The two

around the lamp neck outside of the springs or prongs. porcelain blocks are bolted together, and are provided with holes for the passage of the lamp wires, and terminals by which they may be secured. 2 claims.

1,072. "Improvements in electrical switches." G. BINSWANGER. Dated January 21st. 6d. In one form a lever moving on a centre is supported on a suitably shaped frame (preferabiy of metal), the said frame being secured on to a base of suitable insulating material. The lever has at or near its centre of motion, on its upper side, two teeth or suitably-shaped projections, which gear with one or more teeth forming part of another lever, this lever being pivoted in such a manner as to allow of the teeth gearing together loosely. The second lever, being suitably shaped, serves as an actuating device or handle. On the lower part of the first (or contact) lever directly under its centre of motion is a cam, either formed out of the same piece as the lever or suitably attached to it, triangular in form. A strong flat spring, suitably curved at one end and fastened at the other, either to the base or to a convenient part of the frame, presses against the cam in such a way as to tend to keep the cam on one side or other of the centre of oscillation. 1 claim.

1,903. 'Improvements in the method of treating nervous and other disorders of the human system, and apparatus therefor." W. P.THOMPSON. (Communicated by the Electrolibration Company, of America.) Dated February 4th. 8d. A metallic cord or wire or other conductor is used, provided at one end with a clasp or means of attachment to the body of the patient, and at the other end with a metallic body of suitable character, such for example as a case or shell filled with iron wires or small fragments of iron. 3 claims.

3,082. "An improvement in filaments for incandescent electric lamps." R. LANGHANS. Dated February 26th. 4d. Claim:-The process of covering carbon and metallic filaments for electric incandescent lamps with an electrically-conductive coating which is but little or not at all attacked by oxygen and oxydising gases, this process consisting in bringing the filaments, within a vessel evacuated of air or filled with chemically indifferent gases, in contact with a compound of silicon or boron capable of being decomposed so that silicon or boron separates out in graphitoidal or crystalline form, and exposing the filaments to the action of heat, or of an electric current, or both, with or without the aid of a chemical decomposing medium.

3,094. Improvements in portable electric lamps, more especially intended for miners' use." THE MINING AND GENERAL ELECTRIC LAMP COMPANY, LIMITED, D. G. FITZ-GERALD, and A. H. HOUGH. Dated February 26th. 8d. The casing of the lamp is made of metal, preferably steel, with a lead lining and coating to prevent its being injured by the electrolyte. The elements and electrolyte are contained in a cell, preferably of ebonite, and of such size as to leave a space between it and the metal casing, and in this space pieces or discs of India-rubber or other elastic material may be placed, so that the cell is prevented from being injured by any blow which the casing may receive. 5 claims.

6,032. "Improvements in electric heating apparatus." M. W. DEWEY. Dated April 21st. 8d. The heating devices are in the shape of a floor-mat, which may extend over the entire floor or only a part of the same, so that the heat may be equally diffused throughout the room or apartment. 14 claims.

6,037. "Improvements in and relating to electric railway vehicles." M. W. DEWEY. Dated April 21st. 8d. The object of the invention is to enable the conductor of a car or the passengers thereon to communicate easily and instantly with the motorman when it is desired to have the car started or its speed increased or decreased, or to have the car stopped, and, to effect such communication by means of suitable electric signalling devices in a shunt-circuit around the motor for propelling the car, both the motor and signalling devices being supplied with current through electric connections with the working conductors arranged along the track. 8 claims.

8,392. Improvements in tubes or conduits for electric cables." W. P. THOMPSON. (A communication from abroad by J. Frères et Cie, of Paris.) Dated May 30th. 6d. This conduit is operculated preferably rectangular in shape, having the corners slightly rounded. The upper part fits on the lower part, the joint following a broken line, the shape of which is shown in the drawing, and forms a covering completely joined. This lower part is fitted with insulating supports, which have a longitudinal groove for receiving the cable, and a circular fluting (or neck) for insuring the insulation. At each extremity of these longitudinal grooves, fixing tenions of any suitable shape, form projections on the front and back walls of the insulating supports, and ensure the cables being held firm by means of any suitable material wound round them. 2 claims.

