Purples are of numerous kinds, differing only in their element and place of abode. There is the mud purple, the sea-weed purple, both of which are held in the very lowest esteem; the reef-purple, which is collected on the reefs or out at sea; the color from which is still too light and thin. Then there is the variety known as the pebble-purple, wonderfully well adapted for dyeing; and, better than any of them, that known by the name of “dialutensis,” because of the various natures of the soil on which it feeds. Purples are taken with a kind of osier kipe of small size, and with large meshes; these are cast into the sea, baited with cockles which snap at an object, just as we see mussels do, and close the shell instantaneously. Though half dead when they are returned to the sea, these animals come to life again, and open their shells with avidity; upon which the purples seek them, and commence the attack, by protruding their tongues. The cockles, on the other hand, the moment they feel themselves pricked, shut their shells, and hold fast the object that has wounded them: in this way, victims to their greediness, they are drawn up to the surface hanging by the tongue. The most favorable season for taking these fish is after the rising of the Dog-star, or else before spring; for when they have once discharged their waxy secretion, their juices have no consistency: this, however, is a fact unknown in the dyers’ workshops, although it is a point of primary importance. After it is taken, the vein is extracted, of which we have previously spoken, to which it is requisite to add salt, twenty ounces to every hundred pounds of juice. They are then left to steep for a period not exceeding three days, for the fresher they are, the greater virtue there is in the liquor. It is then set to boil in vessels of tin, and every eight thousand pounds ought to be boiled down to five hundred pounds of dye, by the application of a moderate heat; for which purpose the vessel is placed at the end of a long funnel, communicating with the furnace; while thus boiling, the liquor is skimmed from time to time, and with it the flesh, which necessarily adheres to the veins. About the tenth day, generally, the whole contents of the cauldron are in a liquefied state, upon which a fleece, from which the grease has been cleansed, is plunged into it by way of making trial; but until such time as the color is found to satisfy the wishes of those preparing it, the liquor is still kept on the boil. The tint that inclines to red is looked upon as inferior to that which is of a blackish hue. The wool is left to lie in soak for five hours, and then, after carding it, it is thrown in again, until it has fully imbibed the color of that bright lustre, which approaches the shining crimson hue of the kermes-berry, a tint that is particularly valued.