optically negative

from The Collaborative International Dictionary of English v.0.48
Optically \Op"tic*al*ly\, adv.
   1. By optics or sight.
      [1913 Webster]

   2. With reference to optics.
      [1913 Webster]

   {Optically active}, {Optically inactive} (Chem. Physics),
      terms used of certain isomeric substances which, while
      identical with each other in other respects, differ in
      this, viz., that they do or do not produce right-handed or
      left-handed circular polarization of light. See {optical
      activity}.

   {Optically positive}, {Optically negative}. See under
      {Refraction}.
      [1913 Webster]
    

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