tilthat:

TIL that the replacement for ivory billiard balls were ones made from nitrocellulose, which occasionally exploded on impact with another ball. A bar owner wrote to the inventor saying that they didn’t bother him much but for the fact that every man in his saloon immediately pulled a gun at the sound

via reddit.com

They also used to make clothes and accessories out of it; it was a hell of a fire hazard.