US1344030A - Metallurgical process - Google Patents

Description

W. E.' GREENAWALT.

METALLURGICAL PROCESS. APPLICATION FILED A`uG.II`. Ian.

1,344,030. mmm 2z, 1920.

UNITED STATES PATENT OFFICE.

WILLIAM E. GREENAWALT, OF DENVER, CDLORADO.

METALLUIMrIGAl` PROCESS.

Specification of Letters Patent. Patented June 22, 1920.

Application led August 11, 1917. Serial No. 185,652.

-ing in the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Metallurgical Processes, of which the following is a specification.

This process may be regarded as a modication and continuation of the processes described in my co-pending applications, Serial No. 15,583, filed March 15, 1915, and Serial No. 140,738, filed January 5, 1917, and the apparatus used in carrying out the process, a 'continuation andmodiiication of that described in my co-pending apparatus application, Serial No. 145,884, filed F ebruary 1, 1917.

The process has `for its object the effective application of reducing gases in the electrolysis of impure electrolytes, and the efective reduction of the variable valent salts in the electrolyte by a suitable reducingA agent, such as sulfur dioXid.

The process will be describedmore particularly in reference to the extraction of metals from their ores with chlorid solutions. The ores'may be assumed to be copyper ores carrying variable quantities of the base and the precious metals. It is not intended,l however, to limit the process to anyv particular use.

If copper ores containing precious metals are treated with a chlorid solution, such as a dilute solution of hydrochloric acid con` taining in solution variousother chlorids, such as thechlorids of iron and sodium, the copper will be extracted as the cupricA and cuprous chlorids, and the gold and silver as their respective chlorids. Some of the copper will be in the cuprous condition, but in practical operations, most of it will be in the 'cupric condition.

The solution of the metals from the ore usually involves no particular difficulty. The trouble commences when an attempt is made to electrolyze the chlorid solutions to obtain the copper. If such a solution is electrolyzed, copper 'is deposited at the cathode and chlorin liberated at the anode. This chlorin combines with the ferrous salts in the solution to 'convert it into the fel-ric salts, and the ferrie salts and free chlorin, acting on the copper deposited at the cathode, re-dissolves it, thus causing a loss of efficiency: This loss under aggravated conditions, may be so great that the copper is re-dissolved as rapidly as it is deposited.

On the other hand, it is known that, theoretically at least, twice as much copper is deposited, per unit of current, from a cuprous chlorid solution as from a cupric chlorid or cupric sulfate solution. The advantages in this respect, however, have been largely outweighed by the disadvantages due to the free chlorin and ferrie salts formed by the chlorin. One of the most important objects of this invention is to maintain the electrolyte so reduced as to effectively realize the advantages, without being bothered by the disadvantages.

If a chlorid solution, resulting from treat`- ing ores as described, is treated with sulfur dioXid, the cupric chlorid is reduced to the cuprous condition and the, ferrie salts reduced to the yferrous condition, thus:

If this reduced solution is electrolyzed, and if it were possible to maintain the variable valent salts at their lowest vales a high cathode efficiency could be obtained, and, as stated, twice as much copper deposited as from a cupric solution. The essence of the trouble, however, is in maintaining the solution reduced.

I accomplish this effectively with my process, by using an apparatus, as shown in the accompanying drawings, ,in which Figure l represents a longitudinal section of an electrolyzer in which the process may be carried out, Fig. 2 a transverse section, Fig. 3, a plan, Fig. 4, electrode details, and Fig. 5 a diagrammatic sketch of the preferred method of carrying out the entire process.

In the drawings, 1 is an electrolytic tank, having a removablecover 2, and containing the electrolyte and vertical electrodes 4 and 5., resting on submerged conducting bars 15 at a proper speed by the motor 11.

I on an insulation sisting of a 'shaft 6, rotated in the bearing 8, when driven by the motor 11, and having mounted on its disks 7 which dip into the.

electrolyte, and spray, or atomize, the liquid into the gas confined over it and submerge some of the gas in the liquid, when rotateld T e walls of the tank are arranged with a series of pipes, orducts, 33, so that the liquid sprayed into the Vgas will run down the sides of the cover `and through the pipes, and thus cause a circulation of the electrolyte, due to the diiference in level of the top of the pipes and the surface of the liquid.

