* The old name lingered in popular use. In 2017, when I was visiting Las Vegas, my friend Dan told me that he had paid an acquaintance to fix his truck’s air conditioner on the cheap—for Dan was hardly rich. This time he got what he paid for. As we rolled through the sizzling city with the windows up, and hardly any coolness inside, Dan decided on Plan B: Buy a cylinder of coolant (which he called “freon”) and make use of it until it had all leaked into the atmosphere, then repeat. I demurred, but Dan explained the matter: He could not afford a new air conditioner, and “freon” was cheap. How could I blame him?