Cuttle fish, and all other molluscous animals, can only be preserved in
spirits. The same observation applies to the animals which inhabit that
numerous tribe called Testaceous Shells. They must be detached from the
shells, and put into spirits, while the shells themselves must be
preserved, independent of the animal.
Shells naturally arrange themselves under three distinct heads: Marine,
Land, and Fluviatile, or Fresh Water.
Marine shells are only to be expected perfect, when procured in a living
state. The way to extract the animal is to pour some warm water on it;
but, if too hot, it is liable to crack the shells. When the animals are
dead, they can easily be pulled out with any hooked instrument, or fork,
or if the animal is small, by a common pin. This applies to all marine
shells; whether univalve, bivalve or tubular. It is of great consequence
to preserve the ligament of bivalve shells entire, so that the valves
may not be separated. The animals of land and fresh water shells are
killed by the same means, only that the water requires to be very hot.
Unless the shells are covered with extraneous matter, it is not
necessary to clean them. Marine shells are, however, very liable to be
incrusted with other marine bodies, particularly with serpula and
balani, etc. These must be started off by means of a sharp instrument;
an engraving tool is well adapted for this purpose. This must be done
with great caution, in species which have spines, and other
excrescences, as they are very liable to be broken. Should any of the
calcareous matter still adhere, this must be removed, by applying to it
a _very weak_ mixture of muriatic acid and water, applied with the point
of a quill, and then plunged into water, and allowed to remain till the
acid is quite extracted. But on no account whatever attempt to eradicate
these parasitic bodies by means of acid, or acid and water alone, as the
chances are that the shell will be completely destroyed by their
application. We have seen many fine and valuable shells destroyed by an
injudicious application of acids—they should never be used when it can
possibly be avoided. We have, on the other hand, seen shells which were
so completely enveloped in calcareous crust, that it was impossible to
trace their external surface, most thoroughly cleared of all this,
without being touched at all by acids, the whole being removed by a
small knife or other sharp instrument; and these, in many cases, having
long and tender spines externally.
Nothing can be more monstrous than the application of pumice-stone,
which some recommend, for polishing shells; as is also the use of
tripoli, rotten-stone, and emery. Neither do we approve the application
of varnishes, as such shells never have their natural luster.
If a shell is found dead upon the beach it is probable that it will have
undergone a certain degree of decomposition, that is, it will have
parted with part of its animal matter, and consequently the colors will
have faded and the surface present a chalky appearance. To remove this
take a small proportion of Florence oil and apply it to the surface,
when the colors which were invisible will appear. When completely
saturated with oil let the shell be rubbed dry and placed in a cabinet.
Oil may also be applied after acid has been used, and it will be found
extremely useful when applied to dry the epidermis, which it will
prevent from cracking or quitting the shell entirely, which it
frequently does.
Whether marine shells are procured in a living or dead state, a very
necessary precaution is to immerse them in pure tepid water after the
animal has been extracted, and allow them to continue in it for an hour
or two so as completely to extract any salt or acid which may be in
them.
Fresh water shells are liable to a calcareous or earthy incrustation,
which must be removed by immersing them in warm water, and afterwards
scraping and brushing them with a nail or toothbrush. Much nicety is
necessary in cleaning these, as their great thinness renders them, in
general, liable to be broken. A little Florence oil will improve the
appearance of the epidermis and render it less liable to crack.
Land shells seldom require any cleaning except washing in water, as they
are not liable to incrustations of any kind.
When shells are perforated by marine animals, or otherwise broken, if
the specimen is rare, it is desirable to remedy these defects as far as
possible; they may therefore be filled up, or pieces added to them with
the cement, which may be colored when dry to its original state.
=Of Polishing Shells.= Many species of marine and fresh water shells are
composed of mother-of-pearl, generally covered with a strong epidermis.
When it is wished to exhibit the external structure of shells, the
epidermis is removed and the outer testaceous coatings polished down
till the pearlaceous structure becomes visible. It has been a common
practice to remove the strong epidermis of shells by means of strong
acids, but this is a hazardous and tedious mode of operating. The best
method is to put the shells into a pan of cold water with a quantity of
quicklime and boil it for two to four hours, according to the thickness
of the epidermis. The shells afterwards must be gradually cooled, and
some strong acid applied to the epidermis, when it will easily peel off.
Two hours are sufficient for the common muscle being boiled. The shells
are afterwards polished with rotten-stone and oil, put on a piece of
chamois leather.
The epidermis of the uno margaritifera is so thick that it requires from
four to five hours boiling. After the epidermis has been removed, there
is beneath it a thick layer of dull, calcareous matter, which must be
started off with a knife or other sharp instrument; this requires great
labor, but, when accomplished, a fine mother-of-pearl is exhibited which
adds an agreeable variety as a specimen.
Various turbos and trochuses are also deprived of their epidermis and
polished with files, sand-paper, pumice-stone, etc., till the pearly
appearance is obtained; but all these modes are invented for disfiguring
rather than improving the shells in the eye of the naturalist, and
should never be resorted to except where the species is very common, in
which case it is well enough to do so with one or two specimens to show
the structure of the shells.
After the operation of polishing and washing with acids, a little
Florence oil should be rubbed over to bring out the colors and destroy
the influence of the acid.