12,830. "Improvements in secondary batteries and electrodes therefor. H. H. LAKE. (Communicated from abroad by G. A. Johnson and S. L. Holdrege, of America.) Dated August 15th. 8d. The main feature of that part of the invention relating to the battery is the arrangement of the active material in a number of masses, each of which is in the form of a strip, substantially rectangular in cross-section, and surrounded on all sides with the enveloping material; each electrode being made up of a number of metallic boxes filled with the active material, and so arranged and secured together as to form a compound box divided by partitions into a number of compartments, each compartment containing a mass of the agre material in the form of a long strip with four sides, and the

[APRIL 10, 1891.

enveloping material being perforated to allow proper circulation of the electrolyte. Another feature of the invention relates to the formation of the outer plates or electrodes when three or more are used in one cell, and consists in making the outer plates considerably thinner than the plate or plates between them. 5 claims.

12,979. Improvements in thermo-electric generators." H. B Cox. Dated August 19th. 8d. The object of the invention is to produce in a thermo-electric circuit as pronounced a fall in potential as possible, and to produce as large a movement of heat within the circuit as possible. A further object of the invention is to provide an improved construction of thermo-electric generator and furnace. 12 claims.

13,233. "Improvements in portable electric lamps, more especially intended for miners' use.' THE MINING AND GENERAL ELECTRIC LAMP COMPANY and W. MOSCROP. Dated August 22nd. 6d. Tor inventors make the incandescence lamp bulb itself or the protecting glass which covers it or both of them, so that they are held in ther protruding position by a spring or springs, which, on a blow or pres sure upon either or both of them occurring, will allow either or both of them to yield, and so prevent their fracture, or render them less liable to fracture than would otherwise be the case. 2 claims.

W. P.

13,421. "Improvements in apparatus for working or welding metals electrically, and in the method of effecting the same." THOMPSON. (A communication from abroad by C. L. Coffin, of America.) Dated August 26th. 8d. Relates to apparatus for bring ing the edges or ends of two articles, which are to be welded, in contact or nearly so, clasping the edges to be welded between coductors, connecting one of the articles to be welded with one pole of a generator of electricity, connecting the clasp which embraces the edges to be welded with the other pole of a generator, and passing a heating current through the circuit thus formed. 5 claims.

13,635. "Improvements in or appertaining to electric welding" W. P. THOMPSON. (A communication from abroad by C. L. Coffin, of America.) Dated August 30th. 6d. In one arrangement a voltaic arc is formed in such manner that it shall extend outside of a straight line joining the ends of a positive and negative conductor, and then drawing the conductors while the current is passing along the joints to be welded, whereby the joint is submitted to the action of the voltaic arc; and, as an addition to this process, the invention further consists in feeding to the joints to be welded and within the influence of the voltaic arc a strip of metal, which is fused by the arc and deposited on or in the joint, whereby the welded joint is re-enforced. 4 claims.

13,751. Improvements in electric switches." C. W. HUNTING TON. Dated 2nd September. 6d. The switch consists of a base of insulating material, in the face of which a circular groove or channe! is formed, the bottom of the channel being formed of an ever number of inclined planes, the opposite ends of each of which are respectively in two parallel planes. The surfaces of alternate planes are armed with metallic plates, and the others are left bare. Th number of the inclined planes should not be less than four, and the is the number it is preferred to employ. A centrally pivoted circut controlling arm is pivoted with contact brushes at its opposite ends, which, when the arm is turned in one direction, drag over the inclined surfaces and make or break the electric circuit. A spring is suitably arranged in connection with the circuit controlling arms to hold the brushes in contact with the inclined surface. 1 claim.

