The results are in! Thanks to Richard Evershed and Lucy Cramp (University of Bristol, Organic Geochemistry Unit) we now know that the black coating used to embalm PAHMA crocodile mummy 5-513 consists of a mixture of coniferous resin, beeswax, and fat/oil, all common components of Egyptian mummification balms.
Combinations of organic compounds are frequently found in mummification balms. Embalmers may have had both economic and technological motivations for mixing materials. It’s thought that they may have used cheap, readily available animal fat and plant oils as a hydrophobic base to which they added more expensive materials like resins. Both plant resins and beeswax have hydrophobic and antimicrobial properties, making them effective preservative agents. The use of coniferous resin in conjunction with beeswax became widespread during the Ptolemaic and Roman periods of Egyptian history, consistent with the purported date of the crocodile mummy.
Recent research by Dr. Evershed and others has revealed that the composition of the balms used to mummify animals is often similar to those used to mummify humans, disputing the notion that animals received cheaper, more perfunctory mummification procedures. In addition to PAHMA 5-513, Dr. Evershed also analyzed balm samples from two other crocodile mummies and a human mummy in the museum’s collection. All contained mixtures of organic compounds.
Dr. Evershed and his colleagues used gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) to identify biomarkers characteristic of these classes of compounds. Small samples of balm or balm-soaked linen were dissolved in organic solvents then analyzed. GC separates components of complex organic mixtures based on differing molecular size. MS then identifies the separated compounds by ionizing them with a beam of high energy electrons, causing them to fragment, and weighing the ionized and fragmented compounds. The resulting mass spectra reveal the molecular structures of compounds present in the sample.
The presence and relative ratios of certain biomarkers derived from the original ingredients indicate what types of compounds were used to create the mummy balm. Sometimes the biomarker molecules are molecules that existed in the original plant or animal source, but often they are derivatives of the original molecules, which have altered over time due to natural deterioration processes or actions taken by the embalmers during preparation of the balm. GC/MS analysis of the crocodile mummy’s black coating detected fatty acids and carboxylic acids characteristic of fat/oil, wax esters, hydrocarbons and alcohols characteristic of beeswax, and degradation products of abietic acid, a component of the diterpenoid resins produced by members of the conifer division (conifers include pine, cedar, fir, juniper and cypress). The absence of certain diterpenoid resin alteration products suggests that the resin was not heated at high temperature. Petroleum bitumen (which is often present in later Egyptian mummy balms in low concentrations) could also be present, but was not analyzed for at this stage due to sample size requirements and other constraints.
We are grateful to Dr. Evershed for elucidating the composition of the mummy balm, and delighted to add data from the PAHMA mummies to the growing body of knowledge about Egyptian mummy balm composition and mummification technology.