against the bridge, o; when the bar has passed on and is free the needle falls on the cam, 0, and in pressing it down from its horizontal axle, en, the tooth, , engages in the wheel of 600 teeth, μ, and continues to do so until the cam has travelled so far that the needle leaves it.

The outline of this cam is such that for any position of the needle the angle through which the wheel, u, moves is proportional to the watts in the circuit at the time.

The wheel, μ, advances every 100 seconds, an amount proportional to the watts indicated by the position of the needle at the instant when it is caught by the bar, d.

These individual impulses are added up, as it were, and

of the meter by counting the lamps so registered, and comparing them with the lamps in use.

Wattmeter.-The wattmeter is composed of a fixed series circuit made up of two parallel coils, A A', through which the current to be measured passes on its way to the lamps, and a movable bobbin, B, in parallel with the lamps. This movable coil is fixed on a hollow shaft through which passes the wire suspension, F F', which being fixed rigidly at both ends, serves at the same time the purpose of a torsion spring. When the current passes, this movable coil takes up a position of equilibrium between the force of mutual attraction between itself and the series coil and the resistance of the

communicated to the dials, through a train of clockwork suitable to the units chosen, by means of the bevel wheel, X, and thus the increase in the readings on the dials in a given time denotes the energy expended in the circuit during that time.

A large needle is fixed on the dial, which advances every 100 seconds a certain number of divisions; these divisions indicate in watt-hours the energy expended during that time. By multiplying the number of divisions passed over each time by 36, we arrive at the watts in the circuit, so that each division corresponds to 36 watts, or one 10-C.P. lamp approximately. This is an easy means of making a rough test

torsion spring; this position indicates the power in the circuit at the time, and the needle, L N, acts as the medium between the wattmeter and the dials, as we have seen.

All the instruments of the same size have the same parts and the same cam, so that their construction is absolutely identical, and all the parts are interchangeable, the only difference being in the number of teeth in the bevel wheel.

The adjustment is extremely, simple, in that it may be immediately effected within 1 per cent. by changing the bevel wheel or the horizontal ratchet wheel, x. The maintenance is thereby infinitely simplified, in that any error may be at once rectified in situ,

D

They are able to register very small currents, as their sensibility at 0 is very great owing to the plane of the movable coil being at an angle of 45 degrees with that of the fixed coils.

Alternating currents.-M. Frager's energy meter may be adapted without any essential modification to alternating or undulating currents. The indications given by it are rendered as correct as possible, by virtue of the low coefficient of selfinduction of the movable bobbin and its great resistance, which renders the time-constant of the shunt fine wire circuit very small, and consequently enables the corresponding factor of correction to be entirely disregarded in practice.

Expenditure of the apparatus.-This expenditure may be divided into two parts; one fixed, which is employed in keeping up the movement of the motor and supplying the shunt circuit of the indicating apparatus, and another which varies according to the output, and is equivalent to a certain loss of charge in the fixed circuit.

Loss of charge.-Taken at 100 volts and at the maximum output, i.e., under the most unfavourable circumstances, this loss of charge varies from 007 of the difference of potential at the terminals for the 10 ampère-meter to 0004 for the 200 ampère-meter.

Expenditure of the chronometric motor.-The current passes into the motive bobbin about once every two seconds, the contact takes place during one-sixth of a revolution at about the mean position of the pendulum (balancier), i.e., at the moment of maximum speed.

It lasts during about one-fifth of a single oscillation. The resistance of the bobbin of the motor being 1,000 ohms, if we do not take into account either the period of starting or the counter-electromotive force due to the movement, the expenditure of 100 volts would be 10 watts, but it lasts of

1 10.4

ON May 25th, M. Adolphe Minet read a paper before the French Academy of Science on the above subject. He has sought to generalise the method which he has already applied to the electro-metallurgy of aluminium by extending it to the extraction of the metalloids and those metals the oxides of which are incapable of reduction by means of carbon. The method as applied to aluminium was the subject of a paper before the Academy on February 17th, 1890, and the following references may be found useful in looking up the subject:

[JUNE 19, 1891.

