decomposition,
and for their preservation numerous chemical agents have been
-employed by the different manufacturers, all of whom, who have
succeeded, keep it a secret; it is, however, known that liquid ammonia
is added to the paste of the scales. .
The operation of the manufacture is very difficult, but an experienced workman can manufacture six thousand pearls in a day.
The
chemists have experimented for some years to imitate the extract of
orient,—as it requires such a large quantity of fishes to obtain any
amount of the scales,—and according to Mr. Barbot, the following
preparation has produced a favorable result: which is by distilling one
part of oxide of bismuth and two parts of corrosive sublimate; the
product is a species of butter, which on redistilling yields metallic
quicksilver and a very fine powder; this is the substance used for
orientalizing or coating the artificial pearls with the true gloss-of
an Oriental pearl.
The
same scales are likewise used to coat beads of gypsum, or alabaster,
which are soaked in oil and then covered with wax to give them a pearly
appearance. The Roman beads are made in this manner: the scales are
dissolved either in liquid ammonia, or vinegar, and the solution or
liquid is used for covering those artificial beads. The Turkish
rose-beads are made of an odoriferous paste, and are turned afterwards
like those of coral, amber, agate, or other hard substances. The
knitting beads are sold in meshes of one hundred and fifty, or twenty
strings, of fifty beads each, of various colors; and the large
glass-beads in meshes of twelve strings. There are numerous
manufactories in Germany and Italy of the various kinds of beads, which
are used to a very great extent both in Africa and North and South
America. Germany exports yearly from its different manufacturing
places, such as
