This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
A gas or electric fixture in the center of a room is quite hard to locate in the dark; more so if it is a single-light pendant. The location may be easily found if the fixture is marked as follows: Coat small pieces of cardboard on both sides with phosphorus and suspend them from the fixtures with small wires. No matter how dark the room may be, the phosphorus on the cardboard can be readily seen. The phosphorus is the same as used on matches and can be obtained from any druggist. The phosphorus, being poisonous, should be handled as little as possible, and, after using, should be returned to the water-filled jar in which it was received when bought. If left in the open, it may cause fire. - Contributed by Katharine D. Morse, Syracuse, N. Y.