Let the number thought of be 6, if 1 be taken from it, there will remain 5, the double of which 10, being diminished by 1, and the remainder 9 being increased by 6, the number thought of, the result will be 15, if to this we add 3, we shall have 18, the third part of which, 6, will be the number required.
Take a straw, which is not broken or bruised, and having bent one end of it into a sharp angle, put this curved end into the bottle, so that the bent part may rest against its side, and you may take the other end in your hand, and lift up the bottle by it, without breaking the straw, and this will be more readily accomplished, as the angular part of the straw approaches nearer to that which comes out of the bottle.
Take a small quantity of water in a glass tumbler, and add to it two or three small lumps of phosphoret of lime, shortly will arise little flashes of light, darting out like petty lightning and ascending subsequently into curling clouds, the appearances continue for some time, and constitute a lively illustration of the formation of a light proceeding out of shallow pools of water.
Medallions, after the antique, cameos and intaglios are made by fusing the iron with a small quantity of antimony, performing the operation in a very small furnace. When finished from the mould, rub them over with burnt porcelain earth, from which they will receive the rich hue of jet, rendering them fit to be set, even in gold.
Nothing soils sooner than playing cards. The following method will be found to remove every thing from them but a stain, and will give the dirtiest pack possible the appearance of being new. Rub the soiled card with a piece of flannel and some good fresh butter, until the butter shall have cleaned off all the dirt. So soon as the dirt is removed, wipe off the butter with a clean rag, and to restore the cards to its former gloss, rub the surface sharply with a piece of flannel and some flour, cut the edges neatly with a pair of scissars, and the operation is completed.
Put a grain of fulminating copper on a hearth-stone, rub it with the end of a poker, and a loud explosion will immediately follow.
To a piece of cork tie a small stone that will just sink it, and putting it into a vessel of water, place it under the receiver; then exhausting the receiver, the bubbles of air will expand from its pores, and adhering to its surface, will render it, together with the stone, lighter than water, and consequently both will rise to the surface and float upon it.
If twenty grains of phosphorus, cut very small and mixed with forty grains of powder of zinc, be put into four drams of water, and two drams of concentrated sulphuric acid be added thereto, bubbles of inflamed phosphorated hydrogen gas will quickly cover the whole surface of the fluid in successions forming a real fountain of fire.
If you take up a small quantity of melted glass with a tube (the bowl of a common tobacco-pipe will do) and let a drop fall into a vessel of water, it will chill and condense with a fine spiral tail, which being broken the whole substance will burst with a loud explosion, without injury either to the party that holds it, or to him who breaks it; but if the thick end be struck, even with a hammer, it will not break.
Take a common full blown rose, and having thrown a little sulphur, finely pounded, into a chafing dish with coals, expose the rose to the vapour; by this process the rose will become whitish; but if it be afterwards held some time in water, it will resume its former colour.
Dissolve chalk in aqua-fortis to the consistence of milk, and add to it a solution of silver. Keep this liquor in a glass decanter, well stopped. Then cut out from a paper the letters you would have appear, and paste the paper upon the decanter, which is to be placed in the sun, in such a manner that its rays may pass through the spaces cut out of the paper, and fall on the surface of the liquor. The part of the glass through which the rays pass will turn black, and that under the paper will remain white. You must observe not to move the bottles during the time of the operation.
You must have a curtain ring about the size of a shilling, at first you put the shilling into the handkerchief, but when you take it out again, to convince the company that there is no deception, you slip the curtain ring in its stead, and while the person is eagerly holding the handkerchief, and the company’s eyes are fixed upon the form of the shilling, you seize this opportunity of putting it into a hat or basket; when you get possession of the handkerchief again you slip away the curtain ring.
Put into an earthen mortar some leaf gold, with thick gum water, and grind the mixture till the gold is reduced to small particles. Having done this, a little warm water will wash out the gum, leaving the gold in a pulverized state.
Wrap up a very smooth ball of lead in a piece of paper, taking care that there be no wrinkles in it, and that it be every where in contact with the ball, if it be held, in this state, over the flame of a taper, the lead will be melted without the paper being burnt. The lead, indeed, when once fused, will not fail in a short time to pierce the paper, and run through.
Take half an ounce of sal ammoniac, one ounce of camphor, and two ounces of aqua-vitæ, put them into an earthen pot, narrowing towards the top, and set fire to it. The effect will be so alarming, that persons in the room will fancy their garments are on fire.
Put thirty grains of phosphorus into a florence flask, with three or four ounces of water; place the vessel over a lamp, and give it a boiling heat. Balls of fire will soon be seen to issue from the water, after the manner of an artificial firework, attended with the most beautiful vibrations of light.
Place the glasses (being full of water) upon two joint stools, equally distant from the ground, and from one another the length of the staff, then place the ends of the staff upon the edges of the two glasses, so that they be sharp, this being done, strike the staff in the middle, with all the force you can, with another staff, and it will break without injuring the goblets, or spilling the water.
Take a spectacle glass that magnifies very much, hold it before a book, twice the distance of its focus, and you will see the round body of the sun, and the manner in which the moon passes between the glass and the sun, during the whole eclipse.
Take zaffer, and dissolve it in nitro-muriatic acid, till the acid extracts all the metallic part, then dilute the solution with common water, if you write with this liquid on paper, the writing will appear of a beautiful green, upon being partially warmed before the fire.
Melt in a crucible, seven ounces of pure copper, when fused throw into it three ounces of zinc, and two ounces of tin. These metals will combine forming bronze, an alloy, which, from the exactness of the impression which it takes from a mould, has, in ancient and modern times, been generally used in the formation of busts, medals, and statues.
You must have two rings exactly alike, one of which has a notch which admits your cheek. When you have exhibited the perfect ring, you change it for the other, and privately slip the notch over one side of your mouth, in the meantime you slip the whole ring on your stick, hiding it with your hand, then desire some one to hold the end of the stick, whip the ring out of your cheek, and smite with it instantly upon the stick, concealing it, and whirling the other ring, which you hold your hand over round about the stick.
The person is told to set the hand of his watch at any hour he pleases, which hour he tells you, and you add in your mind twelve to it. You then desire him to count privately the number of that addition on the dial, commencing at the next hour to that at which he intends to rise, and including the hour at which he has placed the hand, which will give you the answer.
A intends to rise at 6 (this he conceals to himself) he places the hand at 8, which he tells B, who, in his own mind, adds 12 to 8, which makes 20. B then tells A to count 20 on the dial, beginning at the next hour to that at which he proposes to rise, which will be 7, and counting backwards, reckoning each hour as 1, and including in his addition the number of the hour hand is placed at, the addition will end at 6, which is the hour proposed; thus,
| The hour the hand is placed at is | 8 |
| The next hour to that, which A intends to rise at, is 7, which counts for 8 | 1 |
| Count back the hours from 6, and reckon them 1 each, there will be 11 hours, viz. 4, 3, 2, 1, 12, 11, 10, 9, 8 7, 6, | 11 |
| Making | 20 |