litmus paper

2 definitions found

litmus paper - Collaborative International Dictionary of English v.0.48 :

  Litmus \Lit"mus\, n. [D. lakmoes; lak lacker + moes a thick
     preparation of fruit, pap, prob. akin to E. meat: cf. G.
     lackmus. See Lac a resinous substance.] (Chem.)
     A dyestuff extracted from certain lichens (Roccella tinctoria
     , Lecanora tartarea, etc.), as a blue amorphous
     mass which consists of a compound of the alkaline carbonates
     with certain coloring matters related to orcin and orcein.
     [1913 Webster]
  
     Note: Litmus is used as a dye, and being turned red by acids
           and restored to its blue color by alkalies, is a common
           indicator or test for acidity and alkalinity.
           [1913 Webster]
  
     Litmus paper (Chem.), unsized paper saturated with blue or
        red litmus, -- used in testing for acids or alkalies.
        [1913 Webster]

litmus paper - WordNet (r) 2.1 (2005) :

  litmus paper
      n 1: unsized paper treated with litmus for use as an acid-base
           indicator