The Collaborative International Dictionary of English v.0.48:

Tossing \Toss"ing\, n.
   1. The act of throwing upward; a rising and falling suddenly;
      a rolling and tumbling.
      [1913 Webster]

   2. (Mining)
      (a) A process which consists in washing ores by violent
          agitation in water, in order to separate the lighter
          or earthy particles; -- called also tozing, and
          treloobing, in Cornwall. --Pryce.
      (b) A process for refining tin by dropping it through the
          air while melted.
          [1913 Webster]