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. may be chased from side to side of a basin. On the other hand, an opposite pole will immediately attract.

It

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 ironfilings 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 ironfilings; 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* from the Land's End,

* The white pebbles found on the banks of the Mersey, although not a pure quartz, answer the purpose perfectly well. It is singular, that the friction is invariably accompanied by a strong sulphureous smell.

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 aeriform; 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."

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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. Take a glass, or any other vessel, (see Plate) ABCD, fig. 10. which has a small bent pipe, EFG, open at each end, running through the middle of it; then, if water or wine be poured into the glass, it will continue in it till the tube is full up to the bend F, which should be a little lower than the upper edge of the glass; but if, after this, you continue to pour more liquor into it, it will endeavour, as usual, to rise higher in the glass, but not finding room for a farther ascent in the tube, it will descend through the part EG, and run out at the end G, as long as you continue to put it in. To those who are unacquainted with the nature of the syphon, the effect may perhaps appear something more extraordinary, if the longest branch of the tube be concealed in the handle of the cup.

This is called the cup of Tantalus, from its resemblance to an experiment of the same kind, by placing an upright image in the cup, and disposing the syphon in such a manner that, as soon as the water rises to the chin of the image, it will begin to run out through the longest leg, in the same manner as from the cup above-mentioned.

A curious Chemical Experiment, called the Tree of Diana. Make an amalgam, without heat, of two drachms of leaf silver with one drachm of quicksilver. Dissolve this amalgam

'wo ounces, 、r a sufficient quantity, of pure nitrous acid a moderate strength: dilute the solution in about a pound and a half of distilled water, agitate the mixture, and preserve it for use in a glass bottle with a ground stopper. When you would make your tree, put into a phial the quantity of an ounce of the above preparation, and add to it about the size of a pea of amalgam of gold or silver, as soft as butter: the vessel must then be left at rest, and soon afterwards small filaments will appear to issue out of the ball of amalgam, which quickly increase, and shoot out branches in the form of shrubs.

A metallic arborisation, somewhat similar, may be produced in the following manner:-Dissolve a little sugar of lead in water, and fill a phial with the solution. Pass a wire through the cork, and affix to the upper part of the wire a small bit of silver, or zinc, in such a manner that it may be immersed in the solution not far from its surface. Set the phial in some place where it may remain undisturbed, and in about twentyfour hours you will perceive the lead beginning to shoot round the wire this process will continue going on slowly, till you have, a beautiful metallic tree. If you have a wide-mouthed phial, or glass jar, the experiment may be pleasingly diversified, by arranging the wire in various forms.

A remarkable Experiment, called Prince Rupert's Drops. Take up a small quantity of the melted matter of glass with a tube, and let a drop of it fall into a vessel of water. This drop will have a small tail, which, being broken, the whole substance of the drop will burst, with great violence, into a fine powder, and give a little pain to the hand, but do no hurt to it.

It is a remarkable circumstance in this experiment, that the bulb, or body, will bear the stroke of a hammer, without breaking; but when the tail is broken, the above-mentioned effect is produced. If the drop be cooled in the air, the same effect will not take place; and if it be ground away on a stone, nothing extraordinary appears; but if it be put into the receiver of an air-pump, and then broken, the effect will be so violent as to produce light.

How to make Sympathetic Inks of various Kinds.

By sympathetic inks, are meant those kinds of liquors, with which if any characters be written, they will remain invisible, till some method is used to give them a colour.

The first class of these inks consists of such as become visible by passing another liquor over them, or by exposin. them to the vapour of that liquor.