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Example I: Water

To hold a Glass full of Water with the Mouth downwards, so that the Water shall not run out.

Take a glass full of water, cover it with a cup that is a little hollow, inverting the cup upon the glass; hold the cup firin in this position with one hand, and the glass with the other; then with a jerk turn the glass and the cup upside down, and so the cup will stand upright, and the glass will be inverted, resting its mouth upon the interior bottom of the cup: this done, you will find that part of the water contained in the glass will run out by the void space between the bottom of the cup, and the brim of the glass ; and when that space is filled, so that the water in it reaches the brim of the glass, all passage being then denied to the air, so that it cannot enter the glass, nor succeed in the room of the water, the water remaining in the glass will not fall lower, but continue suspended in the glass.

If you would have a little more water descend into the cup, you must, with a pipe or otherwise, draw the water out of the must, with a pipe or otherwise, draw the water out of the cup, to give passage to the air in the glass; upon which, part of the water will fall into the glass till it has stopped up the passage of the air afresh, in which case no more will come down; or, without sucking out the water in the cup, you may incline the cup and glass so that the water in the cup shall quit one side of the brim of the glass , and so give passage to the air, which will then suffer the water in the glass to descend till the passage is stopped again.

This may likewise be resolved by covering the brim of the glass that is full of water, with a leaf of strong paper, and that is full of water, with a leaf of strong paper, and then turn the glass as above; and without holding your hand any longer upon the paper, you will find it as it were glued for some time to the brim of the glass, and during that time the water will be kept in the glass.

The Mysterious Watch.

Desire any person to lend you his watch, and ask if he thinks it will or will not go when it is laid on the table: if he says it will, place it over the end of a magnet, and it will presently stop; then mark with chalk, or a pencil, the precise point where you placed the watch, and, moving the position the magnet, give the watch to another person, and desire hi to make the experiment; in which he not succeeding, give it to a third person, at the same time replacing the magnet, and he will immediately perform the experiment.

To make a Glass of Water appear to boil and sparkle. Take a glass nearly full of water, or other liquor, and a glass nearly full of water, or other liquor, and setting one hand upon the foot of it to hold it fast, turn slightly one of the fingers of your other hand upon the brim or edge of the glass, (having before privately wet your finger,) and so passing softly on, with your finger pressing a little, then the glass will begin to make a noise, the parts of the glass will sensibly appear to tremble with notable rarefaction and condensation, the water will shake, seem to boil, cast itself out of the glass, and leap out by small drops, to the great astonishment of the observers, if they are ignorant of the cause, which is only the rarefaction of the parts of the glass, occasioned by the motion and pressure of the finger. How to make a Cork fly out of a Bottle.

Put a little chalk or pounded marble into a phial, and pour on some water, with about a third part of sulphuric acid, and put in a cork: in a few seconds, the cork will be sent off with great violence.

To produce Gas Light, on a small Scale.

Take an ordinary tobacco pipe, and nearly fill the bowl with small coals, and stop the mouth of the bowl with any suitable luting, as pipe-clay, or the mixture of sand and common clay, or, as clay is apt to shrink, of sand and beer, and place the bowl in a fire between the bars of a grate, so that the pipe may stand nearly perpendicular. In a few minutes, if the luting be good, the gas will begin to escape from the stem of the pipe, when, if a piece of lighted paper or candle be applied, it will take fire and burn for several minutes with an intense light. When the light goes out, a residuum of useful products will be found in the bowl.

Thunder Powder.

Take separately, three parts of good dry saltpetre, two parts of dry salt of tartar, and pound them well together in a mortar; then add thereto one part, or rather more, of flour of brimstone, and take care to pound and mix the whole perfectly together: put this composition into a bottle with a glass stopper, for use.

Put about two drams of this mixture in an iron spoon, over a moderate fire, but not in the flame; in a short time it will melt, and go off with an explosion like thunder or a loaded cannon.

To tell, by the Dial of a Watch, at what hour any Person intends to rise. Let the person set the hand of the dial to any hour he pleases, and tell you what hour that is, and to the number of that hour you add, in your mind, 12. After this, tell him to call the hour the index stands at that which he has fixed upon; and by reckoning backwards from this number to the former, it will bring him to the hour required.

EXAMPLE.

Suppose the hour at which he intends to rise be 3, and that he has placed the hand at 5.

Then, adding 12 to 5, you bid him call the hour at which the index stands, the number on which he thought; and by reckoning back from this number to 17, it will bring him to 8, the hour required.