In the process to which Mons. Minet has during the past two years devoted so much attention, the aluminium salt employed by Deville is replaced by a mixture of sodium chloride (60) parts), and the double chloride of sodium and aluminium 30 parts. These substances are fused, and as soon as they melt five parts of silica and the same quantity of alumina is added. The silicon can then be obtained either in the free state or alloyed with aluminium.

The molten mixture only dissolves small quantities of alumina and silica; the greater part of these oxides remain simply in suspension.

The use of the fluoride is superior to that of the chlorides of aluminium, because at the high temperature (700°1,000° C.) they favour electrolysis, and there is, moreover, no loss by volatilisation.

The theory of the reaction which takes place is as follows:-When the current passes the fluoride of aluminium is at first decomposed; the fluorine, which behaves positively in electrolysis, encounters the alumina and silica, and transforms these substances into fluoride of aluminium and fluoride of silicon; these two salts then combine with the fluoride of sodium set free and form the double fluorides, and these are decomposed in their turn.

A mixture of oxyfluoride of aluminium (Al, Fl, 3 Al, 03) with alumina and silica is fed into the bath, and the proportion of the salts present varies with the quantity of silicon which the alloy is desired to contain.

The electrolytic bath is contained in an iron crucible lined with carbon, and which serves as the cathode, the anodes being constituted of plates of compressed carbon.

Relation between the Constants of the Current and the Electrolyte. For a given surface of anodes and of density of current (intensity per square centimetre) varying between zero and a maximum, d, which must be fixed by experiment, the constants of the current and of the electrolyte satisfy the equation

During the whole operation the bath was supplied with chloride of sodium and fluoride of aluminium at such a rate as to maintain the electrical resistance, p, constant. The temperature was 850° C.

Industrial Application.-These experiments show that it is possible to extend this process to industrial applications, treating by electrolysis during fusion such minerals as red and white bauxite and the natural silicates of aluminium so as to produce not only alloys of iron, silicon, and aluminium, but aluminium chemically pure.

Mons. Minet has made some important experiments upon the strength of these alloys, the results of which are sufficiently interesting to warrant their quotation here. These experiments were carried out in Mons. de Ferriers's labora tory at the Conservatoire des Arts et Metiers.

JUNE 19, 1891.]

Composition of the alloy.

Nature of the work,

Cast.

From these figures it will seen that alloys rich in silicon, such as that which contains 8.9 per cent., present qualities as regards fracture superior to those of pure aluminium.... The electrolytic process is stated by Mons. Minet to be capable of application to the salts of boron; it is in this case sufficient to replace the silica by boric anhydride in the double compound with fluoride of aluminium. Alloys are obtained of boron and aluminium in which the metalloid may exist in the proportion of 80 per cent. of the mass. Caustic soda will free it from uncombined aluminium and hydrochloric acid from traces of iron.

Mons. Minet has carried on these experiments at the chemical laboratory of the Ecole Normale Supérieure.

COMPETITION IN ELECTRICAL ENERGY METERS-THE PRIZE INSTRUMENTS. THE City of Paris instituted a competition, placing at the disposal of the Technical Committee appointed to judge the merits of the various apparatus submitted the sum of 20,000 francs to be divided among the different competitors. In the first competition no apparatus was submitted satisfying all the conditions of the pro

785

mittee worthy of prizes, and we will begin with the two meters which shared equally, and in alphabetical order, the prize of 10,000 francs, awarded, according to the programme, to the inventor who should produce a meter giving complete satisfaction, and applicable to alternating as well as continuous currents; these are the electrical energy meters of Mr. Aron, of Berlin, and of Prof. Elihu Thomson, of Lynn (Massachusetts). Three other meters, two sent by M. Frager" and one by M. Marès,† have gained for their inventors the three prizes of 1,000 francs, completing the 15,000 francs at the disposal of the committee.

