“Oh! but I mean, you cut off its supply of oxygen,” said Master Harry. “Cut off its ox’s—eh? what? I shall cut off your nose, you young dog, one of these fine days.” “He means something he heard at the Royal Institution,” observed Mrs. Wilkinson. “He reads a great deal about chemistry, and he attended Professor Faraday’s lectures there on the chemical history of a candle, and has been full of it ever since.” “Now, you sir,” said Uncle Bagges, “come you here to me, and tell me what you have to say about this chemical, eh?—or comical; which?—this comical chemical history of a candle.” “He’ll bore you, Bagges,” said Mr. Wilkinson. “Harry, don’t be troublesome to your uncle.” “Troublesome! Oh, not at all. He amuses me. I like to hear him. So let him teach his old uncle the comicality and chemicality of a farthing rushlight.” “A wax candle will be nicer and cleaner, uncle, and answer the same purpose. There’s one on the mantel-shelf. Let me light it.” “Take care you don’t burn your fingers, or set anything on fire,” said Mrs. Wilkinson. “Now, uncle,” commenced Harry, having drawn his chair to the side of Mr. Bagges, “we have got our candle burning. What do you see?” “Let me put on my spectacles,” answered the uncle. “Look down on the top of the candle around the wick. See, it is a little cup full of melted wax. The heat of the flame has melted the wax just round the wick. The cold air keeps the outside of it hard, so as to make the rim of it. The melted wax in the little cup goes up through the wick to be burnt, just as oil does in the wick of a lamp. What do you think makes it go up, uncle?” “Why—why, the flame draws it up, doesn’t it?” “Not exactly, uncle. It goes up through little tiny passages in the cotton wick, because very, very small channels, or pipes, or pores, have the power in themselves of sucking up liquids. What they do it by is called cap—something.” “Capillary attraction, Harry,” suggested Mr. Wilkinson. “Yes, that’s it; just as a sponge sucks up water, or a bit of lump-sugar the little drop of tea or coffee left in the bottom of a cup. But I mustn’t say much more about this, or else you will tell me I am doing something very much like teaching my grandmother to—you know what.” “Your grandmother, eh, young sharpshins?”