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TECHNICAL ALKALI CHLORIDE . BY RUDOLF TAUSSIG, PH.D, Vienna.

(A Paper read before Section X of the Sevetrth Coitgress of Applied Chemistry, Londoii, 1909.)

[COMIiiUN'ICATED BY THE AUTHOR.]

A briiigcii Tt-mtslatioir by Dr. H. Rov~rs. Very little is published on technical alkali electrolysis in general. In scarcely any other industrial branch is so much secrecy observed as to processes and apparatus. The manufacturers are protected by cartels (" rings ")both as regards the supply of the raw materials (salt) and the sale of the products (chloride of lime and soda). The establishment of new works is thus rendered difficult. Yet the manufacturers are not disposed to exchange information concerning experience gained, not to speak of per- mitting any publication. The antipathy to publication goes so far indeed that, wherever possible, even the application for patents is avoided. A particularly heavy veil is kept over the secrets of works which use mercury cathodes, although secrecy appears little needed in this case. For the many apparently unimportant, and yet most essential devices and experiences, to which success is due, cannot be learnt from a mere visit paid to the works or from publications. We possess only one theoretical research concerning the mercury process, an investigation by Glaser, who studied only the decomposition of chloride, however.

Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. At present the mercury process is exclusively applied for the electrolysis of chloride. The following lines contain the chief results of the only investigations carried out in this field due to Taussig and to Taussig and Aigner. These investigations are confined to the cell, i.e., to the decomposition of sodium chloride, with the aid of platinum and mercury electrodes and the formation of chlorine and of sodium .

APPARATUS. The apparatus employed comprised the following devices :- I. The appliances for supplying and regulating the electric current and for measuring the intensity and electromotive force of the current passing through the electrolyser, as well as the e.m.f. of the polarisation current. 2. The electrolyser. 3. Appliances for maintaining the mercury circulation. 4. Appliances for taking amalgam samples and for estimating the sodium. 5. Appliances for maintaining and controlling the circulation of the brine. 6. Appliances for withdrawing the chlorine from the cell and for its absorption ; and 7. For maintaining certain temperatures in the electrolyser. Ad I. The sources of current were storage batteries of 8 and 24 volts 258 View Article Online

CHLORIDE ELECTROLYSIS 259

The battery leads (Fig. I) were taken to a large double pole-switch, which either cut the apparatus out or joined it to the 8-volt or to the 24-volt battery.

FIG.I.

Ad 2. The electrolyser (Fig. 2) was a glass beaker, IIO mm. in height, 60 mm. internal diameter, 2.5 mm. wall thickness. The wall was perforated immediately above the bottom of the beaker ; a rubber stopper closed this hole of 11 mm., and the mercury tubes passed through this stopper. The feed tube a was the lower of the two and consisted of a rather wide pipe, tapering towards its opening and bent in a horizontal plane to a semicircle. The mercury, introduced under pressure, issued from the opening in a tangential jet, which agitated the amalgam. The mercury layer had a thickness of 15 mm., and the inner mouth of the discharge tube b (which was less wide than the feed tube) for the amalgam was immediately below the surface of the mercury ; the short discharge tube was bent somewhat like an S, the outer end lying at a higher level than the inner end. Another perforation of the glass was 70 mm. above the bottom and at cp" to the first aperture ; this second perforation was closed by a stopper of the same

Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. size, holding the wide discharge pipe for the chlorine and for the spent brine.

I

FIG.2. The large rubber stopper which 5erved as cover for the beaker was provided with six perforations. The glass tube forming the anode support View Article Online

