image: SCIENCE HISTORY INSTITUTE

To promote its “permissible” explosives among coal-mining firms at a 1930s trade fair, the Hercules Powder Company staged a puppet show. The show and its marionettes explained permissible explosives generate a lower temperature and a shorter-duration flame when they detonate, decreasing the chances that the blast will further ignite the methane or coal dust that saturates a mine's air. The show was an updated version of a previous one, “Oil's Well that Ends Well,” shown at an expo, advertising its Vibrogel explosives for use in the petroleum industry.