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
Griess test Griess test The Griess test is an analytical chemistry test which detects the presence of nitrite ion in solution. One of its most important uses is the determination of nitrite in drinking water. The test has also been widely used for the detection of trace explosives containing nitro groups. It is usually necessary to release the nitrite ion from the organic explosive before analysis. This is normally done by alkaline hydrolysis. The "Griess diazotization reaction" on which the Griess reagent relies was first described in 1858 by Peter Griess. Nitrite is detected and analyzed by formation of a red pink