Pennsylvania Statutes Title 52 P.S. Mines and Mining § 70-636. Mudcaps or other unconfined shots shall not be fired underground

Mudcaps (adobes) or other unconfined shots shall not be fired underground in a mine. However, in anthracite mines mudcaps or other open, unconfined shots may be fired, if restricted to battery starting when no gas or fire hazard is present, and if it is otherwise impracticable to start the battery; likewise, in anthracite mines, open unconfined “shake” shots in working places, and other places in pitching veins may be fired, when no gas or fire hazard is present, if the taking down of loose, hanging coal by other means is too hazardous for men working in such places. Only permissible explosives shall be used for such open, unconfined shots in anthracite mines.