In the case of the Cannel gas of the Chartered Company the illuminating power has been equal to 21'02 candles. In all cases this illuminating power is obtained by burning the gas at the rate of 5 cubic feet an hour, from suitable burners, as prescribed by the Referees appointed by the Board of Trade. On four occasions during the quarter the gas of the Chartered Company, at Beckton, was a little below the parliamentary standard. As regards purity, Dr. Letheby reports that sulphuretted hydrogen was, with two exceptions, at all times absent from the gas of all the companies. The two exceptions were in the case of the gas at Beckton, when, from accidental causes, there was a trace of this impurity present. The average proportions of sulphur in the gas have been as follows:Beckton, 12 67 grains per 100 cubic feet; Friendly Place, 10:59 grains; Ladbroke Grove, 12.99; Millbank, 17:12; Chelsea, 19:38; Camden Town, 1791; Graham Road, 13'77; Bruce Terrace, 11:45; and Hill Street, Peckham, 2199 grains. The proportion of this impurity has been in excess of the prescribed amount (25 grains per 100 cubic feet) on four occasions in the Imperial Gas, at Camden Street, and on fourteen occasions in that of the South Metropolitan Gas. Dr. Letheby states that the excess of impurity in the Imperial Company's gas was accidental. The amount of ammonia in the gas of all the companies has been constantly below the prescribed quantity of 2 grains per 100 cubic feet of gas. In most cases it has been considerably less than 1 grain per 100 cubic feet. Important Decision versus the Employment of the Lactometer" used by the Board of Health, of New York City, as a Means of determining Adulteration of Milk.-On September 16th, 1875, a German milk dealer was convicted, in one of the lower Courts, ofthe misdemeanour of keeping and exposing for sale adulterated milk." The prosecution relied entirely upon the fact that milk found in the shop of the accused, when tested by the lactometer, failed to attain the standard which is said to denote pure milk. Prof. Doremus, as expert for the defence, demonstrated by experiments that the employment of the lactometer enabled the fraudulent vendors of milk in the country to remove much of the cream, and also to add water to the halfskimmed milk. He also testified that milk from certain cows, during certain seasons of the year, would yield a pure milk liable to condemnation when criticised by this untrustworthy instrument; that he visited, in the month of September, a celebrated milk and butter district (Orange County, New York State), and obtained twelve specimens of milk from as many pasture-fed cows, five of which samples were of less gravity than the standard adopted by the Board of Health. Chemical analysis showed their richness in butter to be the cause of their want of buoyant power. Dr. Doremus also referred to various French, German, and English authors, as substantiating his views, and quoted the sweeping denunciation of the lactometer by Mr. J. Alred Wanklyn, in his work on "Milk Analysis." Justice John R. Brady, in reversing the judgment of the lower Court, said, that ifby tests made by scientific men-the lactometer or lactodensimeter furnishes only questionable evidence of adulteration, it should not be regarded as sufficient to warrant a conviction. PATENTS. ABRIDGMENTS OF PROVISIONAL AND COMPLETE Jan. 14, 1876. fall in and agitate the water, so as to keep the sediment in motion and Improvements in the manufacture of air-gas for lighting and heating purposes, and in the apparatus connected therewith. C. F. Schüssler, Hamburg. November 23, 1874.-No. 4021. The novelty of the invention consists in the production of a heating and illuminating gas by the construction of a chamber containing tubes or channels in which hydrocarbon liquid is caused to flow and impregnate atmospheric air, which is fed thereto under pressure of an arrangement of bellows worked automatically. Improved compounds or combinations of ingredients for waterproofing filaments, threads, fabrics, and fibrous materials generally, also for coating walls and other bodies. A. Wilkinson, High Street, Marylebone, Middlesex. November 23, 1874.-No. 4026. This relates to forming a composition of ingredients, such as bisulphuret of carbon, benzine, sulphuret of zinc, ammonia mixed with naphtha, india-rubber, gutta-percha, or other like gum, for the purposes stated in the title. In some cases an exterior coating, composed of sugar of lead and linseed oil mixed with whiting and litharge, is applied, and before being completely dry an extra coating of the first mentioned composition is applied to render the materials completely waterproof. Certain improvements in the manufacture of acetate of soda, and in the processes employed therefor. H. B. Condy, Battersea, Surrey. November 24, 1874.