sion. The quarrel in Europe was regarded of so much importance, or amusement, that Hogarth introduced the subject into
one of his paintings. At length the controversy was ended by
experiment, — a method which, it is supposed, ought to have
been applied at the beginning,—and the result proved satisfactory to all parties.
The earlier mineralogists denominated this species of stone
schorl, — a name thought to be derived from a village in Germany, and applied to the gem by the miners, from its association
with this place. The identity of the schorl with the tourmaline was discovered, first by Linnaeus, and subsequently by De
Lisle, after they had been regarded as separate species for two
centuries. Transparent crystals, cut as gems, were first introduced into Europe by the Dutch about the first of the last
century, and with them their Cingalese name — tourmaline.
The term schorl is now applied to a black variety.
The chemical substances forming this mineral are numerous, comprising a dozen or more different elements, silica and
alumina constituting the larger part, while the composition
varies in the different kinds. It has a hardness about equal to
that of quartz. Crystals assume the form of prisms, but often
terminate in a different manner, the positive end having a
greater number of facets than the negative end, a circumstance of rare occurrence in crystallography. It is transparent to opaque, but transparency is exhibited only in one
direction,—a fact important to lapidaries.
Some curious phenomena are exhibited by this wonderful
mineral, which seem to invest it with almost magical powers.
When two slices, cut parallel with the axis, and laid one upon
the other, are viewed in one direction they are both transparent,
but when seen in another direction they are opaque. If a
doubly refracting crystal is placed between the two plates,
