This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
A blue pigment prepared from various species of Roccella.
Litmus Paper, Blue, B. and U.S.P. - Unsized white paper steeped in tincture of litmus, and dried by exposure to the air.
Litmus Paper, Red, B. and U.S.P. - Unsized white paper steeped in tincture of litmus which has been previously reddened by the addition of a very minute quantity of sulphuric acid, and dried by exposure to the air.
Litmus Tincture, B.P.; Solution of Litmus, U.S.P. - A solution prepared by macerating 1 part of litmus, in powder, in 10 parts of proof spirit, B.P., or diluted alcohol, U.S.P., in a closed vessel for two days, and filtering.
Use. - Red litmus paper is used as a test for alkalis, and blue litmus as a test for acids.