Other shellfish of the same general type, known aspurpura lapillus, are found quite abundantly, not only in the Mediterranean, but also on our own coast and along the shores of Central and South America. They have been used by the natives in Nicaragua and elsewhere, from time immemorial, for obtaining a similar color.
Purpura lapillus Murex trunculus Murex Brandaris
These shellfish were so much sought after in the old days that, by the time of the early Middle Ages, they were almost exterminated, and the dye disappeared from commerce entirely. But, long before that, in the early days of the Roman Empire, the coloring matter was so expensive that fabulous sums were paid for cloth or yarns dyed with it, and its use was practically confined to the imperial family. In fact one of the imperial titles in the Eastern empire—purpureogenitus, “born to the purple”—was due to this fact.
Some interesting information upon the value set on this dyestuff by the ancients is afforded by the so-called Edict of Diocletian, fragments of which, engraved on stone tablets, have been found in different parts of the old Roman Empire, ranging from Egypt to Asia Minor. By this edict, issued in A.D. 301, the emperor Diocletian attempted to fix the market price of the principal articles of commerce, for the Eastern empire. According to this, the price of wool, heavily dyed with this color, was worth about $350 a pound, in gold.
The dyestuff, as we learn from the description of the process by ancient writers, was obtained from a whitish or yellowish liquid found, two or three drops at a time, in a particular vein in the body of these animals. This juice, when exposed to air and especially to sunshine, forms the purple or violet color, much in the some manner that the blue color of indigo is formed from the yellow juice of the indigo plant.
The shellfish in question, having for many centuries been left undisturbed, are now quite common in the waters of the Mediterranean, and are occasionally to be found in the poorer quarters of Venice and other Italian seaports, exposed for sale as food.
A year or two ago a German color chemist, famous for his discovery of the brilliant and extremely permanent reddish violet dyestuff, known as Thio Indigo red B., made a careful investigation to see whether, by any chance, this color of his might happen to be the same as the famous old Tyrian purple.
He managed to secure some twelve thousand specimens ofmurex Brandaris, and, with an immense amount of labor, obtained from these twelve thousand specimens about twenty-one grains of pure dyestuff. This he carefully analyzed and experimented with, until finally he was able to prove that, while it was not identical with his own Thio Indigo red dyestuff—which, as the name shows, is a compound of indigo and sulphur—the Tyrian purple was a similar compound of the same indigo dyestuff, with the comparatively rare acid element, bromine. In fact it is what the chemists would call a brom-indigo; and this same famous chemist, Dr. Friedlaender, of Biebrich on the Rhine, after discovering its composition, amused himself by manufacturing some of it artificially; and, with the artificial reproduction of the ancient Tyrian purple, he dyed some skeins of silk, as an illustration to his article detailing his discovery.
Now, if there were any truth in the theory of the superlative value and beauty of these ancient dyestuffs, it is evident that this rediscovery of the true and genuine Tyrian purple would have been a matter of great practical importance. On the assumption that one pound of dyestuff would color at least twenty pounds of wool, this would put the price of the dye itself, in Diocletian’s day, at a pretty high figure.