[757] It was because pearls are calcareous that Cleopatra was able to
dissolve hers in vinegar, and by these means to gain a bet from her
lover, as we are told by Pliny, 1. ix. c. 35, and Macrobius Saturn. 1.
ii. c. 13. She must, however, have employed stronger vinegar than that
which we use for our tables, as pearls, on account of their hardness
and their natural enamel, cannot be easily dissolved by a weak acid.
Nature has secured the teeth of animals against the effects of acids,
by an enamel covering which answers the same purpose; but if this
enamel happen to be injured only in one small place, the teeth soon
spoil and rot. Cleopatra perhaps broke and pounded the pearls; and it
is probable that she afterwards diluted the vinegar with water, that
she might be able to drink it; though dissolved calcareous matter
neutralizes acids and renders them imperceptible to the tongue. We are
told that the dissipated Clodius gave to each of his guests a pearl
dissolved in vinegar to drink:--“Ut experiretur in gloria palati,” says
Pliny, “quid saperent margaritæ; atque ut mire placuere, ne solus hoc
sciret, singulos uniones convivis absorbendos dedit.” Horace, lib. ii.
sat. 3, says the same. That pearls are soluble in vinegar is remarked
in Pausanias, b. viii. ch. 18, and Vitruvius, b. viii. ch. 3.
[758] That pearls are not peculiar to one kind of shell-fish, as many
believe, was known to Pliny. I have a number of very good pearls which
were found by my brother in Colchester oysters. It is more worthy of
remark, and less known, that real pearls are found under the shield of
the sea-hare, (_Aplysia_), as has been observed by Bohadsch in his book
De Animalibus Marinis, Dresdæ, 1761, 4to, p. 39.
[759] In the time of Job, pearls were accounted to be of great value.
Job, chap. xxviii. ver. 18.
[760] [When the surface of pearl is examined with a microscope, it is
found to be indented by a large number of delicate grooves, which by
their effect upon the light give rise to the play of colours; and if
impressions of them be taken upon wax, fusible metal, lead, balsam of
Tolu, &c., the impressed surface exhibits the prismatic colours in
the same manner as the pearl. This principle has been applied by Mr.
Barton and others to the making of ornaments, in the form of buttons,
artificial jewels, &c., by grooving the surface of steel with a very
fine cutting machine. The theory of the production of the colours is
this: the surfaces of the grooves, from their varied inclinations,
reflect the incident white light at various angles, hence the
correspondence of the luminous undulations is interrupted and some of
them check or interfere with one another, others continue their course.
Now, ordinary white light being a mixture of coloured rays, when
some of these are checked or interfered with in their progress, the
remainder continue their course and appear of that colour which results
from the ocular impression communicated by them.]
[761] [One of the most remarkable pearls of which we have any authentic
account, was bought by Tavernier at Catifa in Arabia, a fishery
famous in the days of Pliny, for the enormous sum of £110,000. It is
pear-shaped, regular, and without blemish. It is rather more than half
an inch in diameter at the largest part, and from two to three inches
in length.--Waterston’s Encyclopædia of Commerce.]
[762] Philostrat. in Vita Apollon. lib. iii. cap. 57, edit. Olearii, p.
139. Conrade Gesner, in his Hist. Nat. lib. iv. p. 634, gives a more
correct translation of the passage.
[763] Tsetzes Variorum, lib. ii. segm. 373.
[764] See Dr. Joh. Mayer’s Bemerkungen, in the fourth part of
Abhandlungen einer Privatgesellschaft in Böhmen, p. 165.
[765] Abhand. der Schwed. Akadem. der Wissenschaften, vol. xxxiv.
p. 89. The author of the paper alluded to had a mussel with such
artificial pearls, which had been brought from China. It was a _Mytilus
cygneus_, the swan-mussel, or great horse-mussel. Mention is made also
in Histoire de l’Académie des Sciences de Paris, année 1769, of a stone
covered with a pearly substance which was found in a mussel.
[766] A kind of cockles.
[767] J. C. Fabricius Briefe aus London, Dessau, 1784, 8vo, p. 104.
[768] See Schlözer’s Briefwechsel, number 40, p. 251.
[769] Dr. Stœver, in his Life of Linnæus, vol. i. p. 360, says that the
manuscript containing this secret was in the possession of Dr. J. E.
Smith, at London.--TRANS.
[770] In his Letters, p. 104.