260 TECHNICAL ALKALI

passed through the central hole. The anode consisted of a platinum spiral, strengthened by two ribs and soldered to a shorter platinum wire, which was fused into the glass tube; the latter contained some mercury and the terminal wire. The distance between the two electrodes was always 19 mm. during the current yield determinations. The other perforations admitted the two legs of a glass coil for cooling or heating the electrolyte, a thermo- meter, the brine supply pipe, ending immediately above the kathode, and a short pipe joined to a water-gauge, by the aid of which the internal pressure was reduced by 7 cm. of water. This was done in accordance with the technical practice to withdraw the chlorine under slightly reduced pressure. Ad 3. The following apparatus regulated the circulation of the mercury :- (a) A glass trough, serving as mercury reservoir, capable of being raised and lowered. (b) A glass tube, 2 mm. in width, drawn out to a point and adjustably fixed on a stand ; rubber tubing connecting this glass tube with the amalgam dis- charge pipe of the electrolyser, and the level adjustment permitting of altering the rate of discharge of the amalgam. The latter flowed either through a funnel into the decomposition cell, or into a sample glass. (c) The amalgam-decomposition cell, a stout glass beaker, I litre capacity, was provided with a stirrer and charged with hydrochloric acid of 15' B6. ; the mercury was discharged through a lateral pipe near the bottom. Before returning to the mercury tank, the mercury was twice passed, in drops or in a thin jet, through diluted hydrochloric acid and finally through water. Ad (a). Fig. 3 illustrates the arrangement adopted for regulating the rate of the mercury feed to the electrolyser. The pure mercury entered through Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

FIG. 3. the funnel S, and the cock was opened sufficiently to ensure that at least as much mercury flowed out of the reservoir R as left it through the feed pipe (for the electrolyser) L, ; L is an overflow pipe. The reservoir (15 by 10 cm. base) stood on a board which was suspended over pulleys; the weights Q and QI served as counterpoises. Ad (b). In Fig. 4 (front and side elevations), E is the electrolyser which is cemented to a block of wood, 18 cm. in thickness, the wood itself being cemented to the base. S is the stand ; A is the arrangement by means of which the amalgam is sent either into the test-glass G, or into the amalgam receptacle GI. Ad 4. In conducting the determination of the sodium percentage in the amalgam, the amalgam discharged during a definite period, ranging from View Article Online

CHLORIDE ELECTROLYSIS 261

10 minutes at the lowest to 25 minutes at the highest, was collected in the beaker G, the time being read off within a quarter of a second. The amalgam

FIG.4. was shaken with an excess of titrated hydrochloric acid in a stoppered bottle of I-litre capacity,land the solution titrated back with caustic soda and phenol- phthalein ; I cm.3 of the acid absorbed corresponded to 0'01 grani of Na in the mercury. Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

m

FIG.j. Ad 5. Considerable attention was paid to the important circulation of the brine (Fig, 5). In accordance with the usual practice, the brine feed pipe had its mouth immediately above the mercury surface (cJ Fig. I). A capillary C was inserted in the feed pipe H so as to obtain a rate of flow of not more than 3 cm.3 per minute. The accurate regulation was effected by View Article Online Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

t rJ a- 0 9 CJ0 0- ----.+*.- G - -L.< g --.-- --.-g._._._ _. -..; ______.___-.% -.*-- t Concentration of AmaJqom PLATEI. Current Efficiency as function of the amalgam concentration. Efficiency in per cent. of the theoretical. Concentration of amalgam, per cent. of Na in the Hg. Re-formation of amalgatu, loss of sodium per minute, expressed in tenths of a milligramme. Volts across the cell. Current intensity in amperes. Polarisation in volts. c 0 ti c I

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I 6 cut$& ~d~slhy d9-Y ------01e987

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I 6 Re- Formation of Amalgam 9,2? I Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

TI28 :1.3 3 " 3112 3,1Z 5 g:; ____&o ____.___---0---____&-, ____e--- -. -.-8+!"~?? ----__ *--o

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1 Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

Current efficiency as function of the temperature. Efficiency in per cent. of the theoretical. Temperature in degree Cent. Re-formation of amalgam, loss of sodium per minute expressed in tenths of a milligramme. Volts across the cell. Current intensity in amperes. Polarisation in volts. View Article Online

.c 'o''o,ol E s Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

PLATEIV. Current efficiency as function of the current density and of the amalgam concentration. Efficiency in per cent. of the theoretical. Concentration of amalgam, per cent. of Na in the mercury. Re-formation of amalgam, loss of sodium per minute expressed in tenths of a mflligramme. Volts across the cell. Current density in amperes per dm. Polarisation in volts. View Article Online Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

