If the electrified person put his finger, or a rod of iron, into a dish containing warm spirits of wine, it will be immediately in a blaze; and if there be a wick or thread in the spirit, that communicates with a train of gunpowder, he may be made to blow up a magazine, or set a city on fire, with a piece of cold iron, and at the same time be ignorant of the mischief he is doing.

_The Inconceivable Shock._

Put in a person's hand a wire that is fixed on to the hook that comes from the chain, which communicates with one side of the battery, and in his other hand put a small wire with a hook at the end of it, which you direct him to fix on to a hook which comes from the other chain.

On attempting to do this, he will instantly receive a shock from his body, without being able to guess the cause.

Care should be taken that the shock be not too strong; and regard should be had to the const.i.tution and disposition of the party, as a shock that would hardly affect one person, might be productive of very serious consequences to another.

Much entertainment may be derived from concealing the chain that communicates with that which proceeds from the outside of the battery, under a carpet, and placing the wire that communicates with the chain from the inside, in such a manner that a person may put his hand on it without suspicion, at the same time that his feet are upon the other wire.

The whole company may be made to partake of the shock, by joining hands, and forming a circle. The experiment may also be varied if they tread upon each other's toes, or lay their hands upon each other's heads. It might happen, by the latter method, that the whole company would be struck to the ground; but it will be productive of no danger, and very little inconvenience; on the contrary, it has happened that they have neither heard nor felt the shock.

To exhibit the five following amus.e.m.e.nts in electricity, the room in which they are performed must be darkened.

_The Miraculous Luminaries._

You must previously prepare the following phosphorus: Calcine common oyster-sh.e.l.ls, by burning them in the fire for half an hour; then reduce them to powder; of the clearest of which take three parts, and of flowers of sulphur one part; put the mixture into a crucible, about an inch and a half deep. Let it burn in a strong fire for rather better than an hour; and when it is cool, turn it out and break it in pieces; and, taking those pieces into a dark place, sc.r.a.pe off the parts that shine brightest, which, if good, will be a white powder.

Then construct a circular board, of three or four feet diameter, on the centre of which draw in gum-water, or any adhesive liquid, a half-moon, of three or four inches diameter, and a number of stars round it, at different distances, and of various magnitudes. Strew the phosphorus over the figures, to the thickness of about a quarter of an inch, laying one coat over the other. Place this board behind a curtain; and when you draw the curtain up or back, discharge one electrifying jar or phial over each figure, at the distance of about an inch, and they will become illuminated, exhibiting a very striking resemblance of the moon and stars; and will continue to shine for about half an hour, their splendour becoming gradually more faint.

_The Fiery Shower._

On the plate put a number of any kind of seeds, grains of sand, or bra.s.s dust. The conductor being strongly electrified, those light particles will be attracted and repelled by the plate suspended from the conductor, with amazing rapidity, so as to exhibit a perfect fiery shower.

Another way is by a sponge that has been soaked in water. When this sponge is first hung to the conductor, the water will drop from it very slowly; but when it is electrified, the drops will fall very fast, and appear like small globes of fire, illuminating the basin into which they fall.

_The Illuminated Vacuum._

Take a tall receiver that is very dry, and fix through the top of it, with cement, a blunt wire; then exhaust the receiver, and present the k.n.o.b of the wire to the conductor, and every spark will pa.s.s through the vacuum in a broad stream of light, visible through the whole length of the receiver, let it be as tall as it will. This generally divides into a variety of beautiful rivulets, which are continually changing their course, uniting and dividing again in the most pleasing manner.

If a jar be discharged through this vacuum, it presents the appearance of a very dense body of fire, darting directly through the centre of the vacuum, without touching the sides; whereas, when a single spark pa.s.ses through, it generally goes more or less to the side, and a finger placed on the outside of the gla.s.s will draw it wherever a person pleases. If the vessel be grasped by both hands, every spark is felt like the pulsation of a large artery; and all the fire makes towards the hands. This pulsation is even felt at some distance from the receiver, and a light is seen between the hand and the gla.s.s.

All this while, the pointed wire is supposed to be electrified positively; if it be electrified negatively, the appearance is astonishingly different; instead of streams of fire, nothing is seen but one uniform luminous appearance, like a white cloud, or the _milky way_ in a clear star-light night. It seldom reaches the whole length of the vessel, but generally appears only at the end of the wire, like a lucid ball.

