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Show A Trick with ft CtuidU kod Box. Put In the top ol a light, shallow pasteboard box two holes, each about , an Inch in diameter, and place over each an arpind lamp chimney. In one ' hole stand a cundleout to such a length that it will project about half an inch ; above the box. Liht tho candle and then hold burnin "touch paper" over die other lamp chimney. The smoke, instead of rUin, will go down one chimney, and after it has filled tho box will rise through the other. Tho reason is that the burning candle makes a draught up its chimney, and, if the box is air tight, to supply the place of what is going out air must coiuo down the other chimney. "'Touch paper," by the way, Is made by dipping ungiazed paper in a solution solu-tion of saltpeter. When dry it burns with a smoke, but not with tlauic. Another experiment is to hold the hand tightly over the chimney where the draught is downward. The candle in the other chimney will begin to burn feebly and smoke, and will go out if there are no cracks in the box for air to get in. Tho reason air does not get to it down its own chimney is that the up- i ward draught thero istoostrong. Bos- ton Globe. i |