 CHAPTER XI In no department of the application of electricity to practical work has there been a greater development than in electro-metallogy and electrochemistry. Today there are vast industries depending upon electrical processes, and the developments of a quarter of a century have been truly remarkable. Already more than one-half of the copper used in the arts is derived by electrolytic refining. The production of aluminium depends entirely on electricity. The electric furnace as a possible rival to the blast furnace for the production of iron and steel is being seriously considered, and many other metallurgical processes are being undertaken on a large scale. We have seen in our chapter on electrolysis how a metal may be deposited from a solution of its salt, and how this process could be used for deriving a pure metal, or for plating or coating with the desired metal the surface of another metal, or one covered with graphite. In the following pages it is intended to take up some of the more notable accomplishments in this field achieved by electricity, which have been developed to a state of commercial importance. The electric arc not only supplies light but heat of great intensity, which the electrical engineer as well as the pure scientist has found so valuable for many practical operations. It is, of course, obvious that for most chemical operations, and especially in the field of metallurgy, heat is required for the separation of combinations of various elements, for their purification, as well as for the combination with other elements into alloys or compounds of direct utility. The usual method of generating heat is by the combustion of some fuel, such as coal, coke, gas or oil, and this has been utilized for hundreds of years in smelting metals and ores, and in refining the material from a crude state. Now it may happen that a nation or region may be rich in metalliferous ores, but possess few, if any, coal deposits. Accordingly, the ore must be mined and transported considerable distances for treatment, and the advantages of manufacturing industries are lost to the neighbourhood of its original production. But if water power is available, as it is in many mountainous countries where various ores are found, then this power can be transformed into electricity, which is available as power not only in various manufacturing operations, but for primary metallurgical work in smelting the ores and obtaining the metal therefrom. A striking instance of this is the Kingdom of Sweden, which contains but little coal, yet is rich in minerals and in water power, so that its waterfalls have been picturesquely alluded to as the country's white coal. Likewise at Niagara Falls, a portion of the vast water power developed there has been used in the manufacture of aluminium, calcium carbide, carborundum and other materials, while at other points in the United States and Canada, not to mention Europe, large industries where electricity is used for metallurgical or chemical work are carried on, and the erection of new plants is contemplated. The application of electricity to metallurgical and chemical work has been, in nearly all cases, the result of scientific research, and elaborate experimental laboratories are maintained by the various corporations interested in the present or future use of electrical processes. It is recognised by many of the older workers in this field that electrical developments are bound to come in the near future, and while they have not installed such appliances in their works yet, they are keeping close watch of present developments, and in many cases experimental investigation and research is being carried on where electrical methods have not yet been introduced generally into the plant. Prior to 1886 the refining of copper was the only electrometallurgical industry, and at that time it was carried on on a very limited scale. Today the production of electrolytic copper as an industry is second in importance only to the actual production of that metal. From the small refinery started by James Elkington at Pembury in South Wales, a vast industry has developed, in which there has been a change in the size of operations and in the details of methods, rather than in the fundamental process. For a solution of copper sulphate is employed as the electrolyte, blocks of raw copper as the anodes, and thin sheets of pure copper as the cathodes. The passage of the electric current, as we have seen on page 79 in the chapter on electrolysis, is able to decompose the copper in the electrolyte and to precipitate chemically pure copper on the cathode, the copper of the solution being replenished from the raw material used as the anode, by which the current is passed into the bath. At this Welsh factory two hundred and fifty tons yearly were produced and small earthenware pots sufficed for the electrolyte. Thirty years later one American factory alone was able to produce at least three hundred and fifty tons of electrolytic copper in twenty-four hours, and over four hundred thousand tons is the aggregate output of the refineries of the world, which is about fifty-three percent of the total raw copper production. Of this amount eighty-five percent comes from American refineries whose output has more than doubled since nineteen hundred. The chief reason for this increased output of electrolytic copper has been the great demand for its use in the electrical industries, where not only a vast amount is consumed, but where copper of high purity, to give the maximum conductivity required by the electrical engineer, is demanded. When it is realized that every dynamo is wound with copper wire, and that the same material is used for the trolley wire and for the distribution wires in electric lighting, it will be apparent how the demand for copper has increased in the last quarter of a century. Electrolytic methods not only supply a purer article, and are economical to operate, especially if there is water power in the vicinity, but the copper ores contain varying amounts of silver and gold, which can be recovered from the slimes obtained in the electrolytic process. Wherever possible machinery has been substituted for hand labour. The raw copper anodes have been cast, and the charging and discharging of the vats is carried on by the most modern mechanical methods in which efficiency and economy are secured. On the chemical side of the process, attempts have been made to improve the electrolyte, notably by the addition of a small amount of hydrochloric acid to prevent the loss of silver in the slimes, and this part of the work is watched with quite as much care as the other stages. Electric furnaces have also been constructed for smelting copper ores, but these have not found