Crawford avalanche. (Grayling, Mich.) 1879-19??, 1899-05-04
MAslLxs. SUBSTITUTE FOR GLASS


rhe Queer Chinese Window Oyster-s.Some
Valuable ShelIA
In Manila, where there Is an inter-
esting field open to the naturalist, the
natives have a queer substitute for
glass. 1t Is a bivalve shell of about
nine inches Of surface, SO transparent
that print can readily be seen through
II, and admitting a mellow light In q
room where Ii is used as window
glass.
The shell is an attractive object, per-
fectly straight, and In appearance re-
sembles isinglass. One could almost
Imagine that IL was some skiliful In
vention of the natives, could not the
growth rings be readily observed. The
outer side of the shell Is perceptibly
rough, while the interior is perfectly
glazed over, and In the light has the
pearly lustre found in many of the
thin-shelled oyster-like mollusks Of the
tropics. The shell is the Placuna pla-
centia Of science, and is well known
In China, the common name being the
Chinese window oyster. 1t Is employ
ed there also for windows, and used
In lanterns. The Chinese grind up the
shell and make from il the silver paint
so common in their water cOlors. The
bivalve is very common in the Philip
pines, and forms very good and
cheap substitute for glass; one that is
extremely ingenious and suggestive of
the value of shells.
All shells have a value as curiosities,
and thousands Of dollars are expend-
ed yearly in all parts of the world to-
keep up the supply for the many Gu
riosity stores. The great centre of this
trade Is the South Pacific, where
bought up by the traders who sail
among these islands for the purpose.
The number Of persons engaged in the
collection of shells Is not generally re-
allied, and large prices are paid for
rare shells or even new species. At
one time the orange cowry brought q
fabulous price, and wealthy collectors
have agents constantly on the look
out for rare specimens.
Aside from their use as curiosities,
many shells have decided value. A
single Ceylon fishery produced $780,
worth Of pearls in one year. to obtain
which the native divers handled H.
100000 oysters. The Society Islands
alone have been known to send out
twenty-five tons of pearl oysters years
ly. These find market at Liverpool,
while from Manila thirty-eight tons of
the black-tipped shells have been re-
ceived. The common fresh water mus
sells, formerly despised, contain valu-
able pearls, $4,000 worth having been
taken from the Scottish lakes and
streams during one summer some
years ago. The king Of the clans, the
great Tridacna, has several values. 1t
Is sometimes used as receptacle for
holy water in churches. In Africa the
cowry known as Cypraea moneta is
used as money among certain tribes,
and Liverpool firm in one year sent
to Africa more than sixty tons of the
shells. This was one of the most re-
markable corners ever known. 1t was
learned that the shell was the money
among certain tribes, and the whites
in question bought up the supply from
all quarters until they controlled it
literally by the ton, when their trad
ers, having a monopoly OF money,
went among the tribes and took all
their ivory, slaves and palm oil at an
enormous profit. This was fifty years
ago.
At one time various dyes came from
mollusks. Thus the cuttlefish, or
SQlid furnished the original sonia or
India ink, the latter being the peculiar
secretion Of the squid which it throws
out when alarmed. Many of the
whelks afford n rich crimson dye,
which many years ago the Irish linen
manufacturers employed to color their
goods. This shell is now supposed to
be the origin of the famous Tyrian
dye Of the ancients, whose manufac-
ture Is supposed to be lost art.