[771] This pretty plant, named after the father of botany, grows
in Northumberland and some woods in Scotland, also in Switzerland,
Siberia, and Canada, but particularly in Norway and Sweden, in shady
places amidst the thick woods. The flowers, which appear in May, June
and July, are shaped like a bell, rose-coloured without, yellowish in
the inside, and somewhat hairy. They have a pleasant smell, especially
in the evening. In Tronheim and the neighbouring parts they are drunk
as tea for medicinal purposes.
[772] Pearl. An excrescence on the inside of a shell when the outer
side has been perforated.
[773] See Chemnitz’s theory of the origin of pearls, in the
Beschäftigungen der Berlin. Naturforsch. Gesellschaft, i. p. 348.
[774] The animal part is rendered evident on distillation by the
evolution of an ammoniacal odour and a somewhat inflammable oil; and on
solution in muriatic acid the animal substance is left behind.
[775] Abhand. der Schwed. Akad. iv. p. 245, and xxi. p. 142.
[776] Fabricius, in his Letters, p. 105, mentions such an experiment,
which was however continued only for a year.
[777] Exercitatio Anatom. de Cochleis. Lond. 1694, p. 183.
[778] This manner of preparing _margaritini_ may be seen in my
Anleitung zur Technologie, p. 307.
[779] Massarii in Plinii Nat. Hist. lib. ix. Castigationes. Bas. 1537,
4to, cap. 35.
[780] Mercati Metallotheca, p. 211.
[781] These silver-coloured particles were examined by Reaumur, who
gave a description of them in Histoire de l’Académie, année 1716, p.
229. [In the scales of fishes, the optical effect is produced in the
same manner as in the real pearl, the grooves of the latter being
represented by the inequalities formed by the margins of the concentric
laminæ of which the scales are composed.]
[782] The artist no doubt had in view eastern pearls.
[783] _Girasol._ This word, which is wanting in most dictionaries,
signifies opal, and sometimes that stone called cat’s-eye, _Silex
catophthalmus_, _pseudopalus_, &c. _Couleur de girasol_ is applied to
semitransparent milk-white porcelain.
[784] _Coques de perles_ are flat on one side, and are used for
ornaments, one side of which only is seen. By Pliny they are called
_physemata_. Artificial pearls of this kind have, for some time past,
been employed in making ear-rings. Our toymen, after the French, give
these pearls the name of _perles coques_; but the following account of
Pouget in Traité des Pierres Précieuses, Paris 1762, i. p. 20, makes
me dubious respecting them. “_La coque de perle_,” says he, “is not
formed in a pearl-shell like the pearl; it is procured from a kind of
snail found only in the East Indies. There are several species of them.
The shell of this animal is sawn in two, and one _coque_ only can be
obtained from each. The _coques_ are very small, and one is obliged to
fill them with tears of mastic to give them a body, before they can
be employed. This beautiful snail is found generally in the sea, and
sometimes on the shore.” May not Pouget here mean that kind of snail
which others call _burgeau_, the shells of which are, in commerce,
known by the French under the name of _burgaudines_? Should that be the
case, the animal meant would be the _Nautilus Pompilius_, as may be
concluded from Histoire des Antilles, par Du Tertre, ii. p. 239. For
the author says, “C’est de leur coque que les ouvriers en nacre tirent
cette belle nacre qu’ils appellent la burgaudine, plus estimée que la
nacre de perle.” Irregular pearls are called _baroques_, or Scotch
pearls, because abundance of such were once found at Perth in Scotland.
Some years ago artificial pearls of an unnatural size, called Scotch
pearls, were for a little time in fashion.
[785] A complete account of the art of making glass pearls is contained
in a book, which I have however not seen, entitled, L’Art d’imiter les
perles fines, par M. Varenne de Beost. An extract from it may be found
in Dictionnaire des Arts et Métiers, par M. Joubert, iii. p. 370. See
also the articles _perle_ and _able_ in the Encyclopédie, i. p. 29;
xii. p. 382.
[786] Traité Générale des Pesches, par. ii. p. 403, tab. 23, fig. 1 et
2.
[787] Ichthyologia, Hamb. 1624, 4to, p. 12, tab. 1, fig. 2, albula.
[788] In the Almanach de Strasburg for 1780, p. 76, among the
commodities sold there were, Des écailles d’ablettes dont on tire
l’essence d’orient employée pour les fausses perles.
[789] Déscription Hist. et Topogr. du Duché de Bourgogne, par M.
Courtépée, tom. iv. A Dijon, 1779, 8vo, p. 534.
[790] Pouget. 4to, i. p. 19.