Take a silver ring that is thick gilded. Make a little hole through the gold into the silver; then put the ring into aqua fortis, in a warm place: it will dissolve the silver, and the gold will remain whole.

_To soften Iron or Steel._

Either of the following simple methods will make iron or steel as soft as lead:

1. Anoint it all over with tallow; temper it in a gentle charcoal fire, and let it cool of itself.

2. Take a little clay, cover your iron with it, temper it in a charcoal fire.

3. When the iron or steel is red-hot, strew h.e.l.lebore on it.

4. Quench the iron or steel in the juice or water of common beans.

_To take a Plaster-of-Paris Cast from a Person's Face._

The person must lie on his back, and his hair be tied behind. Into each nostril put a conical piece of paper, open at each end to allow of breathing. The face is to be lightly oiled over, and the plaster being properly prepared is to be poured over the face, (taking care that the eyes are shut,) till it is a quarter of an inch thick. In a few minutes the plaster may be removed. In this a mould is to be formed, from which a second cast is to be taken, that will furnish casts exactly like the original.

_Curious Experiment with a Gla.s.s of Water._

Saturate a certain quant.i.ty of water in a moderate heat, with three ounces of sugar; and when it will no longer receive that, there is still room in it for two ounces of salt of tartar, and after that for an ounce and a drachm of green vitriol, nearly six drachms of nitre, the same of sal-ammoniac, two drachms and a scruple of alum, and a drachm and half of borax.

_To make 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. The method is this:--Fifteen grains of solid phosphorus are to be melted in about a drachm of water: when this is cold, pour upon it two ounces of oil of vitriol; let these be shaken together in a large phial, and they will at first heat, and afterwards will throw up fiery b.a.l.l.s in great number, which will adhere like so many stars to the sides of the gla.s.s, and continue burning a considerable time; after this, if a small quant.i.ty of oil of turpentine be poured in without shaking the phial, the mixture will of itself take fire, and burn very furiously.

The vessels should be large and open at the top.

_Another Method._

Artificial coruscations may also be produced by means of oil of vitriol and iron, in the following manner:--Take a gla.s.s vessel capable of holding three quarts: put into this 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 clear 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 afford a bright fulmination 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 down its neck. The great caution to be used in making this experiment, is the making the vapour of a proper heat; for if made too cold few vapours will arise; and, if made too hot, they will arise too fast, and will only take fire in the neck of the gla.s.s, without any remarkable coruscation.

_To produce Fire from Cane._

The Chinese rattans, which are used, when split, for making cane chairs, will, when dry, if struck against each other, give fire; and are used accordingly in some places, in lieu of flint and steel.

_To make an Eolian Harp._

This instrument may be made by almost any carpenter: it consists of a long narrow box of very thin deal, about five or six inches deep, with a circle in the middle of the upper side, of an inch and a half in diameter, in which are to be drilled small holes. On this side, seven, ten, or more strings, of very fine gut, are stretched over bridges at each end, like the bridges of a fiddle, and screwed up or relaxed with screw pins. The strings must be all tuned to one and the same note, and the instrument be placed in some current of air, where the wind can pa.s.s over its strings with freedom. A window, of which the width is exactly equal to the length of the harp, with the sash just raised to give the air admission, is a proper situation. When the air blows upon these strings, with different degrees of force, it will excite different tones of sounds; sometimes the blast brings out all the tones in full concert, and sometimes it sinks them to the softest murmurs.

_To show the Pressure of the Atmosphere._

Invert a tall gla.s.s or jar in a dish of water, and place a lighted taper under it: as the taper consumes the air in the jar its pressure becomes less on the water immediately under the jar; while the pressure of the atmosphere on the water _without_ the circle of the jar remaining the same, part of the water in the dish will be forced up into the jar, to supply the place of the air which the taper has consumed. Nothing but the pressure of the atmosphere could thus cause part of the water to rise within the jar, above its own level.

_Subaqueous Exhalation._

Pour a little clear water into a small gla.s.s tumbler, and put one or two small pieces of phosph.o.r.et of lime into it. In a short time, flashes of fire will dart from the surface of the water, and terminate in ringlets of smoke, which will ascend in regular succession.

_Remarkable Properties in certain Plants._

Plants, when forced from their natural position, are endowed with a power to restore themselves. A hop-plant, twisting round a stick, directs its course from south to west, as the sun does. Untwist it, and tie it in the opposite direction, it dies. Leave it loose in the wrong direction, it recovers its natural direction in a single night.

