Archaeological chemical laboratories

The development of scientific procedures that are able to use very minute samples (a few micrograms), together with the increased availability of advanced analytical instrumentation, have led to great interest in the chemical study of materials used in cultural heritage. This has given rise to a sharp increase in research studies at the interface between art, archaeology, chemistry and the material sciences. As a result, successful multidisciplinary collaborations have flourished among researchers in museums, conservation institutions, universities and scientific laboratories. 

While thousands of analyses of archaeological bronzes have been reported in the literature, the basis for comparing them, especially those from different laboratories, is shaky. A round-robin project of chemical analyses was attempted to improve the situation. Two ancient bronze objects were milled to a fine powder, sieved, and mixed to a homogeneous mass. Samples of 500 mg each drawn randomly from this mass were circulated, and results were returned from 21 laboratories. Forty-eight elements were analyzed some laboratories did only one element, some did as many as 42. The coefficient of variance (or relative standard deviation) ranges from 4% for Cu up to over 200% for some trace elements. The results are tabulated, and methods are suggested to narrow the spread of results in the next run of this program. 

Chemical analysis of practically every type is used extensively in archaeological chemistry. There are of course important diflFerences between the typical problems which arise in analytical laboratories and those of archaeological chemistry. Ideally in studies of archaeological artifacts the analytical technique should be nondestructive, and if this is not feasible, only a very small sample is to be removed. If a sample is to be removed, a concerted eflFort should be made not to diminish the object s aesthetic appearance. For example, it may be necessary to drill at the bottom of a bronze vase where the damage is not visible. In the case where sample-taking is not allowed, the artifact must be accommo-... 

The laboratory tests normally used to confirm field designations and to establish the boundaries of archaeological occupation were inconclusive because of the nature of the soils at Yagi. A more complete chemical analysis of the soils was attempted by using neutron activation analysis. 

Neutron activation analysis (NAA) is an eminently suitable technique for obtaining the chemical profile of ancient pottery and artifacts made from other earthy materials. This technique can be used to determine where these articles originated. An NAA system that has proved to be adequate for this task is discussed. A brief review is also given of the way archaeologists have decided matters of provenance and the uses to which they put their knowledge. Finally, two examples of archaeological problems are given in which the new horizons opened by the laboratory work are stressed. 

The Laboratory for Archaeological Chemistry at the University of Wisconsin-Madison, founded in 1987, is a center for research and training in the chemical analysis of archaeological materials, one of a few such facilities in the USA. The laboratory and its continuing operation are made possible by grants from the US... 

The ceramic analyses on hand were produced in a niunber of laboratories, mostly in connection with different ad hoc experimental schemes largely dedicated to the solution of specific, closed-end archaeological problems. In only a few cases were there studies aimed at a comprehensive knowledge of the chemical compositional profiles of all the ceramics, tempered and non-tempered, and all the clay and temper resources in a particular region of archaeological interest. 

Neutron activation analysis has proven to be a convenient way of performing the chemical analysis of archaeologically-excavated artifacts and materials. It is fast and does not require tedious laboratory operations. It is multielement, sensitive, and if need be, can be made entirely non-destructive. Neutron activation analysis in its instrumental form, i.e. that involving no chemical separation, is ideally suited to automation and conveniently takes the first step in data flow patterns that are appropriate for many taxonomic and statistical operations. 

Polymerase enzymes are used extensively in the laboratory for the synthesis and manipulation of DNA and RNA (44). One of the most important applications of enzymatic DNA synthesis is in the polymerase chain reaction (PGR), which is used to amplify minute quantities of DNA from a variety of soin-ces, inclnd-ing crime scene evidence, archaeological specimens, or medical samples (45). In PGR, two short oligonucleotide primers are first synthesized by chemical methods. These primers are complementary to the 5 -ends of the two strands which form the DNA duplex of interest (Fig. 11). A large excess of the primers is mixed with the target DNA along with a DNA polymerase enzyme and the nucleoside triphosphate monomers. The sample is heated to disrupt the target duplex. Then, as the... 

On the other hand, the sources and the extent of hazards may be more difficult to assess. There are in effect two sets of raw materials in the workshop the objects being treated, and the materials used to treat them. The object to be treated could present a chemical, biological or mechanical hazard. In some cases, it will be in the laboratory so that more can be learned of its composition or structure. It may, then, be necessary to impute the worst possible hazards to the object until it has been shown to be safe. This is particularly important for some types of biological specimen if there is a history of infection. An example was the archaeological investigation of a graveyard in the City of London in 1985 where it was thought that those interred had died of smallpox. A check was carried out before work started, but no active smallpox was identified. 

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