The Collaborative International Dictionary of English v.0.48:

Fining \Fin"ing\, n.
   1. The act of imposing a fin?.
      [1913 Webster]

   2. The process of fining or refining; clarification; also
      (Metal.), the conversion of cast iron into suitable for
      puddling, in a hearth or charcoal fire.
      [1913 Webster]

   3. That which is used to refine; especially, a preparation of
      isinglass, gelatin, etc., for clarifying beer.
      [1913 Webster]

   Fining pot, a vessel in which metals are refined. --Prov.
      xvii. 3.
      [1913 Webster]

Easton's 1897 Bible Dictionary:

Fining pot
   a crucible, melting-pot (Prov. 17:3; 27:21).