a chemical that turns red when it touches acid, and blue when it touches an alkali (litmosi, from litr + mosi ). Mixture of coloured organic compounds obtained from several species of lichens. In the form of a water solution or as litmus paper, it is the oldest and most-used indicator of whether a substance is an acid or a base. It turns red or pink in acid solutions and blue or purple-blue in alkaline solutions
a coloring material (obtained from lichens) that turns red in acid solutions and blue in alkaline solutions; used as a very rough acid-base indicator
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
{i} blue coloring substance extracted from lichens which turns red in acids and is restored to blue in alkalis (used as a chemical indicator)