13,790. Improvements in conduits for electric conductors and in means for collecting the current from the conductors." H. H LAKE. (Communicated from abroad by H. N. Curtis, of New York Dated September 2nd. 11d. The invention is embodied in a cen duit which may be made of any suitable material, and has a narrow longitudinal slit or opening in its upper surface which constitutes a portion of the roadway over which the vehicles travel, and contains a current supplying conductor suitably supported in the condat below the said slit, and the said invention consists mainly in the combination with such a structure of a flexible conduit slit cover contained within the conduit and normally pressed upward against th inner surface of the top thereof, so as to close the slit from below. 5 claims.

13,802. "Improvements in electrical measuring instruments" G. W. WALKER. Dated September 2nd. 8d. Relate more partic larly to the means for moving or vibrating the needle or other indicating portion thereof, and has for its main object to provide a c struction whereby the deflections or movements of the indicating device may be proportional, or substantially so, to the strength of the electric current employed, in order that an equally divided or graduated scale may be employed, and in order that uniform derec tions and readings may be obtained. 7 claims.

13,905. "Improvements in and relating to the welding of metaby electricity." M. W. DEWEY. Dated September 4th. 8d. sists in making contact with both pieces to be united, and passing current of greater strength or volume through one piece than to other. Consists also in making contact with both pieces to be united passing currents through both pieces and proportioning the valam of the currents to the conductivity of the pieces to produce the sa welding temperature in both pieces simultaneously. Consists furtiv in clamping said pieces at an angle to each other, passing a curren through said pieces until they are sufficiently softened, and the pressing the pieces together to unite them while maintaining ther the angle at which they were clamped. 8 claims.

APRIL 10, 1891.]

13,906. "Improvements in and relating to the welding and brazing of metals by electricity." M. W. DEWEY, Dated September 4th. 8d. Consists essentially in electrically heating the material at the junction to soften the same as by passing a heavy electric current from one side to the other of the joint, and then, when the material is properly beated, subjecting the joint to a force tending to compress and twist the same. 7 claims.

14,186. "Improvements in electric switches." C. G. PERKINS. Dated September 9th. 8d. The principle of the switch is that of storing power during the initial movement thereof, and afterwards releasing the power to effect the quick movement of the contact parts. 12 claims.

M. W.

14,191. Improvements relating to electric railways." DEWEY. Dated September 9th. 8d. Consists in providing suitable apparatus for transforming or converting the current or a portion of the current received on the car into a current of lower voltage and larger volume and by placing the lamps in multiple connection with a secondary circuit through which the transformed current flows, and further in providing switches for each of said lamps in circuit so that one or more of the lamps may be lighted while one or more others are not lighted. 23 claims.

14,603. "Improvements in electric signalling apparatus." W. R. LAKE. (Communicated from abroad by the Hall Signal Company, of America.) Dated September 16th. 8d. Consists in prolonging the cores of an electro-magnet beyond their helices and mounting a novel constructed armature on a shaft, whose bearings are contained in a brass bracket which holds the electro-magnet, cause it to revolve between the cores of the magnet when the magnet is energised. The prolonged cores and the armature are both curved upon the arc of a circle, the radius of the cores being about 4th of an inch greater than that of the armature. The signal disc is attached to the shaft on which the armature rotates, and as the intervening space between the cores and armature is just sufficient for the armature in its revolution to clear the cores, together with the fact that whatever position the signal assumes, the distance between the cores and armature remains the same, the signal can be operated with a much less number of cells of battery than in heretofore devised automatic electro signals. 12 claims.

14,604. "Improvements relating to the heating of metals and other materials by electricity." M. W. DEWEY. Dated September 16th. 8d. By means of the invention a weaker current may be employed, the same strength of current may be used for work of various sizes, blanks of various and peculiar shapes can be worked with one and the same apparatus, many articles can be heated at the same time, large bars or blanks may be quickly heated although the current used may be weak on account of the great amount of heat that may be stored before the work is subjected, and an expert operator is not required. 9 claims.

