Читать книгу The Book of Shells - Society for Promoting Christian Knowledge . Committee of General Literature and Education - Страница 18

This species of Purpura is said to be that which was employed by the Romans in dyeing, but many others of the same family yield a purple colouring-matter. It is nearly three inches in length, and is found in the Atlantic Ocean and the Mediterranean.

The purple colour which this little Molluscous animal produces, was discovered by the inhabitants of the ancient city of Tyre, and was thence called the Tyrian purple. The circumstances which led to the discovery of it are very imperfectly known, but fiction has supplied the want of historical facts, and described its origin with sufficient minuteness of detail. According to one account, the merit of its discovery is due to a dog belonging to a certain Hercules. We are informed that when this dog was accompanying his master along the sea-shore, who was then following the nymph Tyros, the animal seized one of the Purpuræ lying on the sand, and breaking the shell with his teeth, his mouth soon became coloured with the purple juice. The nymph having observed the effect, immediately expressed a strong desire to have a dress dyed of the same beautiful colour; and her lover, no less anxious to gratify her wishes, at last succeeded in discovering a method of applying it to cloth.

This colour was so highly valued by the ancients, that it was either consecrated to the worship of the Deity, or conceived to be fit only for the garments of royalty.

Under the Mosaic dispensation, the stuffs for the service of the altar and the habits of the high-priest were enjoined to be of purple. The Babylonians devoted this colour to the dress of their idols, and most of the other nations of antiquity appear to have done the same thing. Pliny informs us that it was used by Romulus and the succeeding kings of Rome, as well as by the consuls and first magistrates under the republic. The Roman emperors at last appropriated it entirely to their own use, and denounced the punishment of death against those who should dare to wear it, although covered with another colour. This absurd and tyrannical restriction confined the dyeing of the Tyrian purple to a few individuals, and, in a short time, the knowledge of the process was entirely lost.

In the twelfth century, neither the creature that furnished the dye, nor the methods which the ancients employed to communicate to cloths the rich and beautiful purple which it afforded, were at all known; and on the revival of learning, it was even suspected by many, that the accounts which had come down to us respecting this celebrated colour were entirely fabulous.

According to Pliny, the Tyrians removed the finest colouring-matter out of the largest shells, in order to possess it in a more pure state, and to extract it more effectually, but obtained the colour from the smaller by grinding them in mills. He adds, that when the Purpuræ were caught, the receptacle which contained the dyeing-liquor was taken out and laid in salt for three days; and that after a sufficiency of the matter had been collected, it was boiled slowly in leaden vessels over a gentle fire, the workman scumming off from time to time the fleshy impurities. This process lasted ten days, after which the liquor was tried by dipping wool into it, and if the colour produced by it was defective, the boiling was renewed.

Other colouring-matters were employed sometimes to economize, and at other times to vary the effect of the liquors of the Purpuræ. Among these Pliny enumerates Fucus marinus, or Archil, and the Anchusa tinctoria, or Alkanet, both of which are still used as dyes. By these and other means, the purple colour was made to assume a variety of shades, some inclining more to the blue, and others to the crimson.

In modern times several attempts have been made to obtain this dye; but the discovery of cochineal has rendered it a matter of little import.

In the year 1683, Mr. William Cole, of Bristol, being at Minehead, was told of a person living at a seaport in Ireland, who had made considerable gain by marking with a delicate and durable crimson colour, fine linen that was sent to him for that purpose, and that this colour was made from some liquid substance taken from a shell-fish. Mr. Cole, being a lover of natural history, and having his curiosity thus excited, went in search of these shell-fish, and, after trying various kinds without success, he, at length, found considerable quantities of a species of buccinum on the sea-coasts of Somersetshire, and the opposite coasts of South Wales. After many ineffectual endeavours, he discovered the colouring-matter, placed in a white vein, lying transversely in a little furrow, or cleft, next to the head of the fish, “which,” says he, “must be digged out with the stiff point of a horse-hair pencil, made short and tapering, by reason of the viscous clamminess of the white liquor in the vein, that so by its stiffness it may drive in the matter into the fine linen or white silk intended to be marked.” Letters or marks, made in this way, with the white liquor in question, “will presently appear of a pleasant green colour, and, if placed in the sun, will change into the following colours,—that is, if in Winter, about noon, if in the Summer, an hour or two after sunrise, or so much before setting, (for in the heat of the day, in Summer, the colours will come so fast that the succession of each will scarce be distinguishable,) next to the first light green will appear a deep green, and in a few minutes this will change into a full sea-green, after which, in a few minutes more, it will alter into a watchet blue, and from that, in a little time more, it will be of a purplish red, after which, lying an hour or two, (supposing the sun still shining,) it will be of a very deep purple red, beyond which the sun can do no more.”

“But the last and most beautiful colour, after washing in scalding water and soap, will (the matter being again exposed to the sun or the wind to dry,) be a much different colour from all those mentioned, that is, a fair bright crimson, or near to the prince’s colour, which afterwards, notwithstanding there is no styptic to bind the colour, will continue the same, if well ordered, as I have found in handkerchiefs that have been washed more than forty times, only it will be somewhat alloyed from what it was after the first washing.”

Some years after this, Réaumur discovered great numbers of a species of buccinum, on the coast of Poitou, and the stones, round which they had collected, were covered with small oval masses, some of which were white, and others of a yellowish colour; and, having squeezed some of them on the sleeves of his shirt, in about half an hour he found it stained of a fine purple colour, which he was unable to discharge by washing. In repeating his experiment on his return home, he found it was necessary that the cloth should be exposed to the direct rays of the sun.

The difficulty of procuring and preserving a sufficient number of these shell-fish, must always render the use of this dye very limited; but Dr. Bancroft is of opinion, that it might still be rendered beneficial in staining or printing fine muslins, for which purpose but little colouring-matter is required. No substance, he remarks, will afford a substantive purple of equal beauty and durability, and capable of being applied to linen or cotton with so much simplicity and expedition.

Family ALATA.

This family is distinguished, by having a canal of variable length at the base of its opening, and by the fact of the right margin of the shell changing its form during the growth of the animal.