Removing the Animal.—With a large shell, such as a conch, the first step is to remove the living animal. In some cases I have accomplished this by hooking a fish-hook into the head of the animal and hanging it up so that the weight of the shell constantly pulling down on the animal would cause it to gradually relax and draw out. An excellent plan is to place the shell for a few days in fresh water and macerate the animal sufficiently that it may be drawn out. Fortunately the great majority of molluscs are very small, and it is possible to prepare them for
the cabinet without the necessity of removing the animal. Mr. Greegor's plan is to soak the shell in alcohol for a few days, to completely preserve the animal, and then dry it thoroughly to expel all the water from it. When that is done, the final step is to pour into the shell, through a rubber tube, a little thick varnish, or hot beeswax mixed with a little vaseline to make it flow readily, and thus cover the dried-up remains of the animal with an impervious coating which does away with all odors which might otherwise arise from it. This part of the process, be it understood, is to be attended to after the cleaning and polishing has been done.
Removing the Epidermis.—The epidermis is so tough and horny, and sticks so tightly to the shell that tools cannot remove it successfully and it must be done chemically. Make a strong solution of chloride of lime and water, by putting into a jar one-fourth its bulk of chloride of lime, two-fourths water, and leaving the remaining fourth part of the space for the froth that will rise. Soak shells in this pasty solution for a short time, and it will eat the epidermis off.
Removing Limy Accretions.—The bulk of all these thick, irregular coatings must be removed with steel tools—file, scraper, knife, sand-paper, or hammer—to suit each individual case. The tool that Mr. Greegor most relies upon is a small and very light hammer, made especially for him, which is shaped somewhat like a square-headed tack-hammer, with the pointed end drawn out to a blunt cutting edge, like the edge of a cold chisel. With this cutting edge a skilful hand can peck the lime or coral incrustations off a shell very neatly, and without injury to the surface of the specimen. Acid will not remove the thick, limy deposits, and they must be cleaned off by mechanical means.
After the bulk of the limy deposits have been removed by means of tools, the shell usually has a dull, lustreless appearance, and appears to require something that will remove the remaining particles of lime, impart to it a permanent gloss, and bring out its beautiful colors. Fortunately there is a way to do this to perfection, which consists in dipping the shell in a weak solution of muriatic acid and water, boiling hot. The strength of this solution must vary according to the nature of the specimen. For thick and strong shells, which by their solid character you are assured cannot be damaged by a maximum of acid, put 3 parts of muriatic acid in 10 parts water. For thin and delicate specimens, use 1 part acid to 10 of water, varying the amount of acid from 1 part to 3, as your experience will soon teach you is most desirable. Put this solution in a porcelain kettle, bring it to a boil, and then with a pair of wooden tongs or forceps dip each shell into it and hold it there for a second or more, as may be necessary. On removing it, wash it in clear water and dry it, and if its appearance is not satisfactory dip it again.
For very delicate shells, having a thin surface color, such as the Cypreas and Olivias, or such shells as have very delicate sculpture, the weaker solution is best. When it is desired to cut more on one part of a shell than another, the acid may be applied with a brush, finishing with a quick dip. Never allow any of the acid solution to remain on the shell, or it will eat into it and dull the lustre. For fine work, dry each specimen with a towel.
Shells which have on their exterior a great deal of horny or organic matter, such as Haliotis, Ostrea, Lingula, and a few others, work badly in acid, and require to be brushed constantly while cutting, to remove the organic matter, for the reason that the acid acts only on the lime of the shell.
Chloride of lime and muriatic acid are both very volatile, and when not in use should be kept in tightly closed vessels.