14,817. Improvements in and relating to the distribution of electrical energy." R. KENNEDY. Dated September 19th. 8d. In the new system of distributing electrical energy two alternating currents alternating at a difference of phase equal to a quarter of a complete period of alternation are generated at a central station by one or more dynamo-electric machines or generators. These currents are rectified into two unidirection pulsating currents by rectifying commutators on the generators and these two currents are then distributed by main conductors, preferably four, one pair for each pulsating current. Devices requiring pulsating currents are connected to and supplied from either pair of mains; devices requiring continuous unidirection excitement are double wound and connected the one winding to one pair of mains the other winding to the other pair of mains, so that the currents flow in the same direction in both windings and the same devices are operated when singly wound by the two currents in series between the two pair of mains. Devices requiring alternating excitement are likewise double wound and also connected the one winding to one pair of mains and the other winding to the other pair of mains, but the connections are made so that the current in the one winding flows in the opposite direction to the current in the other winding. By coupling one main of the one pair to one main of the other pair through a conductor at the central station (which preferably forms a coil round the dynamo magnet) the inventor puts the two pulsating currents in series, and can obtain them in series from the other two sides of the mains and such pulsating currents are suitable for charging storage batteries and operating motors or lamps. 7 claims.

15,482. Improvements in and relating to electric batteries." H. H. LAKE. (Communicated from abroad by Crosby Electric Company, of America.) Dated September 30th. 6d. Claims-1. A containing jar for electric batteries constructed of paper stock or similar material prepared with an outer coating of shellac and an inner acid proof coating composed of paraffine and ozocerite, substantially as described. 2. In an electric battery an acid proof containing jar, an absorbent pad disposed therein, a zinc plate and carbon plate resting on said pad and surrounded by a packing containing a dry excitant, substantially as described. 3. In an electric battery the combination of an acid proof containing jar, a zinc plate, an absorbent pad saturated with an excitant, and a carbon plate in contact with said pad and surrounded by a packing containing a dry excitant, substantially as described. 4. In an electric battery, a packing separating the positive and negative plates and comprising sawdust or wood fibre mixed with an excitant in a dry or crystallised form, substantially as described. 5. In an electric battery the combination of a paper containing jar coated with an acid proof composition, a zinc plate, a pad of absorbent material disposed within said jar and containing a liquid excitant, a carbon plate on said pad, and a packing comprising sawdust and a dry or crystallised excitant surrounding said carbon, substantially as described.

CORRESPONDENCE.

Electrically Charged Spheres.

479

Mr. Cheshire's letter on the above subject in your last issue, with its imposing array of mathematical symbolism, struck me as being a case of "Much cry for little wool." The result he obtains after much labour may be directly obtained from Maxwell's definition of specific inductive capacity.

We find in Maxwell's "Electricity and Magnetism," Vol. I., p. 94, the following :

"We may express the theory of Faraday in mathematical language, by saying that in a dielectric medium the induction across any surface is the product of the normal electric force into the coefficient of specific inductive capacity of that medium."

Now, as the induction here means the quantity of electricity induced by a given electromotive force on the surface of a conductor, this definition may be stated in Mr. Cheshire's symbols

As an operator I am much interested in your journal, and number after number do I scrutinise carefully with the hope of finding something on practical telegraphy, or some such subject as would interest a wire tapper, but have always been doomed to disappointment; then I begin to think that telegraphy proper has perhaps exhausted itself, and there has been no further improvement or advance made since duplex and quadruplex saw the light. The paper on electro-magnets, by Silvanus Thompson, has afforded many of your readers interest, being altogether a very practical one.

With a view to obtain a little knowledge and to improve the minds of others equally grasping, would you deign to give space in your columns for the following, and be pleased to make explicit replies:

(a). The G.P.O. standard relay is said to be more sensitive than the Siemens polarised improved pattern. Why?

(b). If the latter had larger pole pieces or shoes, would it improve its sensitiveness or working efficiency? in what manner would the inductive capacity be affected, whether to its advantage or otherwise?

(c). In the bridge system of duplex, the bridge wire is shunted with condensers; why, and what capacity is necessary per 100 miles ?

(d). In the differential system of duplex would there be any advantage if each of the coils of the differential relay were shunted with equal condenser capacity?

