Chapter VIII: BIOGRAPHY.--Franz Liszt.--Large Portrait. 4981 (3)

The merits of a brake in which electric apparatus is used, that has been adopted by one large railway company, and is about to be used on the State railways, as well as the fact that arrangements are being made to introduce it in England, demand consideration. It may be that modifications will, under different circumstances, be introduced, or that the system will ultimately be found too cumbersome or too delicate, but before criticism it is necessary to know something of the apparatus. We therefore endeavor to give somewhat in detail the arrangement adopted by M.L. Regray, chief engineer of the Chemin de Fer de l'Est, the electrical system being that of M. Achard. An electro-magnet, A, is suspended on a hinged axis, so that the poles of the magnet have for armatures cylinders of metal fixed upon the axle of the carriage. Suppose now the poles, D D, of the magnet brought into contact with the revolving armatures, the friction between them causes the magnet to revolve. The chain attached to the brake is fixed to the extended axle of the magnet, and consequently when that axle revolves is wound up, bringing the brakes upon the wheels. The friction between the poles and the armature depends upon the strength of the magnet, and this can be regulated at will from a maximum to a minimum. But it will be well to trace the whole action. The electric current may be obtained by means of Planté secondary cells charged by Daniell's cells--in other words, one or two Daniell's cells are constantly in action charging three or six Planté cells, and it is the Planté cells that are called into action to electrify the magnet. The battery is carried in a box in the brake van. The engineers, however, seem to prefer that the current be obtained by means of a small Gramme machine, driven direct by a Brotherhood three-cylinder engine, the steam for which is obtained from the locomotive. The velocity and hence the current of the Gramme machine can be regulated, and so the action of the brakes. M. Achard prefers the Planté cells; he informs us that he has tried the Faure battery, but the results obtained were not satisfactory. The regulator, R², consists of a cylinder of wood around which, as shown, wire is wound. The length of this wire in the circuit, increasing as it does the resistance of the circuit, determines the current to the electro-magnet. The action is as follows: When it is necessary to apply the brakes, a simple pressure of a key or the turn of a handle sends the electric current into the wires of the electro-magnet. An attraction immediately takes place, and the poles and armatures are brought into contact. The friction between these causes the revolution of the magnet, the winding of the chain around the axle, and the application of the brakes. The whole of the brakes of the train enter into action at one and the same time. The brakes are taken off by stopping the current, and a small spring pulls and keeps the magnet from the armatures. A frame--also carriages--fitted with this brake, are shown by the Compagnie des Chemins de Fer de l'Est, which company also shows several other pieces of interesting apparatus, one of which is a carriage fitted with elaborate mechanism, in which electricity plays, perhaps, but a subsidiary part, to obtain the traction of the train under varying circumstances, the pressure on the buffers when stopping, and various phenomena connected with the engine.--_The Engineer._

* * * * *

ELECTRICITY; WHAT IT IS, AND WHAT MAY BE EXPECTED OF IT.[1]

[Footnote 1: A paper read before the Engineers' Society of
Western Pennsylvania, Nov. 15, 1881.]

By JACOB REESE

In the consideration of this subject it is not my purpose to review the steps of discovery and development of electrical phenomena, but the object of this paper is an effort to explain what electricity is; and having done this, to deduce some reasonable conclusions as to what may be expected of it. And while I am profoundly sensible of the importance of the subject, and the difficulties attending its consideration, still with humble boldness I present this paper and ask for it a serious and careful consideration, hoping that the discussion and investigation resulting therefrom may add to our knowledge of physical science.

It is now a well established fact that matter, _per se_, is inert, and that its energy is derived from the physical forces; therefore all chemical and physical phenomena observed in the universe are caused by and due to the operations of the physical forces, and matter, of whatever state or condition it may be in, is but the vehicle through or by which the physical forces operate to produce the phenomena.

There are but two physical forces, i.e., the force of attraction and the force of caloric. The force of attraction is inherent in the matter, and tends to draw the particles together and hold them in a state of rest. The force of caloric accompanies the matter and tends to push the particles outward into a state of activity.

The force of attraction being inherent, it abides in the matter continuously and can neither be increased nor diminished; it, however, is present in different elementary bodies in different degrees, and in compound bodies relative to the elements of which they are composed.

The force of caloric is mobile, and is capable of moving from one portion of matter to another; yet under certain conditions a portion of caloric is occluded in the matter by the force of attraction. That portion of caloric which is occluded (known by the misnomer, latent heat) I shall call _static caloric_, and that portion which is in motion, _dynamic caloric_.

The force of attraction, as I have said, tends to draw the particles of matter together and hold them in a state of rest; but as this force is inherent, the degree of power thus exerted is in an inverse ratio to the distance of the particles from each other. The effective force so exerted is always balanced by an equivalent amount of the force of caloric, and that modicum of caloric so engaged in balancing the effective force of attraction is static, because occluded in that work.

In solid or fluid bodies, where the molecules are held in a local or near relation to each other, the amount of static caloric will be in direct proportion to the effective force of attraction, but in gaseous bodies the static caloric is in an inverse ratio to the effective force of attraction; hence the amount of static caloric present in solid and fluid bodies will be greatest when the molecules are nearest each other, and greatest in gaseous bodies when the molecules are furthest apart.

