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CRYSTALLUS.
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111
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Sudines,
that it was only produced in rocks that faced the south, never in a
watery soil, even where the climate is so cold that the rivers freeze
to the very bottom. The universal opinion as to its origin, that it
was ice, hardened by intense frost (gelu vehemontiore concreto), gave
to Crystal its name, the Greek word for ice. Rain, says Pliny,
mixed with a small proportion of snow, is necessary to its formation ;
and, as a necessary consequence, the substance is unable to bear heat,
and can only be used to contain cold liquids.
Pliny
(xxxvi. 66) quotes a statement that in India glass was made out of
broken Crystal, and hence the incomparable superiority of the Indian
glass to any other. Can some faint report of the excellence of the
Chinese porcelain (in which pounded felspar is the essential
ingredient) have reached the Greek traders and travellers, his main
authorities in this section of his great work?* for it is certain that
glass was unknown in India until imported by the Portuguese ; whilst,
on the other hand, Chinese porcelain, when first brought to Europe, was
considered a species of glass. It is, however, a fact that Crystal, as
being the purest form of Silica, supplies the best possible material
for glass-making ; on which account it was largely used in the
manufactories at Murano in the flourishing times of the Venetian
glass-trade, and now constitutes the chief ingredient of Strass, the
basis of artificial gems. Theophrastus (49) refers to the same belief
thus : " For if glass be made, as it is said, out of tho Hyalites, this
article also is produced by condensation." Now the same stone
apparently is enumerated by him (30) in the list of signet-gems,
where, however, it is distinguished from the Crystal,
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