ining it by lamplight in 1757, in the presence of the
princes Corsini, he observed none of the cracks, clouds and specks
common to emeralds, but detected little bubbles of air. In 1815 the
Allies ordered its return to the cathedral of Genoa. During this
journey the beautiful relic was broken, but its fragments were
restored by a skillful artisan, and it is now supported upon a tripod,
the fragments being held together by a band of gold filigree. This
remarkable object of antiquity, which is of extraordinary beauty of
material and workmanship, furnishes a theme over which the antiquaries
love to muse and wrangle.

Another of the antique monster emeralds, weighing twenty-nine pounds,
was presented to the abbey of Reichenau near Constance by Charlemagne.
Beckman has also detected this precious relic to be glass. And
probably the great emerald of two pounds weight brought home from the
Holy Land by one of the dukes of Austria, and now deposited in the
collection at Vienna, is of the same material. The hardness of our
glass is yet far inferior to that of the ancients, and even the
ruby lustre of the potters of Umbria, which was so precious to the
dilettanti of the Cinque Cento period, has not been recovered.

The emerald has been a subject of controversy among the chemists
and mineralogists, and its character, especially the cause of its
beautiful color, is not clearly defined even at the present day. But
that distinguished chemist, Professor Lewy of Paris, seems to offer,
thus far, the most correct and plausible theory. Ten years ago he
boldly asserted that the hue is not due to the oxide of chromium,
and with this opinion he confronted such eminent men as Vauquelin,
Klaproth and others of high rank in the scientific world. Not content
with his researches in his laboratory in Paris, he resolutely crossed
the ocean and sought the emerald in its parent ledges in the lofty
table-lands of New Granada. Here he obtained new information of a
geological character which goes far to strengthen his position.
The experiments of M. Lewy indicate, if they do not prove, that the
coloring matter of the emerald is organic, and readily destroyed
by heat, which would not be the case if it was due to the oxide of
chromium. All my own fire-tests with the Granada emerald corroborate
the views of M. Lewy, for in every instance the gem lost its hue when
submitted to a red heat.

Nevertheless, the recent researches of Woehler and Rose give negat