration in the anolyte and adjusting the bloarbonate oonoentration in the anolyte by controlling the oarbonatlon of the oatholyta and adding to the anolyte an agent oapable of establishing therein bicarbonate in the desired proportion. . 17. In a prooess of producing white lead by electrolysis in a bifluld oell involving the use of (1) an anolyte oapable under eleotrolysis of yielding a lead solvent and containing a oarbonata and a bloarbonate and (2) a oatholyta containing a oarbonata whioh is altered during the course of the prooess by removal of carbonate ion, end involving oarbonatlon of the oatholyte to restore carbonate ion thereto and re-use of the regenerated oatholyte, the j improvement whioh oamprises maintaining the carbonate oonoen tration in the anolyte at a value less than six one-hundredthq of one percent (0.00) to permit tho production of a white I lead product whioh may be freed readily of deleterious oarbonate by washing, and controlling the oomposition of the precipitated white lead by reference to the bloarbonate oonoentration in the anolyte and adjusting the bloarbonate oonoentration in the anolyte by subjecting the oatholyte to exoess oarbonatlon and incorporating in the anolyte an alkali metal hydroxide to establish therein bicarbonate in the desired proportion. PNYC0C008535 [ 18. In a process of producing whit* lead by eleotrolysis in a bifluid oell involving the use of (1) an anolyte oapable under eleotrolyais of yielding a lead solvent and containing a oarbonete and a bioarbonate and (2) a I catholyte containing a oarbonate which is altered during the j course of the prooess by removal of carbonate ion, and Involving oarbonation of the catholyte to restore carbonate ion thereto and re-use of the regenerated catholyte, the improvement which comprises maintaining the oarbonate concentration in the anolyte at a value less than six onehundredths of one percent (0.06$) to permit the production of a white lead produot whioh may be freed readily of j deleterious oarbonate by washing, and controlling the composition of the preolpltated white lead by reference to the bioarbonate concentration in the anolyte and adjusting the bioarbonate concentration in the anolyte by subjecting I the catholyte to exoesa oarbonation and adding to the anolyte ! sodium hydroxide to establish therein bioarbonate in the ! desired proportion. J 19. In a process of producing white lead by j electrolysis in a bifluid oell involving the use of (1) an anolyte capable under electrolysis of yielding a lead solvent and containing a oarbonate and a bioarbonate and (2} a i catholyte containing a carbonate whioh is altered during the oourse of the prooess by removal of carbonate ion, and involving oarbonation of the oatholyte to restore oarbonate ion thereto and re-use of the regenerated oatholyte, the improvement whioh comprises maintaining the oarbonate oonoentration in the anolyte at a value less than six onehundredths of one peroent (0.06#) to permit the produotion of a white lead produot whioh may be freed readily of deleterious oarbonate by washing, and controlling the I composition of the preoipitated white lead by reference to I the bioarbonate oonoentratlon in the anolyte ana adjusting the bioarbonate oonoentratlon in the anolyte by subjecting the oatholyte to exoeaa oarbonation and adding to the anolyte unoarbonatad oatholyte containing sodium hydroxide to establish in the anolyte bioarbonate in the desired proportion. i 20. In a prooesa of produoing white lead by j electrolysis in a bifluid oell involving the use of two j eleotrolytes of similar but different compositions separated j by a porous diaphragm, the improvement which comprises | mixing a small amount of one eleotrolyte with the other j electrolyte to adjust the composition of the latter. j 21. In a process of produoing white lead by eleotrolyBis in a bifluid cell involving the use of an anolyte and a oatholyte separated by a porous diaphragm, the improvement which comprises mixing a small amount of anolyte with the oatholyte to adjust the composition of the j oatholyte. 22. In a process of produoing white lead by electrolysis in a bifluid coll involving the use of two eleotrolytes of similar but different compositions separated by a porous diaphragm, the improvement which comprises mixing a small amount of oatholyte with the anolyte to adjust the composition of the anolyte.