photogene
  餘像
  Pho·to·gen n.  Chem. A light hydrocarbon oil resembling kerosene.  It is obtained by distilling coal, paraffin, etc., and is used as a lubricant, illuminant, etc. [Written also photogene.]
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  Pho·to·gene n.
  1. A photograph. [Obsoles.]
  2. A more or less continued impression or image on the retina.
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