a strip of paper impregnated with litmus, used as a chemical indicator.
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How to use litmus paper in a sentence
A blue litmus paper turns red in acids while a red litmus paper turns blue in basic solutions.
So they are a litmus paper for wider fertility—not a significant driver of Israeli birthrates.
The solution of lead must contain acid; and if by keeping it does not change litmus-paper, acid must be added till it does.
The blue litmus paper became red showing the presence of an acid.Some Constituents of the Poison Ivy Plant: (Rhus Toxicodendron) | William Anderson Syme
It turns litmus paper red; sometimes very slightly, and occasionally even not at all.