Caloric, whether static or dynamic, is not phenomenal; therefore the phenomena of light, temperature, incandescence, luminosity, heat, cold, and motion, as well as all other phenomena, are due to the movement of matter caused by the physical forces. Thus we find that _temperature is a phenomenal measure of molecular velocity_, as we consider weight to be the measure of matter.

An increase of temperature denotes an increased molecular velocity, and this in solid and liquid bodies unlocks a portion of the static caloric and converts it into dynamic caloric, while an increased temperature of gases occludes additional caloric, thus converting dynamic into static caloric; and a reduction of molecular activity reverses this action. From this we see that a change of temperature either converts static to dynamic or dynamic to static caloric.

Thus we find that the amount of static caloric which a body possesses is in direct relation to its temperature, but, as I have already explained, temperature is a phenomenal indication of molecular velocity, and as increased velocity separates the molecules to a greater distance, which reduces the effective force of attraction and unlocks a portion of caloric, it will be seen that the separation of the molecules from any other cause will have the same effect. I desire now to explain a second method by which the molecules are separated and static caloric is changed to dynamic caloric.

It is not definitely known how much static caloric is occluded in either of the elementary bodies, but it is believed that hydrogen possesses the greatest amount and oxygen the least. Now if we take a molecule of hydrogen containing two atoms, and under proper conditions interpose these atoms between 16 atoms of oxygen (one molecule), the phenomenon of combustion is exhibited, and a molecule of water is formed containing 18 atoms; and if one pound of hydrogen is thus consumed, the atoms of hydrogen are separated from each other to such a distance by the interposing atoms of oxygen as to unlock 34,662 units C. of static, and convert it into dynamic caloric. And if we thus bring a molecule of carbon containing 12 atoms in contact with a molecule of oxygen of 16 atoms, combustion ensues and a molecule of carbonic oxide of 28 atoms is formed, and if we then present another molecule of oxygen, combustion again takes place, and a molecule of carbonic acid, containing 44 atoms, is produced. Now, in the combustion of one pound of carbon in this manner, when the carbon is converted into carbonic oxide (CO), 2,473 units C. of static is converted into dynamic caloric; and when this CO is converted into carbonic acid (CO_{2}) 5,607 additional units C. are unlocked. Thus by the combustion of one pound of carbon to CO_{2}, 8,080 units C. of static caloric are changed to dynamic caloric.

When caloric is thus unlocked from its occlusion it escapes with great velocity until an equilibrium is attained, and in doing so it pushes the particles of matter out of its path. In solid bodies this produces such a high degree of molecular movement as to exhibit the phenomena of incandescence and luminosity, and in liquids increased mobility, while in gases the molecular activity may be so great as to produce the phenomena of sound and light; and the more rapidly combustion takes place the greater will be the volume and velocity of dynamic caloric escaping therefrom; consequently with a slow combustion, the phenomena produced by dynamic caloric will be different from those exhibited at a high degree.

Combustion, as I have before shown, is merely the oxidation of the material; nothing is _consumed_ nor annihilated, and, the phenomena vary with the velocity of oxidation. Now, if we take one pound of zinc and place it in the acid cell of an electric battery, the oxygen of the acid attacks the zinc and oxide of zinc is formed. In this operation the Zn molecule containing 65 atoms is united with one molecule of oxygen of 16 atoms, forming a molecule of oxide of zinc (ZnO) of 81 atoms; and owing to the comparatively small number of oxygen atoms interposed between the 65 atoms of zinc, only 1,301 units C. of static caloric are unlocked to the pound of zinc, and the velocity of oxidation is so low, and the insulation of the vessel so perfect, that the dynamic caloric is caused to flow outward through the copper wire.

ELECTRICITY.--What is it? Why, it is dynamic caloric. Now let us take this oxide of zinc (ZnO) and place it with charcoal in a reducing apparatus which stands on an insulated table; the apparatus is then heated, the carbon vaporizes, and this vapor of carbon (C) robs the oxide of zinc (ZnO) of its oxygen, leaving metallic zinc (Zn) and carbonic oxide (CO). Now, for every pound of zinc so formed 1,301 units C. of static caloric are transferred from the charcoal to the zinc and occluded in it. Hence we find that the 1,301 units C. of caloric which we took out of the zinc, and which we call electricity, is nothing else but the 1,301 units of static caloric which was contained in the charcoal and from it set free by oxidation and transferred to the zinc in the smelting process. Let us follow this matter a little further. Charcoal is made by burning wood under such conditions as eliminate the water and hydrogen and leave the carbon as a residuum which we call charcoal. Thus we find that the caloric contained in the charcoal, transferred from the charcoal to the zinc, and from it developed into what we call electricity, was previously embodied in the wood; and if we study the laws of vegetation, we find that the atmosphere being charged with carbonic acid (CO_{2}), the leaves of plants, shrubs, and trees, breathing, take in the CO_{2}, the sun rays decompose the CO_{2}, set free the oxygen, and supply the necessary amount of caloric for the condensed state of the carbon. Thus we find that the force which we term electricity, developed from the oxidation of zinc, or any other matter, by oxidation, primarily comes from the sun rays.

