Barium, aquarium, solarium. "Hold your breath--" Opium. Sodium. "Okay, now breathe--" Ammonium. Harmonium. Euphonium. "Now hold your breath--" Is that all? That can't be all. There's a ton of chemical names, like molybdenum or however it's spelled. Oh--Symposium!
So, thinking about that. And playing rhyming games. And so passed the time.