I've done this twice and both times involved some blisters! Not sure if it was the same situation you're in but we were faced with some old linoleum that somehow had some tar underneath that adhered it to the hardwood. You could pull the linoleum up without too much hassle, but what was left was that tar. The first time, we literally removed it with chisels, only scraping up a 1 foot section in about an hour - grueling. I had also had a hint that throwing a bunch of dry ice on it would help by making it so cold and brittle that it would just pop off. That didn't work. We also tried heat and that didn't work. So maybe others have had better luck with another tecnique, but we didn't.