Part 3

We now present our readers with a variety of amusing experiments, which may be performed by the foregoing inks; and they will, probably, suggest others equally amusing and useful.

_A Secret Correspondence by means of Invisible Ink._

A person wishing to carry on a correspondence with another, and who is fearful of having his letter opened, or intercepted, can adopt the following plan:

Write any unimportant matter with common ink, and let the lines be very wide apart: then between these lines write the communication you wish to make, with any of the above invisible inks you can most readily procure.

Your correspondent is to be previously apprized of the method of making the characters visible: and writing in common ink will serve to lull the suspicions of those who might intercept the letter, and who, not finding any thing important in it, will either forward or keep it. In either case there can be no danger, as the writing will not be visible without the proper application.

_The Mysterious Writing._

Write on a piece of paper with common ink any question; then underneath it write the answer either in invisible silver ink, or the invisible green ink, made with zaffre and aqua regia, described in pages 24 and 25.

You give this paper to your friend, and tell him to place it against the wall, or on his dressing-table, keeping the door locked, that he may be sure no person has entered his room: he will next day find the answer written on it.

_The Restored Flowers._

Make a bouquet of artificial flowers; the leaves should be formed of parchment. Dip the roses in the red invisible ink, the jonquilles in the yellow, the pinks in the violet, and the leaves in the green ink. They will all appear white; and you show them to the company, observing, that you will restore them to their natural colours, and desiring any person to fix any private mark on them he pleases, that he may be sure there is no deception. You then, unperceived by the company, dip them in the revivifying liquor, used to make the yellow ink visible, described in page 24, and, drawing them gently out, that the liquor may drop, and the flowers have time to acquire their colours, you present them to the company, who will see, with surprise, that they each appear in their natural colours.

_Winter changed to Spring._

Take a print that represents winter, and colour those parts which should appear green, with the second green invisible ink, described in page 25; observing, of course, the usual rules of perspective, by making the near parts deeper in colour than the others. The other objects must be painted in their natural colours. Then put the print into a frame with a glass, and cover the back with a paper that is pasted only at its extremities.

When this print is exposed to a moderate fire, or the warm sun, the foliage, which appeared covered with snow, will change to a pleasing green; and if a yellow tint be thrown on the lighter parts before the invisible ink is drawn over it, this green will be of different shades. When it is exposed to the cold, it will again resume its first appearance of winter.

_The Silver Tree._

Dissolve an ounce of fine silver in three ounces of strong aqua fortis, in a glass bottle. When the silver is dissolved; pour the aqua fortis into another glass vessel, (a decanter will be best,) with seven or eight ounces of mercury, to which add a quart of common water; to the whole add your dissolved silver, and let it remain untouched.

In a few days the mercury will appear covered with a number of little branches of a silver colour. This appearance will increase for a month or two, and will remain after the mercury is entirely dissolved.

_The Lead Tree._

A more modern invention, and an easier method by far than the above, is the following:

To a piece of zinc fasten a wire, crooked in the form of the worm of a still; let the other end of the worm be thrust through a cork. You then pour spring water into a phial or decanter, to which you add a small quantity of sugar of lead; thrust the zinc into the bottle, and with the cork at the end of the wire fasten it up. In a few days the tree will begin to grow, and produce a most beautiful effect.

_To produce beautiful Fire-works in Miniature._

Put half a drachm of solid phosphorus into a large pint Florence flask; holding it slanting, that the phosphorus may not break the glass. Pour upon it a gill and a half of water, and place the whole over a tea-kettle lamp, or any common tin lamp, filled with spirit of wine. Light the wick, which should be almost half an inch from the flask; and as soon as the water is heated, streams of fire will issue from the water by starts, resembling sky-rockets; some particles will adhere to the sides of the glass representing stars; and will frequently display brilliant rays. These appearances will continue at times till the water begins to simmer, when immediately a curious aurora borealis begins, and gradually ascends, till it collects to a pointed flame; when it has continued half a minute, blow out the flame of the lamp, and the point that was formed will rush down, forming beautiful illuminated clouds of fire, rolling over each other for some time, which disappearing, a splendid hemisphere of stars presents itself: after waiting a minute or two, light the lamp again, and nearly the same phenomenon will be displayed as from the beginning. Let the repetition of lighting and blowing out the lamp be made for three or four times at least, that the stars may be increased. After the third or fourth time of blowing out the lamp, in a few minutes after the internal surface of the flask is dry, many of the stars will shoot with great splendour, from side to side, and some of them will fire off with brilliant rays; these appearances will continue several minutes. What remains in the flask will serve for the same experiment several times, and without adding any more water. Care should be taken, after the operation is over, to lay the flask and water in a cool, secure place.

