US709955A

US709955A - Method of producing lead carbonate.

Info

Publication number: US709955A
Application number: US4520901A
Authority: US
Inventors: John W Bailey
Original assignee: UNION LEAD AND OIL Co
Current assignee: UNION LEAD AND OIL Co
Priority date: 1901-01-29
Filing date: 1901-01-29
Publication date: 1902-09-30
Anticipated expiration: 1919-09-30

Description

J. W. BAILEY. METHOD 0F PRDDUCING 'L'.EADCARBONATE;

(Application filed Jan. l29, 1961.7'

Patented sept. 3'0, |902,

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. 4 i Patented sept. 3o, |902;` J. BAILEY. METHOD 0F PRUDUCING LEAD CARBONATE (Appliction med Jan. 29, i901.)

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JOHN IV. BAILEY, OF JERSEY CITY, NEW JERSEY, ASSIGNOR TO THE UNION LEAD AND OIL COMPANY, A CORPORATION OF NEW JERSEY.

METHOD OF PRODUCING LEAD CARBONATE.

SrEGFCATON formingpart of Letters Patent No. 709,955, dated September 30, 1902.

Application filed January 29, 1901. Serial No. 45,209. (No specimen@ To a/ZZ whom it may concern: f

Beit known that I, JOHN W. BAILEY, a citizen of the United States, and a resident of Jersey City, in the county of Hudson and State of New Jersey, have invented an Improved Method of ProducingLead Carbonate, of which the following is a full, clear, and exact specification, reference being had to the accompanying drawings, which form a part 1o hereof. Y

The invention relates to a method of manufacturing or producing lead carbonate, or what is commonly known as white lead, which is automatic and continuous in its character, and the features of my improved method are addressed to the organized treatment of the material employed at certain periods of the process,with definite relation to the peculiarities of the material at different 2o stages of the manufacture and to the chemical action Which is to take place therein.

'lhe object of theinvention is to overcome certain defects or imperfections in the treatment of the lead heretofore employed, which z5 by reason of the peculiar characteristics of the material interfere with the thoroughness of the conversions and tendto prevent homogeneity in the product. e A furtherobject of the invention is t-opro- 3o duce the said white lead quickly and eco# uomically and to furnish a product which isY superior in quality to that which is made by the methods or apparatus now in use.

The most desirable form in which the metallic lead can be presented to the attack of the so-called corroding reagent is that of liber, as it is lcommonly termed, which is necessarily obtained in a more or less matted mass, consisting of the intertwined hairs or 4o fibers as they come through the delivery-apertures of the comminu-ting` apparatus. It is found that this mass if subjected to any handling whatever, or even if allowed to stand for an undue length of time, is liable to become irregularly compacted owing to the very soft character of the metal and the lack of any definite structure in the mass. The resultis that the lead does not aiford uniform access for the corroding reagents, so that local ag- 5o gregations of uncorroded metal are developed, and the product not only lacks homogeneity,

but requires special treatment for the separation of the metallic resid-num. In some measure the same difiiculty is met with When Vother forms of com minuted lead are employed besides that of liber. With these also itis desirable that the individual particles should preserve, as far as possible, Whatever superficial porosity they initially possessed and that the mass of soft particles should not be -6o compacted by handling.

Myinvention comprises first a method of producing lead carbonate which consists in so comminuting metallic lead that it may be maintained in an nncom pacted condition,con 65 veying the lead in this condition into a corroding-chamber, and without substantial disturbance'subjecting the lead therein to the action of a suitable corroding-gas, whereby compacting of the comminuted lead is avoid- 7o ed and a uniform attack of the corroding agenttis facilitated.