Coal is generally supposed to be of vegetable origin, and the caloric occluded in it is derived from the same source as that embodied in charcoal. Now when we burn coal under a steam boiler, the carbon and hydrogen are oxidized, and the static caloric set free. A portion of this caloric passes through the shell or tubes of the boilers, and increases the molecular velocity of the water; increased activity of the molecules tends to separate them to a greater distance from each other. When the molecular velocity of the water acquires the degree indicated by a temperature of 212 degrees F., the water passes from the fluid to the gaseous state, and in doing so expands to 1,696 times its bulk. Now if the steam so developed be confined under a pressure of 105 pounds to the square inch, the water will not vaporize until a molecular velocity is attained indicated by a temperature of 312° F. (Spons' "Engineering," D2, page 418), and then the expansion is only 253 times its bulk. By using this steam, in a steam engine, the caloric in the steam tends to push the molecules of which it is composed into an ultimate expansion of 1,696 times the bulk of the water from which it was generated, and this force acts upon the piston and does the work. Thus we see that the steam engine is driven by the same force which produces the phenomena accredited to electricity.

I have already shown that in what we term combustion not a particle of the ponderable matter is annihilated. Combustion is but a phenomenon resulting from a rearrangement of the particles, and so it is with the imponderable physical force caloric; it is not consumed when light and heat are produced, nor converted into power, as we are sometimes told. But whatever the phenomena produced, the aggregate amount of static and dynamic caloric is always and ever the same.

If we consider the Ritter-Plant-Faure-Battery, which is mentioned as storing electricity, we find that the phenomena exhibited by the use of this apparatus are produced by the same factor. The battery is composed of two sheets of lead, which are covered with a layer of minium (Pb3O4). The sheets are laid one upon the other with an intervening layer of felt. The pack is then rolled up in a spiral form and placed in a vessel containing acidulated water. One of the plates is connected with the positive, and the other plate with the negative pole of a battery or generator.

When the current of electricity enters the battery, the Pb3O4 on the positive plate is reduced to Pb, and the oxygen so set free attacks the Pb3O4 on the negative plate, and oxidizes it to PbO2. In this chemical action, caloric is occluded in the Pb and unlocked in the PbO2, but a much greater amount of caloric is locked up than is unlocked, although the amount of oxygen used in both cases is precisely the same, which has been fully explained in the oxidation of carbon.

Now after the battery has been thus charged and the wires disengaged, the chemical action ceases for want of the reducing agent (_dynamic caloric_), and the apparatus may be held at rest, or transported to any distance required. When it is desired to utilize the force thus stored, the poles are changed by grounding the positive wire, and attaching the other to the conduit through which the electricity is to flow. The chemical action is thus reversed, and the PbO2 is reduced to Pb3O4, the oxygen thus set free attacks the Pb on the other plate, oxidizing it to Pb3O4, thus unlocking all the caloric which was occluded by the first action. In a battery of this kind weighing 75 pounds, we are informed by Sir William Thomson, that one million foot pounds of force may be stored, and again set free for use.

Thus we find that the principle upon which the Faure battery is formed is not new, and the prime factor producing the phenomena is the same as has been shown to have caused all other phenomena referred to, and indeed the principle is the same as now employed by the author in the basic dephosphorizing process, i.e., caloric is occluded in phosphorus by smelting in a blast furnace, and unlocked in the converter, for the purpose of securing the fluidity of the metal during treatment. The difference being, that one is done by non-luminous, while the other is by luminous combustion.

If we consider the phenomenon of light, we find that it is due to the same force. As before stated, when we oxidize carbon, or hydrogen, as in the rapid combustion of wood, oil, or coal, the escaping caloric flies off with such great speed as to cause the molecules in the circumambient medium to assume a velocity which exhibits luminosity. Thus the light produced by burning candles, oil, gas, wood, and coal, is caused by the same prime factor, dynamic caloric.

The force of caloric is imponderable and invisible, and is only known by its effects. We do know that it is occluded in metals and other material, because we can unlock it and set it free, or we can transfer it from one body to another, and by measuring its effects, we can determine its quantity. We know that it prefers to travel over one vehicle more than another, and by this knowledge we are able to insulate it, and thus conduct it in any direction desired. The materials through which it passes with the greatest freedom are called conductors, and the materials which most retard its passage, non-conductors; but these terms must be taken in a comparative sense only, as in fact there are no absolute non-conductors of dynamic caloric, or of what we call electricity.

The dynamo-electric generator simply draws the dynamic caloric from the air or earth, or both, and confines it in an insulated path. Now if that path be a No. 10 wire, the conduit may be sufficient to permit the caloric to pass without increasing the molecular velocity of the metal to an appreciable degree, but if we cut the No. 10 wire and insert a piece of No. 40 platinum wire in the path, the amount of caloric flowing through the No. 10 wire cannot pass through the No. 40 wire, and the resistance so caused increases the molecular velocity of the No. 40 wire to such degree as to exhibit the phenomenon of incandescence, and this is the incandescent electric light. And if we consider the carbon light, we find that the current of caloric, in passing from one pencil to the other, produces a molecular velocity of luminosity in the adjoining atmosphere, and in addition a portion of the carbon is consumed, which sets free an additional amount of caloric, at a very high velocity, hence the intensity of the carbon electric light is largely due to the dynamic caloric unlocked from the pencils, and thus we find that the electric light produced by either method is due to the action of dynamic caloric.

