litmus paper
Étymologie
modifierLocution nominale
modifierlitmus paper
- Papier tournesol.
"ʻOh, we priests pride ourselves on being litmus paper, changing colour in sin's presence,ʼ retorted Father Peregrine, […]."
— (Ray Bradbury, The Martian Chronicles, 1950, éd. 2008, ISBN 9780006479239)