wide application, and the problem is one of the future. For the most part the copper electrically refined is produced in an ordinary smelter. The mints of the United States are now all equipped with electrolytic refining plants to produce the pure metal needed for coinage, and they have proved most satisfactory and economical. As the electrolytic production of copper is an industry of great present importance, so the production of iron and steel by electricity promises to be of the greatest future importance. Electric furnaces for making steel are now maintained, and the industry has passed beyond an experimental condition. But it has not reached the point where it is competing with the besamer or the open hearth process of the manufacture of steel, while for the smelting of iron ores the electric furnace has not yet been found practical from an economic standpoint. Before 1880 Sir William Siemens showed that an electric arc could be used to melt iron or steel in a crucible, and he patented an electric crucible furnace, which was the first attempt to use electricity in iron and steel manufacture. He stated that the process would not be too costly, and that it had a great future before it. This was an application of the intense heat of the arc, which supplies a higher temperature than any source known except that of the sun. This heat is used to melt the metal, in which condition various impurities can be removed, and necessary ingredients added. Siemens furnace did not find extensive application, largely on account of the great metallurgical developments then taking place in the iron industry, and the thorough knowledge of metallurgical processes as carried on possessed by metallurgical engineers. But the idea by no means languished, and in 1899 Paul Ehrhol and other electrometallurgists were active in developing a practical electric furnace for iron and steel work. The Swedish engineer F. A. Kjellin was also active, and as the result of the efforts of these and other workers, by 1909 electric furnaces were employed, not only in the manufacture of special steels, whose composition and making were attended with special care, but for rails and structural material. There were reported to be between thirty and forty electric steel plants in various countries, and the outlook for the future was distinctly bright. The application of electrometallurgy at this time was confined to the manufacture of steel, as the smelting of iron had not emerged from the experimental stage of its development, though extensive trials on a large scale of various furnaces have been undertaken in Europe and by the Canadian government at Sault Ste. Marie, where the Ehrhol furnace, soon to be described, was employed. Electro-metallurgy of steel, as in all utilisation of electrical power, depends upon obtaining electricity at a reasonable cost, and then utilising the heat of the arc, or of the current, in the most practical and economical form. One of the pioneer furnaces for this purpose, which has seen considerable development and practical application, is the Ehrhol furnace, which is a tilting furnace of the crucible type, whose operation depends upon both the heat of the arc and on the heat produced by the resistance of the molten material. In the Ehrhol process the impurities of the molten iron are washed out by treatment with suitable slags. The furnace consists of a crucible in the form of a closed, shallow iron tank, thickly lined with dolomite and magnazite brick, with a hearth of crushed dolomite. The electric current enters the crucible through two massive electrodes of solid carbon, 70 inches in length and 14 inches in diameter, so mounted that they can be moved either vertically or horizontally by the electrician in charge. These electrodes are water-jacketed to reduce the rate of consumption. The furnace contains an inlet for an air blast and openings in its covering for charging the material and for the escape of the gases. The actual process of steel making consists of charging the crucible with steel scrap, pig iron, iron ore, and lime of the proper quality and in the right proportions, placing this material on the hearth of the furnace. Combined arc and resistance heating is applied to raise the charge to the melting point. The current is of 120 volts, or the same as that used in an ordinary incandescent lighting circuit, but is alternating and of 4,000 amperes. This is for a three-ton furnace. As the material melts, the lime and silicates form a slag which fuses rapidly and covers the iron and steel in the crucible, so that the molten bath is protected from the action of the gases which are liberated and the oxygen in the atmosphere. The next step in the process is to lower the electrodes until they just touch beneath the surface of the molten slag, so that subsequent heating is due not to the effect of the arc, but to the resistance which the bath offers to the passage of the current. Air from an air blast is introduced into the crucible to oxidize the impurities of the metal, particularly the sulfur and the phosphorus, which are carried into the slag and this is removed by the tilting of the furnace. Fresh quantities of lime, etc., are added, and the operation is repeated until a comparatively pure metal remains, when an alloy high in carbon is added and whatever other constituents are desired for the finished steel. The charge is then tipped into the casting ladle and the part of the electric furnace is finished. For three tons of steel, eight to ten hours are required in the aero-crucible furnace. Furnaces of an altogether different type are those employing an alternating current, such as the Kellen and Roslin furnaces, where the metal to be heated really forms the secondary circuit of a large and novel form of transformer, which in principle is analogous to the familiar transformer scene, to step down the potential of alternating current as for house lighting. For such a transformer the primary coil is formed of heavy wire, and the secondary circuit is the molten metal, which is contained in an annular channel. The current obtained in the metal is of considerable intensity, but at lower potential than that in the primary coil, and roughly is equal to that of the primary multiplied by the number of turns in the coil. The condition is similar to that in the ordinary induction coil, where the current from a battery at low potential flows round a coil of a few turns and is surrounded by a second coil with a large number of turns of fine wire in which current of small intensity but of high potential is generated. In the induction furnace the reverse takes place, and the current flowing in the metal derived from that of the heavy coil in the primary is of great intensity. For this type