Part 97

If a piece of sealing-wax be rubbed briskly against the sleeve of your coat, or any other woollen substance, for some time, and then held within an inch or less of hair, feathers, bits of paper, or other light bodies; they will be attracted, that is, they will jump up, and adhere to the wax. If a tube of glass, or small phial, be rubbed in a similar manner, it will answer much better. The bottle thus rubbed becomes electric; and when the operation is performed in a dark room, small flashes of divergent flame, ramified somewhat like trees bare of leaves, will dart into the air, from many parts of the surface of the tube, to the distance of six or eight inches, attended with a crackling noise; and sometimes sparks will fly along the tube to the rubber at more than a foot distant.

Cut two bits of cork into the shape and size of a common pea. With a needle, draw a thread through each of the corks, so that they may be made to hang at the ends of the threads with a knot below them. Let the other ends of the threads be inserted in the notch of a small piece of wood, about a foot long, and an inch broad, and the thickness of a common match. Lay the piece of wood over two wine-glasses, a few inches asunder, so that the end of it, in which the threads are, may project over the edge of the glass nearest it, and the corks may be in contact one with another. Take another wine-glass, and, having rubbed it briskly with a piece of flannel, or upon the skirt or sleeve of a woollen coat, hold its mouth to within about an inch of the corks, and they will suddenly start asunder, and continue so for some time.

Lay a pocket-watch upon a table, and take a common tobacco-pipe, and place it on the face of the watch so that it may balance thereon; then, after rubbing a wine-glass, as described in the former experiment, bring it to within an inch of the smaller end of the tobacco-pipe, and by moving the glass gently round in an horizontal circular track, you will cause the pipe to turn round on the watch-glass, as the needle turns on its centre in a mariner's compass.

_A curious Experiment made by Mr. Symmer, on the Electricity of Silk Stockings._

This gentleman having frequently observed, that on putting off his stockings in the evening, they made a crackling or snapping noise, and that in the dark they emitted sparks of fire, was induced to examine on what circumstances these electrical appearances depended. After a considerable number of observations, directed to this point, he found that it was the combination of white and black which produced the electricity, and that the appearances were the strongest when he wore a white and a black stocking upon the same leg. These, however, discovered no signs of electricity while they were upon the leg, though they were drawn backwards and forwards upon it several times; but the moment they were separated, they were both of them found to be highly electrified, the white positively, and the black negatively; and when they were held at a distance from each other, they appeared inflated to such a degree, that they exhibited the entire shape of the leg.

When two black or two white stockings were held together, they would repel one another to a considerable distance; and when a white and black stocking were presented to each other, they would be mutually attracted, and rush together with great violence, joining as close as if they had been so many folds of silk; and in this case their electricity did not seem to have been in the least impaired by the shock of meeting, for they would be again inflated, attract, repel, and rush together, as before.

When this experiment was performed with two black stockings in one hand, and two white ones in the other, it exhibited a still more curious spectacle. The repulsion of those of the same colour, and the attraction of those of different colours, threw them into an agitation, and made each of them catch at the opposite colour in a way that was very amusing.

What was also very remarkable in these experiments with a white and black stocking, was, the power of electrical cohesion which they exhibited; Mr. Symmer having found, that when they were electrified, and allowed to come together, they frequently stuck so close to each other, that it required a weight of sixteen or seventeen ounces to separate them, and this in a direction parallel to their surfaces.

When one of the stockings was turned inside-out, it required twenty ounces to separate them; and by having the black stockings new dyed, and the white ones washed, and whitened in the fumes of sulphur, and then putting them one within the other, it required three pounds three ounces to separate them.

Trying this experiment with stockings of a more substantial make, he found that, when the white stocking was put within the black one, so that its outside was contiguous to the inside of the other, they raised near nine pounds; and when the white stocking was turned inside-out, and put within the black one, so that their rough surfaces were contiguous, they raised fifteen pounds, which was ninety-two times the weight of the stockings. And, in all these cases, he found that pressing them together with his hands contributed much to strengthen the cohesion.

When the white and black stockings were in cohesion, and another pair, more highly electrified, were separated from each other, and presented to the former, their cohesion would be dissolved, and each stocking of the second pair would catch hold of, and carry away with it, that of its opposite co-lour; but if the degree of electricity of both pairs were equal, the cohesion of the former would be weakened, but not dissolved, and all the four would cohere together in one mass.

Mr. Symmer also observed, that white and black silk, when electrified, not only cohered with each other, but they would also adhere to bodies with broad, and even polished, surfaces, though those bodies were not electrified. This he discovered, by throwing accidentally a stocking out of his hand, which stuck to the paper-hangings of the room, and which, in another experiment of this kind, continued hanging there nearly an hour.