_Artificial Rain and Hail._

Make a hollow cylinder of wood; let it be very thin at the sides, about eight or ten inches wide, and two or three feet diameter. Divide its inside into five equal parts, by boards of five or six inches wide, and let there be between them and the wooden circle, a space of about one-sixth of an inch. You are to place these boards obliquely. In this cylinder put four or five pounds of shot that will easily pass through the opening. When turned upside down, the noise of the shot going through the various partitions will resemble rain; and if you put large shot, it will produce the sound of hail.

_Illuminated Writing._

It is well known that if any words are written on a wall with solid phosphorus, the writing will appear as if on fire; but it is necessary to give this caution, lest accidents should occur. In using it, let a cup of water be always near you; and do not keep it more than a minute and a half in your hand, for fear the warmth of your hand should set it on fire. When you have written a few words with it, put the phosphorus into the cup of water, and let it stay a little to cool; then take it out, and write with it again.

_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 phials 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.

_Curious Transcolorations._

Put half a table-spoonful of syrup of violets and three table-spoonfuls of water into a glass; stir them well together with a stick, and put half the mixture into another glass. If you add a few drops of acid of vitriol into one of the glasses and stir it, it will be changed into a crimson; put a few drops of fixed alkali dissolved into the other glass, and when you stir it, it will change to green. If you drop slowly into the green liquor, from the side of the glass, a few drops of acid of vitriol, you will perceive crimson at the bottom, purple in the middle, and green at the top; and by adding a little fixed alkali dissolved, to the other glass, the same colours will appear in different order.

_Another._

If you put a tea-spoonful of a liquor composed of copper infused in acid of vitriol, into a glass, and add two or three table-spoonfuls of water to it, there will be no sensible colour produced; but if you add a little volatile alkali to it, and stir it, you will perceive a very beautiful blue colour. Add a little acid of vitriol, the colour will instantly disappear upon stirring it; and by adding a little fixed alkali dissolved, it will return again.

_Another._

Put half a tea-spoonful of a liquor composed of iron infused in acid of vitriol, into half a glass of water; and add a few drops of phlogisticated alkali, and a beautiful Prussian blue will appear.

_Curious Account of the Electric Effects of a Russian Climate._

Mr. Æpinus in a letter to Dr. Guthrie, relates the following phenomena, which took place in Russia, when a severe frost had continued for several weeks.

Mr. Æpinus was sent for to the palace to see an uncommon phenomenon. On going into the apartment of Prince Orloff, he found him at his toilet, and that every time his valet drew the comb through his hair, a strong crackling noise was heard; and on darkening the room, sparks were seen following the comb in great abundance, while the prince himself was so completely electrified, that strong sparks could be drawn from his hands and face; nay, he was even electrified when he was only powdered with a puff.

A few days after, he was witness to a more striking effect of the electric state of a Russian atmosphere. The Grand Duke of Russia sent for him one evening in the twilight, and told him, that having briskly drawn a flannel cover off a green damask chair in his bed-chamber, he was astonished at the appearance of a strong bright flame that followed; but considering it as an electrical appearance, he had tried to produce a similar illumination on different pieces of furniture, and could then show him a beautiful and surprising experiment. His highness threw himself on his bed, which was covered with a damask quilt, laced with gold; and, rubbing it with his hands in all directions, the young prince, who had then reached his twelfth year, appeared swimming in fire, as at every stroke flames arose all around him, darted to the gold-laced border, ran along it, and up to that of the bed, and even to the very top.

While he was showing this experiment, Prince Orloff came into the room, with a sable muff in his hand, and showed us, that by only whirling it five or six times round his head in the air, he could electrify himself so strongly, as to send out sparks from all the uncovered parts of his body.

_Astonishing Power of Steam._

If you put a small quantity of water into a tea-kettle, and place it on the fire, it will disappear in a short time, having escaped in the steam. But if its escape be prevented by stopping up the spout and crevices, it will force its way by bursting the vessel in which it was confined.

If the steam of boiling water be at liberty, the water never attains more than a certain degree of heat; but if confined in a close vessel, the additional fire not escaping, the power of the steam is increased, it re-acts upon the water, and raises the heat so much higher, that it would keep lead in a melting state; and so penetrating, that it would soften the marrow-bone of an ox, in a few minutes.

