congo paper

1 definition found

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

  Congo red \Congo red\ (Chem.)
     An artificial red dye from which the Congo group received its
     name. It is also widely used either in aqueous solution or as
     test paper (
  
     Congo paper) for the detection of free acid, which turns it
        blue.
        [Webster 1913 Suppl.]