"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 quick-lime, 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?"
"Nowhere," said his mamma, "I should think. It burns to nothing."
"Oh, dear, no!" said Harry, "every thing--every body goes somewhere."
"Eh!--rather an important consideration that," Mr. Bagges moralized.
"You can see it goes into smoke, which makes soot, for one thing," pursued Harry. "There are other things it goes into, not to be seen by only looking, but you can get to see them by taking the right means--just put your hand over the candle, uncle."
"Thank you, young gentleman, I had rather be excused."
"Not close enough down to burn you, uncle; higher up. There--you feel a stream of hot air; so something seems to rise from the candle. Suppose you were to put a very long, slender gas-burner over the flame, and let the flame burn just within the end of it, as if it were a chimney, some of the hot steam would go up and come out at the top, but a sort of dew would be left behind in the glass chimney, if the chimney was cold enough when you put it on. There are ways of collecting this sort of dew, and when it is collected it turns out to be really water. I am not joking, uncle. Water is one of the things which the candle turns into in burning--water, coming out of fire. A jet of oil gives above a pint of water in burning. In some lighthouses they burn, Professor Faraday says, up to two gallons of oil in a night, and if the windows are cold, the steam from the oil clouds the inside of the windows, and, in frosty weather, freezes into ice."