If a small phial be inserted in the neck of a small receiver, so that the external surface of the gla.s.s be exposed to the vacuum, it will produce a very beautiful appearance. The phial must be coated on the inside; and while it is charging, at every spark taken from the conductor into the inside, a flash of light is seen to dart at the same time from every part of the external surface of the phial, so as to quite fill the receiver. Upon making the discharge, the light is seen to run in a much closer body, the whole coming out at once.

_The Illuminated Cylinder._

Provide a gla.s.s cylinder, three feet long, and three inches diameter; near the bottom of it fix a bra.s.s plate, and have another bra.s.s plate, so contrived that you may let it down the cylinder, and bring it as near the first plate as you desire. Let this cylinder be exhausted and insulated, and when the upper part is electrified, the electric matter will pa.s.s from one plate to the other, when they are at the greatest distance from each other that the cylinder will admit. The bra.s.s plate at the bottom of the cylinder will also be as strongly electrified as if it were connected by a wire to the prime conductor.

The electric matter, as it pa.s.ses through this vacuum, presents a most brilliant spectacle, exhibiting sparkling flashes of fire the whole length of the tube, and of a bright silver hue, representing the most lively exhalations of the aurora borealis.

_The Electric Aurora Borealis._

Make a Torricellian vacuum[G] in a gla.s.s tube, about three feet long, and hermetically sealed.[H] Let one end of this tube be held in the hand, and the other applied to the conductor; and immediately the whole tube will be illuminated from one end; and when taken from the conductor will continue luminous, without interruption, for a considerable time, very often about a quarter of an hour. If, after this, it be drawn through the hand either way, the light will be uncommonly brilliant, and, without the least interruption, from one end to the other, even to its whole length. After this operation, which discharges it in a great measure, it will still flash at intervals, though it be held only at the extremity, and quite still; but if it be grasped by the other hand at the same time, in a different place, strong flashes of light will dart from one end to the other. This will continue for twenty-four hours, and often longer, without any fresh excitation. Small and long gla.s.s tubes, exhausted of air, and bent in many irregular crooks and angles, will, when properly electrified, exhibit a very beautiful representation of vivid flashes of lightning.

[G] A Torricellian vacuum is made by filling a tube with pure mercury and then inverting it, in the same manner as in making a barometer; for as the mercury runs out, all the s.p.a.ce above will be a true vacuum.

[H] A gla.s.s is hermetically sealed by holding the end of it in the flame of a candle, till it begin to melt, and then twisting it together with a pair of pincers.

_The Electrical Orrery._

By the motion of circulating points, we may in some measure imitate the revolutions of the heavenly bodies, forming what is called the _Electrical Orrery_. Let a single wire, with the extremities pointed and turned, be nicely balanced on a point; fix a small gla.s.s ball over its centre to represent the sun. At one extremity of the wire, let a small wire be soldered perpendicularly, and on this balance another small wire with its ends pointed and turned, and having a small pith ball in its centre, to represent the earth, and a smaller ball of the same kind at one of the angles, for the moon. Let the whole be supported upon a gla.s.s pillar, and be conducted by a chain proceeding from the prime conductor to the wire supporting the gla.s.s ball. Now, when the machine is put in motion, the wires will turn round, so that the ball representing the earth will move round the central ball, and the little ball at the angle of the smaller wire will at the same time revolve about the earth.

_The Electrified Cotton._

Take a small lock of cotton, extended in every direction as much as can conveniently be done, and by a linen thread about five or six inches long, or by a thread drawn out of the same cotton, tie it to the end of the prime conductor; then set the machine in motion, and the lock of cotton, on being electrified, will immediately swell, by repelling its filaments from one another, and will stretch itself towards the nearest conductor. In this situation let the cylinder be kept in motion, and present the end of your finger, or the k.n.o.b of a wire, towards the lock of cotton, which will then immediately move towards the finger, and endeavour to touch it; but take with the other hand a pointed needle, and present its point towards the cotton, a little above the end of the finger, and the cotton will be observed immediately to shrink upwards, and move towards the prime conductor.

Remove the needle, and the cotton will come again towards the finger.

Present the needle, and the cotton will shrink again.

