Litmus is a water soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity.

History

Litmus was used for the first time about 1300 AD by Spanish alchemist Arnaldus de Villa Nova. From the 16th century on, the blue dye was extracted from some lichens, especially in the Netherlands.

Natural sources

Litmus can be found in different species of lichens. The dyes are extracted from such species as Roccella tinctoria (South America), Roccella fuciformis (Angola and Madagascar), Roccella pygmaea (Algeria), Roccella phycopsis, Lecanora tartarea (Norway, Sweden), Variolaria dealbata, Ochrolechia parella, Parmotrema tinctorum, and Parmelia. Currently, the main sources are Roccella montagnei (Mozambique) and Dendrographa leucophoea (California).

Uses

The main use of litmus is to test whether a solution is acidic or basic. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, colors the red litmus paper blue.

Litmus are a London-based space rock band formed in 2000 by Martin (bass guitar/vocals), Simon (guitar/vocals) and Ben (drums), joined the following year by Andy Thompson (keyboards, 2001–2007) and Anton (synths). Matt Thompson joined on synth (2002–2004), while Marek replaced Ben in 2003. Oli Mayne (keyboards) joined in 2008, then left in 2010, along with Anton. As of November 2012 the line-up is Martin Litmus (bass/vocals), Simon Fiddler (guitar/vocals), Marek Bublik (drums) and James Hodkinson (keyboards/effects). They are influenced by mid-1970s Hawkwind and Black Sabbath, amongst others.

They have played at festivals across the UK and Europe including Yellowstock (Belgium), The Psychotropic Caravan Festival (Finland), Two Days of Love and Peace (Germany), Burg Herzberg (Germany), Stoned from the Underground (Germany), South of Mainstream (Germany), Swamp Room Happening (Germany), Roadburn (Netherlands), Hard Rock Hell (UK), Hawkfest (UK), Sonic Rock (UK), Sonic Rock Solstice (UK), Celtic Warriors (UK), Cambridge Rock Festival (UK), Eastern Haze (UK).

Litmus is a water-soluble mixture of different dyes extracted from lichens.

Litmus may also refer to:

See also