of furnace molten metal is required, and the furnace is never entirely emptied, so that its process is continuous. The temperature attained is not as high as in the arc furnace, so that the raw materials used have to be of a high degree of purity, and this has proved a restriction of the field of usefulness of this type of furnace in many cases. It, however, has been improved recently, and two rings of molten metal employed instead of one, so that a wide centre trough is obtained in which the metal is subjected to ordinary resistance heat by direct or alternating currents. This furnace permits of various metallurgical operations and the elimination of impurities as in the electrical type. A third type of furnace that is meeting with some extensive use is the Giro, which, like the Ero furnace, is based on the arc and resistance in principle, but in its construction has a number of different features. As the current passes horizontally from the upper electrodes through the slag and molten metal in the furnace chamber to the base electrodes of the furnace, it permits of the easy regulation of the arcs and the use of lower electromotive force, while there is only one arc in the path of the current instead of two as in the Ehrl type. Sufficient quantities of steel have been made in electric furnaces to permit of the determination of the quality of the product as well as the economy of the process. It has been found in Germany that rail steel made in the induction furnace has a much higher bending and breaking limit than ordinary Bessemer or Thomas rail steel, and in Germany, in 1908, rails so made commanded a considerably higher price per ton than those of ordinary rail steel. After trial orders had proved satisfactory, in 1908 five thousand tons of rails were ordered for the Italian and Swiss governments at a German works, where furnaces of eight tons capacity had been installed. In the United States only a few electric steel furnaces are in operation, and these for the most part for purposes of demonstration and experiment. But in Europe the industry is well established, and while at present small is constantly growing and possesses an assured future. In addition to the manufacture of steel, the application of the electric furnace for producing what are known as ferroalloys, or alloys of iron, silicon, chromium, manganese, tungsten and vanadium, is now a large and important industry. Special steels have their uses in different mechanical applications, and the advantage of alloying them with the rarer metals has been demonstrated for several important purposes, as for example the use of chrome steel for armour plate, and steel containing vanadium for parts of motor cars. These industries for the most part contain electric arc furnaces, and have, as their object, the manufacture of ferroalloys, which are introduced into the steel, it having been found advantageous to use the rare metals in this form rather than in their crude state. There is one electrometallurgical process that has made possible the production in commercial form, and for ordinary use, of a metal that once was little more than a chemical curiosity. In 1885 there were produced 3.12 tonnes of aluminium, and its value was roughly estimated at about $12 a pound. By 1908 America alone produced over 9000 tonnes, valued at over $500 million, while European manufacturers were also large producers. In 1888 the electrolytic manufacture of aluminium was commenced in America, and in the following year it was begun in Switzerland. Aluminium is formed by the electrolysis of the aluminium oxide in a fused bath of cryolite and fluest bath. The aluminium may be obtained in the form of bauxite, and is produced in large rectangular iron pots with a thick carbon lining. The pot itself is the cathode, while large graphite rods suspended in the bath serve as the anodes. After the arc is formed, and the heat of the bath rises to a sufficient degree, the material is decomposed, and the metal is separated out so that it can be removed by ladling or with a siphon. The application of heat to obtain this metal, previous to the invention of the electric furnace, could only be considered a laboratory problem, and the expense involved did not permit of commercial application. Now, however, aluminium is universally available, and with the exploration of certain patents, the material has sold as low as 25 cents a pound. Electrolytic methods serve also for the refining of nickel, and for the production of lead, and, as in other fields of metallurgy, these processes are attracting the attention of chemists and of engineers. While tin, as yet, has not yielded to electrolytic or electrothermal methods with any success, the removal of tin from tin scraps and cuttings has been carried on with considerable success. With zinc, the electrolytic and electrothermal processes have not been able yet to compete with the older metallurgical method of distillation, but an important industry is electro-galvanising, where a solution of zinc sulfate is deposited on iron and gives a protective coating. Experimental methods, with the use of electricity in extracting zinc from its ores, are being tested at various European plants, but the matter has not yet reached a commercial scale. One of the earliest notable uses of the electric furnace in a large electrochemical industry was for the production of carburundum, a carbide of silicon, which is remarkably useful as an abrasive, being available in the manufacture of grinding stones and other like purposes to replace emery and corundum. It is produced by the use of a simple electric furnace of the resistance type, where coke, sand and sawdust are heated to a temperature of between 2000 degrees and 3000 degrees centigrade. The chemical reaction involves the production of carbon monoxide, and gives a carbide of silicon, a crystalline solid which has the excellent abrasive properties mentioned. The manufacture was first started by its inventor, E. G. H.erson, about 1891 on a small scale, and in the following year 1000 pounds of the material were produced at the Niagara Falls Works. Within 15 years its output had increased to well over 6 million pounds. The electric furnaces at Niagara Falls have supplied many interesting electrochemical processes. After making a carbide in the electric furnace it was found possible to decompose it by further increasing the heat to a point where the second element is volatilized, and the pure carbon in the form of artificial graphite remains. In more recent work the carbide containing the silicon has been done away with and ordinary anthracite coal used as a charge from which the pure graphite is obtained. This graphite has been found especially useful in electrical work as for