My invention also comprises a method of producing lead carbonate which consists in Afeeding comminuted lead onto a suitable carrier, conveying the lead in this condition without substantial disturbance. into a corroding-chamber, causing it to move through Y saidchamberwithoutsubstantialdisturbance,

and subjecting it therein to the action of a 8o suitable corroding-gas. In the best form of my invention a moistening agent, preferably a solution of acetic acid in water, is applied lto the lead withoutdisturbing the lead on its way to the corrodingchamber. The best S5 method known to me of carrying out this particular step of the process is to cause the lead to pass through a bath containing the moisteniug agent before it enters the corrodingchamber. o

My invention also comprises the feeding of the coinminuted lead or lead ber onto a suitable carrier in waves or masses Wholly or partly separated from `one another.. These Waves or masses preferably contain predetermined or regulated quantities of the comminuted lead.

My invention also comprises a method of producing lead carbonate Which consists inV cotnminuting the lead so as to form it into roo lead liber, feeding the lead fiber directly from the comminuting device onto a suitable carrier in waves or wave-like masses, conveying the lead in this condition without substantial disturbance through a bath containing a moistening agent or applying the moistening agent to the lead in some other way Without disturbing the lead, then conveying the lead without substantial disturbance through the air for a certain distance and into a corroding-chamber and causing the lead to move through said chamber without substantial disturbance, and subjecting it therein to the action of a suitable corroding-gas. I prefer to comminute the lead by heating it to a temperatu re only slightly above its melting-point and then causing it to flow through one or more fine orifices, so as to form it into lead liber.

My invention also comprises the feeding of regulated or predetermined quantities of the comminuted lead into the corroding-chamber successively-that is to say, one after another andatsuitableintervals-withoutsubstant-ial disturbance of the lead and causing the lead in the corroding-chamber to move in said chamber while each fresh supply of lead is being fed thereto and to remain at rest during the intervals between the feeding operations and subjecting the lead while in said chamber to the action of a suitable corrodinggas, such as carbonic-acid gas,whereby a certain predetermined or desired quantity ofthe comminuted lead can be fed into the corroding-chamber each day and can be subjected in the said chamber for a sufficient length of time to the action of the corroding-gas and can be discharged from the said chamber when the corroding action is substantially complete.

My invention further comprises the method of producing lead carbonate which consists in conveying comminuted lead through the corroding-clntmber and at suitable intervals inverting orturning overthe lead in a uniform manner and without such irregular disturbance as would tend to injuriously compact it, whereby new surfaces are presented to the attack of the gas in a definite or organized manner.

My invention also comprises applying a moistening agent, preferably acetic acid in water, to the lead in the corroding-chatnber so as not to disturb or compact the lead.

My invention also comprises certain other steps or combinat ions of steps in the treatment of the lead, which will be hereinafter fully described and claimed.

apparatus referred to. Fig. 2 is a vertical section of the corroding-chamber taken on the line a. b of Fig. 1. Fig. 3 is a longitudinal section of the carriers. Fig. 4 is an enlarged View illustrating the manner in which the lead fiber is fed onto the carrier. Fig. 5 is an enlarged View illustrating the manner in which the lead fiber passes from one carrier to another carrier in the corroding-chamber.

Referring to the drawings, 1 is one of a series of melting-pots for melting the pig-lead and converting it into fiber or finely comminuted or Shotty lead. 2 is a dischargepipe leading from the bottom ofsaid meltingpot and provided with a suitable valve 3.

4 is a plate provided with tine openings or orifices and placed at the outlet end of the pipe 2, through which the molten lead is forced by means of the weight of the column of lead in the melting-pot 1.

5 is a feed-hopper into which the lead fiber 6 passes after it has been forced out through the openings in plate 4. This hopper is made of sheet-iron or other suitable material and suspended at its upper end on the rock-shaft 8 and so arranged that it can swing for a short distance back and forth, as represented in dotted lines in Fig. 1. Any suitable device may be used for giving the rocking motion to the said hood.

9 is a carrier in the form of a continuous belt, preferably made about eight feet wide. lt is stretched upon and carried by the pulleys 10 and the idlers 1l. This belt 9 is preferably made of wood slats 9, held together by links or belting 9b, and may be covered with wirecloth 9c or other suitable material, the purpose of this construction being to permit the belt to pass easily over the pulleys and the idlers and at the same time to permit the corroding-gas to pass easily through the belt, so as to reach every part of the comminuted lead which is being carried by the belt. The belt is moved by sprocket-wheels on the pulleys 10.

