Yeah, don't do that. Just.. Sulfur is nasty stuff and it can be quite unpredictable to do this stuff in your backyard without knowledge of chemical procedures.
I remember a well educated friend who thought he could dump a bottle of 96% sulfuric acid down the drain.. His toilet bursted apart and not only were the nasties everywhere, those nasties had a pH value of -10 (negative, yes). His dumpster caught fire because he sweeped it up with paper towels, which caught fire later that evening.
Go with the bottled stuff. I remember the farmers stores having it around.