I remember seeing a gas chamber execution, maybe on Twilight Zone when I was very small. Black & white. A little bowl of acid underneath and behind the strap in chair, a little handle sticking out holding a gauze wrapped package. Guy outside presses a button, the handle drops the package into the bowl, and the fumes start coming out.
OMG, had nightmares for years about that one. Sure and it couldn’t put put on today.
I worked a couple jobs over at San Quentin with their guy who was the last hazmat specialist certified in the maintenance/use of the lethal gas chamber. He was quite the character, like he was time trawled out of the 1870’s. Big handlebar mustache. Gave us out SQ no hostage policy speech (duck if TSHTF, we’re gonna be shooting).