Voltaic electricity

“ Before that electricity was known only by the instantaneous discharge or spark. From the name of Volta is derived the word volt, which designates the unit of electro-motive force. The adjective voltaic is synonymous with galvanic, as voltaic or galvanic cell, voltaic or galvanic current. For a long time it was thought that such an adjective was needed to designate electric currents generated by chemical action as a peculiar kind of electricity. We no longer think of electricity which is generated by chemical action as different from that generated by a dynamo or from any other source. ”

“ Then by shifting the end of the wire from place to place upon the test paper, the effect of the current for five, six, seven, or any number of the beats of the watch (369.) was observed, and compared with that of the machine. After alternating and repeating the experiments of comparison many times, it was constantly found that this standard current of voltaic electricity, continued for eight beats of the watch, was equal, in chemical effect, to thirty turns of the machine; twenty-eight revolutions of the machine were sensibly too few. ”

“ Volta himself knew nothing of the chemical phenomena of the pile; but as soon as these became known, suggestions and intimations appeared that chemical action, and not metallic contact, might be the real source of voltaic electricity. This idea was expressed by Fabroni in Italy, and by Wollaston in England. It was developed and maintained by those 'admirable electricians,' Becquerel, of Paris, and De la Rive, of Geneva. The Contact Theory, on the other hand, received its chief development and illustration in Germany. ”

“ The electricity generated by the voltaic battery is far greater in quantity than the most powerful electrical machine can excite, whilst its intensity is so feeble that it cannot pass in a spark through the smallest interval of air. It presents, therefore, much less difficulty in the insulation of the wires than frictional electricity, whilst the rapidity of its transmission is for practical purposes equally efficient. ”

“ The Voltaic current is a continuous current. Unless artificially interrupted, the electricity flows in an unbroken stream until the battery is exhausted. The current will gradually lessen in power until it ceases, but there will be no break in it, and no change in its direction, which is uniformly from the positive to the negative pole. |Points of distinction between the Voltaic and Faradaic Currents.| It is important to recollect these points, for they constitute the chief physical distinction between the Voltaic and the Faradaic—or, as it is sometimes called, the Induced current. ”

“ But when the strength of a galvanic battery is sufficiently great, or, in other words, when the total amount of chemical action brought into play to generate electricity is sufficient, we obtain voltaic electricity not only surpassing in intensity what can be obtained from electrical machines, but capable of producing spark after spark in a succession so exceedingly rapid that the light is to all intents and purposes continuous. ”

“ Of course, however, it will be understood that for special purposes one method of producing electricity may be more advantageously used than another. Just as heat produced by burning coal is more convenient for a number of purposes than heat produced by burning wood, though there is no scientific distinction between coal-produced heat and wood-produced heat, so for some purposes voltaic electricity is more convenient than frictional electricity, though there is no real distinction between them. ”

“ Electricity as first Obtained by Man. Until modern times the only electricity known to us was that of the lightning flash, which man could neither hinder nor make. But in the year 1800, electricity in the form of a weak current was obtained by Volta of Italy in a very simple way; and even now our various electric batteries and cells are but a modification of that used by Volta and called a voltaic cell. A strip of [307] copper and a strip of zinc are placed in a glass containing dilute sulphuric acid, a solution composed of oxygen, hydrogen, sulphur, and water. ”

“ By this beautiful discovery electricity was for the first time enslaved to man, who was now able to generate and control it at times and in such quantities as he desired. Although the voltaic battery is now nearly obsolete as a source of electricity, its invention must always be regarded as one of the three epoch-making events in the history of the science during the past one hundred and twenty years. ”

“ When a wet thread was interposed in the course of the current of common electricity from the battery (291.) charged by eight or ten [A] revolutions of the machine in good action (290.) , and the discharge made by platina spatulas through the tongue or the gums, the effect upon the tongue and eyes was exactly that of a momentary feeble voltaic circuit. ”

“ The object of these preparations was to arrange a voltaic apparatus, which, by immersion in a given acid for a given time, much less than that required by the needle to swing in one direction, should give equal deflection to the instrument with the discharge of ordinary electricity from the battery (363. 364.) ; and a new part of the zinc wire having been brought into position with the platina, the comparative experiments were made. ”

“ All that I have said about the voltaic arc, the incandescence resulting from resistance to the current's flow, and so forth, in relation to electricity generated by galvanic batteries, applies to electricity generated by induction coils, or by magneto-electric and by dynamo-electric machines. Only it is to be noticed that in some of these machines the currents alternate in direction with each revolution of the swiftly turning coil, in others the currents are always in the same direction, and in yet others the currents may be made to alternate or not, as may be most convenient. ”

“ Indeed it is now the generally received opinion that a current of electricity is merely a continuous transmission of chemical affinity from particle to particle of the substance through which it is passing, and consequently that it is a continuous transmission of force. As the Voltaic battery has become one of the most important engines of physical research, some account of its present condition may not be out of place. ”

“ The light is more brilliant when charcoal is used instead of coke, but then it is necessary to operate in a vacuum, to avoid the combustion of the charcoal. The voltaic arc has recently been applied to illuminate lighthouses, and for other purposes, and will probably soon be more widely employed, for a cheap and convenient mode of producing a uniform current of electricity has recently been discovered and will be presently described. ”

