- a blue coloring matter obtained from certain lichens, especially Roccella tinctoria. In alkaline solution litmus turns blue, in acid solution, red: widely used as a chemical indicator.
Origin of litmus
Examples from the Web for litmus
But when did they become the litmus test of competence in office?100 Years of Right (And Left) Moves
March 31, 2014
So they are a litmus paper for wider fertility—not a significant driver of Israeli birthrates.Israel’s Sperm Clinic Crisis
March 16, 2014
Opposition to the Affordable Care Act in toto might linger as a litmus test for conservatives.Everything is Obamacare!
March 3, 2014
The right-wing base and media will make it a litmus test issue.Could a Larger Minimum Wage Hike Sell?
November 13, 2013
The Veterans of Foreign Wars organized an Americanization committee that promoted the song as a litmus test of loyalty.Star-Spangled Confederates: How Southern Sympathizers Decided Our National Anthem
July 4, 2013
Dip your litmus paper first into one, then into the other, and then back into the first.Common Science
Carleton W. Washburne
It is represented as a more delicate test of acid and alkalis than litmus.Field's Chromatography
Pour off the alcohol, leaving the litmus as dry as possible.The Elements of Bacteriological Technique
John William Henry Eyre
The free alkaloid is soluble in water, but has no action on litmus.Poisons: Their Effects and Detection
Alexander Wynter Blyth
"Like litmus paper under the influence of an acid," explains Guncotton.My Austrian Love
- a soluble powder obtained from certain lichens. It turns red under acid conditions and blue under basic conditions and is used as an indicator
Word Origin and History for litmus
"blue dye-stuff obtained from certain lichens," early 14c., from Middle Dutch lijkmoes (Dutch lakmoes), from lac (see lac) + moes "pulp." Another theory is that it represents Old Norse litmose, literally "lichen for dying," from Old Norse lita "to dye, to stain," from litr "color, dye" (see lit (n.1)) + mos "moss." Yet another idea connects the first element to Middle Dutch leken "to drip, leak" (see leak (v.)).
Whichever was the original word, it probably was influenced by the others. The dye is obtained from certain lichens. It is naturally blue but turns red in acid and is restored to blue by alkalis. Figurative use of litmus test is first attested 1957, from scientific use of litmus-treated paper as a chemical indicator. Litmus paper with this meaning is from 1803.
- A water-soluble blue powder derived from lichens that changes to red with increasing acidity and to blue with increasing basicity.
- A colored powder, obtained from certain lichens, that changes to red in an acid solution and to blue in an alkaline solution. Litmus is a mixture of various closely related heterocyclic organic compounds.♦ Litmus is typically added to paper to make litmus paper, which can be used to determine whether a solution is basic or acidic by dipping a strip of the paper into the solution and seeing how the paper changes color.