3θ6 PRECIOUS STOXES.
worked, it is seldom used by modern engravers except for
small carnei. It has sometimes been taken for ruby, and it is
supposed by some judges that Wallenstein's ruby and many
others seen by Tavernier in Bohemia were garnets, instead
of rubies or spinels. The best specimens of oriental garnets
are obtained from Ceylon and Pegu, and of these the latter
are preferred to the former ; the best European garnets are
those found in Bohemia.
The Tourmaline.—There are several antique gems mentioned by old writers which had some of the characteristics of the modern tourmaline, affording a pretext for
identifying any one of them with this mineral. Theophrastus
refers to a stone found at Cyprus, which was green at one end
of the crystal and red at the other ; and Pliny says of the
lychnis that it attracts chaff and filaments of paper when
heated by the sun or by friction. Both these qualities belong,
though not exclusively, to the tourmaline.
The true nature of this substance was not understood until
within a century, and even at present its peculiar qualities,
which render it an interesting object of scientific study, are
understood by only a few. It stands almost alone in the
mineral kingdom, at least among precious stones, for its constituents and physical properties.
Though the remarkable characteristics of the tourmaline
were made known to the French Academy of Sciences in the
beginning of the eighteenth century, yet they did not attract
general attention until several years afterwards, when, by the
published accounts of a German experimenter, the interest of
the scientists of Europe in this mineral was suddenly aroused.
At first the subject excited opposition, and a "paper warfare"
followed, with a good deal of noise from both parties, which
reached this continent and enlisted Dr. Franklin in the discus-
