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      Knowledge is Power

      Scientific American April 06, 1918

      An Important Biological Problem

      The Significance of Essences and Pigments

      • By Jean Dufrenoy on April 6, 1918

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      More in the April 06, 1918 issue of Scientific American
      • Attraction between Two and Three Bodies
      • Government Department of Inventions in France
      • Optical Properties of Light-Filters
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