Ching Ling Soo was actually William Ellsworth Robinson, an American who performed under the guise of a Chinese conjurer. Amazingly, he kept his real identity and nationality a secret from the public. He was also good friends with Houdini. In fact, Chung Ling Soo was on the same bill as Houdini during his first historic week at the London Alhambra in 1900.
In 2005 Jim Steinmeyer published the excellent biography, The Glorious Deception: The Double Life of William Robinson, aka Chung Ling Soo, the Marvelous Chinese Conjurer, probably the best non-Houdini magician's biography I've ever read. Today David Copperfield owns one of the rifles used in Soo's tragic act 100 years ago.
Below is a clip from YouTube that purports to be the only known footage of "Chung Ling Soo."