Tie up in a bladder of water, an egg and a piece of very soft wax, and place it in a box, so as to touch its sides and bottom; then, lay loosely upon the bladder a brass or other metal plate, upon which place a hundred pounds weight, or more; when the egg and the wax, though pressed by the water with all its weight, being equally pressed in all directions, will not be in the least either crushed or altered in shape. TO EMPTY A GLASS UNDER WATER. Fill a wine-glass with water, place over its mouth a card, so as to prevent the water from escaping, and put the glass, mouth downwards, into a basin of water. Next, remove the card, and raise the glass partly above the surface, but keep its mouth below the surface, so that the glass still remains completely filled with water. Then insert one end of a quill or reed in the water below the mouth of the glass, and blow gently at the other end, when air will ascend in bubbles to the highest part of the glass, and expel the water from it; and, if you continue to blow through the quill, all the water will be emptied from the glass, which will be filled with air. TO EMPTY A GLASS OF WATER WITHOUT TOUCHING IT. Hang over the edge of the glass a thick skein of cotton, and the water will slowly be decreased till the glass is empty. A towel will empty a basin of water in the same way. DECOMPOSITION OF WATER. The readiest means of decomposing water is as follows: take a gun-barrel, the breech of which has been removed, and fill it with iron wire, coiled up. Place it across a chafing-dish filled with lighted charcoal, and connect to one end of the barrel a small glass retort containing some water; and, to the other, a bent tube, opening under the shelf of a water bath. Heat the barrel red hot, and apply a lamp under the retort: the stream of water, in passing over the red-hot iron of the barrel, will be decomposed, the oxygen will unite with the iron, and the hydrogen may be collected in the form of gas at the end of the tube over the water. WATER HEAVIER THAN WINE. Let a tumbler be half-filled with water, and fit upon its surface a piece of white paper, upon which pour wine; then carefully draw out the paper, say with a knitting-needle, so as to disturb the liquids as little as possible, and the water, being the heavier, will continue at the lower part of the glass; whilst the wine, being the lighter, will keep above it. But, if a glass be first half-filled with wine, and water be poured over it, it will at once sink through the wine, and both liquids will be mixed. TO INFLATE A BLADDER WITHOUT AIR. Put a tea-spoonful of ether into a moistened bladder, the neck of which tie up tightly; pour hot water upon the bladder, and the ether, by expanding, will fill it out. AIR AND WATER BALLOON.