Taking this theory based upon physical science, and the facts which we know pertaining to electricity, I conceive that caloric exists in two conditions. _Static caloric_ is what we call _latent heat_, and _dynamic caloric_ is what we call _electricity_. Therefore what may we expect of it (electricity) is merely a matter of economy in the development and utilization of dynamic caloric; in other words, can we unlock static caloric by non-luminous combustion, and thus develop _dynamic caloric as a first power_ more economically per foot pound than we now do or can hereafter do by luminous combustion? Second, can we utilize water and wind for the production of _dynamic caloric as a first power_? Third, can we utilize the differential tension of dynamic caloric in the earth and the atmosphere as _a first power_? Fourth, will it pay to use luminous combustion as a first power to generate dynamic caloric as _a second power_?

WHAT MAY WE EXPECT OF IT.

Let us take the steam engine, and see what we are now doing by luminous combustion. Good Pittsburg coal contains 87 per cent. of carbon, 5 per cent. of hydrogen, 2 per cent. of oxygen and 6 per cent. of ash; we therefore have in one pound of such coal:

8,080 × 9 14,544 × 87
--------- = ----------- = 12,653 units in carbon.
5 100

34,662 × 9 62,391 × 5 3,119 units in hydrogen.
---------- = ---------- = ------
5 100 15,772 units in coal.

15,772 × 772[2] = 12,175,984 foot pounds of energy is occluded in the static caloric contained in one pound of such coal.

[Footnote 2: Dr. Joule--foot pounds in one unit.]

A horse-power is estimated as capable of raising 33,000 pounds one foot high per minute, and for this reason it is termed 33,000 foot pounds per minute. So we have 33,000 × 60 = 1,980,000 foot pounds per hour, as a horse-power.

The best class of _compound condensing_ engines,[3] with all the modern improvements, require 1.828 pounds of coal per 1 h.p. per hour. Thus we have--

12,175,984 × 1.828 .................22,257,699
Foot pounds in one h.p. .............1,980,000
----------
Foot pounds lost per h.p. ..........20,277,699

Per cent utilized per h.p. ..............8.94
Per cent lost per h.p. .................91.06
------
100.00

[Footnote 3: "American Engineer," Vol. II., No. 10, page 182.]

In the ordinary practice of stationary non-condensing engines, from three to four pounds of coal are required per horse-power per hour. Now, taking the best of this class at 3 pounds, we have--

12,175,984 × 3 = 36,527,952
One h.p. 1,980,000
----------
Loss per h.p. 34,547,952

Per cent utilized per h.p. 5.42
Per cent lost per h.p. 94.58
------
100.00

From these facts it may be assumed that after making due allowance for variable qualities of the coal, the steam engine process, as at present practiced, will not utilize more than from 5 to 10 per cent. of the energy contained in the fuel used. It will thus be seen that the process of converting static to dynamic caloric by luminous combustion, by means of the steam engine, is an exceedingly wasteful and costly method, and leaves much room for economy.

Taking an ordinary grade of petroleum as consisting of 13 per cent. hydrogen, 78 carbon, 6 oxygen, 3 nitrogen and ash, we have as its energy in foot pounds per pound of oil--

62,391 × 13 }
----------- = 8,110 H. }
100 }
} 19,454 units.
14,544 × 78 }
----------- = 11,344 C. }
100 }

19,454 × 772 = 15,018,488 foot pounds. Thus, while our best coal contains twelve million, the petroleum contains fifteen million foot pounds of occluded energy in each pound, which is equal to 118,000,000 foot pounds, or 60 horse power for one hour, from one gallon of such oil.

At present electricity is generated by two methods, and both of these are _second powers_. Metals are smelted by luminous combustion as a first power, and then oxidized by non-luminous combustion as a _second power_, and coal is consumed by luminous combustion, by which steam is generated as a first power, to drive a dynamo-generator whereby electricity is obtained as a _second power_. Now, of the two methods, the latter is much the cheaper, and as I have shown that the best compound condensing engines only utilize 8.94, and a fair average single cylinder condensing engine only utilizes 5.42 per cent. of the energy of the fuel consumed, and as at the best not over 70 per cent. of the foot pounds obtained from the engine can be utilized as electricity, from which we must deduct loss by friction, etc., it will be readily seen that not more than 5 per cent. of the energy of the fuel can be developed by the dynamo-generator as electricity by the present method.

The great want of the present age is a process by which the static caloric of carbon or a hydrocarbon maybe set free by non-luminous combustion; or, in other words, a process by which coal or oil may be oxidized at a low degree, within an insulated vessel; if this can be accomplished (and I can see no reason why we should not look for such invention), we would be able to produce from twelve to fifteen million foot pounds of energy (electricity) from one pound of petroleum, or from ten to twelve million foot pounds from one pound of good coal, which would be a saving of from 90 to 95 per cent. of present cost, and leave the steam engine for historical remembrance.

