[COFF] Re: Typical Fate of Older Hardware

Brad Spencer is right about the resistance of gold to attack by acids makes using acids to attack the substrate an effective strategy. One other interesting property of gold is that it dissolves in liquid mercury. One old and primitive--but effective--way to extract gold is to grind the ore finely, mix it with liquid mercury, then allow the substrate to settle out. You then have liquid mercury with gold dissolved in it. You heat the mercury to evaporate it away and there's your gold. The problem with this method is of course the extreme toxicity and volatility of liquid mercury. It's difficult (and expensive) to handle it safely, and in those parts of the world where this method is still in use, it usually isn't handled safely. The mercury-contaminated waste left over after the extraction is also toxic and environmentally damaging to dispose of. -Paul W.