12 is a box containing a regulated solution of a moistening agent, preferably acetic acid and water, supplied automatically and maintained at a given level from the tank 13. The tank 13 is kept suitably supplied with acid ulated water and is connected by means of the pipe 14 with the box 12.

15 represents a float-valve device arranged in the box 12 and adapted to open and close the discharge-valve in the pipe 14, thereby maintaining the solution in thebox 12 at any desired level.

'[he belt 9 after receiving its charge of lead libel' passes underneath the large idler 11 and the lead is thereby made to pass through the bath in the box 12, as a result of which the stock under treatment is wet to properly acidity it before subjecting it to the action of the air and the corroding-gas. The belt 9 is preferably made several hundred feet long-say from three hundred to six hundred feet-so as to give it a capacity of several tons per day.

16 is an apron for conducting the drippings from the belt 9 back into the tank 12.

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IIO

17 is a corroding-chamber, which may be,

say, eight or nine feet Wide and from one hundred to three hundredfeet long and into which the belt 9 feeds the lead ber 6 in the manner illustrated in Fig. 1. The opening through which the belt 9 passes into the corroding-chamber is preferably provided with a flexible curtain 18, adapted to readily yield to permit the passage ofthe belt and comminuted lead without disturbing the lead, but to prevent the escape of any considerable quantity of the corroding-gas.

19 represents a series of belts or conveyers suitably mounted upon and carried by rollers or pulleys 20. These b elts are staggered with reference to one another-that is to say, the uppermost belt 19 projects beyond the belt 9, as shown at the left-hand side in Fig. l-so that the comminuted lead may fall Vfrom the belt 9 upon the uppermost belt or conveyer 19 and be carried backward across the corroding-chamber. The second belt19, counting from the top, projects beyond the belt 19 immediately above it at the right-hand side.

The third belt 19, counting from the top, projects beyond the belt 19 just above it on the left-hand side, and so on down'through the series of belts or con'veyers. lThe pulleys or rollers 20 are provided with sprocket-wheels to drive the belts 19 and also at one end of the corroding-chamber with driving-gears 21. (See Figs.A 1 and 2.) The pulley 10 at the upper end of the corroding-chamber on the left side, as shown in Fig. 1, is also provided with a driving-gear 21. These gears 21 preferably mesh with one another and are connected in any suitable way with a drivingshaft. It will be evidentthat by means of this series of gears adjoining belts will be driven in opposite directions, which will cause the belts to continually carry the comminuted lead back and forth from one sid/e of the corroding-chamber to the other, the com minuted lead falling from each belt to the belt below, and so on until it reaches the lowest belt of the series. The belts 19 are open-meshed belts, such as could be made of wood slat-s held together by links and covered with any open-mesh cloth adapted to permit the corroding-gas to pass freely through the belts.

22 22 are sprinkling-pipes for sprinkling the stock under treatment as it passes through the corroding-chamber. These pipes are connected with any suitable source of supply and extend across the chamber, being of substantially the same Width as the belts 19, andare provided with perfor-ations through which the acid ulated Water is sprinkled or sprayed on the stock which is under treatment. As many ot1 these pipes may be employed as are thought desirable or necessary. The supply of moistening liquid to these pipes may be automatically controlled, as by an automatic governor 35, so that when belts 19 are in m04' tion moistening uid will be supplied to these pipes, but will be shut off when the belts are at rest.

23 is a pipe or conduit for supplying the steam and corroding-gas-namely, carbonicacid gas-and for distributing themv through the bottom of the corroding-chamber. This pipe is provided with perforations on its up- A per side and is connected with any suitable source of supply ofthe said steam and corroding-gas.

24 is a su mp or receptacle for catching the drippings from the moving belts 19 and is preferably shaped as shown in Fig. 2.

25 25fare supporting-rollers for supporting the belt 9 and also the belts 19. Anyrnu'mber of these may be used for this purpose.

