Litmus

Rarity: Rare

A topic known well beyond its field, found in many languages.

Rarity follows how well known the article is: its views on the French and English Wikipedia over a year, and the number of languages it exists in.

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Notion

Domain

Science and technology

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What Wikipedia says

Litmus is a water-soluble mixture of different dyes extracted from lichens. It is often absorbed into filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. In an acidic medium, blue litmus paper turns red, while in a basic or alkaline medium, red litmus paper turns blue.

Excerpt from the Wikipedia article “Litmus”, under the CC BY-SA 4.0 license. Read the article on Wikipedia

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