It is thus with animals of every kind; even minute microscopical insects cannot live without air.

_Experiments with Sparrows._

Count Morozzo placed successively several full-grown sparrows under a gla.s.s receiver, inverted over water. It was filled with atmospheric air, and afterwards with vital air. He found,

First.--That in _atmospheric_ air, HOURS MIN.

The first sparrow lived 3 0 The second sparrow lived 0 3 The third sparrow lived 0 1

The water rose in the vessels eight lines during the life of the first; four during the life of the second; and the third produced no absorption.

Second.--In _vital_ air or _oxygen_, HOURS MIN.

The first sparrow lived 5 23 The second 2 10 The third 1 30 The fourth 1 10 The fifth 0 30 The sixth 0 47 The seventh 0 27 The eighth 0 30 The ninth 0 22 The tenth 0 21

The above experiments elicit the following conclusions:--1. That an animal will live longer in vital than in atmospheric air.--2. That one animal can live in air, in which another has died.--3. That, independently of air, some respect must be had to the const.i.tution of the animal; for the sixth lived 47 minutes, the fifth only thirty.--4.

That there is either an absorption of air, or the production of a new kind of air, which is absorbed by the water as it rises.

AMUSING EXPERIMENTS IN ELECTRICITY.

_The Animated Feather._

Electrify a smooth gla.s.s tube with a rubber, and hold a small feather at a short distance from it. The feather will instantly fly to the tube, and adhere to it for a short time; it will then fly off, and the tube can never be brought close to the feather till it has touched the side of the room, or some other body that communicates with the ground. If, therefore, you take care to keep the tube between the feather and the side of the room, you may drive it round to all parts of the room without touching it; and, what is very remarkable, the same side of the feather will be constantly opposite the tube.

While the feather is flying before the smooth tube, it will be immediately attracted by an excited rough tube or a stick of wax, and fly continually from one tube to the other, till the electricity of both is discharged.

_The Candle lighted by Electricity._

Charge a small coated phial, whose k.n.o.b is bent outwards so as to hang a little over the body of the phial; then wrap some loose cotton over the extremity of a long bra.s.s pin or wire, so as to stick moderately fast to its substance. Next roll this extremity of the pin, which is wrapped up in cotton, in some fine powdered resin; then apply the extremity of the pin or wire to the external coating of the charged phial, and bring, as quickly as possible, the other extremity, that is wrapped round with cotton, to the k.n.o.b; the powdered resin takes fire, and communicates its flame to the cotton, and both together burn long enough to light a candle. Dipping the cotton in oil of turpentine will do as well, if you use a larger sized jar.

_Candle Bombs._

Procure some small gla.s.s bubbles, having a neck about an inch long, with very slender bores, by means of which a small quant.i.ty of water is to be introduced into them, and the orifice afterwards closed up.

This stalk being put through the wick of a burning candle, the flame boils the water into a steam, and the gla.s.s is broken with a loud explosion.

_The Artificial Spider._

Cut a piece of burnt cork, about the size of a pea, into the shape of a spider; make its legs of linen thread, and put a grain or two of lead in it to give it more weight. Suspend it by a fine line of silk between an electrified arch and an excited stick of wax; and it will jump continually from one body to the other, moving its legs at the same time, as if animated, to the great surprise of the unconscious spectator.

_The Miraculous Portrait._

Get a large print (suppose of the king) with a frame and gla.s.s. Cut the print out at about two inches from the frame all round; then with thin paste fix the border that is left on the inside of the gla.s.s, pressing it smooth and close; fill up the vacancy, by covering the gla.s.s well with leaf-gold or thin tin-foil, so that it may lie close.

Cover likewise the inner edge of the bottom part of the back of the frame with the same tin-foil, and make a communication between that and the tin-foil in the middle of the gla.s.s; then put in the board, and that side is finished. Next turn up the gla.s.s, and cover the fore-side with tin-foil, exactly over that on the back part; and when it is dry, paste over it the panel of the print that was cut out, observing to bring the corresponding parts of the border and panel together, so that the picture will appear as at first, only part of it behind the gla.s.s, and part before. Lastly, hold the print horizontally by the top, and place a little moveable gilt crown on the king's head.

Now, if the tin-foil on both sides of the gla.s.s be moderately electrified, and another person take hold of the bottom of the frame with one hand, so that his fingers touch the tin-foil, and with the other hand attempt to take off the crown, he will receive a very smart blow, and fail in the attempt. The operator, who holds the frame by the upper end, where there is no tin-foil, feels nothing of the shock, and can touch the face of the king without danger, which he pretends is a test of his loyalty.