electrodes, while a more recent process enables a soft variety of graphites to be obtained which becomes a competitor of the natural material. One of the most interesting of the many electrochemical processes is the heating of lime and coke in the electric furnace, so as to obtain a product in the form of calcium carbide, which on solution in water forms acetylene gas, a useful and valuable illuminant. This process dates from 1893 when T. L. Wilson in the United States first started its manufacture on a large scale, and the great electrochemist Henri Moisse about the same time independently invented a similar process as a result of his notable work with the electric furnace. The process involves merely a transformation at a high temperature, a portion of the carbon in the form of coke, uniting with pulverized lime to give the calcium carbide or CAC2. Now this material, when water is added to it decomposes, and acetylene or C2H2 is formed, which is a gas of high illuminating value as the carbon separates and glows brightly after being heated to incandescence in the flame. The electric furnace at Niagara Falls has been able to produce still another combination in the form of siloxicon by heating carbon and silicon to a temperature slightly below that required to produce carbon-undom. This product is a highly refractory material, and is valuable for the manufacturer of crucibles, muffles, bricks, etc., for work where extreme temperatures are employed. The electric furnace enables various elements to be isolated, such as silicon, sodium and phosphorus, and when obtained in their pure state they find wide application. The most important electrochemical work of the future is to devise some means of obtaining nitrogen from the air. It is stated by scientists that the nitrogen of the soil is being exhausted, and that at some future time the earth may not be able to bear crops sufficient for the sustenance of man, unless some artificial means be found to replenish the nitrogen. Unlimited supplies of nitrogen exist in the air, but to fix it with other materials in such form that it will be useful as a fertilizer has been one of the problems to which the electrochemists have recently devoted much attention. By the use of the electric arc and passing air through a furnace various substances have been tried to take up the nitrogen of the air. Thus when calcium carbide is heated and brought into contact with nitrogen one atom of carbon is given up, and two atoms of nitrogen take its place, resulting in the production of cyanamide. Other important electrochemical processes are involved in the electrolysis of the various alkaline salts to obtain metallic sodium and such products as chlorates. Thus by the electrolysis of sodium chloride metallic sodium and chlorine is obtained. From the metallic sodium solid caustic soda is then derived by a secondary reaction, while the chlorine is combined with lime to form chloride of lime or bleaching powder. In some processes the electrolysis affords directly an alkaline hyperchlorite or a chlorate, the former being of wide commercial use as a bleaching agent in textile works and in the paper industry. The same process employed in the electrolysis of sodium salts is used in the case of magnesium and calcium. Electrolysis is also made use of in the manufacture of chloroform and iodoform, as the chlorine or iodine which is produced in the electrolytic cell is allowed to act upon the alcohol or acetone under such conditions that chloroform or iodoform is produced. Electrochemistry plays an important part in many other industries whose emission from our description must not be considered as indicating any lack of their importance. New processes constantly are being discovered which may range all the way from the production of artificial gems to the wholesale production of the most common chemicals used in the arts. In many branches of chemical industry manufacturing processes have been completely changed and from the research laboratories which all large progressive manufacturers now maintain as well as from workers in universities and scientific schools new methods and discoveries are constantly forthcoming. End of Chapter 11 Chapter 12 of The Story of Electricity This LibriVox recording is in the public domain. Recording by Ruth Golding The Story of Electricity by John Munn Rowe Chapter 12 Electric Railways The electric railway of Dr. Wanner von Siemens, constructed at Berlin in 1879, was the forerunner of a number of systems which have had the effect of changing materially the problems of transportation in all parts of the world. The electric railway not only was found suitable as a substitute for the tramway with its horse-drawn car, but far more economical than the cable cars, which were installed to meet the transportation problems of large cities with heavy traffic, or as in the case of certain cities on the Pacific Slope, where heavy grades made transportation a serious problem. Furthermore the electric railway was found serviceable for rural lines, where smaller steam engines or dummies were operated with limited success, and then only under exceptional conditions. As a result, practically every country of the world where the density of population and the state of civilization has warranted is traversed by a network of electric railways, securing the most complete intercommunication between the various localities and handling local transportation in a manner impossible for a railway line employing steam locomotives. The great advance in electric transportation, aside from its meeting and economic need, has been due to the development of systems of generating and transmitting power economically over long distances. If water power is available, turbines and electric generators can be installed, and power produced and transmitted over long distances, as for example from Niagara Falls to Buffalo, or even to much greater distances as in the case of power plants on the Pacific Coast, where mountain streams and lakes are employed for this purpose with considerable efficiency. A high tension alternating current thus can be transmitted over considerable distances, and then transformed into direct current, which flows along the trolley wires and is utilized in the motors. This transformation is usually accomplished by means of a rotary converter, that is, an alternating current motor, which carries with it the essential elements of a direct current dynamo, and receiving the alternating current of high potential turns it out in the form of direct current at a lower and standard potential. The alternating current at high potential can be transmitted over long distances with a minimum of loss, while the direct current at lower potential is more suitable for the