There have been but two serious attempts to rediscover the authentic Biblical dye of tekhelet. The first came in the mid-1800s by Rabbi G.H. Leiner. Unaware of all the above history, Rabbi Leiner conducted his own search for the marine animal described in the Talmud, a search which lead him to the great aquarium in Naples.
There he studied at length the squid Sepia officinalis and the black fluid it secreted, although, try as he might, he was unsuccessful in converting this to anything resembling a blue dye. Later accounts claim Rabbi Leiner consulted with local chemists who developed a procedure for changing the black fluid to blue. He then took this formula back home and set up a tekhelet manufacturing plant. While his own followers immediately began using this tekhelet, the large majority of Jews remained skeptical.
The second scholar to pursue tekhelet was Rabbi Isaac Herzog. His 1913 doctoral thesis was based on the very subject of tekhelet and as part of his research he analyzed the tekhelet produced by Rabbi Leiner’s method. He sent samples to chemists in Germany, France, and England and received some surprising results. They told him that the blue color of the tekhelet was due to the presence of inorganic Prussian Blue (ferric ferrocyanide).8 Rabbi Herzog was positive that authentic tekhelet could not be an inorganic compound and therefore investigated further to find out why Rabbi Leiner had, unwittingly, been making tekhelet of Prussian Blue. An examination of the method used in converting the squid’s black fluid to blue lead to a simple conclusion. The formula calls for heating the liquid to a very high temperature and then adding iron filaments. At high temperatures the organic matter from the squid breaks apart and combines with the iron to produce ferric ferrocyanide. Under those conditions any organic substance could be used and the results would be the same, so obviously this tekhelet could not be the real thing.
Rabbi Herzog conducted his own extensive study on the origin of tekhelet and relied heavily on the archaeological and classical information uncovered by secular scholars. He concluded that tekhelet must have, in fact, been closely associated with the well-known Tyrian Purple. "He [Herzog] notes the difficulty with the contention that Jewish tekhelet came from some marine animal different than that used by the entirety of the ancient world, an organism which was unknown to the ancient scholars, and has left no archaeological evidence."9 Of the mollusks known to have been used in the manufacture of Tyrian Purple, Rabbi Herzog heavily considered the species Murex trunculus.
Although he even found proof that M. trunculus was used in ancient times to produce a blue dye, there were still a number of significant difficulties which prevented him from stating unequivocally that this species was the one used by the Jews in their production of tekhelet. The most substantial of these difficulties being that the dye extracted from M. trunculus is a purplish-blue color and not the accepted sky blue.
Coming up in Part 3: The Science of Tekhelet
8 Valette (Fabrique Nationale des Gobelins, Paris), private communication (7 May 1913) in Herzog's unpublished thesis.
9 Sterman, B. Viewpoint, Spring, 34-42, 1997.