英语听力文摘 English Digest 667 火柴

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　　Striking¹ matches, on this Moment of Science.

　　Have you ever had a problem getting a match to light? If so, you might be using the wrong type of match. There are actually two different types of matches: safety matches and strike-anywhere matches.

　　Safety

　　Safety matches are the kind that light only when struck on the striking surface on the side of a matchbox. A striking surface consists of sand, powdered glass, and a chemical called red phosphorus. The tip of a safety match is made of glass powder, sulfur², and an oxidizing agent–a chemical necessary to keep a flame burning.

　　When a safety match scrapes³ against a striking surface, the glass powder on the striking surface and match head rub⁴ together, creating enough heat to turn a bit of the red phosphorus on the striking surface into white phosphorus. The white phosphorus ignites⁵ in air, passing ignition across to the match head.

　　Chemical Reaction

　　This starts a chemical reaction that uses the oxidizing agent on the match to produce oxygen gas. Combined with the heat, the oxygen gas causes the sulfur to catch fire, which then spreads to the wood of the match. A strike anywhere match works⁶ almost the same way, except the red phosphorus is included in the match head. So, a strike anywhere match can be lit by striking the match against any hard surface.

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