Thomas Midgley Jr., born in 1889 in Pennsylvania to a family of inventors, carried a periodic table everywhere and treated chemistry as a practical toolkit. After joining General Motors in 1916 under Charles Kettering in Dayton, he worked through the elements looking for a cure for engine knock. Tellurium worked but smelled like rotting garlic. In December 1921 he found that tetraethyl lead stopped the knocking. This episode explains why GM chose a patentable lead additive over ethanol, branded it Ethyl to keep the word lead out of advertising, and pressed on even after Midgley himself contracted lead poisoning in 1923 and left for Miami to recover.

Workers died at plants in Dayton and at DuPont’s Deepwater, New Jersey, site, and at the Bayway refinery workers suffered hallucinations of insects before five died. On October 30, 1924, Midgley poured tetraethyl lead on his hands and inhaled it for 60 seconds in front of reporters. He then turned to refrigeration and, with chemist Albert Henne, created dichlorodifluoromethane, the first chlorofluorocarbon, sold as Freon. It brought him the Perkin and Priestley Medals and the presidency of the American Chemical Society. Polio left him paralyzed in 1940, and in 1944 he was found strangled in the pulley harness he had built to lift himself from bed. The coroner ruled it a suicide.

• The teenage trick of slippery elm bark saliva on a baseball, later adopted by pitchers
• How lead atoms scavenge oxygen radicals to hold off combustion until the spark plug fires
• New Jersey’s shutdown of the Bayway plant and the restart of production in 1926
• How ultraviolet light breaks CFCs in the stratosphere so one chlorine atom can destroy tens of thousands of ozone molecules
• The 1987 Montreal Protocol, Time’s list of 50 worst inventions and Terence Winter’s planned film Midge