The Collaborative International Dictionary of English v.0.48:

Bowssen \Bows"sen\, v. t.
   To drench; to soak; especially, to immerse (in water believed
   to have curative properties). [Obs.]
   [1913 Webster]

         There were many bowssening places, for curing of mad
         men.
         . . . If there appeared small amendment he was
         bowssened again and again.               --Carew.
   [1913 Webster]