The Little Prospector.

Broncho Billy has exhausted every foot of ground which might have held gold for them and he makes ready to strike new territory. Their little boy gets his hands on some nitro-glycerin. He has dreams of discovering some gold where his father could find none. He "plants" the explosive but it doesn't go off. Then his sister resets it and it explodes in her face. She is knocked unconscious. The girl proves not to have been seriously injured. Out on the ground, by the newly blasted hole, lies the little son, sobbing because he has hurt his sister.