The electric current is supplied to the electrodes by means of the termin/ als 24 and 25, and the conducting bars 15 and 16 in the bottom of the tank. Electrical connections is made with the electrodes by letting the electrodes rest on the conducting bars. The electrodes are held in position by the sidepieces 17, which may be of wood, and having saw-cuts, or

The arrangelmen-t for insulation of the electrodes is shown in detail in Fig. 4f. One end of the electrode rests on its corresponding conducting bar, say 15, while the other end rests plate 19, and this plate, in turn, rests on the opposite'conducting bar. The electrode 4, for example, rests on the conducting bar 16 while the opposite end restson the insulation plate 19, which in turn,frests on the bar 15. The electrode 5 rests `on the conducting bar 15, but is in.

sulated,from bar 16 by the plate 20. A current, therefore, 'entering through the bar 16 would.pass to the electrode 4., and, being insulated from bar 15, would pass through theliquid from electrode 4 to electrode 5, and then to the bar 15 on which electrode 5 rests and with which it is-'in electrical contact, while electrode 4 is insulated from bar 16. The conductor bars 15 andL 16 are preferably made of copper, lwith a sired conductivity, while the lead has' a greater resistance to deteriorationmuch than the copper. The spraying disks are preferably made of rubber, with serrations 27 and small perforations 28, to facilitate the spraying and mixing of the electrolyte and gas. The disks are held in position on the shaft by washers 12 and annular rings 26 inserted between the washers, and

. arranged so`that the whole can be made grooves, 18 to receive the ends of the electrodes.

lead casing 37. The copper gives the de-v` vwise usually a waste product.

tight and rigid by the screws' 29 at the endse` of the shaft. The cover 2, is provided with a lead lining 23 to'resist the corrosive action of the liquid and gases.

In operating the process the leach solution from the ore, and, preferably, having its variable valent salts reduced to their lowest valency, is introduced into Athe electrolyzer 1, through the pipe 9 and is exhausted through the pipe 10. Sulfur dioxid gas is introduced throughthe pipe 21 and exhausted through the pipe 22 in suchl a way as to always maintain a slight inward suction to prevent the corrosive gases from escaping from the cell and contaminating the atmosphere.

When the current is turned on, copper is deposited on the cathode and chlorin liberated at the anode.V Some of the chlorin is consumed in converting the variable valent elements from Ltheir lower to their higher` valencies, and some escapes from the liquid into the hood, above the liquid, where coming in Contact with the sulfur dioxid gas and sprayed liquid, the chlorin combines with the sulfur dioxid tq^form acid. These reactions may be shown by the following equations:

3.' 2CuCl+electric currentM-2Cu-l-2Cl.

If this action were to go on indefinitely,

the acid regenerated, and the cupric and ferrie salts reduced to the cuprous and ferrous condition as rapidly as formed.

In `this way the process may go on efficiently inv-,y definitely. It is very desirable to always ,v

maintain the sulfur dioxid in excess in thei-J;

cell. Fortunately this can readily be done, as -sullid ores are almost always available, and the sulfur dioxid from roasting is other- The excess of sulfur dioxid, issuing from the cells, may be used in reducing the ferrie iron and cupric copper in the solution before electrolyzing it. With a hot or awarm electrolyte the space in the electrolyzer above the liquid 4will contain much of the liquid sprayed into it, as a fine mist and steam, and thus the reactions between the gases and the liquid are rapidly effected. The atomizers are rotated at a fairly high speed so as to effectively spray the liquid into the gas, while at the same time submerging some of the gas in the liquid: ln this way it is quite possible to always maintain a slight excess of sulfur dioxid in the electrolyte. It has been observed thatrwhen there is an excess Qf'sulfur dioxid in the electrolyte a high current efficiency can always be expected.

T he reaction between the sulfur tdio-xid and chlorin is practically instantaneous.

ln carrying out the process, as so far described, by making the initial reduction with sulfur dioxid, sodium sulfate is formed in considerable quantities from the vsodium chlorid which is assumed to be in the solution, and, while this does not appear to exert any influence on the electrolysis, nevertheless, it would soon accumulate in amounts to give trouble by crystallization. Fortunately, the acid regenerated in the process, is in such excess in the treatment of suitable ores, that some of the solutions can be diverted at each cycle, and thus the impurities kept within bounds. To facilitate this, it is preferred to precipitate this diverted portion with hydrogen sulfid, and then use the resulting copper sulfid in the initial reduction. ln this way the solutionA may be re duced, and no sodium sulfate formed by the reactions, thus:

l rlhis not only serves to reduce the cupric and ferric salts, but also serves to` convert the copper in the washwaters and lean foul solutions into the electrolytic metal in the regular process of deposition.

