David W. von Endt

Experimental effects of bone size and temperature on bone diagenesis

Abstract In the ground, bone undergoes chemical and physical changes which affect its preservation. This fact has important implications for dating and other analytical procedures involving bone, as well as faunal analysis where differential preservation of bones of different species may affect conclusions regarding the relative significance of an animal to the economy of a given society. The diagenic processes in bone range from minor changes in the bone protein to complete structural and chemical breakdown. Using fresh cow bone, we conducted laboratory experiments which simulate the effect of temperature and bone size on the rate and nature of bone disintegration in archaeological sites. Temperature influences the rate of chemical change, and bone size and density affect the accessibility of the molecular constituents of bone to extrinsic chemical reactions. These findings clarify the importance of two well-known concepts in bone taphonomy. (1) The rate of chemical breakdown in bone tissues is related to the proximity of a given unit of tissue to the bone surface. This means that, in archaeological bone samples, tissue near the surface may be different chemically from tissue away from the surface and great care is necessary in choosing and preparing bone samples for analytical procedures. (2) In general, small bones are not as well preserved as large bones, therefore small animals are likely to be underrepresented in faunal assemblages.

Amino-acid analysis of the contents of a vial excavated at Axum, Ethiopia

Abstract This report describes in some detail both the chemical technique of ultra-micro amino-acid analysis and some of its applications to archaeology. The technique itself consists of heating a sample of protein weighing less than 1 μg in hydrochloric acid, separating the amino-acids by ion-exchange chromatography, colorimetrically determining the amount of each which is present, and quantifying the results. As an example of the application of this technique to archaeological problems, a seemingly inorganic calcitic concretion found in the bottom of a glass vial excavated at Axum was analysed. The vial was found with associated artifacts which suggested that it had been manufactured around or after about AD 600. Approximately 4% of amino-acids were detected in the concretion. The resulting data suggested the presence of skin and hair. These analytical results were coupled with observations concerning the present day distribution of civet cats in Africa, and lead to the conclusion that the vial originally contained civet cat gland exudate, which has a musky odor. In other words, the vial was probably used originally as a perfume bottle.

Use of FTIR-microspectrometry in examinations of artistic and historic works

Describes the recently acquired Spectra-Tech IR-Plan infrared microscope attachment for the Mattson Cygnus 100 FTIR spectrometer at the Conservation Analytical Laboratory of the Smithsonian Institution, Washington, D.C. Applications include work on dammar resin, Prussian blue in linseed oil then covered with B72, MS2A or dammar films; B72 film on top of aluminium, cadmium yellow, ivory black and vermilion and investigations into a white pigment (calcium carbonate) used in Japanese illustration. Photographs, absorption spectra.