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Archive for November, 2013

This very excellent article is REBLOGGED from John Reid’s WWW.BLACKJAY.NET

Blackjay 


Forest Reserves: 1981 compared with 2013

 

The Sacrificial Stateby John Reid
Back in the sixties in Hobart you could buy a zinc block in the form of a map of Tasmania from the Zinc Works at Risdon. They were about 10 cm across and intended as souvenirs. I believe they were bought more by yachties than by tourists. Boat owners would attach one to the hull below the waterline where it would serve as a “sacrificial anode”. The high electrochemical potential of the metal ensured the zinc map would corrode first, before any of the other metals in the hull such as copper, brass or steel screws, so keeping the hull sound. After a few years under water the zinc map would corrode away and fall off and need to be replaced. (more…)
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