-No. 4037. The novelty of the invention consists in precipitating the organic impurities existing in acetate of lime, and the completion of the decomposition of the solutions of acetate of lime or sulphate of lime (which is dissolved to a small extent) by means of carbonate of soda. The combination of such processes enable me to produce good merchantable acetate of soda by one crystallisation. G. Haycraft, Faversham, Kent. November 25, 1874-No. 4046. My Improvements in refining saltpetre, aad in apparatus for the same. invention relates, first, to the arrangement of the vessels in which the several stages of the refining process are performed, in such a manner that the saltpetre will be caused to pass by gravitation alone from vessel to vessel, whereby hand labour and the use of pumps for lifting the saltpetre from one level to another is dispensed with. Also to the method of boiling the grough saltpetre by introducing steam among the mass, with or without the use of a steam coil. Also to the method of recovering saltpetre from the mother-liquor which drains from the refined saltpetre. Also to the method of cooling the saltpetre during crystallisation, as well as to the construction of the boiling and reducing vats, the agitators, and the arrangement of gearing for driving the same. Improvements in automatic chemical telegraphs, comprising transmitting and receiving instruments, circuits, and apparatus connected therewith, part of the said improvements being also applicable to other telegraphs. A. M. Clark, Chancery Lane, Middlesex. (A communication from W. E. Sawyer, Washington, Columbia, U.S.A.) November 26, 1874.-No. 4063. The present invention relates to a new and improved system of automatic chemical telegraphs, comprising transmitting and receiving instruments, circuits, and apparatus connected therewith. Improvements in bleaching wool, textile fabrics, and fibres. T. N. Palmer, Lansdowne Road, Dalston, Middlesex. (A communication from L. P. H. P. Balna, Rheims, France.) November 28, 1874.-No. 4087. I use a bath composed of bicarbonate of soda and subcarbonate of magnesia, into which air is introduced by pressure. I put into an apparatus the above mentioned matters with the addition of sulphuric acid; the gas which is emitted from this apparatus saturates the bath, and in order to continue the application I saturate the same bath with sulphurous gas, accompanied by the introduction of the oxygen of the surrounding air. I also use chloride of lime in the water saturated with sulphurous gas, always with the addition of the oxygen of the air. I reserve to myself the use of all the means producing sulphurous, carbonic, and oxygen gas applied to the bleaching of the above mentioned materials. A new or improved ink-pencil. J. L. Petit, Birmingham, Warwick. November 28, 1874.-No. 4090. This new or improved ink-pencil consists of aniline dyes, or mixtures thereof, thoroughly incorporated with finely powdered plumbago, or black, or deep coloured chalk, together with gum-water or other adhesive material soluble in water. The paste produced may be made into sticks, and dried, and be used as a crayon or chalk, or be enclosed in cedar as an ordinary black-lead, or be made into fine rods to be used as an ever-pointed pencil. The writing produced by the use of the ink-pencil may be copied by pressing moistened paper upon it. The original writing is thereby made more legible as the moisture dissolves more or less of the anitine compound in the composition, and the dissolved matter dyes the vegetable nbre, and deepens the colour of the writing. Several copies of the writing may be taken. The ink-pencil may be produced in different colours. Improvements in the method of and apparatus for extracting the tion of the same. G. W. Risien, Demerara. (A communication from William Russell, of Demerara.) November 30, 1874.-No. 4094. The features of novelty which constitute this invention consist in passing the cane stalks through two mills spaced about thirty feet apart and connected by a chamber. In this chamber works an endless band or A new or improved mode and means of preventing the deposition of sediment and incrustation in steam boilers. G. Nimmo, Glasgow.juice and crystallisable ma ter from sugar cane, and after manipula November 23, 1874.-No. 4018. This said invention consists in placing within the water in the boiler bags, pads, or " sweeps," made of cottonwaste, hemp, rope, or other soft material (or pieces of wood covered with a soft material), which, when saturated, possess a specific gravity rather heavier than the water; so that these, by the ebullition or boiling of the water, and by their own shape or configuration, rise and carrier, and the chamber is provided with two tiers of pipes, through THE which a continuous supply of hot water, or steam, or cane juice passes in a spray and saturates the expressed cane stalks or begass on passage of same from mill to mill. The hot water, or hot water and steam, is QUARTERLY JOURNAL OF SCIENCE. supplied from the cane juice heaters used in the manufacture of sugar, and the juice from the second mill may also be used for saturation by passing it through a juice heater and then to the supply pipes for saturating the begass before mentioned. Improvements in apparatus employed in the washing and cleansing of wool and other fibres. J. Clough, Manchester Road, Bradford. November 30, 1874.