Fulminating Gold
Put into a small long-necked bottle, resting on a little sand, one
part of fine gold filings, and three parts of aqua regia,
(nitro-muriatic acid.) When the gold is dissolved, pour the solution
into a glass, and add five or six times the quantity of water. Then
take spirit of sal ammoniac or oil of tartar, and pour it drop by drop
into the solution, until the gold is entirely precipitated to the
bottom of the glass. Decant the liquor that swims at the top, by
inclining the glass; and, having washed it several times in warm
water, dry it at a moderate heat, placing it on paper capable of
absorbing all the moisture.
If a grain of this powder, put into a spoon, (it should be an iron
one,) be exposed to the flame of a candle, it will explode with a very
loud report.