Pour into a saucer a little sulphuric acid, and place upon it a chip of sodium, which will float and remain uninflamed; but the addition of a drop of water will set it on fire. WAVES OF FIRE ON WATER. On a lump of refined sugar let fall a few drops of phosphuretted ether, and put the sugar into a glass of warm water, which will instantly appear on fire at the surface, and in waves, if gently blown with the breath. This experiment should be exhibited in the dark. EXPLOSION IN WATER. Throw very small pieces of phosphuret of potassium into a basin of water, and they will produce separate explosions. The same substance will also burn with great brilliancy, when exposed to air. WATER FROM THE FLAME OF A CANDLE. Hold a cold and dry bell-glass over a lighted candle, and watery vapour will be directly condensed on the cold surface; then close the mouth of the glass with a card or plate, and turn the mouth uppermost; remove the card, quickly pour in a little lime-water, a perfectly clear liquid, and it will instantly become turbid and milky, upon meeting with the contents of the glass, just as lime-water changes when dropped into a glass of water. FORMATION OF WATER BY FIRE. Put into a tea-cup a little spirit of wine, set it on fire, and invert a large bell-glass over it. In a short time, a thick watery vapour will be seen upon the inside of the bell, which may be collected by a dry sponge. BOILING UPON COLD WATER. Provide a tall glass jar, filled with cold water, and place in it an air thermometer, which will nearly reach the surface; upon the surface place a small copper basin, into which put a little live charcoal: the surface of the water will soon be made to boil, while the thermometer will show that the water beneath is scarcely warmer than it was at first. CURRENTS IN BOILING WATER. Fill a large glass tube with water, and throw into it a few particles of bruised amber; then hold the tube, by a handle for the purpose, upright in the flame of a lamp, and, as the water becomes warm, it will be seen that currents, carrying with them the pieces of amber, will begin to ascend in the centre, and to descend towards the circumference of the tube. These currents will soon become rapid in their motions, and continue till the water boils. HOT WATER LIGHTER THAN COLD. Pour into a glass tube, about ten inches long, and one inch in diameter, a little water coloured with pink or other dye; then fill it up gradually and carefully with colourless water, so as not to mix them: apply heat at the bottom of the tube, and the coloured water will ascend and be diffused throughout the whole. The circulation of warm water may be very pleasingly shown, by heating water in a tube similar to the foregoing; the water having diffused in it some particles of amber, or other light substance not soluble in water. EXPANSION OF WATER BY COLD.