Having stuck up the black and white stockings in this manner, he came with another pair of stockings, highly electrified, and applying the white to the black, and the black to the white, he carried them off from the wall, each of them hanging to that which had been brought to it. The same experiment also held with the painted boards of the room, and likewise with the looking-glass, to the smooth surface of which, the white and black stockings appeared to adhere more tenaciously than to either of the former.

_To suspend a Ring by a Thread that has been burnt._

The thread having been previously soaked in chamber lye, or common salt and water, tie it to a ring, not larger than wedding-ring. When you apply the flame of a candle to it, though the thread burn to ashes, it will yet sustain the ring.

_Chemical Illuminations._

Put into a middling-sized bottle, with a short wide neck, three ounces of oil or spirit of vitriol, with twelve ounces of common water, and throw into it, at different times, an ounce or two of iron filings. A violent commotion will then take place, and white vapours will arise from the mixture. If a taper be held to the mouth of the bottle, these vapours will inflame, and produce a violent explosion; which may be repeated as long as the vapours continue.

_To make the Appearance of a Flash of Lightning when any one enters a Room with a lighted Candle._

Dissolve camphor in spirit of wine, and deposit the vessel containing the solution in a very close room, where the spirit of wine must be made to evaporate by strong and speedy boiling. If any one then enters the room with a lighted candle, the air will inflame; but the combustion will be so sudden, and of so short duration, as to occasion no danger.

_The Fiery Fountain._

If twenty grains of phosphorus, cut very small, and mixed with forty grains of powdered zinc, be put into four drachms of water, and two drachms of concentrated sulphuric acid be added thereto, bubbles of inflamed phosphuretted hydrogen gas will quickly cover the whole surface of the fluid in succession, forming a real fountain of fire.

_A Lamp that will burn Twelve Months without replenishing._

Take a stick of phosphorus, and put it into a large dry phial, not corked, and it will afford a light sufficient to discern any object in a room, when held near it. The phial should be kept in a cool place, where there is no great current of air, and it will continue its luminous appearance for more than twelve months.

_The Magic Oracle._

Get six blank cards, and write on them figures, or numbers, exactly according to the following patterns.

No. I

17 19 3 13 1 27 21 5 29 47 23 7 31 45 59 15 11 33 43 0 57 9 35 41 55 0 25 39 53 0 37 0 0 49 0 51

No. II.

14 18 3 15 2 35 22 6 34 47 19 10 31 46 59 23 11 30 43 0 58 7 27 42 55 0 26 39 54 0 38 0 0 50 0 51

No. III.

14 13 7 21 4 37 23 5 36 47 20 6 31 46 60 22 12 30 45 0 55 15 29 44 0 0 28 39 54 0 38 0 0 52 0 53

No. IV.

14 15 10 13 8 41 26 9 40 47 27 11 31 46 60 25 13 30 45 0 59 12 29 44 0 0 28 43 57 0 42 0 24 56 0 58

No. V.

22 24 17 26 16 49 23 18 48 55 25 20 31 54 60 27 21 30 53 0 5 19 29 52 58 0 28 51 57 0 50 0 0 0 0 56

No. VI.

38 40 34 39 32 49 41 35 48 55 43 37 47 54 60 42 33 46 53 0 59 36 45 52 0 0 44 51 57 0 50 0 0 56 0 58

You deliver the cards to a person, and desire him to think of any number from one to sixty; he is then to look at the cards, and say in which cards the number he thought of is to be found; and you immediately tell him the number thought of.

EXPLANATION.

This surprising and ingenious recreation is done by means of a key number. There is a key number in every card, viz. the last but one in the second row from the top. From this explanation the reader will perceive that the key numbers are 1, 2, 4, 8, 16, 32. Now whatever number is fixed on, from 1 to 60, will be readily found by privately adding together the key numbers of the cards that contain the number thought on. For instance, suppose a person thinks of number 43; he looks at the cards, and gives you No. 1, 2, 4, 5, 6, as cards which contain the number thought on: you expertly perceive that the key numbers are 1, 2, 8, 32; which numbers added together make 43, the number thought on. Suppose he thinks of No. 15, he gives you No. 1, 2, 3, 4: the key numbers are 1, 2, 4, 8; which added, make just 15; and so of all numbers from 1 to 60.

This recreation may be varied many ways; as, telling the age of a person, &c.; but this is left to the ingenious reader's taste and application.

