Litmus test (politics) Litmus test (politics) A litmus test is a question asked of a potential candidate for high office, the answer to which would determine whether the nominating official would proceed with the appointment or nomination. The expression is a metaphor based on the litmus test in chemistry, in which one is able to test the general acidity of a substance, but not its exact pH. Those who must approve a nominee, such as a justice of the Supreme Court of the United States, may also be said to apply a litmus test to determine whether the nominee will receive their vote.
Marsh test test in Strong Poison to demonstrate that the culprit was secretly in possession of arsenic. In Alan Bradley's "As Chimney Sweepers Come To Dust", 12-year old sleuth and chemistry genius Flavia de Luce uses the Marsh test to determine that arsenic was the murderer's weapon. In the first episode of the 2017 TV series "Taboo" a mirror test, referencing the Marsh test, is used to verify the protagonist's father was killed via arsenic poisoning. However, as the setting of the series is between 1814-1820, a different/earlier process should have been used. Marsh test The Marsh test is a highly sensitive