Calcine oyster-shells, pound them, sift them through a silk sieve, and grind them on porphyry till they are reduced to the finest powder. Then take the whites of several eggs, acco...
Mortars to throw aigrettes are generally made of pasteboard, of the same thickness as balloon mortars, and two diameters and a half long in the inside from the top of the foot: the...
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 ou...
Offer the long card to a person, that he may draw it, and replace it in any part of the pack he pleases. Make the pass, and bring that card to the top. Next divide the pack in thre...
camphor half an ounce, yellow amber half an ounce, charcoal-dust three-fourths of an ounce, salt of Benzoin half an ounce, all powdered very fine and well mixed. II. Saltpetre twel...
If a person look in a concave mirror placed perpendicularly to another, (that is, supposing one mirror to be laid on the floor, and the other attached to the ceiling,) his face wil...
Take a square bottle of thin glass, and of any size. Apply it to the hole of the air-pump, and exhaust the air. The bottle will sustain the weight of the external air as long as it...
Take sulphur and nitre, of each an equal quantity; grind them together very fine, and put them into an unglazed vessel; cover and lute it well; then set it over a slow fire for 24...
Gunpowder being a principal ingredient in fire-works, it will not be improper to give a short definition of its strange explosive force, and cause of action, which, according to Dr...
Take a bit of phosphorus, about the size of a pea; break it into small parts, which you are to put into a glass half full of very pure water, and boil it in a small earthen vessel,...
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 co...
Put litharge of lead into very strong vinegar, and let it stand twenty-four hours. Strain it off, and let it remain till quite settled; then put the liquor in a bottle. You next di...
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 shoul...
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 inv...
Reduce gum ammoniac into powder, and dissolve it in gum arabic water, to which a little garlic juice has been added. This water will not dissolve the ammonia so as to form a transp...
Take the meal of flour of any vegetable, put it into an iron pan over a moderate fire, and keep it stirring with an iron spoon till it changes to a black powder; to one part of thi...
Mix three ounces of saltpetre, two ounces of salt of tartar, and two ounces of sulphur; roll the mixture up into a ball, of which take a quantity, about the size of a hazel-nut, an...
Take two pieces of card, pasteboard, or stiff paper, through which you cut long squares at different distances. One of these you keep yourself, and the other you give to your corre...
Having procured four or five small ships, of two or three feet in length, make a number of small reports, which are to serve for guns. Of these range as many as you please on each...
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 12 to it. You then desire him to count privately the numbe...
Dissolve bismuth in nitrous acid. When the writing with this fluid is exposed to the vapour of liver of sulphur, it will become quite black.
Against the wall of a room, near the ceiling, fix a wheel of twelve or eighteen inches diameter; on the rim of which place a number of bells in tune, and, if you please, of differe...
Opticians sometimes grind a glass mirror concave in one direction only, or longitudinally; it is in fact a concave portion of a cylinder, the breadth of which may be considered tha...
Take a tall receiver that is very dry, and fix through the top of it, with cement, a blunt wire; then exhaust the receiver, and present the knob of the wire to the conductor, and e...
However improbable the following experiment may appear, it has been proved by repeated trials: Sling a shilling or sixpence at the end of a piece of thread by means of a loop. Then...
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 re...
Provide yourself with some of those prints that are commonly used in optical machines, printed on very thin white paper; taking care to make choice of such as have the greatest eff...
the Hand, the Finger, and the Joint on which it is placed. Let a third person double the number of the order in which he stands who has the ring, and add 5 to that number; then mul...
made two feet diameter, without any spokes, and very strong, with any number of sides. On the top of a wheel range and fix in pots, three inches diameter and seven inches high each...
A very pleasing exhibition may be made with very little trouble or expense, in the following manner: Provide a box, which you fit up with architectural designs cut out on pasteboar...