Professor Holloway Token

Thomas "Professor" Holloway was a famous purveyor of pills and ointments to "cure" all sorts of ills. They were the "Coca-Cola of their day" - all advertising hype, and no substance. Indeed, Holloway pioneered many of the advertising techniques later used by other mega-products like Coke. When surviving unopened bottles of his patent medicines are analysed in the lab today, they're found to contain no active ingredients whatsoever - only beeswax, petroleum jelly, charcoal and sugar.

The tokens were part of his advertising blitz. They were struck in England and technically belong in the English token series, but they've earned a place in Australian numismatics. A large shipment of Holloways tokens were sent to Australia at the height of the colonial token issuing period, in 1857. Unfortunately, the ship carrying them, the Dunbar, sank off Sydney Heads. The tokens were retrieved from the wreck sometime later and put into circulation, but they had all had been damaged by immersion in salt water.

SO you can tell the Australian and English ones apart; the English ones aren't corroded, like yours is.

Well, the corrosion damage has already been done - both by the original immersion in the sea and by later slow reaction of residual chloride with the copper. You could "clean" it, but you can't bring it back to it's original uncorroded state; your coin would look "cleaned", and even worse than it looks now. The best you can do is seal it up away from the atmosphere so the corrosion doesn't get worse.