"I wish you'd do that, Harry," said Master Tom, the younger brother of the juvenile lecturer. "I want the proper things," answered Harry. "Well, uncle, the flame of the candle is a little shining case, with gas in the inside of it, and air on the outside, so that the case of flame is between the air and the gas. The gas keeps going into the flame to burn, and when the candle burns properly, none of it ever passes out through the flame; and none of the air ever gets in through the flame to the gas. The greatest heat of the candle is in this skin, or peel, or case of flame." "Case of flame!" repeated Mr. Bagges. "Live and learn. I should have thought a candle flame was as thick as my poor old noddle." "I can show you the contrary," said Harry. "I take this piece of white paper, look, and hold it a second or two down upon the candle flame, keeping the flame very steady. Now I'll rub off the black of the smoke, and--there--you find that the paper is scorched in the shape of a ring; but inside the ring it is only dirtied, and not singed at all." "Seeing is believing," remarked the uncle. "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 vapor 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 every thing," 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 burned in the flame, and, while burning, make the flame bright. They are burned 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."