Salts of lemon

Lemon \Lem"on\ (l[e^]m"[u^]n), n. [F. limon, Per. l[imac]m[=u]n;
   cf. Ar. laim[=u]n, Sp. limon, It. limone. Cf. {Lime} a
   fruit.]
   [1913 Webster]
   1. (Bot.) An oval or roundish fruit resembling the orange,
      and containing a pulp usually intensely acid. It is
      produced by a tropical tree of the genus {Citrus}, the
      common fruit known in commerce being that of the species
      {Citrus Limonum} or {Citrus Medica} (var. Limonum). There
      are many varieties of the fruit, some of which are sweet.
      [1913 Webster]

   2. The tree which bears lemons; the lemon tree.
      [1913 Webster]

   {Lemon grass} (Bot.), a fragrant East Indian grass
      ({Andropogon Sh[oe]nanthus}, and perhaps other allied
      species), which yields the grass oil used in perfumery.

   {Lemon sole} (Zool.), a yellow European sole ({Solea
      aurantiaca}).

   {Salts of lemon} (Chem.), a white crystalline substance,
      inappropriately named, as it consists of an acid potassium
      oxalate and contains no citric acid, which is the
      characteristic acid of lemon; -- called also {salts of
      sorrel}. It is used in removing ink stains. See {Oxalic
      acid}, under {Oxalic}. [Colloq.]
      [1913 Webster]