The Walter Lantz Cartune Encyclopedia:
List of Shorts in the Public Domain
When a film fails to get copyrighted, it falls into the public domain. So was the case with certain films from Universal among other studios. It is because of this copyright negligence that a handful of public domain Walter Lantz titles are available on cheap DVDs and VHS cassettes from small home video distributors. It would be impossible to list all of these compilations, so below is a listing of all the Lantz cartoons that have fallen into the public domain. Most of the discs and tapes that feature these shorts can be easily found at your local department store. Usually, the cartoons on these collections are mastered from fair to poor 16mm film prints and most of the public domain VHS tapes are recorded in EP video speed.
With regard to the pre-Lantz Oswald the Lucky Rabbit cartoons, there are ten in the public domain. These include all of the Disney Oswalds released in 1927 (with the exception of All Wet) and two Winkler Oswalds – South Pole Flight and Bull-Oney – released in 1928.
Information courtesy of Film Superlist: Motion Pictures in the U.S. Public Domain, 1894-1939, Film Superlist: Motion Pictures in the U.S. Public Domain, 1940-1949, and Film Superlist: Motion Pictures in the U.S. Public Domain, 1950-1959 all by Walter E. Hurst.
All 1931-32 Disney Oswald reissues by Lantz, with the exception of All Wet
All 1943-44 stop-motion instructional films for the US Navy
All 1948-49 and 1953 Coca-Cola advertisements
All advertisements for Albers, Auto-Lite, Carnation, Interstate Bakeries Corporation, and Kellogg's
Amazing Recovery of Inbad the Ailer, The [industrial film for Saraka]
Bandmaster, The 
Blood is Needed [produced for the American Red Cross]
Boy Meets Dog! [unreleased short for Ipana Toothpaste]
Enemy Bacteria, The [instructional film for US Navy]
Gremlin Mr. N'Tane [instructional film for US Armed Forces]
House of Magic
Quail Hunt, The
Scrub Me Mama with a Boogie Beat
Story of Human Energy, The [educational film for the Corn Products Refining Co.]
Take Heed Mr. Tojo [instructional film for US Navy with Mr. Hook]