Twist a branch of a tree so as to invert its leaves, and fix it in that position; if left in any degree loose, it untwists itself gradually, till the leaves be restored to their natural position. What better can an animal do for its welfare? A root of a tree meeting with a ditch in its progress, is laid open to the air; what follows? It alters its course like a rational being, dips into the ground, surrounds the ditch, rises on the opposite side of its wonted distance from the surface, and then proceeds in its original direction. Lay a wet sponge near a root exposed to the air; the root will direct its course to the sponge; change the place of the sponge, the root varies its direction. Thrust a pole into the ground at a moderate distance from a climbing plant; the plant directs its course to the pole, lays hold of it, and rises on its natural height. A honeysuckle proceeds in its course, till it be too long for supporting its weight, and then strengthens itself by shooting into a spiral. If it meet with another plant of the same kind, they coalesce for mutual support; the one s.c.r.e.w.i.n.g to the right, the other to the left. If a honeysuckle twig meet with a dead branch, it screws from the right to the left. The claspers of briony shoot into the spiral, and lay hold of whatever comes in their way, for support. If, after completing a spiral of three rounds, they meet with nothing, they try again, by altering their course.

_Flowers curiously affected by the Sun and the Weather._

The petals of many flowers expand in the sun, but contract all night, or on the approach of rain; after the seeds are fecundated the petals no longer contract. All the trefoil may serve as a barometer to the husbandman; they always contract their leaves on an impending storm.

_Easy Method of obtaining Flowers of different Colours from the same Stem._

Scoop out the pith from a small twig of elder, and having split it lengthwise, fill each of the parts with small seeds that produce flowers of different colours, but that blossom nearly at the same time. Surround them with earth; and then tying together the two bits of wood, plant the whole in a pot filled with earth, properly prepared.

_A Luminous Bottle, which will show the Hour on a Watch in the Dark._

Throw a bit of phosphorus, of the size of a pea, into a long gla.s.s phial, and pour boiling oil carefully over it, till the phial is one-third filled. The phial must be carefully corked, and when used should be unstopped, to admit the external air, and closed again. The empty s.p.a.ce of the phial will then appear luminous, and give as much light as an ordinary lamp. Each time that the light disappears, on removing the stopper it will instantly re-appear. In cold weather the bottle should be warmed in the hands before the stopper is removed. A phial thus prepared may be used every night for six months.

_To make Luminous Writing in the Dark._

Fix a small piece of solid phosphorus in a quill, and write with it upon paper; if the paper be carried into a dark room, the writing will appear beautifully luminous.

_The Sublimated Tree._

Into a large gla.s.s jar inverted upon a flat brick tile, and containing near its top a branch of fresh rosemary, or any other such shrub, moistened with water, introduce a flat thick piece of heated iron, on which place some gum benzoin, in gross powder. The benzoin, in consequence of the heat, will be separated, and ascend in white fumes, which will at length condense, and form a most beautiful appearance upon the leaves of the vegetable.

_Easy and curious Methods of foretelling Rainy or Fine Weather._

If a line be made of good whipcord, that is well dried, and a plummet affixed to the end of it, and then hung against a wainscot, and a line drawn under it, exactly where the plummet reaches, in very moderate weather it will be found to rise above it before rain, and to sink below when the weather is likely to become fair. But the best instrument of all, is a good pair of scales, in one of which let there be a bra.s.s weight of a pound, and in the other a pound of salt, or of saltpetre, well dried; a stand being placed under the scale, so as to hinder it falling too low. When it is inclined to rain, the salt will swell, and sink the scale: when the weather is growing fair, the bra.s.s weight will regain its ascendancy.

_Contrivance for a Watch Lamp, perfectly safe, which will show the Hour of the Night, without any trouble, to a person lying in Bed._

It consists of a stand, with three claws, the pillar of which is made hollow, for the purpose of receiving a water candlestick of an inch diameter. On the top of the pillar, by means of two hinges and a bolt, is fixed on a small proportionate table, a box of six sides, lined with bra.s.s, tin, or any shining metal, nine inches deep, and six inches in diameter. In the centre of one of these sides is fixed a lens, double convex, of at least three inches and a half diameter. The centre of the side directly opposite to the lens is perforated so as to receive the dial-plate of the watch, the body of which is confined on the outside, by means of a hollow slide. When the box is lighted by a common watch-light, the figures are magnified nearly to the size of those of an ordinary clock.

_Curious Experiment with a Tulip._