The Collaborative International Dictionary of English v.0.48:

Polytungstic \Pol`y*tung"stic\, a. (Chem.)
   Containing several tungsten atoms or radicals; as,
   polytungstic acid.
   [1913 Webster]

   Polytungstic acid (Chem.), any one of several complex acids
      of tungsten containing more than one atom of tungsten.
      [1913 Webster]