“ Thus it appears that when a voltaic current in one wire is exerting its inductive action to produce a contrary or a similar current in a neighbouring wire, according as the primary current is commencing or ceasing, it makes not the least difference whether the intervening space is occupied by such insulating bodies as air, sulphur and shell-lac, or such conducting bodies as copper, and the other non-magnetic metals. ”

“ The great law which regulates these transactions is this: that the sum of the internal and the external heats is a constant quantity; so that when the platinum wire was ignited we had less heat developed in the battery than before. The zinc in the battery is burned as fuel upon a hearth; the heat, however, being developed either upon the hearth itself or at any distance from it.
“As a primary source of electricity here is the combustion of a metal, the voltaic battery is not an economical source of power for producing electric light. ”

“ Whether the charging of the metallic coating be effected by a powerful electrical machine, a strong and large voltaic battery, or a single pair of plates, makes no difference in the principle, but only in the degree of action (360) . Common induction takes place in each case if the electrolyte be solid, or if fluid, chemical action and decomposition ensue, provided opposing actions do not interfere ”

“ Volta soon found that it was not necessary to have his pairs of metals in actual metallic contact, and that better results were got by placing them in a vessel filled with dilute acid. Fig. 7 is a diagram of a simple voltaic cell of30 this kind, and it shows the direction of the current when the zinc and the copper are connected by the wire. In order to get some idea of the reason why a current flows we must understand the meaning of electric potential. If water is poured into a vessel, a certain water pressure is produced. ”

“ But as the wire has to be charged, enough current to
move the relay may not reach the end for some seconds.
Capacity of Polarization of a Voltaic Cell.
The relative resistance to polarization of a voltaic cell, measured by
the quantity of electricity it can supply before polarization. A
counter-electromotive force may be developed, or the acid or other
solution may become exhausted. ”

“ The body offers too much resistance. But, if the volts were 1,100 instead of the usual 110 used in commercial and private plants for domestic use, the value of C, by this formula at 5,000 ohms, would be nearly 1/5th ampere. To drive 1/5th [Pg 106] ampere of electricity through the human body would be fatal in many instances. The higher the voltage, the more dangerous the current. In large water-power installations in the Far West, where the current must be transmitted over long distances to the spot where it is to be used, it is occasionally generated at a pressure of 150,000 volts. ”

“ If we should increase the voltage tenfold more, say the 110-volt dynamo current (direct current) , and touch the bare conductors with our hands, the ammeter would indicate about .001 ampere. That is, although this current has about seventy times as much push, or voltage, as a dry cell, no more electricity passes through the fingers than did through the tongue in the preceding experiment with one cell. The fingers offer so much greater resistance. ”

“ Fig. 117. Arc-Lighting Circuit.
A high voltage is necessary in order to cause the current to leap across the gap made by the separation of the electrodes
p. 166
The Incandescent System.—This method is entirely different from the arc system. It has been stated that certain metals conduct electricity with greater facility than others, and some have higher resistance than others. If a certain amount of electricity is forced through some metals, they will become heated. ”

“ We have just the same effects in electricity. If we place some substance which is practically a non-conductor, or insulator, such as rubber, around an electric wire, or in the path of an electric current, the electricity, acted upon by the volts of pressure, cannot escape, because the insulation keeps it from doing so, just as the iron of the pipe keeps the [7] water from escaping. Thus, you see, the volt does not itself represent electricity, but only the pressure which forces it through the wire. ”

“ As volta-electro-generation is a case of mere chemical action, so volta-electro-decomposition is simply a case of the preponderance of one set of chemical affinities more powerful in their nature, over another set which are less powerful: and if the instance of two opposing sets of such forces (891.) be considered, and their mutual relation and dependence borne in mind, there appears no necessity for using, in respect to such cases, any other term than chemical affinity, (though that of electricity may be very convenient,) or supposing any new agent to be concerned in producing the results ”

“ Three methods of generating electricity are in general use: static or frictional electricity is generated by "plate" or "static" machines; galvanic, generated by batteries based on Volta's discovery; and induced, or faradic, generated either by chemical or mechanical action. There is still another kind, thermo-electricity, that may be generated in a most simple manner. In 1821 Seebecle, of Berlin, discovered that when a circuit was formed of two wires of different metals, if there be a difference in temperature at the juncture of these two metals an electrical current will be established. ”

“ When an alternating current is set up in the circuit containing the cathode, anode, and secondary of the transformer, the electronic discharge from the cathode closes the circuit and permits a continuous flow of electricity through it when the phase of the current is such than the anode is positively charged, while preventing any flow of current through the tube when the anode is negatively charged. ”

“ From the time of Volta to the time of Faraday the only means of producing an electric current was the "voltaic battery," so called in honor of Volta. The voltaic cell is the simplest form of electric battery. In this cell the zinc and copper plates are placed in sulphuric acid diluted with water. As the acid eats the zinc, hydrogen gas is formed. This gas collects in bubbles on the copper plate and weakens the current. The aim of inventors was to produce a steady current, to devise a battery in which no gas would collect on the copper plate. ”

“ The energy supplied by the generator is 350 volts × 50 amperes = 17,500 watts = 17.5 K. W. The energy delivered to the consumer is 100 volts × 50 amperes = 5000 watts = 5 K. W. In order to deliver fifty cents' worth of electricity per hour to the consumer it would, in this case, be necessary to generate $1.75 worth of electricity at the central station. That is, about seventy per cent. of the energy generated would be wasted in transmission. If now we decide to generate this electrical energy at ten times as high voltage it will be necessary to transmit only one tenth as many amperes, or five. ”