If you really want to learn about salt, check out this book.
http://www.amazon.com/Salt-World-Histor ... 743&sr=8-1
It's a very interesting read about the role of salt through history. Once an extremely valuable trade commodity, only the wealthy had salt on their table, one of the few ways to preserve food, to it's role in the demise of the south in the Civil War.
And if you liked reading "Salt", you'll like another book by the same author "Cod".