The important step in the process is confined to the treatment of the solutions in the electrolyzer. rl`he process, as a whole, is best Adescribed by referring to Fig. 5 in which 50 represents a leaching vat for the treatment of the ores with an acid chlorid solution. rl`he rich solutions flo-w into tank 51 and the lean solutions into tank 65.r 'll`hc lean solutions are drawn from tank into the precipitator 66, where, being treated by hydrogen sullid from the gas generator 67, the copper is precipitated as the ,suliid with a. simultaneous regeneration of an equiva7 lent of acid. rl`he mixture of liquid and sulfid precipitate flows into the separator, or thickener, 68, where the sulfid sludge is separated from the liquid. The weak regenerated acid solution fiows into tank 71, and from there applied to the ore as desired.

The copper sulfid precipitate is introduced into the reducing tank 51, where it is agitated with the rich solutions, and the cupric and ferric salts reduced; it then flows into the separator 52,

where the copperk sulall times reduced and agitated and circu lated, .there is no particular object in causing a rapid flow through the cell, or in liowing the solution throughpa series of cells before returning it to theore. The solution may, therefore remain in the electrolyzer until the copper has been sufficiently extracted from it, or say, down to one or two per cent. from a three to vfour per cent. solution. lt is therefore preferable to feed the first row of cells in multiple, and then pass the solution on to a second series of cells with perhaps a lower current density, on account of the impoverished electrolyte from the first series of cells. rllhe gas, from the sulfur dioxid generator 60 is distributed to the cells by the pipe 61, and enters the cells by the connection pipe 21, and then flowing from one end of the cell to the other end, flows into the next cell, and soon through the series, finally issuing through the pipes 22, where it {iows into the main 62, and by means of the exhauster 63 is forced into the tower 53, where the excess sulfur dioxid is applied to the new elec-1 tyrolyte. of electrolyzers [lows into the second series through the pipes 55, anu on issuing from the second series of electrolyzers, is collected by the pipe 56, and through pipe 5C flows into the storage tank 59, where it may be applied to the ore as desired. lf it is desired to raise the valency of the' variable valent elements, after electrolyzing the solution and before applying it to the ore, the electrolyzed solution is passed through an oxidizer 58 where chlorin or oxygen can be applied to it from the gas generator 27e. lf the ore contains gold the solution should also contain free chlorin, 4before it is ap- -plied to the ore, lf the ore contains precious metals, the solution lfrom the leaching vat flows into the tank 72, and from there, in a regulated stream, through the precipitator 73, where the gold and silver can be precipitated with copper, before entering the storage tankl. lt is usually preferred, however, to omit this step and precipitatev the gold and silver with the copper sulfid in the reducing tank 51, and then from time to time extract the gold and silver from the sulfid residue.

ln electrolyzing solutions by the method purposed in this process, it is evident that the usual electrical connections will not. sufiice. In the swirl of the gases and electrolyte the usual electrical connections rlfhe solution from the first series Ill (l would be tooIconiplicated and would be lvery y the .di iculty of getting at the connections, the practicability of the apparatus niight be questioned. 'lhese dihculties are overcome by having two conducting bars in the 'bottoni of the tanlr; one for the positive and one for Athe negative conductor. These bars are bolted tight to the bottom so that there will be no leak, and the terminaison the outside arranged so that connections with electric dynamo are easily made. llhe electrodes rest on the conducting bars, and the"1 weight suices to malte the proper contact rer the electric current. rllhe edges ci the anodes are insulated troni the cathode bar9 and the` edges of the cathodes are insulated roni the anode bar. The anodes may be either ci lead, carbon, or magnetite, and the cathodes either lead or copper. l the anodes are niade oi" carbon, which .is the material. preferred for chlorid solutions, the construction of the anode is veryv much sinipler than in an ordinary cell where y the electrodes' are suspended from above.

