Detonating Cards. Take a piece of card, about three fourths of an inch in breadth and 12 in length; slit it at one end, and place in the opening a quarter of a grain of fulminating silver, close the end down with a little paste, and when dry light the end in a candle.
Fulminating silver may be used in several other ways, affording a variety in the effect, as the following: Fold a letter in the usual manner, and along with the wafer introduce the fulminating silver mixed with some glass: when the wafer is broken, in the act of opening the letter, a violent explosion will take place.
By placing a quarter of a grain of the powder in the midst of some tobacco in a pipe, or between the leaves of a segar, and closing the end again to prevent the powder from falling out; it need hardly be stated, that on lighting it, an explosion ensues. Such experiments should be made with caution.
One-third of a grain of fulminating silver, folded in a small piece of paper, and wrapped in another piece, then pasted round a pin, which is to be stuck in the wick of a candle, will make a loud report.
As fulminating silver explodes by heat, or friction, it is obvious, that various contrivances may be used for this purpose. If, for instance, half a grain be put on a piece of glass paper, (paper covered with a mixture of powdered glass and gum), then inclosed in a piece of tin foil, and put in the bottom or side of a drawer; on opening or shutting it, the powder will immediately explode. The same effect takes place by putting a quarter of a grain into a piece of paper, and placing it in the snuffers. When the candle is snuffed, it will go off.
Two figures, one of which blows out and the other relights a candle, are sometimes exhibited in rooms. This is performed by making two figures of any shape or material, and inserting in the mouth of one, a small tube, at the end of which is a piece of phosphorus, and in the mouth of the other, a tube containing at the end a few grains of gunpowder; observing that each be retained in the tube by a piece of paper. If the second figure be applied to the flame of a taper, it will extinguish it, by reason of the gunpowder, and the first will light it again.
Candle bombs. These are usually called candle crackers, and are made of glass. They are blown in small bubbles, having a neck about half an inch long, with very slender bores, by means of which a small quantity of water or spirit of wine is introduced. The orifice is then closed. When they are stuck into a candle, the heat converts the water or alcohol into vapour, which breaks the glass with a loud report, extinguishing the flame at the same time.
Detonations by Electricity. The electric fluid, it is known, will inflame combustible bodies, and, for the purpose of experiment, several contrivances have been used. That of placing the substance, gunpowder for instance, on a small insulated stand, and passing the spark through it by means of conductors, will cause its inflammation. The electrical house is also an exemplification of the effect of the electric fluid.
Detonations by Galvanism. Substances, placed on a glass plate, and brought in contact with the positive and negative poles of a galvanic battery, are readily inflamed. Hence phosphorus, gunpowder, the metals, &c. may be inflamed in this manner. The deflagrator of professor Hare of the University of Pennsylvania, is a powerful apparatus for the purpose; for the construction of which, and the details of its effects, see the American Journal of Science by professor Silliman, of Yale College.