The Collaborative International Dictionary of English v.0.48:

Separating \Sep"a*ra`ting\, a.
   Designed or employed to separate.
   [1913 Webster]

   Separating funnel (Chem.), a funnel, often globe-shaped,
      provided with a stopcock for the separate drawing off of
      immiscible liquids of different specific gravities.
      [1913 Webster]