The Aron Meter.-M. Aron's apparatus is an electrical energy meter working on the continuous integration principle, and based on the different speed of two pendulums. A complete description of this apparatus has appeared in an earlier number, and we only need refer to it now to mention one special point, which constitutes an important improvement on the apparatus previously described. In M. Aron's original meter, the principal difficulty lay in the want of perfect synchronism between the two pendulums, which registered either a positive or negative quantity, even when the consumption of energy by the consumer was nil. In the apparatus sent in to the competition this defect, which was a scrious one both for the consumers and the company distributing the electrical energy, has been skilfully overcome by an ingenious device, which consists in connecting the two oscillating pendulums by a little slack wire, supporting in the middle a little weight of about 1 gramme. Under these conditions, the synchronism of the two pendulums is preserved indefinitely and absolutely, when it has once been properly regulated; by a suitable adjustment of the length of the two pendulums.

There is no doubt that the synchronism thus obtained is still maintained when the supply of electrical power to the circuit in connection with the meter is very small, and when the meter does not integrate for these small outputs; but it has been proved experimentally that the disturbing influence of the synchronising arrangement has no more appreciable effect on the constant of the apparatus when the electrical power to be integrated attains to both of the maximum power of the meter, say 10 watts, for example, for a meter of 2,000 watts.

786

electric motor integrates the electrical energy supplied, and enables it to be determined at any moment between two given periods, by taking the difference between the indicacations on the dials at the two periods in question. Although this idea has often been suggested before, and attempts have been made at various times to put it into practice, this is the first time that the problem has been solved by such simple methods, and that the carrying out of the theory has been so satisfactorily combined with the requirements of practice.

The apparatus shown in elevation in fig. 1, and theoretically in fig. 2, consists of three essential parts-an electrodynamic motor, an electro-magnetic brake, and an indicator of the number of revolutions effected by the axle bearing the motor and the brake.

The motor consists of an inductive system, into which the principal current passes, and an armature of fine wire connected in derivation on the terminals of the canalisation, but with the introduction of a suitable resistance to the potential of the distribution, so that the intensity of the current passing through this derived circuit shall not exceed one-tenth of an ampère. Under these conditions, if we call I the intensity of the current passing through the inductors, and e the difference of potential maintained between the terminals of the fine wire, a motive couple is set in action between the movable bobbin and the fixed inductors, in proportion to e I, that is, in proportion to the electrical power to be integrated as a function of the time. The resistant couple is produced by the rotation of a flat disc, D, placed on the lower part of the motive axle between three magnets. The rotation of the disc develops in it induced currents, which render it a sort of electric generator acting upon itself in a closed circuit, and constituting a brake. The power thus absorbed being in proportion to the angular speed of the disc, there would be dynamic equilibrium when the motive couple is equal to the resistant couple, i.e., when the angular speed of the disc is in proportion to the motive couple, and consequently to the power, e I. The mechanism for registering the number of revolutions has no special features, and is worked directly by an endless screw fixed to its upper part.

By the suppression of the iron in the armature and the inductors of the motor, the apparatus is rendered applicable to alternating as well as continuous currents, without any change in the constant of the apparatus.

In order to avoid the error which would be produced in the measurement by the counter electromotive force developed by the rotation of the armature, the angular speed imparted to it is intentionally low, not exceeding one revolution per second at the maximum charge, thus increasing the duration of the pivots of the meter, which is in one single movable piece.

In order to overcome the friction at starting the inductors are provided with a coil of fine wire, connected in the same circuit as the armature and the additional resistauce, R. At the normal potential, this winding produces a constant motive couple practically equal to the resistant. couple of the starting, so that the feeblest current is sufficient to start the apparatus. This coil of fine wire is shown at B' in fig. 2. The variations in the atmospheric pressure have no influence on the accuracy of the meter, as the resistance to the air is very slight, in consequence of the shape and very low angular speed of the moving part.

The influence of the variations in the surrounding temperature is provided for in the construction of the apparatus by a very simple arrangement. The resistances connected in series with the armature are made of copper of the same quality as that used for the armature and the disc forming the brake. Thus, when, owing to a rise in the temperature, and consequently in the electrical resistance of the system, the motive couple decreases, the resistant couple decreases in the same proportion, because the electrical resistance of the disc increases, and this increase of resistance diminishes the intensity of the currents induced in the dise.