26'is a pipe for conveying the Waste gases from the corroding-chamber.

27 27 (see Fig. 2) are tracks or ways which are traveled by the links at the ends of the slats, of which the belt 9 and the belts 19 are made. belts and cause them to move properly over the rollers 20.

28 is a chute for receiving and delivering the corroded product to the wash-machine.

29 is a revolving wash-machine for separating the corroded metal from the portion of the stock that has not been corroded, by means of whichthe latterthat is to say, the waste product-is thrown out and collected Yfor further treatment.

30 is a hopper-bottomed tank in which the wash-machine works and the bottom of which receives the corroded product. The washmachine consists Vol a reel which is covered with a vline brass-wire screenjor other suitable material and vadapted to permit the white lead to pass through the meshes or perforati/ons of the same while preventing the uncorroded product from escaping. tank is provided with sufficient water to partly submerge the lower side'of the reel. The tankY 30 is provided with a pipe 31, through'which the white lead which is suspended in the water can be pumped to the drying-room. The rear end of the reel is provided with diaphragms or partitions 32, eX- tending part ot' the distance from the circumference of the reel toward the axis and adapted to carry the uncorroded portions of the material to the upper side of the reel and to dump them on the inclined chute-33, from which they drop into the receiver 3ft for the waste products.

My improved process is carried out as follows: Metallic lead is melted in the meltingpots 1 by any suitable means. ln the best application of my invention the lead is heated toa temperature only slightly above the melting-point and is caused to flowV through one or more line orifices in the plates 4. It solidities as soon as it reaches the air, forming a rthread-like product in structure like Wool Ipreferto force and knownas lead fiber.

the lead through the tine orifices in the plates 4 by means of the pressure of a column of lead in the melting-pots 1'of sufficient height to force the molten lead through said orifices.

These tracks are simply to guide the IOL) The

IIC

If the metallic lead is heated to a higher degree of temperature, it will break into a line shotty condition. Broadly considered, my invention is not limited to the use of lead ber, although it is particularly adapted and designed to be applied to lead which is comminuted into the form of ber. The hopper 5 is given a rocking motion, swinging between the positions indicated in Fig. 1, one

being in a full line and the other in a broken line. The lead fiber slides down through the hopper 5, and by means of the rocking motion of the hopper 5 is fed onto the carrier-belt 9 in masses or waves wholly or partly separated, each mass or wave containing a regulated quantity of the comminuted lead, or with a waving action which disposes the ber in a mat, having comparatively uniform convolutious which stand in a more or less upright position, as illustrated in Fig. 4. This permits the formation of a comparatively thick mat of fiber, with something in the nature of a structural organization, that resists the tendency of such a body to sink or compact itself together. One result of thus disposing the lead into more or less independent waves or undulations is that the moistening agent, the air, and the corroding-gas are given more complet-e access to the parts thereof and the corrosion is consequently more thorough. The belt or carrier 9 then carries the comminuted lead without substantial disturbance through the bath containing the agent which is employed to make the preliminary attack on the metal. I prefer to use a solution of acetic acid and water for this purpose, although any other suitable agent may be employed, provided it is adapted to accomplish a similar result. This bath is contained in the box 12, which holds a regulated solution of acetic acid and water. This solution is preferably of a strength of about one part of twenty-sixper-cent. acid to eight parts of Water. The supply of the solution in said bath is automatically maintained. An ample supply of the solution at the proper strength is kept in the tank 13 and is fed to the box 12 through the pipe 14 and maintained at a given level in the box 12 by means of the float-valve device 15. After the metallic lead has been thus passed through the bath of the moistening agent it is carried by the belt 9 without substantial disturbance through the air and into the corroding-ehamber 17 in the manner indicated in the drawings. 'While passing through the air to the corroding-chamber the lead or a part of it is oxidized and combining with the acetic acid forms acetate of lead, being thus prepared for the action of the corroding-gas. The lead passes from the belt 9 onto the top one of the series of belts or conveyers 19in the manner illustrated in Fig. 5. In passing from one belt to another in this way the lead is inverted or changed in position, so as to expose new parts or surfaces to the action of the corroding-gas and without such severe or irregular disturbance as would tend to injuriously compact it. The belt 9 and the Various belts 19 are preferably made to travel at the same rate of speed, so that the comminuted lead is not torn apart or compacted. Any part of the moistening solution that drips from the belt 9 on its Way from the bath to the corroding-chamber falls upon the apron 1G and runs back into the bath. The comminuted lead is carried back and forth through the eorroding-ehamber, being delivered from one belt 19 to the next lower belt 19, and during all this time is exposed to the action of the carbonite-acid gas and steam, which are introduced into the chamber through the pipe 23. The lead is thus very thoroughly and uniformly corroded. At the same time the lead is kept wet or moistened by being sprinkled with acidulated water through the sprinkling-pipes 22. The corroded lead is finally delivered by the lowest belt into the chute 28, from which it passes into the washing machine or reel 29. This reel rotates in the tank 30, which is provided with enough water to cover the lower portion of the reel. The Water separates the fine amorphous powder, which is the lead carbonate, from the residue and carries it through the meshes of the reel into the bottom of the tank 30, from which it is pumped to the drying-room. After it has been dried itis the finished dry white lead of commerce. The uncorroded portion, which is usually not more than eight per cent.,cannot pass through the meshes of the wash-machine and is dropped out at the farther end into the receptacle 34 and is subjected to further treatment. The corroding chamber having sixteen of the belts or conveyers 19 and being three hundred feet in length would give a total length of travel of about live thousand feet in the corrodiug-chamber before the stock under treatment would pass into the washing-machine.

