Litmus test (chemistry)

The term litmus test marked a commonly used in chemistry test the pH of a substance by means of the dye litmus ( see also indicator ).

In English, is a litmus test ( litmus test) a decision of a judgmental character, showing how a situation is really classify. For example: " The negotiations on the climate change agreement apply as a litmus test of European-American relations. " (Spiegel Online) In the course of translations from English this meaning emerged as anglicism increasingly during the German texts, a German redensartliche equivalent would be " touchstone ".

Erroneously, the word is also used to define exclusion criteria or to establish direction decisions. A litmus test, however, can not be " passed".