_The Cup of Tantalus._

You place a cup of any sort of metal on a stool of baked wood or a cake of wax. Fill it to the brim with any liquor; let it communicate with the branch by a small chain; and when it is moderately electrified, desire a person to taste the liquor, without touching the cup with his hands, and he will instantly receive a shock on his lips.

The motion of the wheel being stopped, you taste the liquor yourself, and desire the rest of the company to do so; you then give your operator (who is concealed in an adjoining room) the signal, and he again charges the cup; you desire the same person to taste the liquor a second time, and he will receive a second shock.

_Magical Explosion._

Make up some gunpowder, in the form of a small cartridge, in each end of which put a blunt wire, so that the ends inside of the cartridge be about half an inch off each other; then join the chain that proceeds from one side of the electrifying battery, to the wire at the other end, the shock will instantly pa.s.s through the powder, and set it on fire.

_Artificial Earthquake._

In the middle of a large basin of water, lay a round wet board. On the board place any kind of building, made of pasteboard, of separate pieces, and not fastened together. Then, fixing a wire that communicates with the two chains of the electrifying battery, so that it may pa.s.s over the board and the surface of the water, upon making the explosion, the water will become agitated as in an earthquake, and the board, moving up and down, will overturn the structure, while the cause of the commotion is totally concealed.

_The Magic Dance._

From the middle of the bra.s.s arch suspend three small bells. The two outer bells hang by chains, and the middle one by a silk string, while a chain connects it with the floor. Two small k.n.o.bs of bra.s.s, which serve as clappers, hang by silk strings, one between each two bells.

Therefore, when the two outer bells communicating with the conductor are electrified, they will attract the clappers and be struck by them.

The clappers being thus loaded with electricity, will be repelled, and fly to discharge themselves upon the middle bell, after which they will be again attracted by the outer bells; and thus, by striking the bells alternately, the ringing may be continued as long as the operator pleases.

You next suspend a plate of metal from the same part of the arch to which the bells are connected; then, at the distance of a few inches from the arch, and exactly under it, place a metal stand _of the same size_. On the stand place several figures of men, animals, or what you please, cut in paper, and pretty sharply pointed at each extremity.

When the plate that hangs from the arch is electrified, the figures will dance with astonishing rapidity, and the bells will keep ringing, to the no small entertainment of the spectators.

_The Electrical Fountain._

Suspend a vessel of water from the middle of the bra.s.s arch, and place in the vessel a small tube. The water will be one continued stream; and if the electrification be strong, a number of streams will issue, in form of a cone, the top of which will be at the extremity of the tube. This experiment may be stopped and renewed almost instantly, as if at the word of command.

_The Electric Kite._

Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief, when extended; tie the corners of the handkerchief to the extremities of the cross; and you have the body of the kite, which being properly accommodated with a tail, loop, and string, will rise in the air like those made of paper; but this being silk, it is more adapted to bear the wet and wind of a thunder gust, without tearing. To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. To the end of the twine is to be tied a silk ribbon, and where the silk and twine join, a key may be fastened. This kite is to be raised when a thunder-storm appears to be coming on; and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet; and care must be taken that the twine do not touch the frame of the door or window. As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite, with all the twine, will be electrified, while the loose filaments of the twine will stand out every way, and be attracted by an approaching finger. When the rain has wetted the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key, on the approach of your knuckle. At this key an electric phial may be charged; and from electric fire thus obtained, spirits may be kindled, and all the other electric experiments performed which are usually done by the help of a rubbed gla.s.s or tube; and thereby the ident.i.ty of the electric matter with that of lightning completely demonstrated.

_The Magic Chase._

On the top of a finely-pointed wire, rising perpendicularly from the conductor, let another wire, sharpened at each end, be made to move freely, as on a centre. If it be well balanced, and the points bent horizontally, in opposite directions, it will, when electrified, turn very swiftly round, by the re-action of the air against the current which flows from off the points. These points may be nearly concealed, and the figures of men and horses, with hounds, and a hare, stag, or fox, may be placed upon the wires, so as to turn round with them, when they appear as if in pursuit. The chase may be diversified, and a greater variety of figures upon them, by increasing the number of wires proceeding from the same centre.

_The Unconscious Incendiary._

Let a person stand upon a stool made of baked wood, or upon a cake of wax, and hold a chain which communicates with the branch. On turning the wheel he will become electrified; his whole body forming part of the prime conductor; and he will emit sparks whenever he is touched by a person standing on the floor.