most people around these parts seem to recommend soaking in boiling water.
does it sink yet? If not you may as well just find something to put it in, and let it soak for a while (might take a while) then do the boiling water thing when it sinks.
But if I were you I'd wait for someone else to advise...
bog woods need to be washed and soaked to get as much of the tannins out as possible because it will turn the water to a tea kind of color. once i wash,soak,wash,soak mine i put it in boiling water to kill any bugs or bacteria that may be on there.
Wood varies a lot in how much it will color the water with tannins. You just have to soak it, periodically pouring boiling water over it and at some point the tannins will be coming out so slowly and faintly that you'll realize a weekly water change will take care of it.