In the best form of my improved process I feed predetermined quantities of the comminuted lead into the corroding-chamber successively at intervals. For example, I run the belt 9 for two and a half hours, causing it to travel at the rate of about seven feet per minute. This belt receives about fifteen pounds of lead liber perliueal foot if made eight feet wide. Thus I feed about one thousand feet of the comminuted lead into the corroding-chamber and then stop the belts and allow the comminuted lead to remain at rest during the remainder of that day in the said corroding-cham ber, Where it is subjected all the time to the action of the corrodinggas. The next day a similar quantity of commin uted lead is fed into the corroding-chamber, and then the belts are again stopped, and this is continued from day to day. After four days of continuous operation the belts would be nearly full and on the fifth day the machine would begin to discharge the corroded stock into the wash-machine. After this I feed a similar quantity of comminuted lead IOO IIO

into the corroding-chamber each day, and a like quantity of corroded product is discharged from the corroding-chamber each day. This Would give a dail-y output of corroded product of about nine or ten tons, counting on an increase in Weight in thecorvroded product of only about twenty per cent.

In my improved method the treatment of the material is so adapted to the peculiar nature of the same thatthe great diiculties heretofore encountered in handling. the lead in the various stages of its manufacture into White lead are entirely overcome. Indeed the very characteristics of the lead which have given rise to these difficulties are availed of in my method to secure a quicker and more com plete and thorough corrosion. The entire body of the lead is so com pletely exposed to the successive actions of the various agents employed and under such advantageous circumstances that only a very small part of the lead under treatment remains uncorroded. By causing the lead to move in or through the corroding-chamber the circulation of the corroding-gas through the pores o1' interstices of the lead is aided. By moistening the lead from time to time in the chamber the corrosion is greatly assisted and without any danger of compacting the lead or subjecting it to contact with impurities or dust, such as Would exist if the lead had to be removed from time to time from the chamber for the purpose of being moistened.

The white lead made by this process is superior to any form of White lead heretofore produced. It has all the good qualities of lead corroded by the slow processes lheretofore employed-such as body, sticking, and lasting qualities-and is superior to theproducts heretofore produced by the quicker processes in that it has no stains or discolorations and is not in a crystalline condition, like the old Dutch lead. Itis an amorphous powder free from the usual stains and dust resultingY from the processes heretofore in use. It is also superior to White lead produced by chemical precipitation, because the latter is lacking in body, is uy, and will not hold its color, Whereas the product of the present process does not have these defects. In my improved method I can also regulate the percentage of carbonate and hydrate, and thus accurately control the character of the product.