In order to calibrate the meter, we may vary either the resistance, R, which is in series with the armature, or the position of one of the magnets forming the inductors of the brake. The graduation is so arranged that the first needle indicating the number of revolutions makes one complete revolution for 1,000 revolutions of the armature, and as the meter is regulated so that each revolution of the armature represents a

[JUNE 19, 1891.

watt hour, the first dial indicates 1,000 watt hours, each division of this first dial 1 hecto-watt hour, and each of the succeeding dials indicates in the ratio of 10 to 1. The readings are then taken as in the ordinary gas meters.

The graduation is very simple and very rapid. We have only to make a mark on the disc and count the number of times it passes a certain point in a given time. Each appe ratus may be in the same way checked at any moment and its accuracy ascertained. For this purpose it would be an advantage if the meter were enclosed, not in an opaque box of brass, as is the case with the model submitted to the committee, but in a box the front of which at least should be made of glass, so as to show clearly the simplicity of the apparatus, and also a great advantage which it has from the point of view of the interests of the consumer, viz., that of remaining completely motionless when the consump tion is nil.

When the nature of the current passing through the apperatus is changed, the pointers of the meter-go backwards and subtract with the same degree of accuracy, which fact may be turned to account in certain installations those containing accumulators for instance. We may also remark that the meter is absolutely silent, and that its accuracy is practically perfect in every scale of consumption. All these advantages, and those which we have mentioned with regard to M. Aron's motor, justify the committee in dividing of prize of 10,000 francs between two instruments of equal excellence, both of which satisfactorily solve the problem of the practical measurement of the electrical energy supplied by central distributing stations.

La Nature, June 13th, 1891.

E. HOSPITALIER.

THE ELECTROLYTIC METHOD AS APPLIED TO PALLADIUM.

IN the issue of the Chemical News for May 29th there is a paper by E. F. Smith and H. F. Keller upon the elec trolytic method as applied to palladium. It appears that our knowledge bearing upon the behaviour of this meta towards the current is limited and rather indefinite; a brief résume of it, such as it is, is given in the early part of the paper.

In 1868 Wöhler published in the Annalen, No. 143, page 375, an article entitled "Ueber das Verhalten einiger Metalle im Elektrischen Strom," in which, amongst other facts, he stated that palladium as the positive pole of a hattery, consisting of two Bunsen cells, on being immersed in water acidulated with sulphuric acid immediately became coated with a deposit having a bright steel colour, and which was probably palladium dioxide; at the same time black amorphous metal separated upon the negative pole.

It is stated in the second (American) edition of Classen's Quantitative Electrolysis, p. 72, that a feeble current will de posit palladium in a beautiful metallic state from an acid solution, whilst a stronger current will produce a spongy deposit.

Ludwig Schmidt has observed that from an aqueous solction of palladious nitrate, acidulated with a few drops of nitric acid, the current deposits upon the negative pole s bronze-coloured deposit, which becomes denser, darker, and finally black. At the positive pole a deposition of reddish coloured oxide occurs. In alkaline solutions the precipita tion of the metal was much retarded (vide Berg und Hutte mäunische Zeitung, xxxviii., p. 121, also Zeit. für Anna Chem., xxii., p. 240).

Messrs. Smith and Keller have experimented with the double cyanide of palladium in an excess of potassinn cyanide. They observed that there was no metallic depo until all the potassium cyanide had been converted into alkaline carbonates. The deposition was extremely rapi when a solution of palladious chloride in the presence excess of potassium sulphocyanide was used. monium chloride in ammonium hydroxide was also tried, br the precipitation of the metal was incomplete. When th platinum dishes used in the electrolysis were first costel

Palladare

JUNE 19, 1891.]

with silver, before being used, the deposition of the palladium appeared to be hastened.

The authors propose to study further the behaviour of ammoniacal palladium solutions when exposed to the action of the electric current, and an attempt will be made to redetermine the atomic weight of the metal by this method.

THE ELECTRICAL CONDUCTIVITIES OF ORGANIC ACIDS.

MONS. D. BERTHELOT, son of the Academician (Académie des Sciences), has recently been using observations on the electrical conductivity of acids in a most ingenious way, namely, in the determination of their basicity.