motor and can be used with greater advantage. Yet its potential or pressure decreases rapidly over long lengths of line, so that it is more economical to use substations to convert the alternating current from the power plant. It must not be inferred, however, that all electric railways employ direct current machinery. In Europe alternating current has been used with great success, and also in the United States, where a number of lines have been equipped with this form of power. But the greater number of installations employ the direct current at about 500 to 600 volts, and this is now the usual practice. Whether it will continue so in the future or not is perhaps an open question. The electric car, as we have seen, employs a motor which is geared to the axle of the driving-trucks, and the current is derived from the trolley-wire by the familiar pole and wheel, and after flowing through the controller to the motor, returns by the rail. The speed of the car is regulated by the amount of current which the motorman allows to pass through the motor and the circuit through which it flows in order to produce different effects in the magnetic attraction of the magnet and the armature. In the ordinary electric car for urban or suburban uses there has been a constant increase in the power of the motor and size of the cars, as it has been found that even large cars can be handled with the required facility necessary in crowded streets, and that they are correspondingly more economical to maintain and operate. The success of electric traction in large cities had been demonstrated but a few years when it was appreciated that the overhead wires of the trolley were unsightly and dangerous, especially in the case of fire or the breaking of the wires or supports. Accordingly a system was developed where the current was obtained from conductors laid in a conduit on insulated supports through a slot in the centre of the track between the rails. A plow suspended from the bottom of the car was in contact with the conductors which were steel rails mounted on insulated supports, and through them the current passed by suitable conductors to the controller and motors. This system found an immediate vogue in American cities and though more costly to install than the overhead trolley was far more satisfactory in its results and appearance. In certain cities, Washington D.C., for example, the conduit is used in the built up portion of the town and when the suburbs are reached the plow is removed and the motors are connected with the trolley wire by the usual pole and wheel. Perhaps the most important feature of the electric railway in the United States has been the development and increase of its efficiency. Wherever possible traffic conditions warranted it was comparatively easy to secure the right of way along country highways, with little if any expense, and the construction of track and poles for such work was not a particularly heavy outlay. It was found, as we have seen, that the current could be transmitted over considerable distances so that the opportunity was afforded to supply transportation between two towns at some small distance where the local business at the time of the construction of the road would not warrant the outlay. This led to the systems of inter-urban lines, small at first, but as their success was demonstrated gradually extending and uniting so that not only two important towns were connected but eventually a large territory was supplied with adequate transportation facilities, and even mail, express and light freight could be handled. Again the success of such enterprises made it feasible for the electric railways to forsake the public highway and to secure a right of way of their own, and gradually to develop express and through service, often in direct competition with the local service of the steam railways in the same territory. Here larger cars were required and power stations of the most modern and efficient type in order to secure proper economy of operation. The general character of machinery, both generators and motors, was preserved even for these long distance lines, and their operation became simply an engineering problem to secure the maximum efficiency with a minimum expenditure. With the success of electric railways in cities and for suburban and inter-urban service naturally arose the question why electric power, whose availability and economy had been shown in so many circumstances, could not be used for the great trunk lines where steam locomotives have been developed and employed for so many years. The question is not entirely one of engineering, unless as part of the engineering problem we consider the various economic elements that enter into the question and their investigation is the important task of the twentieth century engineer. For he must answer the question not only is a method possible mechanically, but is it profitable from a practical and economic standpoint? And it is here that the question of the production of trunk lines now rests. The steam locomotive has been developed to a point perhaps of almost maximum efficiency, where the greatest speed and power have been secured that are possible on machines limited by the standard gauge of the track, four feet eight and a half inches, and the curves which present railway lines and conditions of construction demand. Now, with all, the steam locomotive mechanically considered is inefficient, as it must take with it a large weight of fuel and water which must be transformed into steam under fixed conditions. If, for example, we have one train a day working over a certain line, there would be no question of the economy of a steam locomotive, but with a number we are having isolated units for the production of power, which could be developed to far greater advantage in a central plant. Just as the factory is more economical than a number of workers engaged at their homes, and the large establishment of the trust still more economical in production than a number of factories, so the central power station producing electricity, which is as plain and used as required, is obviously more advantageous than separate units producing power on the spot with various losses inherent in small machines. But even if the central station is theoretically superior and more economical, it does not imply that it is either good policy or economy to electrify at once all the trunk lines of the states, and to send to the scrap heap thousands of good locomotives at the sacrifice of millions of dollars and the outlay of millions more for electrical equipment. In other words, unless the financial returns will warrant it, there is no good and positive reason for the electrification of our great trans-continental lines and