(e). It is considered an advantage in quadruplex to have the neutral or non-polarised relay of short cores, but as the duration of "no current" at the time of reversal is a function of the length of the line, increasing with its length, will not large cores act better, being less quick working?

66

(f). To bridge over the time of no current in quadruplex, both in the differential and bridge systems, condensers are used to shunt the relays. What average capacity per 100 miles is necessary?

(g). In (f) which is the best form of condensers to employ, would one on the principle of Plante's secondary battery of lead plates with sufficient resistance answer well?

(h). As in d, if the "line" circuit and "compensation " circuit of the relays in quadruplex were each shunted with condensers of equal capacity, what effect would it have on the working of the system?

Madras, March 11th.

Indian Student.

[(a). The moving parts in the G.P.O. standard relay are lighter than those in the Siemens, and they are better balanced, i.e., there is less drag on the pivots; there are also two tongues acted upon instead of one, as in the Siemens, and, owing to the absence of the cross piece on the magnet,

480

the cores demagnetise more readily, and there is therefore less liability to sticking. The improved Siemens pattern is, however, very good for key speed working.

(b). An increase in the size of the pole pieces would not improve the working, it would make practically no difference unless they were very massive, in which case the sensitiveness of the relay would be reduced owing to there being a large amount of iron to magnetise. We do not know what you mean by "inductive capacity; an electro-magnet has no inductive capacity; it has "self induction," and this would be increased by increasing the size of the pole pieces.

(c). It is not clear what you mean by "bridge wire; "the capacity for balancing the discharge from the line for a 100-mile line would be between 1 and 1.5 microfarads if the line were all open work (no underground).

(d). No advantage whatever.

(e). Lengthening the cores would aggravate the effect of the slow discharge from the line and would certainly not improve the working.

(f) (g). Experience has proved that the use of condensers is absolutely unnecessary, and no beneficial effect results from their use. A secondary battery would be perfectly useless, as the discharge would be too prolonged and uncertain.

(h). Practically no beneficial effect whatever.-EDS. ELEC. REV.]

The Elmore System of Patent-Making.

The system of "gleaning" patent specifications for the purpose of strengthening otherwise useless "inventions," is by no means of rare occurrence, but in most instances in which the field of invention is explored, it is the blue-books of defunct patents that furnish the happy hunting ground to the soi-disant patentee, or "first and true inventor," if he prefer it. I am led to these reflections in consequence of having discovered that Mr. A. S. Elmore, in a patent to which his name is attached, has had the temerity-I should say audacity to pluck from a patented process of mine, which is still in force, an important part of my invention. Now, before pointing out to the readers of the ELECTRICAL REVIEW the particular part of my process which Mr. A. S. Elmore has thought fit to appropriate for the purpose of giving to his otherwise perfectly useless patent, a semblance of practicability, it will be necessary to refer to other portions of his somewhat obscure specification, which has for its title "Improvements in the process (sic) of obtaining zinc by electrolysis." Improvements in the process ! Which process?

In this patent the zinc, while being deposited upon the cathodes, which are in the form of a disc or cylinder, is subjected to the action of a burnisher, "but," says the patentee, instead of being in the loose granular state, such as it would hare under the ordinary conditions of electrolytic deposit, it is rendered compact, &c., and "when the deposit has attained the desired thickness, the zinc can be removed in the form of round plates from the discs, or it can be cut longitudinally and stripped off the cylindrical cores." Now with respect to the "loose granular state" of electrolytic zinc "under ordinary conditions," referred to in the above passage, which I have italicised, I have something to say. It is well-known, or should be known, that the Elmores have made many attempts-notably in various parts of Wales-to deposit zinc from its sulphate solutions, and ingloriously failed in every such attempt, and when A. S. Elmore, having the remembrance of those disastrous failures vividly before him, speaks of "the loose granular state" of zinc "under the ordinary conditions of electrolytic deposit," he is simply echoing his own experience of his father's failures in respect of the electro-deposition of zinc from its sulphate solution. I had heard of those failures, as also those of others who had attempted to deposit zinc in a practical scale from a solution of the sulphate, and I had also had a good deal of personal experience myself with respect to this salt of zinc. Knowing the importance that would attach to a good zinc bath, if such could be found, I pursued a long series of experiments with solutions of various zinc salts, employed under many varying conditions, and eventually succeeded in obtaining an electro1 which entirely overcame all the old troubles, polarisation, deposits, "treeing," and other objectionable features, the sulphate of zinc, as an electrolyte, is more