Electricity may be generated by water or wind power to great advantage, and conveyed to a distance for motive power. The practicability of generating electricity at Niagara by which to propel trains to New York and return may be considered almost settled; and I conceive a second invention of importance which is now needed is an apparatus by which the rising and falling tides may be utilized for driving dynamo machines, by which electricity may be generated for lighting the coast cities, and it is not unreasonable to expect that such an apparatus will soon be provided; and in such an event gas companies would suffer.

It is a well known fact among electricians that the volume and tension of electricity vary both in the earth and in the atmosphere at different sections of the earth's surface, and I conceive that we may yet find means of utilizing this differential tension of electricity; indeed, it is reported that during a recent storm the wires of an ocean cable were grounded at both ends and a sufficient current for all practical purpose flowed from the European to the American continent, with all batteries removed, showing that the tension was so much greater in Europe as to cause the electricity to flow through the copper cable to this side in preference to passing through the earth or the sea. It is also said that during an east-going storm it was found impossible to work the telegraph lines between New York and Buffalo, but on taking off the batteries at both ends and looping the ends of the wire in the air, that a constant current of electricity passed from Buffalo to New York, and the line was kept in constant use in that direction without any battery connection until the storm abated. Now, how far or to what advantage we may be able to utilize this differential tension of electricity in the earth and the air, we cannot now say; but I think that we may justly look for valuable developments in this direction.

If, as I verily believe, a process will soon be discovered by which dynamic caloric can be produced by the oxidation of petroleum with non-luminous combustion in an insulated chamber, as we now oxidize zinc, electricity will then be obtained from so small a weight, and at such a low cost, as to insure aerial navigation beyond a doubt. Not with balloons and their cumbrous inflations, but with machines capable of carrying the load, and traveling by displacement of the air at high velocities. Therefore we may expect that aerial navigation will be developed in the near future to be one of the greatest enterprises of the world.

And lastly, will it pay to use luminous combustion as a first power for generating dynamic caloric for use as a second power, as is now practiced?

At the University of Pennsylvania, in Philadelphia, gas is consumed in an Otto gas engine, which drives a Gramme generator; and the lecture room is lighted with electricity, and I am informed that the light is both better _and cheaper_ than when they used the gas in the ordinary gas burners. Hence we may expect to see gas consumed to advantage for producing electric lights.

Considering the difficulties of transmitting steam power to a considerable distance, and the comparative great cost of running small engines, it is more than likely that electricity as at present generated will be found to be economical for driving small motors.

Having thus endeavored to explain what electricity is, and the laws which govern the occlusion of static caloric, and the development of dynamic caloric (electricity), in conclusion I call the attention of the inventors of the age to the great need of a process for oxidizing coal or oil at a low degree, within an insulated vessel. With such an invention electricity would be obtained at such a low cost that it would be used exclusively to light and heat our houses, to smelt, refine, and manipulate our metals, to propel our cars, wagons, carriages, and ships, cook our food, and drive all machinery requiring motive power.

* * * * *

ELECTRIC LIGHT APPARATUS FOR PHOTOGRAPHIC PURPOSES.

By A.J. JARMAN.

For some time past it has been the desire of many photographers to have at hand a ready means of producing a powerful and highly actinic artificial light, suitable for the production of negatives, and easily controllable. Several forms of apparatus have been designed, and I believe have been, to a certain extent, employed successfully in portraiture. But it has been well known for many years that the electric light was just the light that would answer the photographer's requirements, owing to its possessing great actinic power; but the cost of its production was too great for general adoption; indeed, such might be said of it now as far as dynamo-electric machines and steam or gas motors are concerned, for the majority of photographers. It is true that several influential photographers have already adopted the use of the electric light for portraiture, but the primary cost of the apparatus employed by these firms is far beyond the reach of most portraitists. The apparatus about to be described is one that has been carefully worked out to meet the wants of the photographer in almost every particular; in fact, with this apparatus, portraits can, and have been, produced in an ordinary sitting room, as good and as perfect as if taken in a well-lighted studio.

The generator of the electric current consists of a series of voltaic elements of zinc and carbon--forty-eight in number--these elements being made up of ninety-six zinc plates and forty-eight carbon plates; thus the generator consists of forty-eight voltaic elements arranged in rows of twelve; they are all carefully screwed upon suitable bars of wood, and these bars are joined by other cross bars, which bind the whole in a compact form; the battery being suitably connected so as to produce a current of very high electro-motive force, and so arranged over their exciting trough that the plates can be raised or lowered at will, as seen in Fig. 1, which will explain itself almost at first sight.

The troughs are made of mahogany, put together with brass screws, and well saturated with an insulating compound which also makes them acid proof; the cells are charged with a saturated solution of bichromate of potash, to which has been added twenty fluid ounces of sulphuric acid to each gallon.

To produce the electric current, all that is needed is to lower these suspended elements down into the trough, having previously connected the wires as shown in Fig. 1, to the electric lamp, Fig 2. At once a light starts up, between the carbon pencils, of a thousand-candle power or more. With a light of this power, a large head on cabinet or carte size plate may be produced in three or four seconds.

The generator occupies a floor space of three feet six inches by two feet, and stands two feet six inches high. The cells will cost 5s. to charge, and will produce upward of sixty negatives before being exhausted. All that is necessary, in recharging, is to lift the elements up out of the way, take out the troughs by their handles and empty them, charging them again by means of a toilet jug. When replaced, the whole apparatus is fit for use again; the whole of the above operation occupies but a quarter of an hour, and as there are no earthenware cells employed, there is no fear of breakage.

