If a company owned a copyright in 1979 and is no longer in business, would that copyright still be valid?

Also, if the original copyright holder is no longer in business and the copyright is no longer valid, how would one go about obtaining the copyrights for them selves?

*How long is a copyright valid?

The duration of a copyright depends on when the author acquired the copyright. Currently, the duration for individuals is life of the author plus 70 years, or the case of a joint work, the term lasts for 70 years after the last surviving author's death.alternatively 75 years, whichever is longer. If a company is the author, the duration is 95 years from the year of first publication or 120 years from the year of creation, whichever expires first.

*law guru

More on copyright laws

Thanks clarebear, I thought I was on to something there. This company even let all of it's trademarks expire.

So I could aquire the trademark, but the original company still has the rights to the literature. I guess it's not worth it.