ין

[APRIL 10, 1891.

notorious than famous. I resolved to turn my attention to the salts of zinc prepared with the vegetable acids, and some of the results I obtained were remarkable for the fine reguline character of the metal deposited, and its extreme whiteness, the familiar bluish tint of the metal being in some cases scarcely perceptible. Subsequently, further experiment proved to me that a mixture of mineral and vegetable acid zinc salte formed the very best combination for a reliable and practica zinc bath a mixture of zinc sulphate and acetate being specially useful. For these improvements I obtained the necessary patents, and I am amazed to find that Mr. A. §. Elmore had the effrontry to insert the following paragraph at the end of the specification before referred to: Although I have mentioned zinc sulphate as the salt treated, other compounds of zinc, such for instance as the acetate, may be similarly treated."

66

Now the Elmores ought to know perfectly well the nature of my improvements in the electrolytic treatment of zinc, and that the introduction of the paragraph I have quoted interferes with my invention; this being so it is liable to mislead the public, and possibly to involve some mannfacturer, unwittingly, in an action for infringement. The opnions of the Press regarding the financial schemes connected with the Elmore companies, are gradually opening the eyes of the public-at last-and I hope shortly to ask the shareholders, through the medium of these columns, if permitted to do so, if they know what is meant by the "Elmore patents," about which they have heard so much, and for which they have paid so dearly.

April 1st, 1891.

Behind the Age.

Alexander Watt.

While perusing your issue of the 3rd inst., my attention was drawn to a paragraph headed "Behind the Age," which stated that someone had written to the Newcastle Weekly Chronicle to correct a mis-statement of theirs in speaking of the electric pinnace recently floated, viz., "that the first vessel propelled by electricity was launched a week ago on the Thames," &c., and his letter was not published, which you term was the way of newspaper scientists. It became a matter of interest to me to know whether any notice would be taken of the letter, for I have always regarded the Weekly Chronicle as a paper that is in general very far in advance of its contemporaries, and a journal that would stand corrected if the circumstances warranted it. I, therefore, took up the paper on Saturday last, and almost the first letter I read in the columns of "Open Council" was a letter from "ElectroLux" (presumably your correspondent), calling the editor's attention to the mis-statement referred to. As your impatient and irascible correspondent has given rise to a false impres sion, the least I can ask of you is that you will do me ta reader of both papers) the equal justice of correcting it.

April 6th, 1891.

W. Young.

[We are pleased to insert this letter, which shows clearly enough that our correspondent of last week was a little premature, that is assuming "Electro-Lux" and himself are one and the same.-EDS. ELEC. REV.]

Electrolytic Action on Ships' Bottoms.

Will you favour me, through the medium of your valuable journal, with your esteemed opinion upon the following: If a steel or iron ship be electro-plated with copper, and, durit a voyage the copper plating be knocked off so as to expose a part of the iron or steel plate to the action of the salt water, would there be a galvanic action set up between the copper, iron (or steel) and the salt water, and, if so, would the ship's plate be damaged thereby?

By answering the above you will be conferring a very great favour upon me.

April 7th, 1891.

[Decidedly yes.-EDS. ELEC. REV.]

G. E. Bulmer.

SEWAGE TREATMENT-ELECTRICAL

VERSUS CHEMICAL.

