Monday, 30 March 2009

Science & Vocabulary: Litmus Test

From the last entry, I used the term Litmus Test, I wondered how many of you put in effort to find it out. Hopefully a lot, I am an optimistic person.

This term actually originates from Chemistry, and litmus is a so everyday indicator for all kinds of pH (acidity and alkalinity) test. It is a water-soluble mixture of different dyes extracted from lichens and it is often absorbed onto filter paper before using. Basically, it is used to test whether a solution, meaning a mixture of liquid, is acidic or alkaline.

When I was still in school in Singapore, I did a lot of experiments in the Chemistry laboratory. Most of the time, the students were given blue litmus paper to test the acids. The red litmus paper, which is used to test alkalis, was less often used. I have never really got to understand why that was the case; maybe testing acids was a more fun thing to do?

Because of the property of the litmus paper or the litmus solution, and the use of litmus as an indicator of acidity or alkalinity, it is now used in the English of politics and some other means.

Cambridge has the following explanation which I dont really like:

litmus test noun [C usually singular]

someone's decision or opinion about something which suggests what they think about a wider range of related things:

The President's policy on abortion is regarded as a litmus test of his views on women's rights.

I prefer the explanation in the Unabridged:

A crucial and revealing test in which there is one decisive factor.

Or in the WordNet 3.0 by Princeton University:

A test that relies on a single indicator; "her litmus test for good breeding is whether you split infinitives" 

So in even more simple words, it means an important indicator to sth, and it has a synonym, acid test.

This is such a common word and you can easily find tonnes of news that uses this word. Try typing "litmus test, news" in your favourite search engines for more examples of using.

"Inability to succeed is just a litmus test for greater courage." -- Locky

Picture source:

Coming soon: Grammar, grammar, and more grammar

Reply to comments & readers:
  1. Many thanks to Phy and Bo Bo.
  2. Sorry to my students of the last Thursday class because I felt asleep in the staff room and was late for 10 minutes. Too tired. I hope you don't mind my 15 mins extension of that lesson. That was to pay you back the time.