After you posted this I did a little research. Someone put a bottle of salt water in a bucket of water and left it out on the porch. They said in the morning the water was frozen solid.
I've read about that salt water in a bottle thing but have never tried it. Can not think of any reason it would work. Call me a skeptic. Yes, salt water freezes at a lower temperature than fresh water, but the salt in that bottle is not getting into the fresh water. I can understand the...