ELECTRO-CHEMISTRY AND ELECTRO-METALLURGY.
In no department of the application of electricity to practical
work has there been a greater development than in electro-
metallurgy and electro-chemistry. To-day 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 aluminum 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 neighborhood 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 aluminum, 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 recognized 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 electro-
metallurgical industry and at that time it was carried on on a
very limited scale. To-day 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 250
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 350 tons of electrolytic copper in
twenty-four hours, and over 400,000 tons is the aggregate output
of the refineries of the world, which is about 53 per cent, of the
total raw copper production. Of this amount 85 per cent, comes
from American refineries, whose output has more than doubled since
1900.
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
labor, 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 Bessemer 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 Heroult and
other electro-metallurgists 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 electro-
metallurgy 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 Heroult
furnace, soon to be described, was employed. Electro-metallurgy of
steel, as in all utilization of electrical power, depends upon
obtaining electricity at a reasonable cost, and then utilizing 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 Heroult 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
Heroult 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 sulphur 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 Heroult crucible furnace.
Furnaces of an altogether different type are those employing an
alternating current, such as the Kjellin and Rochling 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 seen 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 around 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 Heroult type.
A third type of furnace that is meeting with some extensive use is
the Giroud, which, like the Heroult 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 Heroult 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 5,000
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 ferro-alloys, 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 armor 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 ferro-alloys, 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 electro-metallurgical 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 tons of aluminum, and its value was roughly
estimated at about $12 a pound. By 1908 America alone produced
over 9,000 tons valued at over $500,000,000, while European
manufacturers were also large producers. In 1888 the electrolytic
manufacture of aluminum was commenced in America and in the
following year it was begun in Switzerland. Aluminum is formed by
the electrolysis of the aluminum oxide in a fused bath of cryolite
and fluorspar. The aluminum 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, aluminum is universally available and
with the expiration 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
electro-thermal 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 electro-thermal processes
have not been able yet to compete with the older metallurgical
method of distillation, but an important industry is electro-
galvanizing, where a solution of zinc sulphate 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 electro-chemical industry was for the production of
carborundum, 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 C. 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. Acheson, about 1891 on a small scale, and in the
following year 1,000 pounds of the material were produced at the
Niagara Falls works. Within fifteen years its output had increased
to well over six million pounds.
The electric furnaces at Niagara Falls have supplied many
interesting electro-chemical 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 graphite to
be obtained which becomes a competitor of the natural material.
One of the most interesting of the many electro-chemical 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. Willson in the
United States first started its manufacture on a large scale, and
the great electrochemist, Henri Moissin, 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 carborundum. This product is a highly refractory
material and is valuable for the manufacture 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 electro-chemical 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 electro-chemists 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 electro-chemical 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 hypochlorite 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.
Electro-chemistry plays an important part in many other industries
whose omission 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.
CHAPTER XII.
ELECTRIC RAILWAYS.
The electric railway of Dr. Werner 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 small 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 an 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 sub-stations 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 500-600 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 circuits 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 interurban 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 interurban 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 electrification 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, 4 feet 8 1/2 inches, and the
curves which present railway lines and conditions of construction
demand. Now, withal, 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 simply maintaining 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 can be transmitted along a
line 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 a country such
as the United 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 to-day, but to-morrow is another question, and the far-
seeing railroad man must be ready with his answer and with his
preparations. To-day terminal services in large cities can better
be performed by electricity, and not only is there 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 time
table 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 to-day realizes, 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 summarize 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 50 per
cent, 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. To-day 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 sub-stations. 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 2,000 and 3,000 volts
and in 1908 there was completed the first section of a 1,200-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 neighboring
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 up grade without serious
loss of speed. The single phase system has been carried on on
Swiss and Italian railroads, notably on the Simplon Tunnel and the
Baltelina lines with great success, and the distribution problems
are reduced to a minimum. In the United States a notable
installation has been on the New York, New Haven & Hartford
Railroad, where the section between Stamford and 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 & Hartford and the New
York Central locomotives the armature is formed directly on the
axle of the driving 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.
APPENDIX.
UNITS OF MEASUREMENT.
(From Munro and Jamieson's Pocket-book of Electrical Rules and
Tables).
I. FUNDAMENTAL UNITS.--The electrical units are derived from the
following mechanical units:--
The Centimetre as a unit of length;
The Gramme as a unit of mass;
The Second as a unit of time.
The Centimetre is equal to 0.3937 inch in length, and nominally
represents one thousand-millionth part, or 1/1,000,000,000 of a
quadrant of the earth.
The Gramme is equal to 15.432 grains, and represents the mass of a
cubic centimetre of water at 4 degrees C. 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 1/86,400 part of a mean solar day.
II. DERIVED MECHANICAL UNITS.-
Area.-The unit of area is the square centimetre.
Volume.--The unit of volume is the CUBIC CENTIMETRE.