even shorter railroads. That is the situation today, but tomorrow is another question, and the far-seeing railroad man must be ready with his answer and with his preparations. Today terminal services in large cities can better be performed by electricity, and not only is their economy in their operation, but the absence of dirt, smoke and noise is in accord with public sentiment, if not positively demanded by statute or ordinance. Suburban service can be worked much more economically and effectively by trains of motor cars, and timetable and schedule are not limited by the number of available locomotives on a line so equipped. On mountain grades, where auxiliary power, or engines of extreme capacity are required, electricity generated by water power from melting snow, or mountain lakes or streams in the vicinity may be availed of. Under such conditions powerful motors can be used on mountain divisions, not only with economy, but with increased comfort to passengers, especially where there are long tunnels. All this and more the railway man of today realises, and electrification to this extent has been accomplished or is in course of construction. For each one of the services mentioned typical installations can be given as examples, and to accomplish the various ends there is not only one system, but several systems of electrical working which have been devised by electrical engineers to meet the difficulties. To summarise then, electric working of a trunk line results in increased economy over steam locomotives by concentration of the power and especially by the use of water power where possible. Thus economy is secured to the greatest extent by a complete electrical service and not by a mixed service of electric and steam locomotives. Electrification gives an increase in capacity both in the haulage by a locomotive, an electric locomotive being capable of more work than a steam locomotive, and in schedule and rate of speed, as motor-car trains and electric terminal facilities make possible augmented traffic, and an increased use of dead parts of the system such as track and roadbed. There is a great gain in time of acceleration and for stopping, and for the Boston terminal it was estimated that with electricity fifty percent more traffic could be handled as the headway could be reduced from three to two minutes. The modern tendency of electrification deals either with special conditions or where the traffic is comparatively dense. From such a beginning it is inevitable that electric working should be extended and that is the tendency in all modern installations, as for example at the New York terminal of the New York Central and Hudson River Railroad, where the electric zone, first installed within little more than station limits, is gradually being extended. As examples of density of traffic suitable for electrification, yet at the same time possessing problems of their own, are the great terminals such as the Grand Central Station of the New York Central and Hudson River Railroad in New York City, the new Pennsylvania Station in the same city and that of the Illinois Central Station in the city of Chicago. Not only is there density here, but the varied character of the service rendered, such as express, local, suburban and freight involves the prompt and efficient handling of trains and cars. Now with suburban trains made up of motor cars, a certain number of locomotives otherwise employed are released, for these cars can be operated or shifted by their own power. Such terminal stations are often combined with tunnel sections, as in the case of the Great Pennsylvania Terminal, where the tunnel begins at Bergen, New Jersey, and extends under the Hudson River, beneath Manhattan Island and under the East River to Long Island City. It is here that electric working is essential for the comfort of passengers as well as for efficient operation. But there are tunnel sections not connected with such vast terminals, as in the case of the St. Clair Tunnel under the Detroit River. While the field and future direction of electrification is fairly well outlined, and its future is assured, yet this future will be one of steady progress rather than one of sudden upheaval for the economic reasons before stated. Today there are no final standards either of systems or of motors, and the field is open for the final evolution of the most efficient methods. Notwithstanding the extraordinary progress that has been made, many further developments are not only possible now, but will be demanded with the progress of the art. The great problem of the electric railway is the transmission of energy, and while power may be economically generated at the central station, yet, as Mr. Frank J. Sprague, one of the pioneers and foremost workers in the electrical engineering of railways, has so aptly said, it is still at that central station, and it will suffer a certain diminution in being carried to the point of utilization, as well as in being transformed into power to move locomotives, so that these two considerations lie at the bottom of the electric railway, and on them depend the choice of the system, and the design and construction of the motor. The two fundamental systems for electric railways, as in other power problems, are the direct current and the alternating current. In the former we have the familiar trolley wire, fed perhaps by auxiliary conductors carried on the supporting poles, or the underground trolley in the conduit, or the third rail laid at the side of the track. All of these have become standard practice, and are operated at the usual voltage of from 500 to 600 volts. The current on lines of any considerable length is alternating current, supplied from large central generating stations, and transformed to direct, as occasion may demand, at suitable substations. Recently there has been a tendency to employ high voltage direct current systems, where the advantages of the use of direct current motors are combined with the economies of high voltage transmission. Chief of which are the avoiding of power losses in transmission, and the economy in the first cost of copper. These high voltage direct current lines were first used in Europe, and during the year 1907 experimental lines on the Vienna railway were tested. In Germany and Switzerland tests were made of direct current system of 2000 and 3000 volts, and in 1908 there was completed the first section of a 1200 volt direct current line between Indianapolis and Louisville, which marked the first use of high tension direct current in the United States, and this was followed by other successful installations. With alternating current there can be used the various forms of single phase or polyphase current familiar in power work, but