_The Electric Sparks._

When the prime conductor is situated in its proper place, and electrified by whirling the cylinder, if a metallic wire, with a ball at its extremity, or the knuckle or a finger be presented to the prime conductor, a spark will be seen to issue between them, which will be more vivid, and will be attended with a greater or less explosion, according as the ball is larger. The strongest and most vivid sparks are drawn from that end or side of the prime conductor which is farthest from the cylinder. The sparks have the same appearance whether they be taken from the positive or negative conductor; they sometimes appear like a long line of fire reaching from the prime conductor to the opposed body, and often (particularly when the spark is long, and different conducting substances in the line of its direction) it will have the appearance of being bent to sharp angles in different places, exactly resembling a flash of lightning.

The figure of a spark varies with the superficial dimensions of the part from which it is taken. If it be drawn from a ball of two or three inches in diameter, it will have the appearance of a straight line; but if the ball from which it is drawn be much smaller, as half an inch in diameter, it will a.s.sume the zig-zag appearance above mentioned.

_Dancing b.a.l.l.s._

Take a common tumbler or gla.s.s jar, and having placed a bra.s.s ball in one of the holes of the prime conductor, set the machine in motion, and let the b.a.l.l.s touch the inside of the tumbler; while the ball touches only one point, no more of the surface of the gla.s.s will be electrified, but by moving the tumblers about, so as to make the ball touch many points successively, all the points will be electrified, as will appear by turning down the tumbler over a number of pith or cork b.a.l.l.s placed on a table. These b.a.l.l.s will immediately begin to fly about.

_The Leyden Phial._

When a nail or piece of thick bra.s.s wire, &c., is put into a small apothecary's phial, and electrified, remarkable effects follow; but the phial must be very dry or warm. Rub it once beforehand with your finger, on which put some pounded chalk. If a little mercury, or a few drops of spirit of wine, be put into it, the experiment succeeds the better. As soon as this phial and nail are removed from the electrifying gla.s.s, or the prime conductor, to which it has been exposed, is taken away, it throws out a stream of flame so long, that with this burning-machine in your hand, you may take about sixty steps in walking about your room. When it is electrified strongly, you may take it into another room, and there fire spirits of wine with it. If, while it is electrifying, you put your finger, or a piece of gold which you hold in your hand, to the nail, you receive a shock which stuns your arms and shoulders.

A tin tube, or a man placed upon electrics, is electrified much stronger by these means than in the common way. When you present this phial and nail it to a tin tube, fifteen feet long, nothing but experience can make a person believe how strongly it is electrified.

Two thin gla.s.ses have been broken by the shock of it. It appears extraordinary, that when this phial and nail are in contact with their conducting or non-conducting matter, the strong shock does not follow.

_The Self-moving Wheel._

The self-moving wheel is made of a thin round plate of window-gla.s.s, seventeen inches in diameter, well gilt on both sides, to within two inches of the circ.u.mference. Two small hemispheres of wood are then fixed with cement, to the middle of the upper and under sides, centrally opposite, and in each of them a thick strong wire, eight or ten inches long, making together the axis of the wheel. It turns horizontally on a point at the lower end of its axis, which rests on a bit of bra.s.s, cemented within a gla.s.s salt-cellar. The upper end of its axis pa.s.ses through a hole in a thin bra.s.s plate, cemented to a long and strong piece of gla.s.s, which keeps it six or eight inches distant from any non-electric, and has a small ball of wax or metal on its top.

In a circle on the table which supports the wheel, are fixed twelve small pillars of gla.s.s, at about eleven inches distance, with a thimble on the top of each. On the edge of the wheel is a small leaden bullet, communicating by a wire with the upper surface of the wheel; and about six inches from it is another bullet, communicating, in like manner, with the under surface. When the wheel is to be charged by the upper surface, a communication must be made from the under surface with the table.

When it is well charged it begins to move. The bullet nearest to a pillar moves towards the thimble on that pillar, and, pa.s.sing by, electrifies it, and then pushes itself from it. The succeeding bullet, which communicates with the other surface of the gla.s.s, more strongly attracts that thimble, on account of its being electrified before by the other bullet; and thus the wheel increases its motion, till the resistance of the air regulates it. It will go half an hour, and make, one minute with another, twenty turns in a minute, which is six hundred turns in the whole, the bullet of the upper surface giving in each turn twelve sparks to the thimbles, which make seven thousand two hundred sparks, and the bullet of the under surface receiving as many from the thimble, these bullets moving in the time nearly two thousand five hundred feet. The thimbles should be well fixed, and in so exact a circle, that the bullets may pa.s.s within a very small distance of each of them.