Platinum wire

“ The incandescent light is in principle the same as the arc, produced by the same means and based upon the same principle of impediment to the free passage of the current. It was first produced by heating with the current to incandescence a fine platinum wire. As stated above, electricity that quietly traverses a large wire will suddenly develop great heat upon reaching a point where it is called upon to traverse, a smaller one. Platinum was attempted for this place of greater resistance because of its qualities. ”

“ As showing how platinum itself is not uniform, it may be mentioned that almost any two pieces of platinum wire, if not from the same length, will cause a deflection on a sensitive galvanometer when made into a junction and heated. It is therefore customary for makers to obtain considerable quantities of wire of a given kind, homogeneous as far as possible, in order that a number of identical instruments may be made, and the junctions replaced, when necessary, without alteration of the scale of the indicator. ”

“ A platinum wire is stretched in front of the table, and through it an electric current flows. It is warmed by the current, and may be felt to be warm by the hand. It emits waves of heat, but no light. Augmenting the strength of the current, the wire becomes hotter; it finally glows with a sober red light. At this point Dr. Draper many years ago began an interesting investigation. He employed a voltaic current to heat his platinum, and he studied, by means of a prism, the successive introduction of the colours of the spectrum. ”

“ When the length of the wire in the helices of an electro-magnet is very great, it offers increasing resistance to the passage of the electricity, so that the cessation of magnetism is not instantaneous when the contact with the Voltaic battery is broken. To remedy that defect an instrument has been invented which instantaneously deprives the apparatus of the remaining electricity. A great length of fine wire gives the severest shocks, while a shorter and thicker wire gives the longest sparks and ignites the greatest quantity of platinum wire. ”

“ In 1813 Wollaston proposed fine platinum wires, prepared by surrounding a platinum wire with a cylinder of silver, and drawing out the cylinder with its platinum axis into a fine wire. [7] The surrounding silver was then dissolved by nitric acid, and a platinum wire of extreme fineness remained. But experience soon proved the superiority of the spider web; its perfection of shape, its lightness and elasticity, have led to its universal adoption. ”

“ If the copper wire is drawn through a piece of 1/4-inch soft glass tubing so that only the platinum wire projects from the end of the tube, and the tube is then sealed around the platinum by holding it in a Bunsen burner a few minutes, your electrodes will be more permanent and more satisfactory. ”

“ It is well known that by closing the circuit of a voltaic current by means of thin platinum wire, or by fine iron or steel wire, the platinum becomes red-hot, and the iron or steel becomes instantly fused. ”

“ The platinum wires are usually rolled spirally, with the object in view of concentrating the heat into a small space, in order to raise the temperature of the wire as much as possible. There is thus need of a less intense current to produce the inflammation than with a wire simply stretched out. In fact, the same wire traversed by a current of constant intensity scarcely reaches a red heat when it is straight, while it attains a white heat when it is wound spirally, because, in the latter case, the cooling surface is less. ”

“ The machine which cuts up and ‘heads’ the platinum wire is a marvellous little creature. A correspondent of an American paper writing of it says, ‘Here is a spitefully busy little machine, too busy with one particular process to tell us what it is doing, and yet we discover that it is eating platinum wire and spitting out tiny pins at the rate of six hundred a minute. Each comes out with a solid head like that of a brass pin, with rough indentations in the other end, so as to be firmly held in the plastic body of the tooth until fierce heat makes the union indissoluble. ”

“ It is held in suitable terminals, and close to it, or round it, but not touching it, is a loose coil of platinum wire, also covered with oxide and called the “heater” (fig. 18) . In series with it is a spiral of iron wire, enclosed in a bulb full of hydrogen, which is called the “ballast resistance.” The socket also contains a switch controlled by an electromagnet. When the current is first switched on it passes through the heater coil which, becoming incandescent, by radiation heats the glower until it becomes conductive. ”

“ The metal, copper say, is steeped in a solution of the coating substance, and connected by means of wires with a galvanic battery, under the action of which the metal in solution unites with the surface of the plate immersed in it. Heat also is developed under magnetic influence, and that often of great intensity. Thus, if we connect the poles of a voltaic battery by means of a platinum wire, heat will develop to such a degree that the platinum will almost instantaneously become red hot and emit a bright light, and that along a wire of some considerable length. ”

“ The two wires being connected so as to form a single circuit, and the armature made to rotate in the opposite direction to that of the hands of a watch, powerful electrical effects were produced. The electricity generated by this motion of the armature soon made four inches of platinum wire red-hot, and decomposed water. These effects were thus explained by Professor Wheatstone: The electro-magnet always retains a slight residual magnetism, so is always in the condition of a weak permanent magnet ”

“ Early electrical instrumentation based on the heating effect took an unusual form. Shortly after 1800, W. H. Wollaston, an English M.D., learned a method for producing malleable platinum. He kept the process secret, and for several years enjoyed an extremely profitable monopoly in the sale of platinum crucibles, wire, and other objects. About 1810, he invented a technique for producing platinum wire as fine as a few millionths of an inch in diameter, that has since been known as “Wollaston wire.” ”

“ If traces of air exist in the globe, they very quickly manifest themselves by the surface of the glass becoming blackened, while an increased energy is required to maintain the brightness of the light.
In the early days of this lamp it was thought necessary to remove the delicate platinum wire which forms the core of the filament, by raising the strength of the current sufficiently to destroy it in the course of manufacture. This, however, was given up, and the platinum now remains either as a continuous wire or as a series of small separated granules. ”

