Positive electrode

“ The discharge seems to be independent of the position of the positive electrode, and to take place in nearly straight lines, which start normally from the negative electrode. If two negative electrodes be fixed in the tube, the discharge from one seems to be deflected by the other, and two discharges which meet at right angles seem to deflect one another.
If the discharge from a flat electrode be made to fall upon a body which can be moved, such as a glass film, or the vane of a light wheel, mechanical motions will be set up. ”

“ Strong shadows cast upwards indicate a lamp burning “upside down”. The positive electrode retains heat longer than the negative. The quality and size of electrodes has much to do with successful operation. Always use the kind of electrodes recommended by the maker of the lamp.
Direct-current arc lamps do not require much in the shape of reflectors as they naturally throw most of the light downward, when the upper electrode is positive. They should as a rule be suspended high. ”

“ An electrode is what we call any piece of metal or wire which is so placed as to let us get at electrons (or 42ions) to control their motions. Let us see how it does so.
To start with, we shall forget the grid and think of a tube with only a filament and a plate in it–a two-electrode tube. We shall represent it as in Fig. 6 and show the battery which heats the filament by some lines as at A. In this way of representing a battery each cell is represented by a short heavy line and a longer lighter line. The heavy line stands for the negative plate and the longer line for the positive plate. ”

“ These corpuscles bombard the anode and keep it incandescent. They ionize also, either directly by collision or indirectly by heating the anode, the gas and vapour of the metal of which the anode is made, and produce in this way the supply of positive ions which keep the cathode hot.
Discharge from a Point.—A very interesting case of electric discharge is that between a sharply pointed electrode, such as a needle, and a metal surface of considerable area. At atmospheric pressures the luminosity is confined to the immediate neighbourhood of the point. ”

“ If, when a hot metal is emitting ions in a rarefied gas, an electromotive force be established between the metal and a neighbouring electrode, either the positive or the negative ions are urged towards the electrode by the electric field, and a current is thus transmitted through the intervening space. ”

“ A number of electrodes are required; thus for the application of sparks a brass ball and brass roller electrode, for the “breeze” a single point and a multiple point electrode, and another multiple point electrode in the form of a metal cap that can be placed over the patient’s head. The polarity of the machine must always be tested, as either knob may become positive or negative, though the polarity rarely changes when once the machine is in action. The oldest method of subjecting a patient to electric influence is that in which static electricity is employed. ”

“ These electrodes must be so arranged that firm connection, best by a screw, can be made with the rheophore; and one of the intrauterine electrodes must be of non-corrodable metal, best of platinum, for use in connection with the positive pole; as oxygen and acids are set free at this pole, an electrode of corrodable metal is soon affected and is not only rendered useless, but is imbedded in the tissues and hard to withdraw.
It will be found convenient to have a stylet and sound in one and the same instrument, of platinum, one end straight and pointed, the other curved and blunt, which. ”

“ At the + electrode is the - element of H2O, and at the - electrode the + element. Note, page 43, whether H or O is positive with reference to the other, and write the symbol for each at the proper electrode. Compare the diagram with the apparatus, to verify your conclusion. Why does gas collect twice as fast at one electrode as at the other? What does this prove of the composition of water? When filled, test the gases in each tube, for O and H, with a burning stick. Electrical analysis is called electrolysis. ”

“ In water these exchanges produce, on the whole, no observable effect, but no sooner does the electromotive force begin to act, than it exerts its guiding influence on the unattached molecules, and bends the course of each toward its proper electrode, till the moment when, meeting with an unappropriated molecule of the opposite kind, it enters again into a more or less permanent union with it till it is again dissociated by another shock. Electrolysis, therefore, is a kind of diffusion assisted by electromotive force. ”

“ But if the electrolysis is conducted in suitable vessels, such as U-shaped tubes or vessels with a porous diaphragm, so that the substance surrounding each electrode can be examined separately, it is found that at the anode of the sulphate of soda there is an equivalent of sulphuric acid as well as an equivalent of oxygen, and at the cathode there is an equivalent of soda as well as two equivalents of hydrogen. ”

“ But, on the other hand, if a few drops of acid be placed in the vessel with the platinum, bubbles of hydrogen appear, and a current flows, zinc dissolving at the anode, and hydrogen being liberated at the cathode. In order that positively electrified ions may enter a solution, an equivalent amount of other positive ions must be removed or negative ions be added, and, for the process to occur spontaneously, the possible action at the two electrodes must involve a decrease in the total available energy of the system. ”

“ In order that the current should be maintained, and the electromotive force of the cell remain constant during action, it is necessary to ensure that the changes in the cell, chemical or other, which produce the current, should neither destroy the difference between the electrodes, nor coat either electrode with a non-conducting layer through which the current cannot pass. ”

“ The secondary cell of Planté is an example of a cell made directly by electrolysis, as has been assumed in the preliminary discussion. The electrodes are both lead plates, and the electrolyte dilute sulphuric acid. When a current is passed through the cell, the oxygen evolved on the anode combines with the lead to form peroxide of lead, which coats the surface of the electrode. When the cell is inserted in a circuit, a current is set up, the peroxide is reduced to a lower oxide, and the metallic lead of the other plate is oxidized. ”

“ When is equal to nine-tenths of the electromotive force of a Daniell's cell, the electrode to which relates remaining in its natural state, the tension of the surface of the other electrode has a maximum value, and there is no excess or deficiency of hydrogen at that surface. This is the condition toward which a surface tends when it is extended while no flux of electricity takes place. ”