_Cheap and Easy Method of constructing a Voltaic Pile._

Mr. Mitchell, in his useful little work on natural philosophy, proposes the following cheap and easy method of constructing a Voltaic Pile. Zinc is one of the cheapest of metals, and may be easily melted, like lead. Let the student cast twenty or thirty pieces, of the size of a penny-piece, which may easily be done in moulds made in clay. Let him then get as many penny-pieces, and as many pieces of paper, or cloth cut in the same shape, and these he must dip in a solution of salt and water. In building the pile, let him place a piece of zinc, wet paper, (the superabundant water being squeezed out,) after which the copper; then zinc, paper, copper, &c. until the whole be finished. The sides of the pile may be supported with rods of glass, or varnished wood, fixed in the board on which it is built. The following experiment may then be performed:--

Having wetted both hands, touch the lower part of the pile with one hand, and the upper part with the other, constant, little shocks of electricity will be felt until one hand be removed. If the hand be brought back, a similar repetition of shocks will be felt. Put a basin of water near the pile, and put the left hand into it, holding a wire, one end of which touches the top of the battery or pile; then put the end of a silver spoon between the lip and the gum, and with the other end of the spoon touch the lower part of the pile; a strong shock is felt in the gum and in the hand. Take the left hand from the water, but still keep hold of the wire, and then perform the last experiment in the same manner, and a shock will be felt in the gum only. Hold a silver spoon in one hand, and touch with it the battery at the lower part, then touch the upper part with the tongue; the bitter taste will be extreme.

In performing the above experiments, if, instead of the two ends of the pile, the one end and the middle of it be touched, the sensations will not be nearly so strong. If the student be desirous of having still more sensible proofs of the effect of galvanism, let him hold a wire to the top of the battery, and let him place one end of a silver spoon to the lower part, and the other end within his mouth, so as to touch the gums; a severe set of shocks will be felt. In performing this experiment, move the spoon to the roof of the mouth, and a strong sensation will be felt. Let the end of the spoon be run up the nose so as to touch the cartilaginous bone; shocks like the stabs of a needle will be felt. Let the end of the spoon be put under the eye-brow, close to the ball of the eye; a sensation will be felt like the burning of red-hot iron, but which ceases the instant the spoon is removed.

_Magnetical Experiments._

The magnetic attraction will not be destroyed by interposing obstacles between the magnet and the iron.

Lay a small needle on a piece of paper, and put a magnet under the paper; the needle may be moved backwards and forwards.

Lay the needle on a piece of glass, and put the magnet under the glass; it will still attract the needle. The same effects will take place if a board be interposed between the magnet and the iron. This property of the magnet has afforded the means of some very amusing deceptions.

A little figure of a man has been made to spell a person's name. The hand, in which was a piece of iron, rested on a board, under which a person, concealed from view, with a powerful magnet, contrived to carry it from letter to letter, until the word was made up.

The figure of a goose or swan, with a piece of iron concealed about the head, is set to float in water. A rod, with a concealed magnet at the end, is presented to the bird, and it swims after it. The effect is still more amusing, when some food is put on the end of the rod.

The figure of a fish is thrown into the water, with a small magnet concealed in its mouth. Of course, if a baited hook be suspended near it, the magnet and iron, by mutual attraction, will bring the fish to the bait.

Put a piece of iron in one scale of a balance, and an equal weight in the other scale; bring a magnet under the scale which contains the iron, and it will draw it down. Reverse this experiment, and put the magnet in the scale, and balance it; bring the iron under it, and it will draw down the magnet. Suspend a magnet by a string, and bring a piece of iron near it, and it will attract.

If a magnet suspended by one string, and a piece of iron suspended by another, be brought near one another, they will mutually attract each other, and be drawn to a point between.

Suspend a magnet nicely poised by a thread, and it will point north and south, the same end pointing invariably the same way.

Rub a fine needle with a magnet, and lay it gently on the surface of the water; it will point north and south. Rub various needles with the magnet, and run them through small pieces of cork, and put them to swim in water; they will all point north and south, and the same end will invariably point the same way. This mode of finding the north is sometimes of the utmost service at sea, when the compass is destroyed.

Opposite poles attract; poles of the same name repel. Take two magnets, or two needles rubbed with the magnet, and bring the north and south poles together, and they attract.

Bring the north poles near each other, and they repel. Bring the south poles near each other, and they repel. Rub a needle with a magnet, and run it through a piece of cork, and put it to float in water. Hold a north pole of a magnet near its north pole, and it will keep flying away to avoid it. It may be chased from side to side of a basin. On the other hand, an opposite pole will immediately attract.

Rub four or five needles, and you may lift them up as in a string, the north pole of one needle adhering to the south pole of another.

Put a magnet under a piece of glass, and sprinkle iron-filings on it; they will arrange themselves in a manner that will be very surprising. At each pole will be a vast abundance standing erect, and there will be fewer and fewer as they recede, until there are scarcely any in the middle. If the iron-filings are sprinkled on the magnet itself, they will arrange themselves in a manner very striking.

Lay a needle exactly between the north and south pole, it will move towards neither.