carbon electrodes are usually manufactured in slabs, but there has been sonic diliiculty in assembling these slabs tol malre a large anode, to overcome corrosion and resistance. l overcome these .diliculties very easily by laying the first slab on the conductor bars with one end properly insulated from the cathode conducting bar, and by .other gases downwardly. The

means ol wooden grooved pieces at the sides, lay one slab vertically on top of another with the adjacent edges contacting, as shown in Fig. i. may be built vertically as large as desired, While the electrical contact between the slabs is all that is necessary. li perfect abutting edges are desired to give a better electrical contact, the abutting edges may be planed to a true surface. rlhis will not ordinarily be necessary, for, even il the contact in the beginning is not perfect, it will soon be made so by the electrolytic action of the current in depositing copper between the gaps.

ln chlorid solution, especially, the conducting bars are more likely to corrode than in sulfate solutions although in any case the corrosion is quite slow. lt is almost entirely avoided, by surrounding the conducting bars with a covering ol lead. 'l

ln practically all electrol 1c\processes,-

hydrogen is, or may be, liberated. The hy-` drogen is undesirable in the upper part of the cell: lt may act to ditions, become explosive. These diiliculties are overcome by having a 'small hydrogen outlet in the top of the cover of the cell. Hydrogen, being by far the 'lightestl gas likely to be in the cell, ancy in a quiescent space 3, displace the ydrogen -niay be continuously and uiclrly corroded, and on account ofv ln this way an electrode free sulfur from the sulfur dioxid, or it may, under certain con?" matejl" quired to make this will by its own buoy? recibes automatically allowed to escape through the valve 30 in the amounts termed, or used as desired.

To avoid the diculty,

stagnant and impoverished electrolyte at the bottoni ol"V the tank, provisioniis made to cause a positive circulation and distribution of the electrolyte, by means of the pipes, or ducts, 33, the atomizers, or spraying disks, l, and the cover 2. FShe amount of electro'u lyte sprayed into the gas over it regulated by the speed and submergence oir the disks, and the dislrs spraying the electrolyte into the gas also causes it to' hit the sides of the cover, and this electrolyte, eliilectively treated with the gas, passes down the sides oil the cover, and enters the .pipes is easily in deep cells, of a 33, and is again introduced into thev body oli the electrolyte at duced electrolyte trodes in the lower-as well as in the upper portion ci the cell. This saine procedure Yis observed in dowing the electrolyte from one cell to another: the electrolyte is preferably taken from the top of the irst cell and. introduced into the bottone of the next.

the bottom, and causes a- Icirculation upward, and brings freshly rein contact with the elec-y lt might be thought that the covered elecl trolyaers would complicate the electrolysis and increase the ycost of operation: lt is incre likely to simplify the. operatiouand cheapen the cost ot deposition. 'lhe idea,

of course, is, to use fairly large units,y and greatly increased, installation as a whole is materially decreased. VElectrolytic dynamos with a ca. pacity of 10,000 ainperes are regularly made as a standard size, and SSXSXQ inches is, a stoclr size carbon slab from which anodes.

38X48X2 inches could easily be constructed, as described. Electrodes tive area of 25 square feet may therefore be considered a fair standard.' -With a current conditions, olfl about 96' per cent. or 2.5 lbs.

of copper fromcupric solutions, per 1000 'ampere-hours, there would-be deposited 25 lbs. of copper per hour with 10,000 amperes or 600 lbs. per day of 24 hours, per cell. the (deposit on each side of the cathode 1s the cost of the electrolytic .while the cest of the individual cells isg--l 5 f 100 having a total ac onehalf inch thick, the total Weight of the copper on each cathode would be approxi- 1155 lbs. and ,for 40'cathodes it woul 'be 46,200 lbs. 'Depositing at the rate 0h60() lbs. per day,

deposit-, Or in other Words, the cell would not have to?- 'be disturbed or the cover lifted-for a period of 77 days, when it would be cut out ofthe circuit, and 46,200v lbs.. ci copper removed 77 days would be retherefrom. lt is true that trees may form, but with a low current density and adequate circulation and agitation of the'electrolyte, this is not likely to cause trouble.

