reflection
from the two sides of each film, as may be seen in soap-bubbles. The
nacreous laminae when magnified are seen to be of minute cellular
structure.
The
first adaptation of the abalone shell to ornamental purposes was made
by an English worker in mother-of-pearl who went to San Francisco more
than twenty years ago. He saw the possibilities of the wonderful,
brilliant shell, and began a business which now requires the services
of more than ten men. The little trifles made of this shell are
considered by the eastern visitor and the European tourist as
distinctively Californian as a piece of big-tree bark. The
incrustations were formerly removed by soaking the shells in a bath of
muriatic acid, but it was found that this process injured the texture,
and they are now cleaned and polished by friction lathes. Twenty years
ago abalone shells were considered so worthless that freight steamers
would not transport a bag of them without advance payment for the
freight. Now they are worth $150 to $175 a ton in New York and
Liverpool. The shells are shipped first to San Francisco, where they
are assorted and the damaged ones thrown aside, about three tons of
merchantable shells being procured from five tons of material as it
comes from the abalone hunters. These shells are quoted (1889) in San
Diego at $20, $25, and $35 a ton according to quality, and in
consequence of such low prices the trade is comparatively dull. The
output of the shells during 1888 was estimated at 300 tons. The amount
of shells made into jewelry in San Francisco is very small compared
with that consumed by the button-makers of France, England, Germany,
and New York. Orders for abalone shells are constantly received from
these places, and there are times when the export reaches as high a
figure as 100 tons a week. The collector of customs at San Francisco
furnishes the information that for the fiscal year 1887-1888 the
export of abalone shell amounted to $185,414, which, together with
$35,000, the value of the dried meat annually exported, makes this
quite an important industry. These shells secrete very curious pearly
masses, sometimes of fine lustre and choice enough to deserve a place
among pearls. A pearl measuring 2 inches in length and from £ to \ inch in width has been