N the trials made during last summer at the Salford and endleton Sewage Works, the electrical treatment of sewage as tested alongside the processes of the International ewage Purification Company, the Barry Patent Company, nd that of Messrs. Spence and Sons. It is intended to disharge the sewage after treatment into the Ship Canal, and is therefore essential to obtain an effluent which is not nly inoffensive on leaving the sewage works but which will ot undergo any subsequent putrifactive change. Two hemists working independently were appointed to pronounce n the character of the effluents and, generally, on the fficiency of the various processes. An electrical engineer eported on the working of the plant put down for the trial f the electrical process, and estimates were prepared by the ngineers employed by the Salford Corporation of the cost hich the various systems would involve.

Two of the four competitors are now practically out of the anning, the only difficulty being to decide between the relative herits of the Electrical and International systems of treatment, oth of which alike for efficiency and cheapness prove to be preerable to the others. The process of the Electrical Purifiation Company was as follows:-The current was provided ya Charlesworth and Hall dynamo (50 volts 50 ampères), riven direct by a small tandém compound engine at about 00 revolutions with 100 lbs. steam pressure. The current as conveyed by 'copper strips to the iron electrodes. These ere placed in an inclined brick channel or shoot 90 feet ong, through which the sewage flowed at the rate of 2,300 allons per hour. The channel was divided into 28 cells, in ach of which were 13 plates 4 feet × 2 feet 8 inches x 1 nch, presenting an effective surface of 256 square feet per ell. The sections were connected in series in the same way 8 in ordinary accumulators, viz., positive and negative alterately, and the direction of the current was reversed at inervals of from 8 to 12 hours, to prevent the back E.M.F. geneated in the cells from becoming too great. A brick partition xtending below the surface of the liquid, and another rising

Experiments with High Tension Alternating Currents (illus.)... 506 On Rotary Currents and the Art of Measuring them (illustrated) 506 Proceedings of Societies:

Institution of Electrical Engineers (illustrated) Abstracts of Published Specifications

Correspondence :-The Invention of the Dynamo

Elmore Copper Companies...

Manganese in Cells of the Leclanché Type

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from the bottom between the intermediate sections, served to ensure the proper circulation of the sewage. From the result of the trials, it is calculated that to deal with the ten million gallons per diem of the Salford and Pendleton sewage 334 electrical H.P. would be required. Assuming the E.H.P. to be 80 per cent. of that indicated by the engine, an engine yielding 417.6 I.H.P. would be needed. The weight of iron consumed would be 674 tons per annum. From the channel or shoot the sewage flowed into five tanks, containing altogether 16,500 gallons, and thence to the filters. The rationale of the purifying process which goes on is explained by one of the consulting chemists as follows:-Ferrous oxide (Fe O) formed on the anode is dissolved off at once by the action of the sewage matter, then oxidised by the air to ferric oxide (Fe, 0), which is again reduced by the sewage matter; the ferric oxide acting as a carrier for the oxygen of the air. Finally, ferric oxide is left in a very finely divided state, difficult to remove by filtration. The ferric oxide imparts a brown colour to the effluent, but is in itself quite unobjectionable. According to the analyses of one of the chemists, the insoluble matter consists almost entirely of this ferric oxide, and if this is so, the subsidence and filtration might be dispensed with. This would effect an important economy, and would bring down the estimated cost of the electrical treatment nearly to a level with that of the International Company. However, the views of the second consulting chemist by no means agree with those of the first the matter in suspension being, according to this authority, largely organic, and subsidence and filtration therefore absolutely necessary. It is an unfortunate circumstance that the complete disaccord throughout in the chemical evidence renders it difficult to judge of the relative efficiency of the two processes (electrical and international) in the matter of purification. Both undoubtedly worked in the experimental trials with great success, and the International Company, as is well known, have carried on their process for some years at Acton with, apparently, excellent results. The precipitant in this process is the material known as ferozone, in which, as in the electrical process, the real purifying agent is the iron which passes from the ferrous