-No. 4095. In conveying wool or other fibrous material (after being washed) from the washing bowl or trough to the squeezing rollers, a carrying fork is employed, operated by crank motion with balance wheel on the end of the shaft, and worked in a curved plate, the curve of which is suited to the movement the fork is desired to describe; this curve may be flatter or quicker according to the distance the squeezing rollers may be from that part of the bowl or trough where the wool is lifted by the last washing fork and placed upon the curved plate. The curve of this plate begins at the point where the wool is leaving the sud or wash liquor and continues upwards as far as is necessary to give the wool sufficient fall down an incline leading to the nip of the rollers, and so to pass it through the rollers. This curved plate has two sides or guards to prevent the wool from falling off it when being taken forward by the carrying folk to the rollers. Stationary holders are placed at the foot and on the top of the curved plate to retain the wool, when lifted from the bowl or trough and placed upon it, until the carrying folk working in the curve comes and takes such wool forward to the top of the inclined plane, and from whence it slides down to the nip of the rollers. There are holders called ratch tooth holders (by the teeth taking the form of ratch teeth). The head of the carrying fork which works in the curve is fixed upon a square part of the lower end of the "stalk," and is movable up and down it; an adjustable steel spring, being placed on the stalk above the head of the fork, gives way by compression according to the thickness of the body of wool which it may for the time be carrying, and by which it readily suits either a larger or a smaller amount of material under operation. The prongs of this fork are formed slightly rounded at the front part, running out conically to the back part. Disincrusting and preventing the incrustations in steam boilers. J. B. Deluy, Naples, Italy. November 30, 1874.-No. 4108. My invention is an improvement on all the discoveries made until now; it is the result of my studies, and consists in a powder made out of one only vegetable produce pulverised, which I introduce in the boiler through the manhole when the supply of water is completed. My HOW TO MAKE MONEY BY PATENTS. disincrusting powder, which I name Disincrustant Marseillais," is neither a compound or a mixture, and it disincrusts, cleanses, clears out all deposit by spontaneous action. By the ebullition the incrustation is dissolved and goes out through the tap purger. NOTES AND QUERIES. Terra Alba.-Is the article called terra alba made entirely from the ground alabaster of Derbyshire, or is there another kind of terra alba made or manufactured at the Salt or Acid Works of Newcastle or elsewhere in England? Assuming that it is also made at the Salt Works as well as at Derbyshire, is the former better in any way, and what is the price per ton laid down at Liverpool? Please give present market prices for the Derbyshire, and that which is manufactured at salt works or elsewhere. There is another article called pearl hardening which I do not wish confounded with the other, but would like the present market price of this also.-THOMAS MANNING. Geological, 8. "On some Unicellular Alga Parasitic within Silurian and Tertiary Corals, with a Notice of their Presence in Calceola sandalina," by Prof. P. Martin "How AngleDuncan, F.R.S., V.P.G.S. sey Became an Island," by Prof. A. C. Ramsay, LL.D., F.R.S. "On the Influence of Various Substances in Accelerating the Precipitation of Clay Dissolved in Water," by William Ramsay. THURSDAY, 20th.