600 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1962 



showed that the alteration characteristic of annealing did not occur 

 until the silver was heated to 900° C, i.e., only 50 degrees below the 

 melting point of silver. However, by carrying out the annealing 

 under strictly controlled conditions in an inert atmosphere, it was 

 possible to restore ductibility to the silver, so that the reshaping and 

 restoration of the vessel could be successfully carried out. 



PHYSICAL TECHNIQUES OF ANALYSIS 



The analysis of antiquities undertaken in order to provide the 

 archeologist with a knowledge of their composition (which can be 

 used to deduce information about techniques, date of production, and 

 provenance) is a major activity in museum laboratories. 



If a sufficiently large sample can be taken, the ordinary methods 

 of chemical — or, more often, microchemical — analysis can be used. 

 However, very often the objects are so precious that the permissible 

 sample may be of the order of only a few milligrams, or, indeed, it 

 may not be possible to take any sample at all. For this reason, 

 physical tecliniques of analysis of increasing refinement are now being 

 extensively employed. Whenever a small sample can be taken, the 

 well-known tecliniques of spectrochemical analysis and X-ray diffrac- 

 tion analysis can be used. By these means, results have been obtained 

 which are of considerable value to the archeologist. Thus, for exam- 

 ple, in a recent study of Romano-British and Mycenaean pottery, 

 Richards and Hartley [12] used spectrochemical analysis to demon- 

 strate a link between a given pattern of minor impurities and a par- 

 ticular geographical origin. Also, the same teclmique is being 

 extensively used to determine the composition of ancient bronzes in 

 an attempt to indicate the sources and trade-routes of the contempo- 

 rary supply of metal. Recently a series of no less than 438 analyses 

 was carried out by Brown and Blin-Stoyle [13] on British middle 

 and late Bronze Age material in order to provide results available for 

 statistical examination. 



The technique of X-ray diffraction analysis is used to obtain infor- 

 mation about the chemical composition of antiquities and the nature 

 of corrosion products. One example, which clearly shows the value 

 of this technique, is the interesting study which has been recently 

 carried out by Turner and Rooksby [14] in order to determine the 

 chemical nature of materials used as opacifiers in ancient opal glass 

 made over a period of 3,400 years. The evidence thus obtained 

 indicated the different techniques of manufacture used at various 

 periods. 



With more precious objects such as Chinese porcelain or valuable 

 coins, it is usually not possible to take a sample for analysis, and it is, 

 therefore, necessary to use methods of analysis which are completely 



