Litmus paper and Testing agent

Litmus paper noun - Unsized paper treated with litmus for use as an acid-base indicator.

Testing agent and litmus paper are semantically related. in acid-base indicator topic. In some cases you can use "Testing agent" instead a noun phrase "Litmus paper".

Litmus paper and testing agent are semantically related. Sometimes you can replace phrase "Litmus paper" with "Testing agent", this phrases are similar.