It will be apparent that by means ofmy improved method White lead' can be produced very quickly and With a minimum of labor, thus securing great ecomomy Without endan-v gering the health of the Workmen.

What I claim as new, and desire to secure by Letters Patent, is-

1. The method of producing lead carbonate which consists in so comminuting metallic lead that it may be maintained in an uncompacted condition, conveying the lead in this condition Without substantial disturbance into a corroding-chamber, causing it to move through said chamber withoutsubstantial disturbance and subjecting it therein to the action of a suitable corroding-gas whereby compacting of the comminuted lead is avoided and the uniform attack of the corroding agent is facilitated, substantially as described.

2. The method of producinglead carbonate which consists in so comminuting metallic lead that it may be maintained in an uncompacted condition,applying a moistening agent to the lead without disturbing the lead, conveying the lead in this condition Without substantial disturbance into a corroding-chamber, causing it to move through said chamber without substantial disturbance and subjecting it therein-to the action of a suitable corroding-gas whereby compacting of the comminuted lead is .avoided and the uniform at tack of the corrodiug agent is facilitated, substantially as described.

3. The method of producing lead carbonate which consists in so comminuting metallicY 'lead that it may be maintained in an uncompacted condition, conveying the lead in a substantially undisturbed condition throughl a bath containing a moistening agent and then into a corroding-chamber, causing it to move through said chamber Without substantial dis-y tu rbance, and subjecting it therein to the action of a suitable corroding-gas whereby compacting of the com minuted lead is avoided and the uniform attack of the moistening and Ycorroding agents is facilitated, substantially as described.

4. The method of producing lead carbonate which consists in subdividing metallic lead into a hair-like or fibrous condition, forming the lead thus comminuted into uncompacted Waves or masses wholly or partly separated, applying a moistening agent to the lead Without disturbing the lead, conveying the lead in this condition Without substantial disturbance into a corrodingchamber, causing it to move through said chamber Without substan- IOO tial disturbance and subjecting it therein to the action of a suitable corrodin g-gas whereby compacting of the comminuted lead is avoided and the uniform attack of the corroding agent is facilitated, substantially as described.

5. The method of producing lead carbonate which consists in forming lead fiber into uncompacted Waves or masses wholly or partly separated, applying a moistening agent to the lead Without disturbing the lead, conveying the lead inthis condition without substantial disturbance into a corroding-chamber, causing it to move through said chamber without substantial disturbance and subjecting it thereinto the action of a suitable corrodinggas whereby compacting of the comminuted lead is avoided and the uniform attack of the corroding agent is facilitated, substantially as described.

6. The method of producing lead-carbonate which consists in comminuting the lead so as to form it into lead ber, forming the lead fiber into uncompacted waves or masses, conveying the lead in this condition without substantial disturbance through a bath containing a moistening agent, then conveying the lead without substantial disturbance through the air and into a corroding-chamber, causing the lead to move through said chamber without substantial disturbance and subjecting it therein to the action of a suitable corroding-gas, substantially as described.

7. The method of producing lead carbonate which consists in comminuting the lead so as to form it into lead fiber, forming the lead fiber into uncompacted wave-like masses, applying a moistening agent to the lead without disturbing the lead, conveying the lead in a substantially undisturbed condition through the air for a certain distance and then into a corroding-chamber,causingitto move through said chamber without substantial disturbance, applying a moistening agent to the lead in said chamber and subjecting the lead in said chamber to the action of a suitable corroding-gas, substantially as described.

8. The method of producing lead carbonate which consists in so comminuting the lead that it may be maintained in an uncompacted condition, applyinga moistening agent to the lead without disturbing the lead, forwarding predetermined quantities of the lead without substantial disturbance into the corrodingchamber successively and at intervals, causing said lead to move in said corroding-chamber without substantial disturbance while each fresh supply of lead is being fed into said chamber and to remain at rest during the intervals between the forwarding operations, subjecting the lead in said chamber to the action of a suitable corroding-gas, substantially as described.

