Redox Indicator

[Xylene]

Today I found a fluid ounce of 5% Methylene Blue in an aquarium supply store at $5
(Aquatronics. PO box 6028 Zuma Station, Malibu California 90265)

Methylene blue in weak aqueous solution is an indicator of Redox reactions. My 5% ounce could be further diluted to 2 ounces. It shows blue when in oxidized solution.... and goes clear in reduced solution.

http://en.wikipedia.org/wiki/Methylene_blue