There is no difficulty in removing the cover from the cells. lThe cells are easily arranged so that they can be disconnected one at a time, and a traveling crane used to lift the cover and place it on a fresh cell, while the one from which it was takenA has its copper removed. ln taking the copper out of the cells, the individual cathodes are lifty ed out with pincers suspended from the crane. lf lead cathodes are used, the copper is easily pried od, and the cathode returned to the cell. ylhe anode is not removed until worn out.` o

lf the current density is doubled, say t amperes per square foot, which is by no means excessive, twice the amount of copper would be deposited with the same cells, and in the same time, or, 1200 lbs. per day. lf the solution is cuprous, and the deleterious reactions can be held in check by the eilicient use of sulfur dioxid made possible in these cells, '1200 lbs. of copper will be deposited per day with a current density of l0 amperes per square foot, and 2400 lbs., with a current density of 2() amperes per square foot. D

lin the operation of these cells it is unnecessary to resort to expensive absorption towers and an elaborate system of pumping andJ circulation. All this is eliminated. Manifestly if the variable valent salts can be reduced by sulfur dioxid at all, they can always be maintained reduced under the action of this cell, especially at' fairly high temperatures, say from 130 to li6() deg. l?. lt will. not be necessary to pass the electrolyte through more than one cell, although in large plants it is preferred to pass it through. two, and possibly three in series, with different current densities.

lt is well known that the E. M. ll". required in copper deposition from solutions containing considerable ferrous sulfate, is greatly reduced on account of depolarization at the anodes. The difficulty has been to practically maintain the iron in the ferrous condition, for, depolarization is effected bcy the ferrous salts being oxidized, or reduce to the ferric condition, and if the reduction to the ferrous salts is promptlymade, the advantages gained by the reduced E. M. F. due to depolarization, greatly outweighs the disadvantages due to the corrosive action of the small amount of ferric salts which can possibly exist in the electrolyte.

ln this process, it is purposed to reduce the ferric and cupric salts as rapidly as formed, so that all the advantages of depolarization with ferrous iron, cuprous copper, or sulfur dioxid, canv be realized without any of the corresponding disadvantages. Itis believed that with a current density of 10 amperes per square foot and with an electrolyte at a temperature of 130 to 160 deg. F., the process can be carried out indefinitely with a very high current efficiency, and an E. M. F. of not to exceed one volt. At fairly high temperatures sulfur dioxid is quite active in reducing the ferric and cupric salts; on the other hand, it is not as soluble in the electrolyte. But, as the object is, not so much to absorb large quantities of the gas as to maintain the ferric and cupric salts reduced, the solubility of the gas, as used in this process, is not a matter of much consequence.

lf violent agitation is desired, a portion of thegas from the exhaust pipe 22 may be introduced into the cell through the pipe le. Air agitation cannot well be used, nor is it necessary, asthe agitation can just as well, or better, be carried out with the reducing gas, of. which only a small amount would be used for agitation.

The process is applicable to sulfate as well as to chlorid solutions. lt may also be applied to oxidizing reactions as well as to reducing reactions. f

lf chlorid solutions are used, there should vbesuiflcient base metal chlorids in the solution to retain the cuprous chlorid in solution.

The cover 2, of the electrolyzer, will usually be lined with lead to resist the corrosive action of the gas and electrolyte. To 'prevent any possibility of the current short circuiting through the supporting strips l?, thin strips of rubber 38, may be placed in the joints.

l claim:

l. A process which consists in confining a gas over a metal solution containing cona stituents capable of chemically reacting with the gas, electrolyzing the liquid, spraying the electrolyzed liquid into the gas confined over it, and maintaining a supply of gas over the liquid from which the liquid may be charged with the gas as rapidly as the gas in the liquid is combined with the constituents in the liquid capable of combining with it.

2. A process which consists in confining sulfur dioxid over a copper solution containing constituents capable of combining with it, electrolyzing the liquid, spraying the electrolyzed liquid into the gas confined over it, and maintaining a supply of the gas over the liquid'from which the liquid may be charged with thegas as rapidly as the gas in the liquid is combined with the constituents in the liquid capable of' combining with it. 'y

3. A process which consists in confining a gas over a liquid containing constituents capable of combining with the gas, charging the liquid with the gas by intimately mixing the liquid and the gas, the liquid, and maintaining a'supply of the gas over the liquid from which the liquid may be charged with the gas as rapidly as the gas in the liquid is consumed in reacting with the constituents in the liquid capable of reacting with it.

d. A process which consists in confining sulfur dionid over a copper lsolution containing salts ol the variable valent elements, electrolyzing the liquid, treating'the liquid with the gas during electrolysis, and maintaining a supply ofthe gas over the electrolyte to maintain the variable valent salts rei duced to their lower valencies, and maintainlng an excess oil sulfur dioxid in the electro-l lyte.

