How Rubber Became Useful

[A] Natural rubber reached Europe as a curiosity and stayed one for seventy years, because nobody could keep it in a usable state. In summer it softened into a sticky mass that smelled and lost its shape; in winter it went hard and cracked. [B] A waterproof coat made in May was ruined by August. The problem was not the substance but its temperature range, which was far too narrow for any climate people actually lived in. [C]

[D] The answer, found by trial rather than theory, was to heat rubber with sulphur. Charles Goodyear spent a decade on the problem and arrived at the method partly by accident, and the result is a material with an entirely different character. The sulphur forms bridges between the long molecules, so that they can still slide a little and can no longer slide past one another altogether. That single change gives rubber both of the properties it is now valued for: it returns to its shape after being stretched, and it keeps doing so across the range of temperatures a tyre or a seal actually meets. What is striking is how little the discovery owed to chemistry. The molecular account came half a century later, and it explained a process that had by then been in factory use for two generations.