Northwestern’s Melville J. Herskovitz Library of African Studies holds an important collection of Arabic Manuscripts, including the intact library of Nigerian scholar-trader ‘Umar Falke (1893-1962). Falke’s collection of over three thousand original 19th– and 20th-century manuscripts was collected on his travels through Nigeria, Ghana, Sierra Leone, and Senegal. The documents span all aspects of Islamic learning, and provide a unique opportunity to study the tradition of manuscript production during this time period in Western Africa. Very little has been recorded or published about the material history of this tradition, or the practices of scribes and copyists who created these documents.
During a recent survey of the Falke collection, a single instance of the yellow pigment orpiment (As2S3) was identified. While some literature states that yellows in manuscripts of this time and location were made exclusively with locally sourced yellow ochres (various iron-oxide and –hydroxide pigments), it is possible that orpiment was still in use, consistent with the practices of earlier centuries. Conservation Fellow Graham Patten is currently undertaking a research project that focuses primarily on the yellow pigments, as well as the binding media used to make the inks.
The main questions raised at the outset of the research are: what are the identities of the pigments and binders, how did they come to be in Western Africa, why were specific pigments chosen for various specific uses in the texts, and what can these issues tell us about the nature of trade and manuscript production during the time period in question? These ideas will be addressed in terms of their social, religious, and economic contexts.
In order to determine how commonly yellows occur in the collection, locate examples for chemical analysis, and aid future research on other colors, Graham made a visual survey of all colors used in the collection, looking at a random sampling of about one-third of the collection. His survey predicts that approximately 4% of the manuscripts contain yellow pigment, a finding consistent with the earlier preservation needs assessment survey.
Currently, Graham is conducting Raman spectroscopy on the pigments at Northwestern University’s Atomic and Nanoscale Characterization Experiment Center (NUANCE) to identify the particular yellow colorants used. Raman spectroscopy is well suited to the study of minerals and other inorganic materials, and has been used successfully in recent years for the identification of artists’ pigments. One aspect of this technique that is particularly attractive for library and archives materials is that analysis can be performed in-situ without the need for destructive sampling. The results of this analysis will add a great deal to our knowledge of materials used in this relatively undocumented tradition, and bring us a step closer to answering some of the questions we have about this unique collection.