_Artificial Coruscations._

There is a method of producing artificial coruscations, or sparkling fiery meteors, which will be visible not only in the dark but at noon-day, and that from two liquors actually cold. Fifteen grains of solid phosphorus are to be melted in about a drachm of water: when this is cold, pour upon it about two ounces of oil of vitriol; let these be shaken together, and they will at first heat, and afterwards they will throw up fiery balls in great numbers, which will adhere like so many stars to the sides of the glass, and continue burning for a considerable time; after this, if a small quantity of oil of turpentine is poured in, without shaking the phial, the mixture will of itself take fire, and burn very furiously. The vessel should be large, and open at the top. Artificial coruscations may also be produced by means of oil of vitriol and iron, in the following manner:--Take a glass body capable of holding three quarts; put into it three ounces of oil of vitriol and twelve ounces of water; then warming the mixture a little, throw in, at several times, two ounces or more of clean iron-filings; upon this, an ebullition and white vapours will arise; then present a lighted candle to the mouth of the vessel, and the vapour will take fire, and will afford a bright illumination, or flash like lightning. Applying the candle in this manner several times, the effect will always be the same; and sometimes the fire will fill the whole body of the glass, and even circulate to the bottom of the liquor; at others, it will only reach a little way down its neck. The great caution to be used in this experiment is, in making the vapour of a proper heat; for, if too cold, few vapours will arise; and, if made too hot, they will come too fast, and only take fire in the neck of the glass, without any remarkable coruscation.

_To make an Egg enter a Phial without breaking._

Let the neck of a phial be ever so strait, an egg will go into it without breaking, if it be first steeped in very strong vinegar, for in process of time the vinegar does so soften it, that the shell will bend and extend lengthways without breaking: and when it is in, cold water thrown upon it will recover its primitive hardness, and, as Cardan says, its primitive figure.

_Light produced by Friction, even under Water._

Rub two pieces of fine lump sugar together in the dark; the effect is produced, but in a much greater degree, by two pieces of silex, or quartz: but that which affords the strongest light of any thing, is a white quartz[25] from the Land's End, considerable quantities of which are brought to Bristol, and enter into the composition of china ware. By means of two pieces of such quartz, pretty forcibly rubbed together, you may distinguish the time of the night by a watch: but, what is more surprising, the same effect is produced equally strong by rubbing the pieces of quartz together under water.

_Rosin Bubbles._

The following account of a simple and curious experiment is extracted from a letter written by Mr. Morey, of Oxford, New Hampshire, to Dr. Silliman, the editor of the American Journal of Science and Arts.

"If the end of a copper tube, or of a tobacco-pipe stem, be dipped in melted rosin, at a temperature a little above that of boiling water, taken out and held nearly in a vertical position, and blown through, bubbles will be formed of all possible sizes, from that of a hen's egg down to sizes which can hardly be discerned by the naked eye; and from their silvery lustre, and reflection of the different rays of light, they have a pleasing appearance. Some that have been formed these eight months, are as perfect as when first made. They generally assume the form of a string of beads, many of them perfectly regular, and connected by a very fine fibre; but the production is never twice alike. If expanded by hydrogen gas, they would probably occupy the upper part of the room.

"The formation of these bubbles is ascribed to a common cause, viz. the distention of a viscous fluid by one that is aëriform; and their permanency, to the sudden congelation of the rosin thus imprisoning the air by a thin film of solid matter, and preventing its escape."

_A curious Hydraulic Experiment, called the Magical Bottle._

Take a small bottle, (see Plate) AB, Fig. 9, the neck of which must be very narrow, and provide a glass vessel, CD, the height of which exceeds that of the bottle about two inches; fill the bottle, by means of a small funnel, with red wine, and place it in the vessel CD, which is to be previously filled with water. Then, if the bottle be uncorked, the wine will presently come out of it, and rise in form of a small column, to the surface of the water; and at the same time the water entering the bottle, will supply the place of wine; for water being specifically heavier than wine, it will consequently subside to the lowest place, while the other naturally rises to the top.

A similar effect will be produced, if the bottle be filled with water, and the vessel with wine, for the bottle being placed in the vessel, in an inverted position, the water will descend to the bottom of the vessel, and the wine will rise in the bottle. The same effect may also be produced by any other liquors, the specific gravities of which are considerably different.

_Another Hydraulic Experiment, called the Miraculous Vessel._

Take a tin vessel of about six inches in height, and three in diameter, having a mouth of only a quarter of an inch wide, and in the bottom of the vessel make a number of small holes, of a size sufficient to admit a common sewing needle.

Plunge the vessel into water, with its mouth open, and when it is full, cork it, and take it out again; then, as long as the vessel remains corked, no water will come out of it; but as soon as it is uncorked, the water will immediately issue from the small holes at the bottom. It must be observed, however, that if the holes at the bottom of the vessel be more than one-sixth of an inch in diameter, or if they be too numerous, the experiment will not succeed; for, in this case, the pressure of the air against the bottom of the vessel will not be sufficient to confine the water.

_A curious Hydraulic Experiment, called Tantalus's Cup._