Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1890-10-12
A Very Familiar Application Of the
Mysterious Current.
HOW IT STORES UP ENERGY
So Great Amount Can be Utilized in an
Instant of Time.
GAS LIGHTING BY ELECTRICITY
WRITTEN FOR THE DIspATcH.l


an electric current is passed through coil
of insulated wire surrounding it. Under
those circumstances the iron is called an
electro-magnet. IF the core be piece OF
steel it will retain its magnetism, even
though the electric coils be removed-and IL
is then called permanent magnet. Ii,
however, the iron core is made OF soft an
nealed iron, it will only be magnetic SO long
as there is current flowing through the coil,
An electro-magnet has two poles; north
and a south, just like permanent magnet.
Surrounding every magnet there are what
are called, "liues of force" We cannot see
these lines of force, nor can we touch them.
We know of their existence by experiment
only, and study them by their effects. If we
cover a bar magnet with a piece of glass
and then sift fine iron filings into the glass.
the filings will arrange themselves in curved
lines reaching from pole to pole.
DIRECTION BUT NOT MOVEMENT.
These lines form closed circuits, and are
supposed to have direction, but no motion
or flow like current. That is, the lines of
force are supposed to have an outward dl-
rection from the North Pole ana thenacurve,
through the space surrounding the magnet,
to the South Pole, and, returning again to
the North Pole through the body of the
magnet, thus close tine magnetic circuit.
An electric current is also said to have
direction, and, although we use the express
sion current" there Is no actual flow that
we know of. The expression is simply
matter of convenience and is used for lack
of something better.
Now, if we reverse the direction of the
current in an electro-magnet, the poles OF
the magnet will be reversed, and so, of
course, the direction of the lines of force.
If looking directly at the end of an electro
magnet, the electric current has direction
from right to left around the iron core, that
is, in an opposite direction from the hands
of clock, the near pole will be positive and
the other negative. If, looking at the pole
as before, the direction of the current is from
LETT to right, that is, having the direction of
the hands of clock, the near pole will be
the negative pole and the other the positive.
In short, with an electro-magnet we can in
terchange the poles of the magnet by chang
ing the direction of the electric current and
we can remove its magnetism by removing
or turning of the electric current.
ELECTRICITY AND MAGNETISM.
Magnetism is form OF energy, and elec-
tricity is form of energy, and further the
two are directly interchangeable. In fact,
the core of an electro-magnet will store
electric energy much as storage battery
does. In previous article we have ex-
plained how that energy is condition of
things. That is, if weight is raised, it
represents energy by virtue Of Its position.
The condition of things here is the separa-
tion OF two things-the earth and a weight
that have a strong attraction for each
other. However, energy had to be expended
&lor asn~hf ov,l tha
will be returned by the falling of the weight.
And so it is with electricity and cleo
tro-magnets. If we send a current of cleo
tricity through the coils of an electro-mag-
net its iron cor e will be energised, that is,
the condition or character OF the iron will
be 50 changed that it will have "lines of
force" From the above we might reason
ably expect that, if those lines of force
should in any way be made to disappear,
they would give back their energy to the
wire coil. And this is in fact found to be
the case, and can be proved in a great many
different and very interesting ways. How
ever, few examples must suffice.
TRANSFORMATION OF ENERGY.
Take an ordinary electromagnetic, such as
we have described, and over this slip an.
other coil, having its ends connected to
galvanometer or other currentindicating
instrument. If then the current flowing
through the electro-magnet coil is suddenly
opened, the iron core will lose its magnetic
properties and surrender or transfer its en-
ergy to the second coil, that we have
slipped over the magnet, and a momentary
current of electricity will be induced in this
coil, as will be seen by the current indicat-
ors or galvanometers, that was placed in the
circuit.
Tv how {ro,, ,,sfo 81 -
energy into magnetic energy, and then this
magnetic energy back into electricity again.
However, this storage and transformation
of energy differs from the storage of energy
in a wound-up spring, for with the spring
there is catch to hold the spring in Its
strained condition after it is wound up.
But with the electromagnetic we have no
catch, and the moment the magnetizing
force-that is the currents removed or
stopped, the magnetism, that is the strained
condition of the iron, ceases, the lines of
force disappear. However, in ceasing, the
magnetism, like the spring, will give up its
energy in some other form.
PROOF BY SENSATION.
Another very forcible way of demonstrate
ing this storage of energy in the electro
magnet is to open the circuit of such
magnet with the hands, keeping hold of the
bare ends of the wire. A very severe shock
will be experienced, caused by what is
called "the extra current" or 'tthe discharge
current" This extra current that is sud-
denly generated when the circuit of the
electromagnetic is opened, is simply the
energy OF the magnet suddenly transformed
and concentrated into very intense current,
having short duration. With powerful
magnets this discharge current is very dam
gerous, if not fatal.
Iu the industries the most powerful
electromagnetic are found In dynamos,
motors and converters and in those machines
electro. magnets of smaller sizes are also
used. The magnetizing power of an electro
magnet coil is measured by its ampere
turns-that is the magnetizing power is
proportional to the number of turns of
wire, multiplied by the units (amperes) of
current flowing. For example, eight
amperes with two turns of wire would give
just the same magnetlzing power as four
amperes with four turns, and in each case
the magnetizing power would be called 16
ampere-turns.
The smaller electromagnetic are found at
every hand. 1t is by their means that we
are able to communicate at distance with
the telegraph, telephone, annunciator and
other such like instruments In the electric
gas-lighter we have practical and interest
ing application of the smaller electro
magnets, or Induction coils" as they are
often called. Here a small electro-magnet
is placed in an open circuit. The circuit is
closed only at the instant of turning on the
gas, and it is done in such q way that the
two ends of the circuit are brought just over
the burner. The current is furnished by a
small battery.
Now. when this contact is made and the
circuit thus closed, the electro-magnet in