9. The method ot' producing lead carbonate which consists in conveying comminuted lead through a corroding-chamber and at suitable intervals inverting the lead therein without compacting the same, and subjecting the lead in said chamber tothe act-ion of a suitable corroding-gas whereby new surfaces are presented to thc attack of the gas in a definite and organized manner, substantially as described.

10. The method ofproducing lead carbonate which consists in so comminuting the lead that it may be maintained in an uncompacted condition, applying a lnoistening agent to the lead without disturbing the lead, conveying the lead in this condition without substantial disturbance into a corroding-chambcr, causing the lead to move through said chamber without substantial disturbance and at suitable intervals inverting the lead and subjecting it in said chamber to the action of a suitable corroding-gas, substantially as described.

ll. The method of prod ucing lead carbonate which consists in so comminuting the lead that it maybe maintainedin an uncompacted condition, applying a moistening agent to the lead without disturbing the lead, conveying the lead in this condition without substantial disturbance into a corroding-chamber, causing the lead to move through said chamber without substantial disturbance and at suitable intervals inverting the lead, applying a moistening agent to the lead in said chamber at intervals without disturbing the lead, and subjecting it in said chamber to the action of a suitable corroding-gas, substantially as described.

12. The method of producinglead carbonate which consists in arranging the comminuted lead so as not to compact it but to presentan extended surface to the action of the dierent agents employed, applying to it in this condition a solution of acetic acid and water, passing it without substantial disturbance through the air to the corroding-chamber so as to form acetate of lead, causing it to move without su bstan tial disturbance in said chamber for a period of time and exposing it during said time to the action of a current of carbonio-acid gas, then causing it to fall through said chamber for asufticient distance to rearrange the mass without compacting it so as to expose new surfaces to the corrodinggas, then causing it to move again througll said chamber and repeating this operation until the lead is su ciently corroded, substantially as described.

13. The method of prod ucinglead carbonate which consists in arranging the comminuted lead so as not to compact it but to present an extended surface to the action of the different agents employed, applying to it in this condition a solution of acetic acid and water, passing it without substantial disturbance through the air to the corroding-chamber so as to form acetate of lead, causing it to move withoutsubstantialdisturbancein said chamber for a period of time and exposing it during said time to the action of a current of carbonicacid gas, then causing it to fall through said chamber for a sufficient distance to rearrange the mass without compacting it so as to expose new surfaces to the corrodinggas, then causing it to move again through said chamber, moistening it at intervals in said chamber with a solution of acetic acid and water and repeating this operation until the lead is sufficiently corroded, substantially as described.

14. The method of producing lead carbonate, which consists in so comminuting metallic lead that it may be maintained in an uncompacted condition, conveying the lead in this condition intoa corroding-chamber, and without substantial disturbance subjecting the lead therein to the action of a suitable corroding-gas, whereby compacting of the comminuted lead is avoided and the uniform attack of the corroding agent is facilitated.

15. The method of producing lead carbonate, which consists in so comminuting metallic lead that it may be maintained in an uncompacted condition, conveying the lead in this condition into a corroding-chamber, applyiug a moisteuing agent to the lead while in the corroding-chamber, and withoutsubstantial disturbance subjecting the lead in the corroding-chamber to the action of a suitable corroding-gas, whereby compacting of the comminuted lead is avoided and the uniform attack of the corroding agent is facilitated.

16. The method of producing lead carbonate, which consists in subdividing metallic lead into a line hair-like or fibrous condition, conveying the lead in this condition Without substantial disturbance into a corrodingchamber, and Without substantial disturbance subjecting the lead in the corrodingchamber to the action of a suitable corrodiugf gas, whereby compacting of the comminuted lead is avoided and a uniform attack of the corrodingV agent is facilitated. Y

17. The method of'producing lead carbon- JOHN W. BAILEY.

Vitnesses:

JOHN O. GEMPLER, Guo. W. MILLS, J r.