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Discovered for the first time in 1947 by Bedouin shepherds in search of a lost sheep, ancient Hebrew texts known as Dead Sea Scrolls are among the oldest and best preserved writings ever found. . Today, a study by researchers at MIT and elsewhere elucidates a unique ancient technology for making parchment and provides new information on possible methods for better preserving these valuable historical records.
The study focused in particular on a scroll, called Temple Scroll, among the approximately 900 complete or partial rolls found in the years since this first discovery. The rolls were found in jars hidden in 11 caves on steep slopes just north of the Dead Sea in the area around the ancient Qumran settlement, which was destroyed by the Romans about 2 years ago. 000 years. It is believed that, to protect their religious and cultural heritage from the invaders, members of a sect called the Essenes hid their precious documents in caves, often buried under a few meters of debris and armed with a bat. guano to help thwart looters.
The Scroll Temple is one of the largest (nearly 10 meters long) and best preserved, even though its material is the finest of all (one-tenth of a millimeter, about 1/250 of an inch). thick). It also has the clearest and whitest writing surface of all rollers. These properties brought Admir Masic, Assistant Professor of Civil and Environmental Engineering to the Esther and Harold E. Edgerton Career Development Department, as well as a faculty member specializing in archaeological materials from the Department of Materials Science and Engineering. Engineering, and its collaborators to wonder how the parchment was made.
The results of this study were made with Roman Schuetz, a former PhD student (currently at the Weizmann Institute of Science in Israel), Janille Maragh, MIT graduate student, James Weaver of the Wyss Institute of the United States. Harvard University and Ira Rabin of the Federal Institute for Materials Research and Testing and the University of Hamburg in Germany, were published today in the journal Progress of science. They discovered that the parchment was treated in an unusual way, using a mixture of salts found in evaporites – the material resulting from the evaporation of brines – but different from the typical composition found on other scrolls.
"The scrolling of the temple is probably the most beautiful and best preserved parchment," says Masic. "We had the privilege of studying fragments of the Israeli Museum of Jerusalem, called the Book Sanctuary", which had been specially built to house the Dead Sea Scrolls. A relatively large fragment of this roll was the main subject of the new document. The fragment, measuring about 2.5 cm (1 inch) in diameter, was studied using various specialized tools developed by researchers to map, at high resolution, the detailed chemical composition of objects relatively large under the microscope.
"We were able to perform a large-scale, non-invasive, sub-micron scale characterization of the fragment," says Masic – an integrated approach developed by him and Weaver for the characterization of biological and non-biological materials. "These methods allow us to conserve materials of interest in more environmentally friendly conditions, while we collect hundreds of thousands of different elemental and chemical spectra on the surface of the sample, allowing us to map its composition variability in great detail, "says Weaver.
This fragment, which has escaped any treatment since its discovery and which could have altered its properties, "allowed us to deepen its original composition, revealing the presence of certain elements at completely unexpected concentrations," explains Masic.
The elements discovered included sulfur, sodium and calcium in different proportions spread over the surface of the parchment.
The parchment is made from animal skins from which all hairs and fatty residues have been removed by soaking them in a solution of lime (from the Middle Ages) or by enzymatic and other treatments (in the 39, Antiquity), scraping them, then stretching them a frame to dry. Once dried, the surface was sometimes rubbed with salts, as was apparently the case with the temple roll.
The team has not yet been able to determine the origin of the unusual combination of salts on the surface of the Scroll Temple, says Masic. But it is clear that this unusual covering, on which the text was written, helped to give this parchment its exceptionally bright white surface, and perhaps contributed to its state of preservation, he says. And the elemental composition of the coating does not correspond to that of the water of the Dead Sea itself; it must therefore come from an evaporite deposit located elsewhere, which researchers do not yet say.
The unique composition of this surface layer demonstrates that the process of producing this parchment was very different from that of other manuscripts in the region. Masic said, "This work is a perfect illustration of what my lab is trying to do: use modern, secret analytical tools from the ancient world. "
Understanding the details of this ancient technology could help to better understand the culture and society of this time and place, which played a central role in the history of Judaism and Christianity. Among other things, an understanding of parchment production and its chemistry could also help identify counterfeits of supposedly ancient writings.
According to Rabin, an expert on the materials of the Dead Sea Scrolls, "this study has profound implications beyond the Dead Sea Scrolls. For example, it shows that at the dawn of parchment in the Middle East, several techniques were used, which contrasts sharply with the unique technique used in the Middle Ages. The study also shows how to identify initial treatments, thus providing historians and curators with a new set of analytical tools for the classification of Dead Sea Scrolls and other ancient scrolls. . "
This information could indeed be crucial to guide the development of new conservation strategies for these ancient manuscripts. Unfortunately, it seems that most of the damage seen in the manuscripts today is not the result of their more than 2,000 years in the caves, but their efforts to soften them to unwind and read them immediately afterwards. their discovery, says Masic.
In addition to these existing concerns, the new data now clearly demonstrates that these unique mineral coatings are also highly hygroscopic – they readily absorb any moisture in the air and could then quickly begin to degrade the underlying material. These new findings further underscore the need to store parchments in a permanently controlled humidity environment. "There could be unanticipated sensitivity to changes in humidity, even on a small scale," he says. "The fact is that we now have evidence of salts that could accelerate their degradation. These are aspects of conservation that must be taken into account. "
"For conservation issues and programs, this work is very important," says Elisabetta Boaretto, director of the Kimmel Center for Archaeological Science at the Weizmann Scientific Institute in Israel, who was not associated with this. job. She says, "This indicates that you must be very familiar with the document to be preserved and that preservation must be appropriate to the chemistry of the document and its physical state."
Boaretto adds that the study of this team on the unusual mineral layer on parchment "is fundamental for future work in conservation, but especially to understand how these documents were prepared in antiquity. This work certainly sets a standard for other researchers in this field. "
The work was partially supported by DFG, the German Research Foundation.
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