-Royal, 8.30. F. Royal Institution, 3. "On the Chemistry of the Non-Metallic Elements," by Prof. Gladstone. Chemical, 8. "On Narcotine, Cotarnine, and Hydro-cotarnine," by G. H. Beckett and Dr. Wright. "On a Method of Estimating Bismuth Volumetrically," by M. M. Pattison Muir. London Institution, 7. Also free byl post, "Five Minutes' Advice respecting Patents for Inventions." A BARLOW & CO., 23, Southampton Buildings, W.C. New Illustrated Catalogue of Telescopes, Water-glass, or Soluble Silicates of Soda and Potash, in large or small quantities, and either solid or in solution, at ROBERT RUMNEY'S, Ardwick Chemical Works, Manchester. ROYAL POLYTECHNIC INSTITUTION. -NEW MUSICAL ENTERTAINMENT by Mr. G. BUCKLAND, GABRIEL GRUB AND THE GRIM GOBLIN. Magnificent views and effects. A new Experimental Lecture, by Professor GARDNER, "A Holiday Budget of Curious Experiments.' Progress of Royalty in India, with new views and effects, by Mr. J. L. KING.Admission to the whole, Is.; children under 10, half price. ROYAL POLYTECHNIC INSTITUTION. -Another Polytechnic Novelty. The marvellous AERIAL MERCURY: a New Song written by H. Edmonds, music by J. A. Jopp, will be sung by G. Jopp, R.A.M., on each occasion of exhibiting this illusion. The Compound Cycloidal Apparatus, producing beautiful patterns before the visitors. The GEOLOGICAL PIANO, or MUSICAL STONES, by M. HONORE BAUDRE. Admission is.; children under 10 half-price. ROYAL INSTITUTION of GREAT BRITAIN, ALBEMARLE STREET, PICCADILLY, W. Jo OHN HALL GLADSTONE, Esq., Ph.D., F.R.S., Fullerian Professor of Chemistry, R.I., will begin a Course of Eight Lectures ON THE CHEMISTRY OF THE NON-METALLIC ELEMENTS, on THURSDAY next, January 20 to March 9. Subscription to this Course, One Guinea; to all the Courses in the Season, Half-a-Guinea. AY, 21st.-Royal Institution, 8. Weekly Evening Meeting. "The PYROLOGY; or, ANALYSIS AND SYN Optical Deportment of the Atmosphere in relation THESIS BY THE BLOWPIPE. Gentlemen wishing to join the Class of Instruction now being given in this important Science are requested to communicate with Messrs. SPON, Scientific Publishers, Charing Cross, or with Messrs. GRIFFIN and Sons, 221 Garrick Street, Covent Garden. CAST-IRON COILS. EXPANSION AND CONTRACTION UNLIMITED. For Testimonials and particulars, apply to ANDREW BELL & COMPANY, LIMITED. Carr Hall Iron Works, HASLINGDEN, LANCASHIRE. STAMP YOUR BOTTLES, PACKETS, PARCELS, PAPER, PILL-BOXES, JARS, &c., BY WATTS'S FLEXIBLE STAMP. The impressions may be gilt, which gives a most elegant appearance to Glass, China, &c., and does not wear off. Price 5/6, post free, or for Stamping in Gold, 6/6. Send for Specimens of Work to W. F. WATTS, CLAPHAM, S.W. N.B. Instructions for Patients stamped upon bottles look very effective, and are stamped in less time than gumming a label. WILLIAM HARVEY, Plymouth Tar & Chemical Works, CATTEDOWN, PLYMOUTH. S. A. SADLER, Jan. 14, 1876. JOHN PAGE, (Late Page & Tibbs), 47, BLACKFRIARS ROAD, S.E., Continues to supply the Trade with Phosphorus, Chlorate of Potash, Pure Acids, Pyrotechnic and all other Chemicals, Pure and Commercia at the Lowest Prices. SPECIAL QUOTATIONS ON APPLICATION. SPENCE BROTHERS CHEMICAL Co. LIM., Manufacturers of LIQUOR AMMONIA, SULPHATE of AMMONIA, VITRIOL, Brown and Rectified, ALUM CAKE, &c., &c. MAWSON AND SWAN SUPPLY Maker of Refined Anthracene, Naphtha (Crude and AND ABSOLUTELY PURE CHEMICALS FOR ANALYSIS AND RESEARCH. Makers of every description of Chemical, Colliery, Copper Ore, Gold Mining and Glass Machinery, including Crown, German Sheet, and Plate Glass Plant, as supplied to some of the largest Firms in England Ireland, Scotland, and Wales. Makers of the latest Improved Revolving Black Ash Furnace with Siemens's Patent Gas Arrangement, and as used in the Manufacture of Soda. Improved Valveless Air Engines, and Pumps or Acid Forcing, Air Agitators, Compressors for Collieries, and Weldon's Patent Chlorine Caustic, Chlorate, Decomposing, and Oxalic Pans. Gas Producers for Heating Furnaces. Chemical Works, Wolverhampton. Process. EXTRACTOR OF COAL-TAR PRODUCTS. JAMES WOOLLEY, SONS, & CO., 69, MARKET STREET, MANCHESTER, DEALERS IN CHEMICAL AND SCIENTIFIC APPARATUS CHEMICAL REAGENTS, &c., OR THE USE OF ANALYSTS, SCIENCE TEACHERS, AND MANUFacturers. Price Lists on application. Pyrites Burners for Irish, Norwegian, and Spanish Ores. Retorts, Acid Gas, Nitre, Nitric Acid, and Vitriol Refining. Improved Steam Superheaters for Resin Refining, &c. Improved Steam Sulphur Pans. Photographs, and other information, supplied on receipt of Orders. WM. HENRY KING, ALBUMEN MANUFACTURER, &c. Raw Materials for Manure Manufacturers. 78 & 80, ST. ANDREW STREET, LIVERPOO . THE CHEMICAL VOL. XXXII. No. 843. An experiment was made with the apparatus figured in NEWS. Fig. 2 to show that the force in action is not induced electricity. All the parts are insulated except the gas fixture. A is the battery; B, a common telegraphic key; C, an electro-magnet; D, a bar of cadmium (or other metal, cadmium being the best) supported by an insulated stand; E is a mirror galvanometer; F, the gas pipe; G, a dark box enclosing pencils with graphite points (common lead-pencils). The unknown current passes from the bar of cadmium through the galvanometer without causing the slightest deflection, and-notwithstanding the gas THE NEW PHASE OF ELECTRIC FORCE. PROFESSOR E. J. HOUSTON has kindly forwarded to us an early proof of an article he has contributed to the January number of the Journal of the Franklin Institute. Before, however, referring