the latter is now preferred, and in Europe and in the United States in the latter part of 1908 the number of single phase lines was estimated at 27 and 28 respectively, with a total mileage of 782 and 967 miles. A trolley wire or suspended conductor is used. To employ a single phase current motors of either the repulsion type or of the series type are used, and are of heavier weight than the direct current motors, as they must combine the functions of a transformer and a motor. It is for this reason that we often see two electric locomotives at the head of a single train on lines where the single phase system is employed, while on neighbouring lines using direct current one locomotive of hardly larger size suffices. With the polyphase current a motor with a rotating field is used, and they have considerable efficiency as regards weight when compared with the single phase and with the direct current motor. The polyphase motor however is open to the objection that it does not lend itself to regulations as well as the direct current form, and with ingenious devices involving the arrangement of the magnetic field and the combination of motors various running speeds can be had. The usual voltage for these motors is 3,000 volts, but in the polyphase plant designed for the Cascade Tunnel 6,000 volts are to be used. They possess many advantages, especially their ability to run at overload, and consequently a locomotive with polyphase motor will run upgrade without serious loss of speed. The single phase system has been carried on on Swiss and Italian railroads, notably on the Saint-Plain Tunnel and the Balterliner lines with great success, and the distribution problems are reduced to a minimum. In the United States a notable installation has been made on the New York, New Haven and Hartford Railroad where the section between New York has been worked by Electricity exclusively since July 1, 1908. Here the single phase motors use direct current while running over the tracks of the New York Central from Woodlawn to the Grand Central Terminal. On both the New York, New Haven and Hartford, and the New York Central locomotives, the armature is formed directly on the axle wheels, so consequently much interest attaches to the new design adopted for the Pennsylvania Tunnels, where the armatures of the direct current motors are connected with the driving wheels by connecting rods, somewhat after the fashion of the steam locomotive, and following in this respect some successful European practice. End of Chapter 12 Appendix of the story of Electricity, this LibriVox recording is in the public domain recording by Ruth Golding The Story of Electricity by John Monroe Appendix, Units of Measurement from Monroe and Jameson's pocketbook of electrical rules and tables. Fundamental Units The electrical units are derived from the following mechanical units. Centimeter as a unit of length the gram as a unit of mass the second as a unit of time. The centimeter is equal to 0.3937 inches in length, and nominally represents 1,000 millionth part, or 1 over 1,000 million of a quadrant of the earth. The gram is equal to 15.432 grains, and represents the mass of a cubic centimeter of water at 4 degrees centigrade. Mass is the quantity of matter in a body. The second is the time of one swing of a pendulum making 86,164.09 swings in a sidereal day, or one 86,400th part of a mean solar day. Two derived mechanical units. Area The unit of area is the square centimeter. Volume The unit of volume is the cubic centimeter. Velocity is rate of change of position. It involves the idea of direction as well as that of magnitude. Velocity is uniform when equal spaces are traversed by time. The unit of velocity is the velocity of a body which moves through unit distance in unit time, or the velocity of one centimeter per second. Momentum is the quantity of motion in a body, and is measured by mass times velocity. Acceleration is the rate of change of velocity, whether that is in the direction of motion or not. The unit of acceleration is the acceleration of a body which undergoes unit change of velocity in unit time, or an acceleration of one centimeter per second per second. The acceleration due to gravity is considerably greater than this, for the velocity imparted by gravity to falling bodies in one second is about one centimeters per second, or about 32.2 feet per second. The value differs slightly in different latitudes. At Greenwich the value of the acceleration due to gravity is g equals 981.17 At the equator g equals 978.1 At the north pole g equals 983.1 Force is that which tends to alter a body's natural state of rest or of uniform motion in a straight line. Force is measured by the acceleration which it imparts to mass, i.e. mass times acceleration. The unit of force, or dyne, is that force which acting for one second on a mass of one gram, gives to it a velocity of one centimeter per second. The force with which the Earth attracts any mass is usually called the weight of that mass, and its value obviously differs at different points of the Earth's surface. The force with which a body gravitates, i.e. its weight in dynes, is found by multiplying its mass in grams by the value of g at the particular place where the force is exerted. Work is the product of a force and a distance through which it acts. The unit of work is the work done in overcoming unit force through unit distance, i.e. in pushing a body through a distance of one centimeter against a force of one dyne. It is called the erg. Since the weight of one gram is one times 981, or 981 dynes, the work of raising one gram through the height of one centimeter against the force of gravity is 981 ergs, or g ergs. One kilogram meter equals 100,000 g ergs, equals 9.81 times 10 to the power of 7 ergs. One foot pound equals 13,825 g ergs, equals 1.356 times 10 to the power of 7 ergs. Energy is that property which possessed by a body gives it the capability of doing work. Kinetic energy is the work a body can do in virtue of its motion. Energy is the work a body can do in virtue of its position. The unit of energy is the erg. Power or activity is the rate of work. The practical unit is called the watt, equals 10 to the power of 7 ergs per second. A horsepower equals 33,000 foot pounds per minute, equals 550 foot pounds per second. But as seen above under work, one foot pound equals 1.356 times 10 to the power of 7 ergs. And under power, one watt equals 10 to the power of 7 ergs per second. Therefore a horsepower equals 550 times 1.356 times 10 to the power of 7 ergs, equals 746 watts. Or EC over 746 equals C squared R over 746 equals E squared over 746 R, equals horsepower. Where E equals volts C equals ampere and R equals ohms. The French force to chivalre equals 75 