Litmus "Lecanora tartarea" (Norway, Sweden), "Variolaria dealbata", "Ochrolechia parella", "Parmotrema tinctorum", and "Parmelia". Currently, the main sources are "Roccella montagnei" (Mozambique) and "Dendrographa leucophoea" (California). The main use of litmus is to test whether a solution is acidic or basic. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, turn the red litmus paper blue. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or
Ammonia solution number series as E527. Aqueous ammonia is used as an acidity regulator to bring down the acid levels in food. It is classified in the United States by the Food and Drug Administration as generally recognized as safe (GRAS) when using the food grade version. Its pH control abilities make it an effective antimicrobial agent. In furniture-making, ammonia solution was traditionally used to darken or stain wood containing tannic acid. After being sealed inside a container with the wood, fumes from the solution react with the tannic acid and iron salts naturally found in wood, creating a rich, dark stained