482

to the ferric state, and back again to the ferrous under the successive action of the oxygen of the air and of the sewage matter. The special feature of the International system is, however, the employment of the material known as polarite in the filters. It is claimed that this material is efficient in the removal of organic matter. It is said to be prepared from black-band ironstone, which is heated for 24 hours in gas retorts, after which treatment it is found to be magnetite, and is said to contain a magnetic oxide. This magnetic oxide cannot, however, be the same as the mineral magnetite, commonly known as magnetic oxide of iron, since the latter is an actual magnet, whereas the material in polarite is attracted by both poles of the magnet, and does not itself attract unmagnetised iron. It does not appear to contain metallic iron, since it does not yield any hydrogen when treated with an acid. The analyses given of the polarite present great discrepancies, which it is hard to account for, except on the supposition that one or both of the analysts failed to obtain a representative sample. Not less divergent are the views expressed by these authorities on the efficiency of polarite as a purifying material, one of the chemists admitting its efficacy; the other being altogether sceptical, and regarding it as so much inert material. One other point with regard to the polarite filtering beds requires further investigation. Supposing polarite to be really a purifying material, how long will it retain its efficiency, and how often will the beds require to be renewed? This is a question which has an important bearing on the cost of the process. The engineer's estimate apparently makes no allowance for the possible wearing out of the material, perhaps owing to want of data. Should it be found that the life of the polarite filter beds is a short one, it is conceivable that the balance of cost may turn in favour of the electrical process. With regard to the Electrical Company's process, the best and the worst is at any rate known, and there remains no such important outstanding question as that of the life of the filter beds employed by the International Company.

We turn now to the all-important estimates given of the cost of the two processes.

[APRIL 17, 1891.

mates for the Spence and Barry systems much exceed thos given above (Spence £17,817, Barry £24,612): we believe however, that it is contemplated to give one of these another trial. Perhaps a satisfactory solution of the difficult ques tion of the rival merits of the Electrical and Internationa processes may be found if the Salford authorities decide t have experimental works erected and to conduct the twe processes for themselves for a sufficient length of time; th works being open for inspection and the collection of sample at all times to the engineering and chemical advisers ap pointed by the Corporation.

THE COST OF ELECTRICAL ENERGY

RELIABLE data on the consumption of fuel and on the co of producing a given quantity of electrical energy at centra lighting stations is very scarce indeed. Young engineer have been and are apt to compute the item of fuel in the following way :-Since it is possible, with a first-rate engine to produce an indicated horse-power for one hour with two pounds of good coal, and since the combined efficiency of an engine and dynamo may be over 80 per cent., therefore the electrical horse-power, or 746 watts, need not require mor than 25 lbs. of fuel for its generation. Consequently, the Board of Trade unit of 1,000 watt hours would be produced by 3.35 lbs. of coal. This economical condition can only b reached in cases where the plant is working at full load, an that occurs in electric lighting for but a small fraction of the day. Electrical engineers in general should feel gratef to Mr. Crompton for the admirable paper which he presente to the Institution of Civil Engineers, on the 7th inst entitled "The Cost of the Generation and Distribution of Electrical Energy." Mr. Crompton carefully analyses the wide difference between the "calculated" cost of energy ar the figures attained in practice. The three items of c namely, material, labour, and upkeep, were influenos chiefly by the "load-factor," the design and arrangement plant, and the local cost of material and labour.

The name "load-factor" expresses the relation which the actual output of a given plant bears to what would be its out put if it were worked continuously at full load. For in stance, if in a lighting station the output of the plan working continuously day and night, and the full power for the month of November, be taken at 100 units, whereas it i found that the actual output is 166 units, then it would be said that the load-factor was 16.6 per cent. In the summer months, at the same station, it may fall as low as 5 per cent In order to compare the relative economy of fuel, water, other material used in generating electrical energy, th author has fixed on a consumption of 25 lbs. of water and 2.5 lbs. of Welsh coal per unit generated as a standard which might be reached in the future, although nothing approachi those figures had yet been attained in practice. M Crompton hoped to be able to make his paper perfety general and impersonal, that is to say, to collect and tabab data from a large number of supply stations, and from the to draw general conclusions as to the influence of the ti items of load-factor, design and cost of material and lai upon the cost of energy. Unfortunately, however, he not obtain sufficient replies to his queries, and hence ha