There is an instrument contrived for the foregoing purposes, called Papin's Digester, from the name of its inventor, and from its digestive powers on substances exposed to its action. It is a very strong vessel, made of copper, fitted with a thick close cover, and fastened down by several strong screws, so as to render it steam-tight in great degrees of heat. To render it safe, while being used, there is a valve on the cover, to let out the steam, when it is too violent; this valve is kept down by a steel-yard, with a weight moveable upon it, to regulate the degrees of the steam within.

The following account of an accident with one of these instruments, will give some idea of the great force of steam.

Mr. Papin (the inventor) having fixed all things right, and included about a pint of water, with two ounces of marrow-bone, he placed the vessel horizontally between the bars of the grate, about half-way into the fire. In three minutes he found it raised to a great heat, and perceiving the heat in a very short time become more raging, stepped to a side-table for an iron to take the digester out of the fire, when it suddenly burst with the explosion of a musket. It was heard at a considerable distance, and actually shook the house. The bottom of the vessel that was in the fire gave way; the blast of the expanded water blew all the coals out of the fire into the room, the remainder of the vessel flew across the room, and, hitting the leaf of an oak table, an inch thick, broke it all in pieces, and rebounded half the length of the room back again. He could not perceive the least sign of water, though he looked carefully for it; the fire was quite extinguished, and every coal black in an instant.

The following accident was attended with more fatal consequences.

A steam-engine was repairing at Chelsea, and, as the workmen were endeavouring to discover the defect, the boiler suddenly exploded, and a cloud of steam rushing out at the fracture, struck one of the men who was near it, like a blast of lightning, and killed him in a moment; when his companions endeavoured to take off his clothes, the flesh came off with them from the bones.

_Account of the Wonderful Effects of two immense Burning-Glasses._

Mr. de Tschirnhausen constructed a burning-glass, between three and four feet in diameter, and whose focus was rendered more powerful by a second one. This glass melted tiles, slates, pumice-stone, &c., in a moment; pitch, and all resins, were melted even under water; the ashes of vegetables, wood, and other matters, were converted into glass; indeed, it either melted, calcined, or dissipated into smoke, every thing applied to its focus.

Mr. Parker, of Fleet-street, made a burning-glass, three feet in diameter; it was formed of flint glass, and when on its frame, exposed a surface of 2 feet 8-1/2 inches to the solar rays. It had a small glass fitted to it, to converge the rays, and heighten the effect. The experiments made by it were more powerful and accurate than those performed by any other glass. The following is a brief epitome of its astonishing power.

+-------+-------+ Substances melted, with their weight; |Weight | Time | and the Time in Seconds, which | in | in | they took in melting. |Grains.|Seconds| --------------------------------------+-------+-------+ Pure gold | 20 | 4 | ---- silver | 20 | 3 | ---- copper | 33 | 20 | ---- platina | 10 | 3 | Nickel | 16 | 3 | A cube of bar-iron | 10 | 12 | --------- cast-iron | 10 | 3 | --------- steel | 10 | 12 | Scoria of wrought-iron | 12 | 2 | Kearsh | 10 | 3 | Cauk, or terra ponderosa | 10 | 7 | A topaz, or chrysolite | 3 | 45 | An oriental emerald | 2 | 25 | Crystal pebble | 7 | 6 | White agate | 10 | 30 | Oriental flint | 10 | 30 | Rough cornelian | 10 | 75 | Jasper | 10 | 25 | Onyx | 10 | 20 | Garnet | 10 | 17 | White rhomboidal spar | 10 | 60 | Zeolites | 10 | 23 | Rotten-stone | 10 | 80 | Common slate | 10 | 2 | Asbestos | 10 | 10 | Common lime-stone | 10 | 55 | Pumice-stone | 10 | 24 | Lava | 10 | 7 | Volcanic clay | 10 | 60 | Cornish moor-stone | 10 | 60 | --------------------------------------+-------+-------+

_Fulminating Powder._

This powder is made by rubbing together, in a hot marble mortar, with a wooden pestle, three parts, by weight, of nitre, two of mild vegetable alkali, and one of flowers of sulphur, till the whole is accurately mixed. If a drachm of this powder be exposed to a gentle heat, in an iron ladle, till it melts, it will explode with a noise as loud as the report of a cannon.

_A more powerful fulminating Powder._

The most wonderful instance of chemical detonation is formed by the combination of volatile alkali with silver. Gunpowder, or fulminating gold, are not to be compared with this invention, and the great danger attending its manufacture prevents us from giving a methodical account of its preparation to our readers, particularly as it can be purchased, properly prepared, of the chemists.

