David Ratzan
In this report we will discuss the results and interpretation of three related and recently completed studies: (1) a Raman study of 17 papyri from Egypt, spanning the 4th cent. BCE to the 10 cent. CE; (2) a Raman study of the so-called “Gospel of Jesus’ Wife” and the Gospel of John, both the subjects of heated debate with respect to provenance, date, and authenticity; and (3) a scanning electron microscope study of the morphology of ink particles on papyri and ink pots or wells from Karanis in the Kelsey Museum at the University of Michigan. Given the deeply collaborative and integrated nature of this work, we will present two papers, one on the scientific method and results and one on the papyrological and historical dimensions, in one 40-minute joint presentation, reserving discussion of both until the end. The Raman spectra that we gathered from our sample set reveal specific variations in those spectra that correlate closely with the date of writing. This discovery thus enables us to determine the average Raman spectroscopic parameters as a function of manuscript date. In other words, the observed systematic variation in Raman spectral parameters with manuscript age establishes, in principle, the basis for a non-destructive scientific means for estimating the date of ancient Egyptian manuscripts written in carbon ink from the period defined by this study. We hypothesize that the observed changes in Raman spectra reflect changes on the nanometer scale in the chemical structure of the carbonaceous material of the ink from oxidation under ambient conditions. We are developing an increasingly sophisticated statistical method for interpreting our complex spectrographic data, with the aim of deriving the most precise and robust explicit date range possible for the manuscripts we test. We have also applied this methodology to two recently reported Coptic papyrus fragments: the “Gospel of Jesus’ Wife” and a fragment with text from the Gospel of John. We will present our data on these two particular fragments in the context of our wider study and the current debate. Besides reporting on our methodology and results, our chief aim in our remarks is to highlight two important points: (1) the significant parameters of interpretation, i.e., what our data mean and do not mean in light of the nature of these studies and our current scientific knowledge; and (2) the new and unanticipated avenues of inquiry that have emerged from these studies, beyond the present lines of debate. One example is our interest in the production of the inks we have tested. The existence of the Raman correlation strongly suggests that these pigments were manufactured using identical or very similar processes. We have independently supported this hypothesis by examining several papyri and modern inks with a scanning electron microscope. By the time we deliver this presentation we hope also to have studied ink from several ink pots or wells from Karanis, now in the Kelsey Museum. The morphology of the pigment particles we have examined to date strongly suggests that they are derived from soots with similar morphologies to “lamp black,” rather than chars, such as traditional “vine black.” This finding in turn raises some interesting questions about the industrial production of ink in antiquity.