When an excess of acid is added to solution containing normal salts of monobasic organic acids consisting of a onehundredth of a gramme-molecule per litre, an electrical conductivity is obtained agreeing with the value calculated on the assumption that no chemical change takes place.

In the case of formic acid, as a single exception, there is a reduction of the conductivity below the value calculated.

From these facts it may be deduced that acid salts of monobasic acids do not exist in solution at the degree of dilution specified. When an excess of alkali is added there is a reduction of conductivity of about 5 per cent. for the first equivalent, but the second equivalent has practically no effect. Normal salts of bibasic acids behave differently. When an excess of acid is added the electrical conductivity is lower than the value calculated for a simple mixture, the reduction being due in this case to the formation of acid salts. But the actual values show that the acid salts undergo considerable dissociation into normal salt and free acid.

It is interesting to observe that all these results agree precisely with the conclusions deduced from thermo-chemical considerations and data.

The addition of excess of acid to normal salts of tribasic organic acids produce, as in the case of bibasic acids, an electrical conductivity lower than that calculated for a mixture of normal salt and free acid, but the effect is more prolonged than in that case owing to the existence of a second acid salt.

Berthelot has made measurements with tricarballytic, citric, aconitic and mellitic acids, these may be found in the Comptes Rendus, cxii., p. 335.

When the molecular weight of an acid is known its basicity. can be readily determined by adding successive quantities of an alkali, and then determining the point at which the reduction of the electrical conductivity below that of a mere mixture ceases. But it must be remembered that the addition of excess of alkali to the normal salts also produces a small effect which ceases with the first equivalent in excess when the acid is monobasic, with the second when it is bibasic, with the third when it is tribasic, and with the sixth when it is hexabasic.

THE FARADAY CENTENARY.

A BRILLIANT audience assembled on Wednesday afternoon at the Royal Institution to hear Lord Rayleigh deliver the first of the two lectures appointed in honour of the centenary of the birth of Michael Faraday, the second of which, to be given by Prof. Dewar, will be delivered next week. The Prince of Wales, President, was in the chair, and there were also present the Duke of Northumberland, Lord Morris, Sir G. Stokes, M.P., Sir H. Roscoe, M.P., Sir William Grove, Sir Frederic Leighton, Admiral Mayne, M.P., Sir F. Abel, Sir Frederick Bramwell (hon. secretary), the Lord Mayor and Lady Mayoress, the Dowager Lady Stanley of Alderley, Sir A. Geikie, Sir William Thomson, Dr. Meymott Tidy, Sir W. Bowman, Sir Benjamin Baker, Sir Joseph Lister, Sir F. Galton, Mr. Diggle, and Mr. Humphry Ward. The PRINCE of WALES, who was cheered as he rose, said: Ladies and Gentlemen,-I can well remember that 22 years ago I had the high privilege of presiding at a meeting here, which was a very large one, and included many of the most eminent scientific men of the day. Among those present on that occasion, I remember, were the illustrious chemist, Prof. Dumas, Sir Edward Sabine, Sir Roderick Murchison, Sir Henry Holland, a very old personal friend of mine, Dr. Bence Jones, Dr. Warren de la Rue, and many others, who, I regret to say, have now passed away. The object of our meeting on that occasion was to select a suitable memorial to the memory of the

787

great Faraday, the eminent chemist and philosopher, who, I may say, was also the founder of modern electricity. As you are all aware, the fine statue by Foley which is down in the hall below was, we thought, a suitable memorial to that great man. As for myself personally, I feel proud to think that in the days of my boyhood my brother and myself used to attend his chemical lectures here about Christmas time. We shall ever remember the admirable and lucid way in which he delivered those lectures to us, who were mere boys, and gave us thereby a deep interest in chemistry, which we kept up for many years, and which I had the opportunity of practising at the University of Oxford. I can only regret that I have not since had the time to pursue that interesting science. To-day is a memorable day, as this year we are celebrating the centenary of the birth of that great man, and I think that all of us have every reason to feel grateful that two such eminent men as Lord Rayleigh and Prof. Dewar should have consented to give lectures on the work of the great Faraday. I have only now to beg Lord Rayleigh to be so good as to give us his address.

