I cut a bottle with fire tonight!
Being that I am not someone who usually likes to play with fire-- literally or figuratively-- this was big for me.
The cut is not perfect, but it'll do for the purpose of the Halloween project I want to do.
You simply wrap acetone (nail polish remover)-soaked yarn around a bottle, and light it on fire (I know!!). Once it burns out, dunk it in cold water. The glass separates, making a clean break!
As I said, my seam isn't totally straight or smooth, but it will work, and now I know to wrap it tighter and straighter next time.
Finished project coming later this week (or sooner, as I keep choosing these trivial things over my legitimate to-do list...)