at length to his experiments we will reproduce from the Scientific American three diagrams of the apparatus used by Mr. Edison during his experiments. Mr. Edison and his assistants were experimenting with a vibrator magnet consisting of a bar of steel fastened at one end, and made to vibrate by means of a magnet when they saw a spark coming from the core of the magnet so bright that they suspected something more than induction. The vibrator and battery were then placed on insulated stands, and the wire connected with x (Fig. 1) was carried over to the stove about 20 feet distant. On rubbing the end of the wire against the stove, splendid sparks were observed. With the wire permanently connected with the stove, sparks could be drawn from any part of the stove with a piece of metal held in the hand. Again, while the Fig. 3. pipe connection, which would drain the wire of induced electricity, if there were any-bright sparks are visible between the graphite points in response to the motion of the telegraphic key. Standing on an insulated stool, the experimenters draw sparks from the following arrangement (Fig. 3), in which x is the end of the vibrator (which, as well as the battery, is insulated); A, a secondary battery; B, a 200 ohm coil or copper wire; C is a block of iron, and D, a condenser, all well insulated except A, which is of glass, and stands on the table. In another experiment a glass rod four feet long with a piece of carbon fixed to one end, was well rubbed with a silk handkerchief over a hot stove, and the carbon point presented to the apparatus, the other end of the rod being held in the hand with the handkerchief; sparks were drawn, yet the galvanometer chemical paper, the sense of FIG. 2. phenomena, observed by himself as well as by Mr. Edison; and he pointed out in what particulars the new spark is similar to some forms of electricity, and in what it appears to differ from the various known forms of that force. Like a true scientist, he pointed out that only such phenomena as every competent experimenter is able to verify at any time are worth consideration; and he spoke of the sources of illusion and delusion which misled Reichenbach, and afterwards others who asserted that they had verified his alleged discovery of the so-called odic force. In 1871 Professor Houston published the description of some experiments* which bear, both in method and results, a partial resemblance to those by Mr. Edison. The original experiments, made with a Ruhmkorff induction coil, capable of throwing the induced spark six inches in free air, have now been repeated by Professors Houston and Elihu Thomson. The results are thus described by Professor Houston : The induction coil was worked by means of an electropoin battery of ten cells coupled for an intensity of ten. The elements of each cell consist of a single plate of zinc placed between two plates of carbon. The available surface in each cell is about three by six inches. One pole of the battery was placed in metallic connection with a gas-pipe and the other in similar connection with a large insulated conductor. On working the interrupting break-piece a torrent of characteristic white sparks of condensed electricity passed between the platinum points of the coil. Under these circumstances, that is, while the discharges were occurring between the points, sparks could be drawn from all metallic objects in the same room with the coil, or in adjoining rooms. The sparks were especially noticeable when metallic objects were approached to the gas- or water-pipes of the building, or to metallic surfaces in connection therewith, as in the case of the pneumatic trough, steam-engines, and boiler before mentioned. As already implied, actual contact between the gas- and water-pipes and one of the wires leading from the coil, was unnecessary, as distinct sparks were afforded by a stove in the same room, and from another in an adjoining room. In order to test the suspected similarity between these sparks and those described by Mr. Edison, we submitted them to the tests proposed by him. We made a number of experiments and obtained the following general results, viz. First. The gold leaves of a delicate electroscope did not diverge on being brought into contact with metallic objects yielding the sparks, although in every case the sparks could be seen at the point of contact. Second. The needle of a delicate astatic galvanometer was not sensibly deflected by the sparks, on an apparent current being caused to traverse the coils of the instrument. - Third. A small shred of cotton-wool was not sensibly attracted or repelled by objects from which the spark might be obtained. ог Edison and Dr. Beard, it appears that the alleged discovery of a new force is based on their failure to obtain from the sparks indications of electrical charges currents; or in