Melt a small quantity of the sulphate of potass and copper in a spoon
over a spirit-lamp; it will be fused at a heat just below redness,
and produce a liquid of a dark green colour. Remove the spoon from the
flame, when the liquid will become a solid of a brilliant emerald-green
colour, and so remain till its heat sinks nearly to that of boiling
water, when suddenly a commotion will take place throughout the mass,
beginning from the surface, and each atom, as if animated, will start
up and separate itself from the rest, till, in a few moments, the whole
will become a heap of powder.