Dr. Leeds was an astronomer and scientist, who helped identify Kryptonite in the 1948 serial, Superman.

Superman serial

Dr. Leeds got a sample of meteorite from the planet Krypton which fell to the Earth. When Clark Kent arrived to see the glowing sample, he apparently fell dead immediately. When the Kryptonite was recovered, Clark recovered, and revealed his identity as Superman, asking Leeds to discard the Kryptonite. Leeds agreed to throw it in the ocean after a few days of study. ("Superman")