The Collaborative International Dictionary of English v.0.48:

Bleaching \Bleach"ing\, n.
   The act or process of whitening, by removing color or stains;
   esp. the process of whitening fabrics by chemical agents.
   --Ure.
   [1913 Webster]

   Bleaching powder, a powder for bleaching, consisting of
      chloride of lime, or some other chemical or chemicals.
      [1913 Webster]

WordNet (r) 3.0 (2006):

bleaching powder
    n 1: a white powder comprised of calcium hydroxide and chloride
         and hypochlorite and used to bleach and/or disinfect [syn:
         bleaching powder, chlorinated lime, chloride of lime]