“ Having observed the effect with the faradic current, and the results having been recorded, the continuous current is used, and the electrodes made use of in an exactly similar fashion. When a small electrode is used, the superficial nerves and muscles are more stimulated than those lying deeply. It is necessary, therefore, to begin with a small current and gradually increase it until the individual muscle responds. ”

“ In the same way, any other kind of work done during electrolysis will have an effect on the value of the electromotive force, as, for instance, if a vertical current passes between two zinc electrodes in a solution of sulphate of zinc a greater electromotive force will be required when the current in the solution flows upwards than when it flows downwards, for, in the first case, it carries zinc from the lower to the upper electrode, and in the second from the upper to the lower. ”

“ But since in a patient the electrode cannot be applied directly to the nerve, the lines of force from the electrode pass into the nerve both in an upward and downward direction, and hence there are two poles produced by each electrode. If the current be suddenly reversed, so that what was the anode becomes the kathode, a stronger contraction is obtained than by simply making and breaking the current. To avoid the four poles on the nerve to be tested, it is found most satisfactory to have one electrode placed at some distance, on the back or chest, not on the same limb. ”

“ For if the ion must pass immediately into the non-conducting mass, while the electricity passes into the electrode, it is evident that the only possible terminus of an electrolytic current is at the line where the electrode, the non-conducting mass, and the electrolytic fluid meet, so that the electrolytic process is necessarily greatly retarded, and an approximate ceasing of the current cannot be regarded as evidence that a state of approximate equilibrium has been reached. ”

“ Again, the consideration of the electrical potential in the electrolyte, and especially the consideration of the difference of potential in electrolyte and electrode, involves the consideration of quantities of which we have no apparent means of physical measurement, while the difference of potential in "pieces of metal of the same kind attached to the electrodes" is exactly one of the things which we can and do measure. ”

“ Since the ions which carry the current have to travel all the way from one electrode to the other, any obstacle which is impervious to these ions will, if placed between the electrodes, stop the current to the electrode where there is no ionization. A plate of metal will be as effectual as one made of a non-conductor, and thus we get the remarkable result that by interposing a plate of an excellent conductor like copper or silver between the electrode, we can entirely stop the current. ”

“ The intensity of electromotive response varies with the substance, and is sometimes considerable, for example, with "tin," a single vibration may give rise to as high a value as 0.4 volt. The intensity of response does not depend on the chemical activity of the substance, for the electromotive variation in the relatively inactive tin is greater than that in zinc. Again, the sign of response, positive or negative, is sometimes modified by the molecular condition of the wire (see below) . In the cell form of apparatus the wires are immersed to a definite depth in the electrolyte ”

“ In the experiments described in this paper the electrodes were generally made of aluminium. Some experiments, however, were made with iron and platinum electrodes.
Though the value of m/e came out the same whatever the material of the electrode, the appearance of the discharge varied greatly; and as the measurements showed, the potential-difference between the cathode and anode depended greatly upon the metal used for the electrode; the pressure being the same in all cases. ”

“ One of the best methods of determining whether a body is or is not an electrolyte is to place it between platinum electrodes and to pass a current through it for some time, and then, disengaging the electrodes from the voltaic battery, and connecting them with a galvanometer, to observe whether a reverse current, due to polarization of the electrodes, passes through the galvanometer. ”

“ The best and whitest light can be obtained when a 5⁄8-inch cored-carbon electrode is used above and a 1⁄2-inch solid-carbon electrode below, care being taken not to get solid carbons too hard. The average current in the arc should not exceed 30 amperes and it will be found that excellent pictures can be obtained with 25 amperes or even less and the cost of energy, carbons, and condensers will be less. ”

“ In a galvanic battery the surface of the zinc plate is charged with
negative electricity.
According to the single fluid theory negative electrification consists
in a deficiency of electricity.
[Transcriber's note: Negative electrification is an excess of
electrons.]
Negative Element.
In a voltaic cell the plate not dissolved by the solution; the one which
is positively charged; the copper, platinum, or carbon plate in the
usual type of battery.
The current is assumed to flow from negative element to positive element
(the zinc plate) through the wire or other external conductor. ”

“ If such an electrolytic cell has a continuous electromotive force applied to it tending to force a current through the electrolyte from the platinum wire to the lead plate, we can distinguish three stages in its operation, which are determined by the electromotive force and the inductance in the circuit. First, if the electromotive force is below sixteen or twenty volts, then ordinary and silent electrolysis of the liquid proceeds, bubbles of oxygen being liberated from the platinum wire and hydrogen set free against the lead plate. ”

“ In a highly exhausted bulb, electricity is carried off from the electrode by independent carriers, which are partly the atoms, or molecules, of the residual atmosphere, and partly the atoms, molecules, or lumps thrown off from the electrode. If the electrode is composed of bodies of different character, and if one of these is more easily disintegrated than the other, most of the electricity supplied is carried off from that body, which is then brought to a higher temperature than the others, and this the more, as upon an increase of the temperature the body is still more easily disintegrated. ”

“ What is positive and what negative electricity?
No difference in electricity in itself. When a body has more than its natural amount of electricity, it is said to be charged positively; when it has less than its natural amount it is negatively charged.
What is a Cell; what a Battery?
If a piece of zinc and copper joined by a wire be dipped in a liquid—generally weak sulphuric acid—which will act chemically on the metals, a current is produced. Such an arrangement is called a couple, or cell. If many cells are connected, then it is called a battery. ”