litmus paper

American  

noun

1. a strip of paper impregnated with litmus, used as a chemical indicator.

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Etymology

Origin of litmus paper

First recorded in 1795–1805

Example Sentences

The best way to confirm that the solution is neutralized is with litmus paper.

From Seattle Times • Nov. 7, 2022

Watson recalls one telling advertising campaign: posters printed on litmus paper that said: “When acid rain is falling, you should see red” – offering a vivid illustration of the problem.

From The Guardian • Oct. 12, 2020

But that is not an immutable piece of parchment that judges can apply to laws like litmus paper.

From Time Magazine Archive

We are not dealing here," said Acheson, "with the kind of situation where we can go from one country to another with a piece of litmus paper and see whether everything is true blue.

From Time Magazine Archive

Neutralise carefully to litmus paper by the successive additions of small quantities of decinormal soda solution.

From The Elements of Bacteriological Technique A Laboratory Guide for Medical, Dental, and Technical Students. Second Edition Rewritten and Enlarged. by Eyre, J. W. H. (John William Henry)