GOLD. 
487 
gold in aqua regia, a reddish yellow powder is pre- 
cipitated, which is called aurum fulminans. A few 
grains of this powder explodes with a prodigious 
noise when exposed in a metallic spoon or plate, 
over a candle, coals, or a red-hot iron ; or when by 
other means it is sufficiently heated, the powder 
detonates with a crash sixty-four times greater than 
an equal quantity of gunpowder. A moderate 
degree of heat is sufficient to produce this amazing 
explosion, by which the most violent effects are 
produced. Ten or twelve grains exploded on a 
metal plate, perforated it completely ; and a few 
ounces having accidentally exploded together, shat- 
tered the doors and windows of the apartment where 
it was drying. Even simple trituration, or per- 
cussion alone, is enough to cause this powder to 
explode with all its violence. A melancholy in- 
stance of this is related by Macquer, of a young 
man of his acquaintance, two-and-twenty years old, 
who, in closing a small phial of this powder, kin- 
dled a little by the friction of the glass stopple : 
the bottle instantly burst into pieces ; and the con- 
cussion was so great that he was struck to the 
ground, and totally lost his sight, 