The small amount of labor and cost of working the above apparatus will compare favorably with the production of the electric light from a dynamo-electric machine for the photographer, and when we consider that the cost of the whole of the above apparatus, consisting of a generator automatic lamp, reflector, and all the necessary appendages, is less then one-tenth of the dynamo machine, motor, shafting, etc., to produce the same result, it would seem to have a greater claim for its adoption with those who wish to employ the electric light, whether for work at night, use in the sitting room, or to assist daylight on the dark and foggy days of winter.

Fig. 2 shows the arrangement of the electric lamp. A is the automatic regulator; B, the reflector; C, top extension of the reflector; D, small tissue paper screen to prevent the intense arc-rays from coming in contact with the sitter; E, stand with sliding rod. This appendage can be wheeled about with ease, as it is arranged to run upon four casters.

When the generator is in use it may be placed within easy reach of the operator, so that the exposure may be made by lowering the elements in their troughs just for the requisite time, and withdrawing immediately the exposure is made; there is no need to fear any inconvenience from deleterious fumes as none are given off, so it may be used in any studio or sitting-room without any inconvenience from this source, and as far as many trials have gone, it seems to meet every requirement demanded by the photographer for the production of portraits by means of the electric light.--_Photo. News._

* * * * *

DESRUELLES'S ELECTRIC LIGHTER

The little apparatus shown in the accompanying cut will certainly find favor with smokers, as well as with persons generally who often have need of a fire or light. It forms one of the most direct applications of dry piles of all the systems on the Desruelles plan. Instead of filling piles with a liquid, this plan contemplates the introduction into them of a sort of asbestos sponge saturated with an acid or any suitable solution. In this way there is obtained the advantage of having a pile which is in some sort _dry_, that may be moved, shaken, or upset without any outflow of liquid, and which will prove of special value when applied to movable apparatus, such as portable lighters, alarms on ships, railroads, etc. It is hardly necessary to say that while the introduction of this inert substance diminishes the volume of the liquid, the electro-motive force of the pile is thereby in nowise affected, but its internal resistance is increased. This, however, is of no consequence in the application under consideration. The lighter consists of a small, round, wooden box containing the pile, and surmounted by a spirit lamp. A platinum spiral opposite the wick serves for producing the light. The pile is a bichromate of potash element, in which there is substituted for the liquid a solution of bichromate identical with that used in bottle piles. The zinc is suspended from a small lever, in which it is only necessary to press slightly to bring the former in contact with the asbestos paste, when, the zinc being attached, a current is set up which traverses the spiral, heats it to redness, and lights the spirit. The pile, when once charged, may be used for several hundred lightings. When the spiral no longer becomes red hot, it is only necessary to replace the paste--an operation of extreme simplicity. When the pressure is removed from the little lever, the zinc, being raised, is no longer acted upon by the liquid with which the asbestos is saturated. Mr Desruelles is constructing upon the same principle a gas lighter, the pile of which is fixed at the extremity of a handle whose length varies with the height of the gas burners to be reached. These little domestic apparatus are being exhibited at the Paris Electrical Exhibition.

* * * * *

SOLENOID UNDERGROUND WIRES IN PHILADELPHIA.

The _Evening Bulletin_ of the 29th October has the following:

This afternoon a series of experiments were conducted at the Public Buildings which will be of great interest to electricians all over the country, and upon which the success of a number of underground telegraph projects in different parts of the United States depends. In all projects of this kind the problem which has given most trouble to inventors has been to overcome the induction. In other words, electric currents will leave their original conductors and pass to other conductors which may be near at hand. This interchange of currents may take place without seriously hindering ordinary telegraphy, as the indicators are not delicate enough to detect the induction. When telephones came into use, however, the induction became a great source of trouble to electricians, it often being the case that the sounds and influences from without were sufficient to drown out sounds in a telephone. To-day's experiment was conducted by Mr. J.F. Shorey, a well-known electrician, who exhibited Dr. Orazio Lugo's cables for electric light, telephone, and telegraphic purposes.

A large number of prominent electricians were present, including the following: General J.H. Wilson, President of the N.Y. and N.E. Railroad, of Boston; Messrs. Frank L Pope, S.L.M Barlow, George B. Post, Charles G. Francklyn, Col. J.F. Casey, W.H. Bradford, and Selim R. Grant, of New York; James Gamble, General Manager of the Mutual Union Telegraph Co.; T.E. Cornich and W.D. Sargent, of the Bell Telegraph Co.; S.S. Garwood and J.E. Zeublen, of the Western Union, and others.