kilogram meters per second. Equals 736 watts. Equals 542.48 foot pounds per second. Equals 0.9863 horsepower. Or 1 horsepower equals 1.01385 foster chivalre. Derived electrical units. There are two systems of electrical units derived from the fundamental CGS units. One set being based upon the force exerted between two quantities of electricity. And the other upon the force exerted between two magnetic poles. The former set are termed electrostatic units. The latter, electromagnetic units. Three, electrostatic units. Unit quantity of electricity is that which repels an equal and similar quantity at unit distance with unit force in air. Unit current is that which conveys unit quantity of electricity along a conductor in a second. Unit electromotive force or unit difference of potential exists between two points and the unit quantity of electricity in passing from one to the other will do the unit amount of work. Unit resistance is that of a conductor through which unit electromotive force between its ends can send a unit current. Unit capacity is that of a condenser which contains unit quantity when charged to unit difference of potential. Four, magnetic units. Unit magnetic pole is that which repels an equal and similar pole at unit distance with unit force in air. Strengths of magnetic field at any point is measured by the force which would act on a unit magnetic pole placed at that point. Unit intensity of field is that intensity of field which acts on a unit pole with unit force. Moment of a magnet is the strength of either pole multiplied by the distance between the poles. Intensity of magnetization is the magnetic moment of a magnet divided by its volume. Magnetic potential the potential at a point due to a magnet is the work that must be done in removing a unit pole from that point to an infinite distance against the magnetic attraction or in bringing up a unit pole from an infinite distance to that point against the magnetic repulsion. Unit difference of magnetic potential Unit difference of magnetic potential exists between two points when it requires the expenditure of one erg of work to bring a north or south unit magnetic pole from one point to the other against the magnetic forces. 5. Electromagnetic Units Unit current is that which in a wire of unit length bent so as to form an arc of a circle of unit radius would act upon a unit pole at the centre of the circle of force. Unit quantity of electricity is that which a unit current conveys in unit time. Unit electromotive force or difference of potential is that which is produced in a conductor moving through a magnetic field at such a rate as to cut one unit line per second. Unit resistance is that of a conductor in which unit current is produced by unit electromotive force between its ends. Unit capacity is that of a condenser which will be at unit difference of potential when charged with unit quantity. Electric and magnetic force varies inversely as the square of the distance. Practical Units of Electricity Resistance R The Ohm is the resistance of a column of Mercury 106.3 cm long 1 square millimeter in cross section weighing 14.4521 grams and at a temperature of 0 degrees centigrade. Standards of wire are used for practical purposes. The Ohm is equal to 1000 million 10 to the power of 9 electromagnetic 2mg second CGS units of resistance. The Meg Ohm is 1 million Ohms. The Microme is 1 millionth of an Ohm. Electromotive Force E The Volt is that electromotive force which maintains a current of 1 ampere in a conductor having a resistance of 1 Ohm. The Electromotive Force The Clark Standard Cell at a temperature of 15 degrees centigrade is 1.434 volts. The Volt is equal to 100 million 10 to the power of 8 CGS units of electromotive force. Current C The Ampere is that current which will decompose 0.09324 milligrams of water H2O per second or deposit 1.118 milligrams of silver per second. It is equal to 1 tenth of a CGS unit of current. The Millie Ampere is one thousandth of an ampere. Quantity Q The Coulomb is the quantity of electricity conveyed by an ampere in a second. It is equal to 1 tenth of a CGS unit of quantity. The Micro Coulomb is one millionth of a Coulomb. Capacity K The Farad is that capacity of a body say a Leiden jar or condenser which a Coulomb of electricity will charge to the potential of a Volt. It is equal to CGS unit of capacity. The Micro Farad is one millionth of a Farad. By Ohm's law current equals electromotive force divided by resistance or C equals E over R. Ampere equals Volt over Ohm. Hence when we know any two of these quantities we can find the third. For example, if we know the electromotive force or difference of potential in volts and the resistance in Ohm's of an electric circuit we can easily find the current in amperes. Power P The What is the power conveyed by a current of one ampere through a conductor whose ends differ in potential by one Volt. Or in other words doing work when an ampere passes through an Ohm. It is equal to 10 million 10 to the power of 7 CGS units of power or ohms per second. That is to say to a joule per second or one 746th of a horsepower. A watt equals Volt times ampere and a horsepower equals watts divided by 746. Heat or work W The joule is the work done or heat generated by a watt in a second. That is the work done or heat generated in a second by an ampere flowing through the resistance of an Ohm. It is equal to 10 million 10 to the power of 7 CGS units of work or ohms. Assuming joule's equivalent heat and mechanical energy to be 41,600,000 it is the heat required to raise 0.24 grams of water one degree centigrade. A joule equals Volt times ampere times second. Since one horsepower equals 550 foot pounds of work per second W equals 550 over 746 E Q Equals 0.7373 E Q foot pounds Heat units The British unit is the amount of heat required to raise one pound of water from 60 degrees to 61 degrees Fahrenheit. It is 251.9 times greater than the metric unit, therm or calorie which is the amount of heat required to raise one gram of water from 4 degrees to 5 degrees centigrade. Joule's equivalent J is the amount of energy equivalent to a therm or calorie the metric unit of heat. It is equal to 41,600,000 Ergs. The heat in therms generated in a wire by a current equals Volt times ampere in seconds times 0.24 Light units The British unit is the light of a spermaceti candle 7 eighths inch in diameter, burning 120 grains per hour 6 candles to the pound. They sometimes vary as much as 10 percent from the standard. Mr. Vernon Harcourt's standard flame is equal to an average standard candle. The French unit is the light of a carcel lamp and is equivalent to nine and a half British units. End of the appendix and end of the story of electricity by John Monroe.