11th September 1942, Page 31
11th September 1942
Page 31

Page 31, 11th September 1942
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Finding Flaws By "black Light"
In the "Glow-Crack" System Fluorescent Solution Retained in Crevices and Crannies Becomes Brightly Luminous Under the Ultra-violet Ray O NE of the problems of both mannfacture......