A very interesting experiment may be performed with two drinking glasses, a small candle end and a piece of blotting paper, says the Pathfinder. The glasses must be the same size and of the thin-glass kind. The candle end is lighted and set in one glass; the blotting paper is well dampened and placed on top of the glass, and the other glass inverted and its rim placed exactly over the lower one and pressed down tightly. The candle will burn up all the oxygen in the glass and go out.
The air in the glass being heated will expand and some of it will be forced out from under the moist paper, and then, as the portion remaining cools, it will contract and draw the upper glass on the paper and make an air-tight joint. The upper glass can then be taken up and the lower one will cling to it.
Excerpt from the book:
The Boy Mechanic – BOOK 2 – 1000 THINGS FOR BOYS TO DO