138 ery of the He-method recommended to destroy it and separate it en- Clyde, and of Loch Ken in Galloway, where it is said of the Habitation of tirely froin the shell, is to boil it in water for a very great numbers of pearls are fished in dry summers, ma- bitation of Shells, &c. short time, and after allowing it to cool gradually, to ny of which sell from one shilling to one guinea. But Shells, &c. Jay it in cold water till it is cleaned. By this process, the greatest pearl-fishery which has ever been establish137 Method of the attachment between the shell and animal is de- ed in Scotland, of which there is any record, is that kiling the stroyed, and the latter, which has become hard and of the river Tay, about 30 years ago. The pearl. animal. contracted, is easily picked out from its covering. mussel is found in every part of this river, from its The shell, after this treatment, is ready to be placed source in Loch Tay, to its junction with the sea. In 11,000l. worth of pearls were sent to London between Pearl-fish- As the pearl has been held in high estimation in all the years 1761 and 1764. They were sold from 105.. ages of the world, and as it is an important object of to 1). 166. per ounce. About this time one pearl was connot fail to be interesting. 139 land, seems to be greatly exhausted, and very probain Britain. In different parts of Britain the pearl-fishery has bly, as it has been supposed, from the improvident been carried on to a considerable extent ; and in some avarice of the undertakers, not allowing the animal to 140 To the ac- The heart, that nobody, probably not even the conjuror prayers. a (D.) Perhaps near 100,000l. sterling. The pagoda is from 79. to 8s. 6d. sterling. a 2 of the Ha. prayers would be of no avail; they are, however, al- appearance, as they are found when living at sea ; but of the Habitation of lowed to drink, which privilege they indulge in a high others who make collections, bate the disagreeable bitation of Shells, &c. degree, and are frequently so giddy as to be rendered outsides, and will have all such polished. It would be Sbells, &c. very unfit for devotion. Some of these conjurors ac. very advisable, however, for both kinds of collectors to per time, they should be washed over with diluted mu riatic acid, when the skin may be easily removed by Sect. III. Of the Methods of Polishing Shells. rubbing it off with the fingers. Though the art of polishing sbells is a very valuable a have naturally a smooth surface, or be covered with tu- only on the surface, and the wearing away ever so little Anong the shells which are found naturally polished of the shell defaces them. A shell that is rough, foul, employed. are the porcelains, or cowries; the cassanders; the do- and crusty, or covered with a tartareous coat, must be lia, or conchæ globosæ, or tuns; some buccina, the vo- left a whole day steeping in hot water : when it has im- rubbed 142 141 Mlethods 2 Of the Ha- rubbed with linen cloths, impregnated with common bitation of soap; and when by these several means it is made perShells, &c. fectly clean, the polishing is to be finished with fine emery and a hair-brush. If after this the shell when dry appears not to have so good a polish as was desired, it must be rubbed over with a solution of gum arabic; and this will add greatly to its gloss, without doing it the smallest injury. The gum-water must not be too thick, and then it gives no sensible coat, only heightening the colours. The white of an egg answers this purpose also very well; but it is subject to turn yellow. If the shell has an epidermis, which will by no means admit the polishing of it, it is to be dipped several times in diluted aquafortis, that this may be eaten off; and then the shell is to be polished in the usual way with putty, fine emery, or tripoli, on the hair of a fine brush. When it is only a pellicle that hides the colours, the shell must be steeped in hot water, and after that the skin worked off by degrees with an old file. This is the case with several of the cylinders, which have not the natural polish of the rest. When a shell is covered with a thick and fatty epidermis, as is the case with several of the mussels and tellina; in this case aquafortis will do no service, as it will not touch the skin: then a rough brush and coarse With pu- emery are to be used; and if this does not succeed, mice-stone. seal-skin, or, as the workmen call it, fish-skin, and pumice-stone, are to be employed. 