PLATE V. Current efficiency as function of the current density. Efficiency in per cent. of the theoretical. Concentration of amalgam, per cent. of Na in the mercury. Rate of circulation of mercury in cm.3 per minute and per dm.2 of kathode surface. Re iormation of amalgam, loss of sodium iii tenths of a milligramme per minute and per dm.' of kathode surface. Current density in amperes per dm.' of kathode surface. View Article Online

CHLORIDE ELECTROLYSIS 263

adjusting the pressure in the brine tank V, a bottle whose stopper was fitted with two perforations ; connection was thereby established either with the atmosphere, or through g and S with a vacuum vessel whose controlling pressure gauge was filled with coloured brine. The spent brine flowed through the pipe R into a calibrated cylinder M,from which it was with- drawn at intervals. As indicated in Fig, 5, V acts as Mariotte bottle, the cock h being open. When lz is closed, and g raised above the level of the brine at N,the pressure above the brine in V can be reduced through the suction pipe S by the water-jet pump. The vacuum was adjusted by altering the depth to which the tube T dipped into mercury. Ad 6. The chlorine was discharged together with the spent brine through the pipe R (Fig. 5). The chlorine mixed with air was sucked through three large bottles, twice through milk of lime, once through concentrated caustic soda, under a vacuum of 7 cm. of water ; the electrolyser itself was, there- fore, under this partial vacuum, as alrcady stated. Ad 7. The temperature regulation in the electrolyser was effected by circulating hot or cold water, cold brine, or sometimes superheated steam through the glass coil. The mercury and brine were themselves preheated or precooled with the aid of a copper coil and water or ice, the brine or mercury being sent through glass coils. As this temperature regulation had to be very accurate, the cooling coil was not directly joined to a tap in the water-supply pipe, but to an intermediate vessel. The results of the experiments are summed up in the curves of Plates I. to V., and in the tables which follow them. The curves show current efficiencies, expressed as functions of various quantities.

RELATIONBETWEEN POTENTIALDIFFERERCE AND CURRENTDENSITY. Electrode Distance : 19 ~nm. Mean Temperature : 16.8' C. At - 0.49 amp./dm." the P.D. was 3.34 volts.

099 ,f ,, 3'32 ?7 1.95 >* >> 3'53 99 3'41 99 9, 4-30 B9 5'2.1 99 ,9 4-93 ),

,? 9, ?9 Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. 6.99 4-98 8.71 ,, 77 5.15 ,9 10.34 19 ,> 5'42 9) 13-82 97 ,, 6.06 ,,

17'67 ,t ,I 6'59 ,9 35-00 )I 9, 8-10 ,, RELATIONBETWEEN POTEXTIAL DIFFEREXCEAND TEMPERATURE. Electrode Vistaizce : 10 mm. Meaii Citrrent Demity : 7-00 amn~.ldrn:. At- - 5*oothe P.D. was 5.93 volts.

- 2'5 ,9 5'90 ,, + 2.8 >7 5'70 9, + 7'3 99 5'50 99 + 17'0 9) 4'98 ?) + 30'0 77 5-02 ,, + 50'3 ,, 4'35 9) + 58'9 ,, 4'24 9) + 82.9 ?, 3-78 9, + 90.0 97 3'74 ?) + 10g.o ,7 3'70 ,) View Article Online

264 TECHNICAL ALKALI

RELATIONBETWEEN POTENTIAL DIFFERENCEAND AhfALG.4M CONCENTRATION.

Electrode Distance : 19 irtm. Mean Current Density :7.00 aritl)./dm:. Mean Temperature : 16.6~C. With- 0'0280 per cent. of Na in the amalgam, the P.D. was 4.93 volts.

000263 ,, 99 ?9 9, 4'97 ?, 0'0200 ,, 9, 9) ,, 4'98 ?,

0*0141 ,, ,, 99 7, 4'94 >)

0.0094 ,, 99 9 ,? 4-98 9, 00062 ,, 3, >) 9, 4'72 99

RELATIONBETWEEN POTENTIALDIFFERENCE AND RATE OF CIRCULATION OF THE ELECTROLYTE.

Electrode Distance, 19 mm. ; Mean Cwrent Density, 6.95 arnp.ldm: ; Mean Temperature, 16-2' C. N'ith a circulation of- o*oo cm.3 per minute, the P.D. was 4.97 volts.