5. A process which consists in confining a gas over metal solution containing constituents capable o reacting with kthe gas, electrolyzing the liquid, and spraying the liquid into the gas above it during electrolysis.

6. A process which consists in confiningv a gas over a metal solution containing constituents capable oi chemically reacting with the gas, electrolyzing the liquid, and intimately mining the liquidf'and the gas confined over the liquid.

7. A process which consists in confining a gas over a liquid containing constituents capable of chemically reacting with the gas, electrolyzing the liquid, spraying the liquid into the gas over it, and catching a portion .ot the liquid sprayed into4 the'gas and by its own gravit through a confined channel introducing itfinto the lower portion of the electrolyte.

8. A process which consists in confining a gas over a liquid containing constituents capable of chemically reacting with the gas,

electrolyzing theliquid, spraying the liquid into the gas confined over it, and causing a circulation of the electrolyte by withdrawoverv an electrolyte a gas capable of reacting electrolyte,

chemically I with the anode products ofthe electrolysis,

intimately mixing the gas and and maintaining a supply of the gas over the electrolyte as rapidly as the gas .is consumed in combining with the anode products of electrolysis.

l1. A process lwhich consists in confining electrolyzing y process which consists in confining sulfur dioxid overa metal solution containlng constituents capable of chemically reacting with the gas, electrolyzing the liquid,

spraying the liquid into the gas over it, and conducting a. portion of the sprayed liquid through a confined channel intothe lower portion of the liquid; f v

12. A process which consists in confining sulfur dioxid over a metal solution containing constituents capable of chemically reacting with the gas andcapable of releasing hydrogen, electrolyzin the liquid, intimately mixing the liquid it, and separating the released hydrogen from the gas `over the liquid by displace ment in a quiescent space.

i3. process which consists in treating solutions obtained from leaching ores of metals with precipitated copper sulfid, electrolyzing the solution, confining sulfur dionid over the electrolyte, and intimately mining the gas and the electrolyte.

l. 'i process which consists in confining a gas over a liquid containing constituents capable of combining with it, spraying the liquid upwardly into the confined gas, maintaining a iiow of gas through the sprayed liquid, and electrolyzing the liquid.

l5. A process which consists in electrolyzing a `cuprous chlorid solution containing ferrous chlorid, land maintaining the "'cuprous and ferrous chloridsl reduced by spraying the electrolyte during electrolysis into sulfur dionid gas conlined over the electrolyte.

16. An electrolytic process which consists in spraying the electrolyte into a gas conlined over it, and circulating the electrolyte within the cell.

17. An electrolytic process which Aconsists in spraying the electrolyte into a gas confined over it, eirculatingthe electrolyte, and agtating the electrolyte.

18. An electrolytic process which consists in spraying the electrolyte into sulfur dioxid gas confined over it, and agitating the electrolyte with sulfur dioxid gas injected into it.

19. A process which consists in confining.' a gas over a liquidcontaining constituents capable of chenncally reacting with the gas, electrolyzingthe liquid, and agitating the liquid with the gas.'1

20. An electrolyticprocess which consists in treating an electrolyte with a gas .con-

and the gas over fined over it, causing a flow of electrolyte longitudinally through the cell, and `a circulation ofthe electrolyte transversely of the cell.

- 2l. A process which consists in confining a gas over a liquid containing constituents capable of chemically reacting with the gas, electrolyzing the liquid, spraying the liquid into the gas confined over it transversely of the How ofthe liquid, and causingailow ff 1,344,030 i' l f7 'gas through the sprayed liquid longitudithe liquid, causing a flow of gas through nally With the How of the liquid. the sprayed liquid longitudinally with the 10 22. A process which consists in confining lflow of the liquid, and passing an electric a gas over a liquid containing constituents current through the electrodes.

capable of chemically reacting with the gas WILLIAM E; GREENAWALT. under the action of an electric current7 Witnesses: spraying the liquid upwardly into the gas MARY H. WOOLSEY,

confined over it transversely of the flow of i Y HILDA L. GREENWALT.

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