Opening one end of the box (the end marked "open") released a coil spring that caused the acid to drip from its vial onto the blasting caps; the acid ate through the caps, igniting them and detonating the dynamite.
Opening one end of the container (the side marked "open") triggered a spring that allowed acid to flow from its vial onto the blasting caps; the acid dissolved the caps, igniting them and detonating the dynamite.