Before 1978 U.S. copyrights were periods of fixed duration that needed renewing a couple of times, but a max. of 56 years. In 1978 copyright was changed to life of the author/composer +50 years. In the 90's that was changed to life +70 years. You get that magic date in the 1920's because the 78 law applied to words still under copyright & earlier than 1923 was already public domain. That extended the coverage for anything still under copyright to 75 & now 95 years.

Even under current rules if the creator has been dead for 70 years you are probably safe. The continuing existance of the publisher has nothing to do with it, except in making it really hard to find the person you need to arrange permissions with.

Publishers will claim rights to music they have reset because of editorial changes. Corporate copyright was set at 75 years in 1978 and extended to 95 recently. That area gets confusing, but if you're in the US & your music was printed prior to 1923 you should have nothing to worry about. If you're not in the US, I think the life +50 years rule was in effect far earlier so you don't have 1923 as a safe cutoff.

There have been many previous threads on copyright. If you enter "copyright" in the thread box & refesh for 3 or 6 months you'll get quite a few. Click here for document that explains it more for you.