You're getting lots of conflicting advice, so I'll go ahead and throw in some more. Replace the floors if they're made out of something common like skinny oak boards that you can still buy today. It's soooo much easier than farking around with solvents and scrapers and steam and whatnot. Probably less expensive, too. It doesn't take much time to tear out a floor by making a few slices with a circular saw and prying sections of flooring/tile/whatever up with a crowbar. If you want the new floor to look 100 years old, have at it with a hammer and a drill and you can make dents, holes, and gouges just like your restored original floor would have.