Wafers Investigation in the Academician von Struve's Manuscripts from the Archive of the Russian Academy of Sciences, Saint-Petersburg Branch
The presented work is devoted to the study of wafers - objects in demand in the 17th-19th centuries, widely used to seal letters. A wide variety of wafers founded in the Academician Friedrich Georg Wilhelm von Struve manuscripts (Archive of the St Petersburg Academy of Sciences, Fund N 721). A set of studies was carried out using optical methods to determine the composition of wafers in order to preserve archival documents. Two types of wafers - of starch and gelatin origin, were specified. The following pigments were in their composition: cinnabar, red, ultramarine, massicot, Prussian blue, and an anthraquinone group pigment.