play of colours internally, resembling sheets of flame. The Iris can be
artificially produced by flawing a Crystal with a sharp blow of a
mallet, or by throwing it into boiling water.
the Ceraunia, Pliny (65) enumerates other stones that fall from heaven
amidst thunderstorms and rain, such as the Ombria, called by some the
Notia (Rain, or Scirocco-stone), and the Brontia (thunder-stone), all
supposed to possess the same virtues. It was also pretended that if the
latter were laid upon an altar, the offerings could not be consumed as
long as it remained there. Another version, "if we have faith
sufficient," says Pliny, was that the Brontia got into the heads of
tortoises after thunderstorms, and was to be found in their brain. This
possessed the virtue of extinguishing all fires caused by lightning.
fossil Belemnite, popularly called Thunderbolt in England, was a few
years ago (in my recollection) universally believed to fall from the
sky under the same circumstances as the Ceraunia; perhaps, indeed, the
Bsetyli of Sotacus, "black and round," may have signified this fossil,
and not the artificially-made Celts.