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 in equal intervals of time The unit of
velocity is the velocity of a body which moves through unit
distance in unit time, or the VELOCITY OF ONE CENTIMETRE PER
SECOND.
MOMENTUM is the quantity of motion in a body, and is measured by
mass x velocity.
ACCELERATION is the rate of change of velocity, whether that
change take place 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
centimetre-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 981 centimetres
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=981.17; at the Equator g=978.1;
at the North Pole g=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 x acceleration.
THE UNIT OF FORCE, or DYNE, is that force which, acting for one
second on a mass of one gramme, gives to it a velocity of one
centimetre 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 grammes) 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 centimetre against a forch of one dyne. It is called the
Erg. Since the "weight" of one gramme is 1 X 981 or 981 dynes, the
work of raising one gramme through the height of one centimetre
against the force of gravity is 981 ergs or g ergs. One
kilogramme-metre = 100,000 (g) ergs = 9 8 1 X 10^7 ergs. One foot-
pound = 13,825 (g) ergs, = 1 356 X 10^7 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. Potential 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--10^7 ergs per second.
A Horse-power = 33,000 ft--Ibs per minute = 550 ft--Ibs per
second, but as seen above under Work, 1 ft--Ib = 1 356 X 10^7
ergs, and under Power, 1 Watt = 10^7 ergs per sec a Horsepower =
550 X 1 356 X 10^7 ergs = 746 Watts; or, =EC/746=C^2R/746=E^2/(746
R) =HP where E = volts, C = amperes, and R = ohms.
The French "force de cheval" = 75 kilogramme metres per sec = 736
Watts = 542 48 ft--lbs. per sec. = .9863 H.P.; or one H.P. =
1.01385 "force de cheval."
DERIVED ELECTRICAL UNITS.--There are two systems of electrical
units derived from the fundamental "C.G.S." 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 electro-static units,
the latter electro-magnetic units.
III. 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 when 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.
IV. MAGNETIC UNITS.--
UNIT MAGNETIC POLE is that which repels an equal and similar pole
at unit distance with unit force in air.
STRENGTH 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 MAGNETISATION 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 an (N. or S.) unit
magnetic pole from one point to the other against the magnetic
forces.
V. ELECTRO-MAGNETIC 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 with unit force.
UNIT QUANTITY of electricity is that which a unit current conveys
in unit time.
UNIT ELECTRO-MOTIVE 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 electro-motive 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 centimetres long, 1 square millimetre in cross-section,
weighing 14.4521 grammes, and at a temperature of 0 degrees
centigrade. Standards of wire are used for practical purposes. The
ohm is equal to a thousand million, 10^9, electromagnetic or
Centimetre-Gramme-Second ("C. G. S.") units of resistance.
The megohm is one million ohms.
The microhm is one millionth of an ohm.
ELECTROMOTIVE FORCE--E.--The Volt is that electromotive force
which maintains a current of one ampere in a conductor having a
resistance of one ohm. The electromotive force of a Clark standard
cell at a temperature of 15 degrees centigrade is 1.434 volts. The
volt is equal to a hundred million, 10^8, C. G. S. units of
electromotive force.
CURRENT--C.--The Ampere is that current which will decompose
0.09324 milligramme of water (H2O) per second or deposit 1.118
milligrammes of silver per second. It is equal to one-tenth of a
C. G. S. unit of current.
The milliampere 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 one-tenth of a C. G. S.
unit of quantity.
The micro-coulomb is one millionth of a coulomb.
CAPACITY--K.--The farad is that capacity of a body, say a Leyden
jar or condenser, which a coulomb of electricity will charge to
the potential of a volt. It is equal to one thousand-millionth of
a C. G. S. unit of capacity.
The micro-farad is one millionth of a Farad.
By Ohm's Law, Current = Electromotive Force/ Resistance,
or C = E/R
Ampere = Volt/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 ohms of an
electric circuit, we can easily find the current in amperes.
POWER--P.--The Watt 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, the rate of doing work when an ampere
passes through an ohm. It is equal to ten million, 10^7, C. G. S.
units of power or ergs per second, that is to say, to a Joule per
second, or 1/746 of a horse-power.
A Watt = volt X ampere, and a Horse-power = Watts/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 ten million, 10^7, C. G. S. units of work or ergs.
Assuming "Joule's equivalent" of heat and mechanical energy to be
41,600,000, it is the heat required to raise .24 gramme of water 1
degrees centigrade. A Joule = Volt x ampere x second. Since 1
horse-power = 550 foot pounds of work per second,
W = 550/746 E. Q. = .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 gramme 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 = Volt X
ampere X time in seconds X 0.24.
LIGHT UNITS
The British Unit is the light of a spermaceti candle 7/8-inch in
diameter, burning 120 grains per hour (six candles to the pound).
They sometimes vary as much as 10 per cent, 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 9 T/Z British units.