and
under its feet a Sea Lamprey ; and wear the Stone against disturbance,
and dreams, and stupidity. It causes Best to Lunaticks, and to them
that are troubled with the Cholick ; and it is better if the Fat of the
Sea-Lamprey be put underneath; for such is Divine." The ancients were
never tired of looking at their rings when garnished with this Jewel,
because of its being such a strengthener of the eyes. Rabbins declare
that the pleasure derived from viewing an Emerald is due to the
refreshing influence exercised by the green colour, this Stone being
the nearest resemblance to the luxuriant verdure of the fields, and
trees. Isidorus, Bishop of Seville, supposed that it even gives a green
colour to the surrounding air. Some persons further tell that
engravers, and workers in Precious Stones, place Emeralds before them,
to rest their eyesight upon whilst engraving minute objects. Certain
lapidaries assert that the Siberian Emerald, which surpasses the others
in value because of its great hardness, and freedom from defects,
originates in Copper mines, where Verdigris is formed.
Boetius, De Natura Gemmarum, says
of the Emerald : " It discovers false witnesses by suffering alteration
wdien meeting with such persons." Formerly it was supposed that the
colouring matter of the Emerald is the oxide of chrome; but the
quantity of chromic-Acid obtainable by analysis is so small as to be
inappreciable ; it is therefore supposed that the exquisite tint of
this Gem (being a Carburet of Hydrogen) is similar to that termed "
Chlorophylle," which constitutes the green colouring matter in the
leaves of plants. It is possible that this organic colouring matter may
be derived from decomposition of the animals whose remains are now
fossilised in the rock which forms the
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