144 With acids, &c. When a shell has a thick crust, which will not give way to any of these means, the only way left is to plunge it several times into strong aquafortis, till the stubborn crust is wholly eroded. The limpets, auris marina, the helmet-shells, and several other species of this kind, must have this sort of management; but as the design is to shew the hidden beauties under the crust, and not to destroy the natural beauty and polish of the inside of the shell, the aquafortis must be used in this manner: A long piece of wax must be provided, and one end of it made perfectly to cover the whole mouth of the shell; the other end will then serve as a handle, and the mouth being stopped by the wax, the liquor cannot get into the inside to spoil it; then there must be placed on a table, a vessel full of aquafortis, and another full of common water. The shell is to be plunged into the aquafortis; and after remaining a few minutes in it, is to be taken out, and plunged into the common water. The progress the aquafortis makes in eroding the surface is thus to be carefully observed every time it is taken out the point of the shell, and any other tender parts, are to be covered with wax, to prevent the aquafortis from eating them away; and if there be any wormholes, they also must be stopped up with wax, other wise the aquafortis would soon eat through in those places. When the repeated dippings into the aquafortis show that the coat is sufficiently eaten away, then the shell is to be wrought carefully with fine emery and a brush; and when it is polished as high as can be by this means, it must be wiped clean, and rubbed over with gum-water or the white of an egg. In this sort of work the operator must always have the caution to wear gloves; otherwise the least touch of the aquafortis will burn the fingers, and turn them yel low; and often, if it be not regarded, will eat off the Of the Haskin and the nails. bitation of These are the methods to be used with shells which Shells, &e. require but a moderate quantity of the surface to be taken off; but there are others which require to have a larger quantity removed and to be uncovered deeper: this is called entirely scaling a shell. This is done by means of a horizontal wheel of lead or tin impreg nated with rough emery; and the shell is wrought down in the same manner in which stones are wrought by the lapidary. Nothing is more difficult, however, than the performing this work with nicety: very often shells are cut down too far by it, and wholly spoiled; and to avoid this, a coarse vein must be often left standing in some place, and taken down afterwards with the file, when the cutting it down at the wheel would have spoiled the adjacent parts. After the shell is thus cut down to a proper degree, it is to be polished with fine emery, tripoli, or rotten stone, with a wooden wheel turned by the same machine as a leaden one, or by the common method of working with the hand with the same ingredients. When a shell is full of tubercles or protuberances which must be preserved, it is then impossible to use the wheel: and if the common way of dipping into aquafortis be attempted, the tubercles being harder than the rest of the shell, will be corroded before the rest is sufficiently scaled, and the shell will be spoiled. In this case, industry and patience are the only means of effecting a polish. A camels-hair pencil must be dipped in aquafortis; and with this the intermediate parts of the shell must be wetted, leaving the protuberances dry: this is to be often repeated; and after a few moments the shell is always to be plunged into water to stop the erosion of the acid, which would otherwise eat too deep, and destroy the beauty of the shell. When this has sufficiently taken off the foulness of the shell, it is to be polished with emery of the finest kind, or with tripoli, by means of a small stick; or the common polishing-stone used by the goldsmiths may be used. This is a very tedious and troublesome thing, especially when the echinated oysters and murices, and some other such shells, are to be wrought: and what is worst of all is, that when all this labour has been employed, the business is not well done; for there still remain several places which could not be reached by any instrument, so that the shell must necessarily be rubbed over with gum-water or the white of an egg afterwards, in order to bring out the colours and give a gloss; in some cases it is even necessary to give a coat of varnish. 145 These are the means used by artists to brighten the Some shells colours and add to the beauty of shells; and the are dischanges produced by polishing in this manner are so guised by great, that the shell can scarcely be known afterwards polishing, to be the same it was; and hence we hear of new shells in the cabinets of collectors, which have no real existence as separate species, but are shells well known, disguised by polishing. To caution the reader against errors of this kind, it may be proper to add the most remarkable species thus usually altered. such as 146 The onyx-shell or volute, called the purple or violet- the onyx tip, which in its natural state is of a simple pale brown, shell. when |