The principal tests were made through the conduits on Market Street, laid by the National Underground Electric Company as far as Ninth Street. A cable of five conductors was laid through the conduit. Two of these conductors consisted of simple "circuit wires," while the other three were what is known as "solenoids." A solenoid wire is a single straight wire, connected at each end with and wound closely around by another insulated wire, this forming a complete system, the electric currents returning into themselves. Electricians claim that the solenoid effectually overcomes all induction, and this afternoon experiments were made for the purpose of proving that assertion. In the telephones, connected by the ordinary wires, a constant burr and click could be heard, that sound being the induction from the wires on the poles on Market Street, sixty feet overhead. With the solenoid the only sound in the telephones was the voices of the persons speaking. The faintest whispers could be heard distinctly, and the ease and comfort of conversation was in marked contrast to the other telephone on the ground wires. A set of telegraph indicators was also attached to the wires in use in the cable. The sounds were transferred from one "ground wire" to the other, while the solenoids seemed to resist every influence but that directed upon them by the operators. Another interesting test was made. The electric current for a Hauckhousen lamp was passed through a long coil of solenoid wire. Separated from this coil by a single newspaper, lay a coil of wire attached to telephones, yet not a sound could be heard in the telephones but the voices of the persons using them. The current of electricity created by a dynamo-electric machine is of necessity a violent one, and in the use of ordinary wires the induction would be so great that no other sounds could possibly be heard in the telephones.

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DR. HERZ'S TELEPHONIC SYSTEMS.

In an article by Count du Moncel, published in SCIENTIFIC AMERICAN SUPPLEMENT, No 274, page 4364, the author, after describing Dr. Herz's telephonic systems, deferred to another occasion the description of a still newer system of the same inventor, because at that time it had not been protected by patent. In the current number of _La Lumière Electrique_, Count Moncel returns to the subject to explain the principles of these new apparatus of Dr. Herz, and says:

I will first recall the fact that Dr. Herz's first system was based upon the ingenious use (then new) of derivations. The microphone transmitter was placed on a derivation from the current going to the earth, taken in on leaving the pile, and the different contacts of the microphone were themselves connected directly and individually with the different elements of the pile. The telephone receiver was located at the other end of the line, and when this receiver was a condenser its armatures were, as a consequence of this arrangement, continuously and preventively polarized, thus making it capable of reproducing conversation.

This arrangement evidently presented its advantages; but it likewise possessed its inconveniences, one of the most important of these being the necessity of employing rather strong piles and consequently of exposing the line to those effects of charge which react in so troublesome a manner in electrical transmissions when they occur on somewhat lengthy lines. Now the fact should be recalled that Dr. Herz's principal object was the application of the telephone to long lines, and he has been applying himself to this problem ever since. He at first thought of employing reversed currents, as in telegraphy; but how was such a result to be attained with systems based upon the use of sonorously-vibrating transmitters? He might have been able to solve the problem with the secondary currents of an induction bobbin, as Messrs. Gray, Edison, and others had done; but then he would no longer have been benefited by those amplifications which are furnished by the variations of pressure-derivations in microphones, and this led him to endeavor to increase the effects of the induced currents themselves by prolonging their duration, or rather by combining them in such a way that they should succeed each other, two by two, in the same direction; and this is the way he solved the problem in the beginning.

The fact should also be recalled that Dr. Herz had, from his first experiments, recognized the efficiency of those microphonic contacts that are obtained by the superposition of carbon disks or other semi-conducting substances. He has employed these under different arrangements and with very diverse groupings, but, as a general thing, it has been the horizontal arrangement which has given him the best effects.

Let us suppose, then, that four systems of contacts of this nature are arranged at the four corners of an ebonite plate, C C (Figs. 1 and 2), at A, A¹, B, B¹, and that they are connected with each other, as shown in the cuts--that is to say, the upper disks, _e_, _f_, _g_, _h_, parallel with the sides of the plate, and the lower disks, A, A¹, B, B¹, diagonally. Let us admit, further, that the plate pivots about an axis, R; that the disks are traversed by small pins fixed in the plate; and that small leaden disks rest upon the upper disks. Finally, let us imagine that the plate is connected at one end, through a rod T, with a telephone diaphragm. Now it will be readily understood that the vibrations produced by the diaphragm will cause the oscillation of the plate, C C, and that there will result therefrom, on the part of the disks, two effects that will succeed one another. The first will be, for the ascending vibrations, an increase of pressure effected between the disks of the left side, by reason of their force of inertia being increased by that of the lead disks; and the second will be, for the disks to the right, and, for the same reason, a reduction of pressure which will take place through resilience, at the moment of change in direction of the vibrating motions.

If the current from a pile, P, traverses all these disks, through the connections that we have just mentioned, and passes through the primary helix (through the wire, I) of an induction coil H H' (Fig. 2), located beneath the apparatus, and if the secondary current from this bobbin corresponds, through the wire I, with a telephone line in which there is interposed a telephone or a speaking condenser, there will be set up an inverse induced current, which, being reversed as a consequence of the crosswise connections of the disks, will continue the action of the first or increase its duration, and, consequently, its force, through the telephone receiver.

