“But,” proceeded Harry, “there is more in the candle-flame than the gas that comes out of the candle. You know a candle won’t burn without air. There must be always air around the gas, and touching it like, to make it burn. If a candle hasn’t got enough air, it goes out, or burns badly, so that some of the vapour inside of the flame comes out through it in the form of smoke, and this is the reason of a candle smoking. So now you know why a great clumsy dip smokes more than a neat wax candle; it is because the thick wick of the dip makes too much fuel in proportion to the air that can get to it.” “Dear me! Well, I suppose there is a reason for everything,” exclaimed the young philosopher’s mamma. “What should you say, now,” continued Harry, “if I told you that the smoke that comes out of a candle is the very thing that makes a candle light? Yes; a candle shines by consuming its own smoke. The smoke of a candle is a cloud of small dust, and the little grains of the dust are bits of charcoal, or carbon, as chemists call it. They are made in the flame, and burnt in the flame, and, while burning, make the flame bright. They are burnt the moment they are made; but the flame goes on making more of them as fast as it burns them; and that is how it keeps bright. The place they are made in, is in the case of flame itself, where the strongest heat is. The great heat separates them from the gas which comes from the melted wax, and, as soon as they touch the air on the outside of the thin case of flame, they burn.” “Can you tell how it is that the little bits of carbon cause the brightness of the flame?” asked Mr. Wilkinson. “Because they are pieces of solid matter,” answered Harry. “To make a flame shine, there must always be some solid—or at least liquid—matter in it.” “Very good,” said Mr. Bagges,—“solid stuff necessary to brightness.” “Some gases and other things,” resumed Harry, “that burn with a flame you can hardly see, burn splendidly when something solid is put into them. Oxygen and hydrogen—tell me if I use too hard words, uncle—oxygen and hydrogen gases, if mixed together and blown through a pipe, burn with plenty of heat but with very little light. But if their flame is blown upon a piece of quicklime, it gets so bright as to be quite dazzling. Make the smoke of oil of turpentine pass through the same flame, and it gives the flame a beautiful brightness directly.” “I wonder,” observed Uncle Bagges, “what has made you such a bright youth.” “Taking after uncle, perhaps,” retorted his nephew. “Don’t put my candle and me out. Well, carbon or charcoal is what causes the brightness of all lamps, and candles, and other common lights; so, of course, there is carbon in what they are all made of.” “So carbon is smoke, eh? and light is owing to your carbon. Giving light out of smoke, eh? as they say in the classics,” observed Mr. Bagges. “But what becomes of the candle,” pursued Harry, “as it burns away? where does it go?”