0'27 ,, 9, ?? 4'97 ,, 0'75 ?) 9, 9, 5-02 9, 1'02 ,, 9, 1, 4'97 7, 2'23 ,, 9, ?9 4.9' J?

RELATIONBETWEEN POTESTIALDIFFEREXCE AND ELECTRODEDISTANCE.

ilIeait Current Density, 35 nmp.ldnt: ;Alean Tena$erature, 22' C. With an electrode distance of- 3 mm. the P.D. was 5-76volts. 5 ,, ?, 6.35 ?9 7 9, ,J 6'67 ,I 12 9, 9, 7.20 ,? Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. 15 ,, ,? 7'75 )Y 2o JP ,? 8-17 >, 30 99 )9 8-50 ?, 40 1, 9, 9'70 99 The apparent slight discrepancies in the results of these tables, corre- sponding to small differences in the potential difference, amounted to a few hundredths of a volt only, and should not be overrated ; those small diff ereiices were fair estimates. All the experiments were made with the same anode, a platinum wire of 0.90 mm. diameter, spirally wound in a plane and radially stiffened by other wires. The anode weighed 8.gBoo grams. The surface of the anode was hence approximately 18 cm.*, and the anodic current density 14 times that of the kathodic current density. The current density of the anode was, of course, not without influence upon the potential difference. Yet the increase in the potential difference by an increase in the anodic current density will not progress at the sa.me rate as it would do with an equal increase in the kathodic current density, in cases where the kathode is a more or less plane surface, while the anode may be shaped in a manlier so as to admit of a ' point effect.' When, moreover, a gas is generated at the anode, which is View Article Online

CHLORIDE ELECTROLYSIS 265

hardly to dissolve in the electrolyte as in this case, an anode of very large surface would be unfavourable, since the anode product would be liberated in too fine a state of subdivision. IXDUSTRIALLYAPPROVED PROCESSES. Four types of technically applied processes may be distinguished :- I. The old Castner-Kellner cell (rocking apparatus at Oldbury). 2. The Kellner apparatus (compressed air, at Jajce). 3. The Kellner-Solvay apparatus (cup wheel, at Jemeuppe). 4. The new Castner-Kellner apparatus (Archimedean screw, at Weston Point).

I. The Old Castvier-h'ellrrer Cell. This oldest type of cell is sufficiently known. The anodes of the cell con- sisted of carbon, the kathodes of iron-wire grating. The fact that various detailed descriptions of this type of cell have been published will suggest even to those not familiar with the subject that the apparatus must already have been superseded, and that is indeed so. At present only apparatus are constructed which take at least ten times the amount of current of the old Castner-Kellner cell, The rocking cell is divided into three compartments, and the mercury is moved by means of an eccentric which is attached to the side of the cell, and which alternately raises and lowers that side. The movement is so small and slow as to be scarcely perceptible. The disadvantage is that the units are small; they can only take 400 or 500 amperes. Enormously large buildings are required, all leads and pipes (for current, brine, lye, and chlorine) become very long, com- plicated, and expensive, and the superintendence of the large spacc (there were about 600 of these apparatus at Weston Point) is difficult.

2. The Keltrter Apparatus (Compressed Air Type.) This is the most interesting apparatus. It consists (cf. diagram Fig. 6) of three compartments, joined by siphons, the chlorine cell being in Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50.

FIG.6.-Kellner (Compressed Air) Cell. the middle, while the caustic soda compartment was in the middle of the old Castner cell. The two alkali compartments are provided with wells, into which the vessels for the compressed air dip. The mercury is driven (by the air) from the one compartment into the other, taking up sodium in the central compartment and giving it up again in the last. The anodes of platinum are mounted in electrode boxes of cement, which I introduced six years ago, and which have answered better than the previously applied clay boxes. The anodes themselves are wire gauze sheets, of 50 by jo mm., weighing I gram each, including the platinum pin ; the latter is fused into a glass tube charged with mercury, into which a stranded copper wire is View Article Online

