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
Piranha solution and carbon char left by the initial dehydration process. In time, piranha solutions in which organic materials have been immersed typically will return to complete clarity, with no visible traces of the original organic materials remaining. A final minor contribution to the piranha solution cleaning is its high acidity, which dissolves deposits such as metal oxides and carbonates. However, since it is safer and easier to remove such deposits using milder acids, the solution is more typically used in situations where high acidity facilitates cleaning instead of complicating it. For substrates with low tolerance for acidity, the alkaline oxidising solution