Source of the Light recorded in Photographs of Shocked Granular Pressings

Abstract

ABOUT ten years ago Stewart Paterson¹ illustrated by means of several wave-speed photographs the previously discovered² fact that a large part of the light from a detonating charge was due to the system of shock waves produced in the surrounding air. Further, he showed that the light still reaching the camera when light from these shock waves was eliminated did not arise from chemical reaction of the explosive. He accomplished this by observing the light from a water-surrounded high-explosive charge which included in its length short sections of granular sodium chloride kept dry by a thin plastic tube. The explosive parts of the charge gave very faint wave-traces, but the salt layers gave very intense bursts of light as the disturbance passed through them. Additional photographs showed that a similar brilliant light was produced by explosives when in a granular loose-pressed form.