266 TECHNICAL ALKALI

lowered. Every chlorine cell contains six electrode boxes, each with eighty- eight pieces of platinum wire gauze, giving a total of 518 sheets of platinum 'weighing 500 grams per 4,000-ampere cell. The kathodes are grids of cast iron. The current passes from the anode through the brine to the mercury or the amalgam ; the sodium ions con- tained in the amalgam carry the current further through the caustic soda to the kathode. There is a shunt for the current-a short circuit between the mercury and the iron. This has long been known, and the respective patents have long expired ; but the object of the device may be explained. The shunt is to prevent loss of mercury. The chlorine held by the brine reacts, in the chlorine compartment, on the sodium of the amalgam, and some sodium chloride is again formed. The sodium ions which have taken part in this reaction are wanted in the alkali compartment, and in their absence mercury would participate in the current conduction, mercury oxide would be formed, and some mercury be lost. The shunt provided by the short circuit rapidly and almost instantaneously decomposes the. amalgam. The mercury is hence quickly regeneratcd and enabled to absorb more sodium ; the arrangement therefore admits of applying very high-current densities. It is Kellner's greatest merit that he has drawn attention to the ad- vantages of working with high-current densities at a time when low electromotive force was the only criterion of the value of a cell. He recognised that other factors, notably simplification of the operations by putting higher loads on the electrodes and consequently increased output, are equally important, The short-circuit cell may be adapted to various conditions; it is chiefly intended for cheap water-power however. 3. The Kelliter-Solvay Apparatus (Cup-wheel). The apparatus in use at Jemeuppe (Belgium), Brescia (Italy), Lubimoff (Russia), consists of two parallel troughs, inclined and communicating with one another, in which a cup-wheel keeps the mercury in circulation. This type of cell is constructed in the largest units. Originally designed for 6,000 amperes, it is now built for 10,000,and even 15,000 amperes. The Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. cell is fitted with a weir (D.R.P. No. 100,560) over which the amalgam, which is chiefly formed near the surface, is carried. Platinum wire gauze anodes are used; they are larger, however, than those already mentioned, being cp x cp mm., and the gauze is, moreover, interlaced, the work being done by the experienced lace-makers of the Brussels district. The works at Jemeuppe rely on steam ; at Brescia water-power is utilised.

4. The New Castner-Kellner Apparatiis (Archinzedean Screw). The chief difference between this type and type 3 is that an Archimedean screw replaces the cup-wheel in moving the mercury. The type does not otherwise constitute an improvement on the Solvay apparatus. It works with smaller current densities, and is designed for about 4,000 amperes; this figure might be raised, but the present type is not likely to prove suitable for the large units of the Solvay cell. The apparatus is exclusively intended foreexpensive power. It works with low-current densities and very low e.m.f., and the carbon electrodes are arranged according to the British Patent No. 14,133 of I~Z.Blocks or plates of carbon are placed between the copper bars which act as leads, and the parts are bolted together. View Article Online

CHLORIDE ELECTROLYSIS 267

The Sodium Chloride.-The sodium chloride should, particularly where carbon electrodes are applied, be freed from sulphates. At Weston Point the brine flowing into the works used to be purified with lime and soda (by the Castner process) and then evaporated ; the resulting salt was further washed with concentrated brine in order to remove all the sulphates. This method gave too much trouble. At present the brine is, at Weston Point, purified in a similar manner and then sent to the cells ; the impoverished brine is deprived of its chlorine by means of lime and then allowed to run to waste. The Caustic Soda.-The caustic soda, the chemically pure caustic of the trade, is used chiefly for the production of metallic sodium by the Castner process. The Materials.-The choice of materials is an extremely iinportant problem. When the material out of which the cells are built up turns soft or leaky, losses of mercury will arise, and then the process becomes illusory. With low-current density the temperature in the cell will not grow high, and the strength of the cell frame will not be severely strained. The caustic lye compartments and the siphons are most exposed. Concrete finished with cement is almost the universal cell material at present ; slate and other materials have been abandoned. The above outlined processes have so far alone been in the field. Of recent inventions only those of Wildermann, Bell, and Rink, and a few diaphragms deserve mention. The Wildermairn process is based on the British Patents No. 18,958 of 1898, No. 22,90.2 of 1900, and No. 9,803 of 1902. The mercury is contained in troughs which are so piled upon one another, ribs of the trough above entering the trough below, that they form a diaphragm between the amalga- mation and the decomposition compartments. The mercury does not cir- culate, but is agitated on the chlorine side. The method permits of applying extraordinarily high-current densities without risking the solidification of the amalgam or the oxidation of the mercury. The buoyancy of the specifically lighter amalgam takes charge of the transport of the sodium ions from the chlorine cell to the caustic compartment. The whole apparatus is built of iron and liiied with a special ebonite.

Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. Carbon anodes can be used in spite of the high-current density. The current density at the mercury may amount to 30,40, and even 60 anips./dtn.* ; at the carbon anode it will only be about 10amperes. Owing to the very small quantity of hypochlorite formed, the carbons are said to have proved very durable in three years' working. The floor space wanted is only 4 cm.* per ampere, while the old Castner-Kellner cell requires 30 to 40 cm.*, and the Jajce cell II cm.*. The Wilderinann cell has so far been constructed for 2,200 amperes. At a current efficiency of 93 per cent. and an e.m.f. of 5 volts, it requires 3-58 kw.-hours per kg. of caustic soda, at 4'5 volts 3.2 kw.-hours. The Bell cell has been tried by the Pennsylvania Salt Manufacturing Company at Wyandotte. Definite iiiformation is not available. The Bell patents are the British Patents No. 20,542 of 1895, No. 11,133 of 1896, No. 25,890 of 1899, and No. 10,655 of 1902. They also make provision for preventing the contamination of the mercury, which is spread on a diaphragm, by the impurities dropping from the carbon anode. Soap Diafilzragms.--The Kellner soap diaphragm (Ber. DeufscJt. Chent. Ges., 1893, p. 1159)is to be tried in the electrolytic works at Briickl in Styria. Those who have worked with soap diaphragms will have their doubts as to the possibility of their continued use ; the chlorine acts on the soap, and the VOL. V-T10 View Article Online

268 CHLORIDE ELECTROLYSIS

soap is soluble in the concentrated brine to a sufficient amount to cause various difficulties.':: The Rirzk process (Fig. 7) has only been tried in experimental installations. A larger plant is now being built. The chief advantage is apparently that the diaphragm does not allow the impurities in the carbons to pass over to the mercury, and that the latter can be cleaned without opening the apparatus.

A'et Electrode

FIG.7.-The Rink Apparatus. The chief disadvantage will probably be found in the intense agitation of the mercury, which may lead to losses of mercury and may demand an unusual amount of power. The choice of the best material for the net electrodes is not yet decided. Baiyta Diaphragm.-The Kaliwerke Aschersleben have for some time been using a cell which I adapted to operations on a large scale as early as 1904 in the laboratory of Kellner. The principle is that a vessel closed above is placed within a shallow kathode vessel. A layer of baryta connects the anode and kathode space ; these diaphragms offer the advantages of great durability and of small rcsistance. Published on 01 January 1910. Downloaded by University of Chicago 26/10/2014 23:43:50. The Townserzd cell is said to answer very well in England and America. The Electrolytic Alkali Company, Ltd., of Middlewich, has improved the Hargreaves-Bird process by producing bicarbonate instead of crystal soda. There are both technical and commercial advantages in this change which, however, appears to have brought about a decided fall in the price of bicarbonate. In spite of the occasional overproduction of chloride of lime, which is strongly felt just at present in two fields, neither means nor pains are spared for working out new processes, and new plants arise, while those in existence are being enlarged. Yet the largest consumers of chloride of lime, the bleach works for cotton and linen, and especially for cellulose, have made them- selves independent of the market, either by building electrolytic works of their own, or by diminishing their consumption of chloride of lime with the aid of rational methods of bleaching. These facts prove that the consumption of chlorine and of chlorine compounds is increasing owing to their low prices. * The above-mentioned doubts were evidently justified. Kellner's rights as claimed in E.P. 7801 of 1894,were bought in 1904by the Bosnische Elektrecitats Aktien-Gesellschaft of Vienna. Apparently all efforts to find a practical cell with the soap diaphragms were unsuccessful, as the said Company erected baryta diaphragm cells at Bruckl.