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. Mitch.e.l.l, 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 gla.s.s, 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 repet.i.tion 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 gla.s.s, and put the magnet under the gla.s.s; 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 compa.s.s 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 gla.s.s, 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 b.a.l.l.s in great numbers, which will adhere like so many stars to the sides of the gla.s.s, and continue burning for a considerable time; after this, if a small quant.i.ty 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 gla.s.s 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 gla.s.s, 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 gla.s.s, without any remarkable coruscation.

_To make an Egg enter a Phial without breaking._