The results of this system are very good; but Dr. Herz has endeavored to simplify it still further, and with this object in view has experimented on several arrangements. For example, to obtain inversion a contact was simply placed on each side of the vibrating plate. Although the movements of this latter are not, as we know, of the nature of ordinary sonorous vibrations, it was thought that they might prove to be in opposite directions on the two sides of the plate, and that one of the contacts might be compressed while the other was free. So notwithstanding the advantages of this arrangement, it was thought necessary to place the plate vertically in order to give the same regulation to the two contacts which it is essential should be identical. But it became difficult to regulate by weight; and even to succeed in regulating at all, it became necessary to employ two parallel diaphragms, vibrating in unison, and each carrying its contact, but in opposite directions. Afterwards, the horizontal arrangement was again adopted; but, by a clever combination, the two principles applied by Dr. Herz--derivation and inversion--were united. The current is then led to a double contact, where it divides. This contact is arranged under the plate in such a way that its two points of variable resistance act in opposite directions to each other, or, in some apparatus, so that one of the points has no variation, while the other is in action. The result that occurs may be easily imagined. The system has been experimented with under different forms; in one case the derivation is simple, that is, a single one of the currents being sent into the line, while in another case it is double, each of the branches being provided with a bobbin and communicating with the receiver. In the latter case the result is remarkably good, but the apparatus is not free from a certain amount of complication, and demands, moreover, particular care in its construction, experience having shown that the induction coils must not be equal, but that they must present resistances combined according to the circuit doing duty. It should be added that researches have been continued as to the bodies proper to be employed as microphonic contact, with the result of bringing out the important fact that the number of substances that can be put to this use is almost unlimited. The contacts of the Herz apparatus are now being made of conducting bodies (metals for example) reduced to powder and conglomerated by chemical means with a sort of non-conductive cement. The proportion of the elements depends upon the conductivity of the materials employed, and it alone determines the microphonic value of the compound, the nature of the elements apparently having scarcely any influence.

Nor has the speaking condenser been neglected. As regards this, efforts have seemingly been made toward finding a convenient arrangement and a regular mode of construction, the good working of these apparatus being absolutely dependent upon the care with which they are set up.

In Dr. Herz's opinion, the telephone is not to remain a single apparatus, varied only as to form, but, on the contrary, must be actually modified according to the purposes for which it is designed. He thinks that a telephone operating at great distances must differ from a city apparatus, and that an instrument for transmitting song can not be absolutely the same as one for conversational purposes. So he has endeavored to create types that shall prove appropriate for these different applications.

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DECISION OF THE CONGRESS OF ELECTRICIANS ON THE UNITIES OF ELECTRIC MEASURES.

For these measures there are adopted the fundamental unities--centimeter, gramme, second, and this system is briefly designated by the letters C., G., S. The practical units, the _ohm_ and the _volt_, will retain their present definitions; the ohm is a resistance equal to 10^{9} absolute unities (C., G., S.), and the volt is an electromotive force equal to 10^{8} absolute unities (C., G., S.). The practical unit of resistance (ohm) will be represented by a column of mercury of 1 square mm. in section at the temperature of 0°C. An international commission will be charged with ascertaining for practice, by means of new experiments, the height of this column of mercury representing the ohm. The name _ampère_ will be given to the current produced by the electromotor force of 1 volt in a circuit whose resistance is 1 ohm. _Coulomb_ is the quantity of electricity defined by the condition that in the current of an ampère the section of the conductor is traversed by a coulomb per second. _Farad_ is the capacity defined by the condition that a coulomb in a condenser, whose capacity is a farad, establishes a difference of potential of a volt between the armatures.

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SECONDARY BATTERIES.

By J. ROUSSE.

In order to accumulate electricity for the production of light or motive power, the author has arranged secondary batteries, which differ from those of M.G. Planté. At the negative pole he uses a sheet of palladium, which, during the electrolysis, absorbs more than 900 times its volume of hydrogen. At the positive pole he uses a sheet of lead. The electrolyzed liquid is sulphuric acid at one tenth. This element is very powerful, even when of small dimensions. Another secondary element which has also given good results, is formed at the negative pole of a slender plate of sheet-iron. This plate absorbs more than 200 times its volume of hydrogen when electrolyzed in a solution of ammonium sulphate. The positive pole is formed of a plate of lead, pure or covered with a stratum of litharge, or pure oxide, or all these substances mixed. These metallic plates are immersed in a solution containing 50 per cent. of ammonium sulphate. Another arrangement is at the negative pole, sheet-iron; at the positive pole a cylinder of ferro-manganese. The electrolyzed liquid contains 40 per cent. ammonium sulphate.

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THE TREATMENT OF QUICKSILVER ORES IN SPAIN.

Though known from remote times, the date of the first opening of the famous mines of quicksilver of Almadén has not been precisely determined. Almost all the writers on the subject agree that cinnabar, from Spain, was already known in the times of Theophrastus, three hundred years before the Christian era, although there is evidence in the writings of Vitruvius that they were worked at a still earlier date, Spanish ore being sent to Rome for the manufacture of vermilion. Such ore constituted a part of the tribute which Spain paid to Rome emperors, and there are records of its receipt until the first century after Christ. The history of Almaden during the reign of the Moors is so much involved in doubt that some writers deny altogether that the Arabs worked the deposit; still the very name it now bears, which means "the mine," and many of the technical terms still in use, give evidence that they knew and worked that famous deposit. As for their Christian conquerors, there are stray indications that they extracted mercury during the twelfth and thirteen centuries. In 1417, Almaden was given the privileges of a city, and from 1525 to 1645 the working of mines was contracted for by the wealthy family of Fugger, of Augsburg, Germany. Since then, the mine has been worked by the state, though the Rothschilds have controlled the sale of the product.