Lord RAYLEIGH, who was received with cheers, said that the man whose name and work they were celebrating was identified in a remarkable degree with the history of that Institution. If they could not take credit for his birth, in other respects they could hardly claim too much. During a connection of 54 years, Faraday found there his opportunity, and for a large part of the time his home. The simple story of his life must be known to most who heard him. Fired by contact with the genius of Davy, he volunteered his services in the laboratory of the Institution. Davy, struck with the enthusiasm of the youth, gave him the desired opportunity, and, as had been said, secured in Faraday not the least of his discoveries. The early promise was indeed amply fulfilled, and for a long period of years, by his discoveries in chemistry and electricity, Faraday maintained the renown of the Royal Institution and the honour of England in the eyes of the civilised world. He should not attempt in the time at his disposal to trace in any detail the steps of that wonderful career. The task had already been performed by able hands. In their own "Proceedings" they had a vivid sketch from the pen of one whose absence that day was a matter of lively regret. Dr. Tyndall was a personal friend, had seen Faraday at work, had enjoyed opportunities of watching the action of his mind in face of a new idea. All that he could aim at was to recall, in a fragmentary manner, some of Faraday's great achievements, and if possible to estimate the position they held in contemporary science. Whether they had regard to fundamental scientific import, or to practical results, the first place must undoubtedly be assigned to the great discovery of the induction of electrical currents. He proposed first to show the experiment in something like its original form, and then to pass on to some variations, with illustrations from the behaviour of a model, whose mechanical properties were analogous. He was afraid that these elementary experiments would tax the patience of many who heard him, but it was one of the difficulties of his task that Faraday's discoveries were so fundamental as to have become familiar to all serious students of physics. Lord Rayleigh then illustrated the discovery, by such methods as were open to Faraday, without calling in aid the more elaborate resources of modern science. But, with all his skill, Faraday did not light upon the truth without great delay and difficulty. In December, 1824, he had attempted to obtain an electric current by means of a magnet, and on three occasions he had made elaborate, but unsuccessful, attempts to produce a current in one wire by means of a current in another wire, or by a magnet. He still persevered, and on the 29th of August, 1831, he obtained the first evidence that an electric current could induce another in a different circuit. On September 23rd he wrote to his friend, R. Phillips :-"I am busy just now again on electromagnetism, and think I have got hold of a good thing, but can't say. It may be a weed instead of a fish that, after all my labour, I may at last pull up." It proved a very big fish indeed. Lord Rayleigh then, by a series of experiments with models, indicated, as he said, with substantial accuracy, all the phenomena of electric induction. He also illustrated the operation of Prof. Clerk Maxwell's differential gearing and of Huggins's gearing, and observed that it was a remarkable achievement of modern mathematics that all the results of these different experiments could be represented by the same equation. By a series of interesting experiments he illustrated the propagation of energy across intervening space by means of dielectric rings, and explained the decomposition of water by electricity, which could not be effected solely by a single Daniell cell, but could be done with the aid of self-induction. Faraday had always felt great uneasiness as to the soundness of contemporary views, and always experienced a fear of being misled by words. Having proved the complete identity of the electricity in lightning with that in the voltaic cell, he abandoned the term "pole" for "electrode," and considered the expression "electric fluid" a dangerous one. It was, indeed, a term which, as Maxwell observed, ought to be banished to the region of newspaper paragraphs. Diamagnetism was another subject for the researches of Faraday which had been more fully developed by Sir William Thomson. Lord Rayleigh then illustrated by some beautiful experiments the magnetisation of a ray of light, the full significance of which, not fully understood by Faraday, was realised to a great extent by Sir W. Thomson. His observations in acoustics were also of great value. Faraday had made one singular remark as to a particular formation of waves generated under the action of wind, which he had himself, after patient observation for half an hour or three-quarters of an hour, verified at a French watering place. He was disposed to doubt whether anybody else save Faraday and himself had ever noticed that phenomenon. But it was one thing to have discovered, and quite another to have verified the discovery once made. The philosopher had also made a number of minor observations of great value, and he was reminded of one by a recent lamentable accident caused by the breaking of a paraffin lamp. Faraday had shown a method of holding the breath for a prolonged