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By Root 3144 0

“Long” is an accurate adjective: if a rubber molecule were as thick as a pencil, it would be as long as a football field. “Chain,” too, is accurate: all rubber molecules are made up of tens of thousands of identical, repeating links, each consisting of five carbon atoms and eight hydrogen atoms. The molecules of ordinary solid substances—the copper in a wire, say—are usually distributed in orderly arrays. Rubber molecules, by contrast, are higgledy-piggledy, the chains scrambled around each other in no discernible pattern. “The classic analogy is a bowl of spaghetti,” Coughlin explained to me. “But the analogy doesn’t really work unless you’re willing to say the noodles are a hundred yards long.” Stretching a rubber band pulls the tangled molecules into alignment, lining them up in parallel like strands of spaghetti in a box. As they unkink, the molecules go from a clumped snarl to their full length, which is why rubber can stretch. By contrast, the copper molecules in a wire are already lined up in an array, making it much harder for the material to lengthen—the difference is the difference between pulling the end of a loose, tangled string and trying to tug at a fully extended string. (The energy required to pull the chains straight is why rubber heats up when stretched.) As soon as the pressure is relaxed, the rubber molecules begin moving randomly, which naturally ensnarls them again; the rubber shrinks back to its original size.

When a lump of pure rubber is heated up, the rubber chains vibrate and slither around each other every which way and get even more chaotically disordered; the rubber loses whatever shape it has and turns into a puddle. Vulcanization prevents this. Immersing rubber in sulfur causes a chemical reaction in which rubber molecules link themselves together with chemical “bridges” formed of sulfur atoms. So ubiquitous are the bonds that a rubber band—a loop of vulcanized rubber—is actually a single, enormous, cross-linked molecule. With the molecules anchored together, they are more resistant to change: harder to align, harder to entangle, more resistant to extremes of temperature. Rubber suddenly becomes a stable material.

The impact of vulcanization was profound, the inflatable rubber tire—key to the adoption of both the bicycle and the automobile—being the most celebrated example. But rubber also made electrification possible: try to imagine a modern building without insulation on its wiring. Or imagine dishwashers, washing machines, and clothes dryers without the belts that transmit the motion of their engines to the appliance itself. Equally important but less visible, every internal combustion engine contains many pipes and valves that channel, usually under pressure, water, oil, gasoline, and exhaust vapor. Unless the parts are manufactured perfectly, engine vibrations will cause liquids or gases to vent dangerously from the joints. Flexible rubber gaskets, washers, and O-rings almost invisibly fill the gaps. Without them, every home furnace would be at constant risk of leaking natural gas, heating oil, or coal exhaust—a potential death trap.

“Three fundamental materials were required for the Industrial Revolution,” Hecht, the UCLA geographer, told me. “Steel, fossil fuels, and rubber.” The rapidly industrializing nations of Europe and North America had more than adequate access to steel and fossil fuels. Which made it all the more imperative to secure a supply of rubber.

“THE BATHER IN THE BUBBLY”

In my living room hangs a portrait of either my grandmother’s uncle or her great-great-uncle. Both men were named Neville Burgoyne Craig. My grandfather, who found the painting in a thrift shop, thought that the subject was the older Craig (1787–1863), founding editor of the first daily newspaper in Pittsburgh. But the late-nineteenth-century style of the painting suggests that it was the younger Craig (1847–1926), an engineer who took ship for the Amazon a week after his thirty-first birthday. He intended to make his fortune in rubber.

Craig was not planning to work directly with rubber. Instead