“ When the wire has got to a certain fineness it is attached to a cylinder and drawn away, at the same [Pg 398] time being wound round the cylinder over a small fire. Some metals can be drawn much finer than others. Gold wire can be obtained of a “thickness” (or thinness) of only the 5,000th part of an inch, 550 feet weighing one grain! But platinum has exceeded this marvellous thinness, and wire the 30,000th part of an inch has been produced. Ductility and malleability are not always found in the same metal in proportion. ”

“ The temperature of such wire will depend especially upon the intensity of the current traversing it; and, if this is too great, the platinum (chosen because of its inoxidizability and its elevated melting point) will rapidly melt; while, if the intensity is too little, the temperature reached by the wire will itself be too low, and no inflammation will be brought about. Practice soon indicates a means of obviating these two inconveniences, and teaches how each apparatus may be placed under such conditions that the wire will hardly ever melt, and that the lighting will always be effected. ”

“ The physical properties requisite to make useful wire are possessed by only a limited number of metals and metallic alloys. The metals must in the first place be ductile; and, further, the wire when drawn out must possess a certain amount of tenacity, the quality on which the utility of wire principally depends. The metals suitable for wire, possessing almost equal ductility, are platinum, silver, iron, copper, aluminium and gold ”

“ The other end of the platinum wires are extended to connect with the earth. The radio-active substance198 electrifies the gold leaves and causes them to be extended, and upon being extended they come in contact with the platinum wires and their charge of electricity is lost, being conducted through the wires and dispersed in the earth, and the leaves losing their charge fall by the force of gravity from the wires back to their position near the tube containing the radio-active substance to be again charged, to again move to and touch the platinum wires, and again lose their charge ”

“ Iron seems to be the most desirable material for guard wires because it gives the required mechanical strength and sufficient conductivity at a less cost than copper, aluminum, or bronze, and is easier to handle and less liable to break than steel. It was formerly the practice to staple guard wires to the tops of poles or to the ends of cross-arms, but it was found that the wire was more apt to rust and break at the staple than elsewhere, and in the better class of work such wires are now mounted on small insulators. ”

“ The piles of this equipment, waiting shipment in the Roebling storerooms, give proof that the satire of the cartoonist and the mockery of the funny writer cannot destroy an ancient faith.
The telephone and telegraph companies use uncountable miles of copper wire in line service and other miles in fine sizes for instrument coils and divers other functions. Electricity as an agent would be a halting cripple without wire. The dynamo would have little more utility than a washtub. Armatures, frames for which are formed from flat steel wire, are wound in the Roebling plant in impressive number. ”

“ In some of the newer cables wires covered with cotton soaked in paraffine are used instead of gutta-percha-covered wires. The distances within this city are so short that neither induction nor retardation has to be considered in the telegraph wires. Electric-lighting wires, we have seen, are not affected. The telephone wires are in Paris protected from these evils by an extremely simple though expensive device. Instead of a single wire for each circuit, two wires twisted together are used, the current going out over one and returning over the other. ”

“ The purpose of the iron core is to concentrate the magnetic field and make the coil more efficient. Since currents are only induced in the secondary when the magnetic field is changing, an automatic device called an interrupter or sometimes a vibrator, is employed to rapidly turn the current flowing through the primary on and off. The interrupter consists of a spring carrying a platinum point against which presses a second piece of platinum on the end of an adjustable thumbscrew. Platinum is necessary because the current of electricity would quickly oxidize and burn up any other material. ”

“ There are no cylinders to be shaved; all that is needed to use the wire again is to pass a magnet over it, automatically erasing any previous record that you do not wish to preserve. You can dictate into it, or, with this plug in, you can record a telephone conversation on it. Even rust or other deterioration of the steel wire by time will not affect this electromagnetic registry of sound. It can be read as long as steel will last. It is as effective for long distances as for short, and there is wire enough on one of these spools for thirty minutes of uninterrupted record. ”

“ As soft copper has greater conductivity per unit of area than any of the other available metals, it clearly has an advantage over all of them as to inductance and increase of resistance with alternating current.
At very high voltages there is an important leakage of energy between the conductors of a circuit, and this loss varies inversely with the distance between these conductors. Thus it happens that inductance makes it desirable to bring the parallel wires of a circuit close together, while the leakage of energy from wire to wire makes it desirable to carry them far apart. ”

“ No joint can possibly be perfect that is not metallically continuous. Careful soldering is the only certain mode of securing this, and that this is practicable is evident from the millions of perfect joints in telegraph wires. To scrape the ends of wire bright, and cover the whole with thin sheet lead, as is done by one firm, is simply to court danger. The absence of joints in wire rope is one great element in its favour.
(21) 5. Attachment to building, how made. Some attach the conductor to the building by copper straps and nails; some use holdfasts, either of copper wire or gun metal ”

“ But as a momentary exposure in a powerful electrical circuit was sufficient to give permanent polarity to steel, it appeared equally obvious, that needles placed transversely to a wire at the time that the electricity of a common Leyden battery was discharged through it, ought to become magnetic; and this he found was actually the fact, and according to precisely the same laws as in the Voltaic circuit; the needle under the wire, the positive conductor being on the right hand, offering its north pole to the face of the operator, and the needle above, exhibiting the opposite polarity. ”