Paper that is yellow from being saturated with turmeric and is used to detect the presence of alkalis, which turn the paper brown, or boric acid, which turns it red-brown.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Chemistry) chem paper impregnated with turmeric used as a test for alkalis, which turn it brown, and for boric acid, which turns it reddish brown
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014