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Example I: Voltaic

Cheap and Easy Method of constructing a Voltaic Pile. Mr. Mitchell, in his useful little work on natural philosophy, proposes the following cheap and easy method of constructing a Voltaic Pile. Zinc is one of the cheapest of metals, and may be easily melted, like lead. Let the student cast twenty or thirty pieces, of the size of a penny-piece, which may easily be done in moulds made in clay. Let him then get as many penny-pieces, and as many pieces of paper, or cloth cut in the same shape, and these he must dip in a solution of salt and water. In building the pile, let him place a piece of zinc, wet paper, (the superabundant water being squeezed out,) after which the copper; then zinc, paper, copper, &c. until the whole be finished. The sides of the pile may be supported with rods of glass, or varnished wood, fixed in the board on which it is built. The following experiment may then be performed :- Having wetted both hands, touch the lower part of the pile with one hand, and the upper part with the other, constant little shocks of electricity will be felt until one hand be removed. If the hand be brought back, a similar repetition of shocks will be felt. Put a basin of water near the pile, and put the left hand into it, holding a wire, one end of which touches the top of the battery or pile; then put the end of a silver spoon between the lip and the gum, and with the other end of the spoon touch the lower part of the pile; a strong shock is felt in the gum and in the hand. Take the left hard from the water, but still keep hold of the wire, and then perform the last experiment in the same manner, and a shock will be felt in the gum only. Hold a silver spoon in one hand, and touch with it the battery at the lower part, then touch the upper part with the tongue; the bitter taste will be extreme.

In performing the above experiments, if, instead of the two ends of the pile, the one end and the middle of it be touched, the sensations will not be nearly so strong. If the student be desirous of having still more sensible proofs of the effect of galvanism, let him hold a wire to the top of the battery, and let him place one end of a silver spoon to the lower part, and the other end within his mouth, so as to touch the gums; a severe set of shocks will be felt. In performing this experiment, move the spoon to the roof of the mouth, and a strong sensation will be felt. Let the end of the spoon be run up the nose so as to touch the cartilaginous bone; shocks like the stabs of a needle will be felt. Let the end of the spoon be put under the eye-brow, close to the ball of the eye; a sensation will be felt like the burning of red-hot iron, but which ceases the instant the spoon is removed.

Magnetical Experiments.

The magnetic attraction will not be destroyed by interposing obstacles between the magnet and the iron. obstacles between the magnet and the iron.

Lay a small needle on a piece of paper, and put a magnet under the paper; the needle may be moved backwards and forwards.

Lay the needle on a piece of glass, and put the magnet under the glass; it will still attract the needle. The same effects will take place if a board be interposed between the magnet and the iron. This property of the magnet has afforded the means of some very amusing deceptions.

A little figure of a man has been made to spell a person's name. The hand, in which was a piece of iron, rested on a board, under which a person, concealed from view, with a powerful magnet, contrived to carry it from letter to letter, until the word was made up.

The figure of a goose or swan, with a piece of iron concealed about the head, is set to float in water. A rod, with a concealed magnet at the end, is presented to the bird, and it swims after it. The effect is still more amusing, when some food is put on the end of the rod.

The figure of a fish is thrown into the water, with a small magnet concealed in its mouth. Of course, if a baited hook be suspended near it, the magnet and iron, by mutual attraction, will bring the fish to the bait.