Science: Testers & Acid Doctor

In 1896 Antoine Henri Becquerel of France left some uranium salts lying in the dark near a photographic plate. When he developed the plate he found that some sort of rays from the uranium, passing through a metal container and several other obstacles, had left an image on the plate. Thus by accident Becquerel, who shared a Nobel Prize with Pierre and Marie Curie, discovered radioactivity.

The same principle underlies a technique, explained last week, for ferreting out defects in thick masses of steel. At the convention of the American Society for...

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