other words, in the apparent absence of electric polarity. All the effects noticed, however, are readily explainable by reference to the presence of an instantaneous outgoing current, immediately followed by an incoming one, with the complete re-establishment of electrical equilibrium. When we bear in mind the enormous velocity of electrical currents of this character, probably some hundred thousand miles per second, we can readily understand that the flow and reversion of the current would take place in an exceedingly small fraction of a second; a space of time sufficient, were the current merely direct, to produce any decided divergence of the leaves of the electroscope or the needle of the galvanometer. The presence of the inverse current, immediately following the direct current, would absolutely and necessarily prevent the exhibition of electrical polarity as exhibited in the motion of the electroscopes, galvanometers, and of similar instruments. It is doubtless due to the fact that the direct and inverse currents are opposite in their effects, and therefore produce instantaneous electrical equilibrium, that Mr. Edison failed to obtain the characteristic twitching of frogs' legs or the discolouration of iodised paper; for, although these results would unquestionably follow an electric current in one direction, their presence would be masked by the opposite effects produced by the instantaneously following inverse current. currents, as above described, may be questioned; but when The possibility of the existence of the direct and inverse we bear in mind that the sparks can only be obtained by the interruption of the battery current, and that it is necessary to pass the battery current through a long coil of wire, conditions in every way favourable to the production of instantaneous induced or extra currents, the direct and the inverse currents follow as a matter of necessity; for the induced or extra currents in the coil of wire necessarily produce, in the core of the magnet and the metallic wire in connection therewith, an electrical current in one direction, instantaneously followed on the cessation of the induced or extra current, by a current in the opposite direction for the re-establishment of the electric equilibrium in the cores of the magnet. that the induced current produced at the moment of making contact with the interrupter flows in the opposite direction to that produced on breaking the contact. This fact would in itself, exclusive of the above explanation, be sufficient to account for the production of inverse cnrrents in the core of the magnet, when the interruption of the that the phenomena may be referred to a somewhat battery current was sufficiently rapid. Dr. Beard admits similar explanation, but the value he attaches to his supposition may be judged from his subsequent adoption of the term "apolic force " as a preferable term to "etheric It is a fact well known to all versed in electrical science force." Fourth. The so-called retroaction of the spark was It is matter of surprise to us that both Mr. Edison and distinctly observed. On looping a wire back on itself, a Dr. Beard endeavoured by careful insulation to eliminate decided spark was seen at the point of contact made by electricity or induction, since it is a recognised fact in in the apparatus employed by them the effects of induced the end of the wire with any portion of the wire itself. All the above results are in strict accordance with the electrical science that the more perfect the insulation the known laws of electricity, as will appear hereafter. more decided the effects of induction, of which, perhaps, no To still further compare these results with those better instance could be found than the care taken to obtained by Mr. Edison, we dispensed with the use of the thoroughly insulate the secondary coils in the induction induction coil, and employed an apparatus similar to that on Ruhmkorff apparatus. In view of the above considerdescribed by him, viz.,: An electro-magnet in connection ations, we feel warranted in the belief that all the phenowith the battery already mentioned, the current of which nomena noticed by Mr. Edison and Dr. Beard are explainwas rendered intermittent by means of an ordinary in-able by the presence of inverse electrical currents of conterrupter. With this arrangement, a wire in contact with the core of the magnet yielded sparks having all the properties described by Mr. Edison. From a careful reading of the published accounts of Mr. *Journal of the Franklin Institute, June, 1871. siderable quantity, but comparatively small intensity, instantaneously produced at the making or breaking of the battery circuit. There was noticed during the progress of our experiments with the induction coil the following curious phenomenon, which appears to us favourable to the explanations |