TO BREAK A STONE WITH A BLOW OF THE FIST. Select two stones from three to six inches long, and about half as thick; lay one flat on the ground, on which place one end of the other, raising the reverse end to an angle of forty-five degrees, and just over the centre of the stone (with which it must form a T,) supporting it in that position by a piece of thin twig or stick, one, or one and a half inch long; if the raised stone be now smartly struck about the centre, with the little finger side of the fist, the stick will give way, and the stone will be broken to pieces: the stones must be laid so as not to slip, otherwise the experiment will fail. MIMIC FROST-WORK. Fasten a sprig of fresh rosemary, or any similar shrub, to the inside of a small bandbox, near the top; heat a thick tile, and sprinkle it with gum benzoic, and immediately place the bandbox over it, when the acid will be sublimed by the heat, and will condense in a white vapour upon the green plant, giving it the appearance of being covered with hoarfrost. TO MELT LEAD IN A PIECE OF PAPER. 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 everywhere 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. HYDROSTATIC BALANCE. Provide a pair of scales, in one of which place a tumbler filled with water, and poise it by placing weights in the opposite scale; then hold in the tumbler a block of wood, or any substance nearly the size of the tumbler, but so that it shall not touch the sides or bottom; when, although nearly the whole of the water will have to run over the sides, and only a spoonful may remain, the scales will continue balanced; and all this without regard to the weight of the body you plunge into the water, taking care to hold it entirely clear of the tumbler, so that it touch it nowhere; for the effect will be the same if what you plunge in be scooped hollow and made water-tight. A bladder blown up, tied fast, and held down in the water, so as to leave only a spoonful of water surrounding it, will keep the scales balanced just as well as a block of lead of the same size. METALLIC REDUCTION. Mix a little red lead with some powdered charcoal, and with the mixture fill the bowl of a tobacco-pipe; set it over a common fire, and in about twenty minutes the lead will be found reduced to its metallic state. SIMPLE ELECTRICITY. ELECTRICAL ATTRACTION AND REPULSION.