ADVENTURERS have long dreamed of treasure from the sea. Usually they have booty from bygone eras in their sights – as happened this September, for example, when divers discovered a hoard of gold coins off Cape Cod, Massachusetts. The coins most probably came from the 1717 wreck of pirate "Black Sam" Bellamy's flagship, the Whydah Gally , and the treasure-hunters had to penetrate several feet of dark and slimy ocean-floor seaweed to reach them: like "diving in a vat of black gelatin", according to one news report.
It was Italian chemist Faustino Malaguti who first raised the promise of marine bounty a little closer to the surface. In 1850, he discovered that seawater itself contains silver chloride, raising the question of how the silver might be extracted. In an address to the British Association in Birmingham in 1865, the former governor of Hong ...
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