| Description | Replying to Granville's letter, he mentioned amalgram of copper at the Athenaeum dinner party. Casting his mind back to 1798, Sir Joseph Banks gave him a metallic coffee-style cup in a wooden case which had been forwarded to him as proof of the 'alchemical desideratum' of the fixation of mercury. Hatchett analysed the cup and although he cannot find his written memoranda, he recalls it being an amalgam of copper and quicksilver. It was light copper-coloured with green streaks and spots, hard and brittle. Parts of the lip could be broken by the fingers, the fractures silvery white, tarnishing to spots of brown and green. Peter Woulfe, who supervised the building of Hatchett's Hammersmith laboratory, said that it had been used in parts of the continent to take impressions of seals, having the property of becoming hard by atmospheric exposure. Hatchett relates Woulfe's method of forming the amalgam, saying that he 'was certainly mad in respect to alchemy and mystical chemistry, but full of information and very sensible on all other subjects'. Hatchett did not doubt Woulfe's statements and would have tried the experiment if his attention had not been drawn elsewhere in the eventful year of 1798. He became engaged with Mr Cavendish in the manipulations of the Royal Mint, at the request of the Privy Council, which led to experiments and observations on the alloys, specific gravity and wear of gold, and a Philosophical Transactions paper in 1803. |