The label -
PANNED FROM THE SUISGILL BURN, STRATH OF KILDONAN, SUTHERLAND, SCOTLAND. 1st - 4th AUGUST 1977. 10 HOURS OF PANNING YIELDING 400 FLAKES, WT = 0.3491g VALUE AT £60 PER OUNCE = 74p THE LARGE NUGGET WEIGHS 0.0215g ASSAYED AT 22 CARAT OR 80% GOLD, 20% SILVER - ELECTRUM. R.G.CURRY
This on-line book (orig. pub. 1898) will be of great interest to those given to auriferous endeavours.
The following are some interesting experiments from the book -
Professor Bischof - gold chloride & potassium silicate
Deposition of fine gold crystals on pyrite
Daintree & Wilkinson - nucleation of gold around pyrite, galena & organic matter
Newbury produces 'golden skeletons' of dead flies
Johnson boils auriferous ferro-sulphides
THE ALCHEMISTS SEARCH FOR TRANSMUTATION ENDS IN AN EXPENSIVE DETONATION
In the late sixteenth century, alchemists made a startling discovery. The element of their dreams - gold - showed a dark side to it`s character. The alchemists used gold as a seed for their transmutational follies, and those who dissolved gold in aqua-regia (3:1 HCl + HNO3) had faith that their financial investment was secure. The products of experimentation (however disappointing) could always be reduced in a furnace to recover the precious metal. Or so they thought -
Unfortunately, the unknown alchemist was no-doubt devastated, both physically and financially, upon determining the properties of the gold hydrazide (AuHN.NH2) he had prepared.
Upon heating, crushing or scratching the dried, dense, olive-green powder, his invested gold would have been vapourised by a chemical decomposition so violent as to endanger his life.
Fulminating Gold was the first high-explosive to be made. Before then, chemical explosions had only been observed when a vigorous exothermic gas-evolving reaction was contained by an enclosure (such as black-powder in a shell-case).
The dried powder is extremely sensitive to percussion. Robert Hooke in 1660 put the powder into a spoon, put a heavy coin over it and, by tapping the spoon on a table top, detonated the fulminating gold and sent the coin to the rafters. He used this demonstration of 'exploding without fire' to formulate ideas on combustion, which challenged the Aristotelian doctrine of combustion.
He recommends preparing the Aurum Fulminans (exploding gold) by precipitation from the gold solution (in aqua-regia), not by using Salt of Tartar (potassium carbonate, made by heating cream of tartar, or potassium tartrate), but with Salt of Urine (ammoniacal salts containing ammonium carbonate).
The preparation of Salt of Urine is a Bacchanalian process, with unpleasant storage problems. Here is an account from The Art of Distillation by John French, 1651.
"Take of the urine of a young man drinking much wine, as much as you please. Let it stand in glass vessels in putrefaction forty days. Then pouring it from its feces, distill it in a glass gourd in sand until all be dry. Then cohobate the said spirit on the caput mortuary three times. Then distill it in a gourd of a long neck and there will ascend, besides the spirit, a crystalline salt which you may either keep by itself, being called the volatile salt of urine, or mix it with its spirit which will thereby become very penetrating if they be digested for some days together."
Cohobate means "To repeat the distillation of, pouring the liquor back upon the matter remaining in the vessel", as for caput mortuary.....?
Glauber then describes mixing half an ounce of fulminating gold with a flux as a moderator or damper. Half an ounce of any fulminating compound is a huge quantity.
Only milligrams of silver fulminate is used in 'Snaps', small twists of paper containing fulminate coated sand. They explode when thrown onto a hard surface. Fulminating silver is a topic mentioned several times in "The Young Man`s Book of Amusement".
The amount of fulminating gold Glauber used is frightening because of the unpredictable nature of the substance, particularly when impure. From an alchemical text -
"One must, in this case, submit it to difficult and dangerous manipulations, for one may transform the metal into gold fulminate,... several mortal accidents following upon this preparation. But if the disciple has been instructed in a good school, he will avoid this sophistic snare and operate hermetically; he will thus avert this redoubtable danger."
Note: Fulminating gold is above referred to as gold fulminate. This is incorrect; strictly speaking a fulminate is a salt of fulminic acid CNOH. Gold fulminate Au(OCN) is equally explosive, but is quite different chemically to fulminating gold. Glauber embeds the needles in his moderated Fulmen (the aurum fulminans and flux mix) and detonates it. The decomposition of the fulminating gold releases gold vapour, which plates the steel needles in a highly spectacular manner. Glauber made explosively plated needles as gifts -
"It is also no contemptible curiosity to see needles changed to gold, their pristine form remaining. I took once 20 or 30 needles, which I put with their points up to the midst in the said Fulmen, their upper halves remaining untouched by it, and after Fulmination took out the needles, the lower part of which was pure gold, the upper continuing Iron, which I distributed amongst my Friends and Lovers of Art for a remembrance. The same may be performed with Nails."