Photo by C. Lloyd at SSERC (Public Domain)
This simple experiment involves the creation of a supercorroding galvanic cell. Steel wool is wrapped round magnesium ribbon and put in water. Nothing happens. But when they are placed in salt water, there is vigorous bubbling.
This reaction is the principle behind sacrificial anodes used in shipping. It is also used to produce flameless ration heaters for warming up rations for the US army.
Galvanic cell – Risk Assessment
Image of Sacrificial anode by Zwergelstern uswed under Creative Commons License CC BY-SA 3.0