The slightest agitation or friction is sufficient to cause its explosion. When it is once obtained, it can no longer be touched with safety. The falling of a few atoms of it, from a small height, produces an explosion; a drop of water falling on it has the same effect. No attempt, therefore, can be made to enclose it in a bottle, but it must be let alone in the capsule, wherein, by evaporation, it obtains this terrible property. To make this experiment with safety, no greater quantity than a grain of silver should be used; the last process of drying should be made in a metallic vessel, and the face of the operator defended by a mask with strong glass eyes.

_To make the Phosphorus Match Bottles._

Nothing more is necessary for this purpose, than to drop small pieces of dry phosphorus into a common phial; gently heat it till it melts; and then turn the bottle round, that it may adhere to the sides. The phial should be closely corked; and when used, a common brimstone match is to be introduced, and rubbed against the sides of the phial: this inflames the match when it is brought out of the bottle. Though there is no danger in phosphorus, till friction, or fire, is applied, yet persons cannot be too cautious in the use of it, as instances have been known of one of these bottles catching fire in the pocket, and very much endangering the person who carried it; likewise, if carelessly used, small particles are apt to get under the nails, or on the hand; and if, by accident, they are held to the fire, or rubbed together, a flame will presently kindle.

_To make a Ring suspend by a Thread, after the Thread has been burned._

Soak a piece of thread in urine, or common salt and water. Tie it to a ring, not larger than a wedding-ring. When you apply the flame of a candle to it, it will burn to ashes, but yet sustain the ring.

_To form Figures in relief on an Egg._

Design on the shell any figure or ornament you please, with melted tallow, or any other fat oily substance; then immerse the egg into very strong vinegar, and let it remain till the acid has corroded that part of the shell which is not covered with the greasy matter: those parts will then appear in relief, exactly as you have drawn them.

_To give a ghastly Appearance to Persons in a Room._

Dissolve salt in an infusion of saffron and spirits of wine. Dip some tow in this solution, and, having set fire to it, extinguish all other lights in the room.

_To change Blue to White._

Dissolve copper filings in a phial of volatile alkali; when the phial is unstopped, the liquor will be blue; when stopped, it will be white.

_Magical Transmutations._

Infuse a few shavings of logwood in common water, and when the liquor is sufficiently red, pour it into a bottle. Then take three drinking-glasses, and rinse one of them with strong vinegar; throw into the second a small quantity of pounded alum, which will not be observed if the glass has been recently washed, and leave the third without any preparation. If the red liquor in the bottle be poured into the first glass, it will appear of a straw colour; if into the second, it will pass gradually from bluish-grey to black, when stirred with a key, or any piece of iron, which has been previously dipped in strong vinegar. In the third glass, the red liquor will assume a violet tint.

_To make Pomatum with Water and Wax._

Water and wax are two substances that do not naturally unite together; therefore, to those who witness the following process, without knowing the cause, it will have the appearance of marvellous. Put into a new glazed earthen pot, six ounces of river water and two ounces of white wax, in which, you must previously conceal a strong dose of salt of tartar. If the whole be then exposed to a considerable degree of heat, it will assume the consistence of pomatum, and may be used as such.

_Iron transformed into Copper._

Dissolve blue vitriol in water, till the water is well impregnated with it; and immerse into the solution small plates of iron, or coarse iron filings. These will be attacked and dissolved by the acid of the vitriol, while the copper naturally contained in the vitriol will be sunk and deposited in the place of the iron dissolved. If the piece of iron be too large for dissolving, it will be so completely covered with particles of copper, as to resemble that metal itself.

_Iron transformed into Silver._

Dissolve mercury in marine acid, and dip a piece of iron into it, or rub the solution over the iron, and it will assume a silver appearance.

It is scarcely necessary to say, that these transmutations are only apparent, though to the credulous it would seem that they were actually transformed.

_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.

_The Philosophical Candle._

Provide a bladder, into the orifice of which is inserted a metal tube, some inches in length, that can be adapted to the neck of a bottle, containing the same mixture as in the last experiment. Having suffered the atmospheric air to be expelled from the bottle, by the elastic vapour produced by the solution, apply the orifice of the bladder to the mouth of the bottle, after carefully squeezing the common air out of it, (which you must not fail to do, or the bladder will violently explode.) The bladder will thus become filled with the inflammable air, which, when forced out against the flame of a candle, by pressing the sides of the bladder, will form a beautiful green flame.

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