How can I find out where to buy the publishing rights to a book that is out of p

Question:

How can I find out where to buy the publishing rights to a book that is out of print?

I have tried to contact the original publisher with no response.

Best Answer - Chosen by Asker: Ask the librarian in a larger city or university library. They will have sources not on the Internet (you did use the Internet to search for the author, right?). For example, who's who of authors that lists artists' representatives. They may also be able to track successors to the publishing company. The library of Congress and their copyright division may be able to help you determine if the copyright has been reissued or renewed as by the estate of the author.
US copyright law has changed through the years. Prior to about 1970 a copyright was issued for a specific number of years and had to be renewed by the holder. Then it was changed to the life of the author plus 50(?) years and made automatic on creation, not requiring registration, putting it in line with the rest of the world.
So it may be that a book published before 1970 was not renewed under the old rules and is in the public domain. If you do a reasonable search and document it and can not find any record that the book might be in copyright and cannot track the author, and keep the documentation, then you probably can legally cover yourself with a notice at the beginning of the republication mentioning your efforts and set aside in escrow a percentage of sales that an copyright lawyer says represents a fair market value.