Tonight, as you brush your teeth, you’ll be scrubbing them with the same material that goes into stockings, combs, parachutes, spaceships, car engines — the list seems infinite. That stuff turned 75 this year, but it’s tragic human back story is rarely told. It was a decade when chemistry was the most exotic of sciences — exotic fluids percolating through mysterious mazes of stop-cocked glassware, phallic retorts, flasks, and beakers. It was the era when chemistry was doing for the public imagination…