CONSERVATION OF ANTIQUITIES — WERNER 601 



nondestructive. In this field the work being done by Hall and his 

 coworkers of the Oxford Archaeological Kesearch Laboratory is of 

 outstanding importance. They have succeeded in adapting techniques 

 of X-ray fluorescent analysis and neutron activation analysis to the 

 examination of antiquities. The former teclmique is admirable for 

 the analysis of the surface of an object; it is rapidly carried out so 

 that a large number of samples can be analyzed in a short time and it 

 is entirely nondestructive. A striking example of the manner in 

 which this teclinique can be used to reveal important information has 

 recently been published by Young [15]. The problem was to find a 

 means of distinguishing between imported cobalt and native cobalt 

 ores used in making the blue pigment on "blue and white" Chinese 

 porcelain. The imported cobalt ore from Persia was known to be free 

 from manganese, whereas the cobalt ores occurring in China contained 

 a high proportion of manganese. By measuring in less than 20 hours 

 the ratio of manganese to cobalt in the blue pigment on some 80 

 pieces of porcelain, he obtained results which told a significant story, 

 namely, that imported ores were used from the 14th century until the 

 end of the 16th century, and that native ore did not start to be used 

 until the beginning of the 15th century. 



The technique of X-ray fluorescence analysis is confined to the ex- 

 amination of the actual surface layers, and, therefore, with respect 

 to metal antiquities, the results may be misleading because of surface 

 enrichment or the presence of corrosion products. With such, the 

 technique of neutron activation followed by gamma-ray spectrom- 

 etry has to be employed. This method has, for example, shown its 

 value in the analysis of trace elements in Greek silver coins [16] and 

 in ancient ceramic objects [17] with a view to obtaining analytical 

 information which could be used to establish a link between a given 

 pattern of impurities and a particular location for the manufacture 

 of the objects. 



Finally, mention must be made of the latest addition to the arma- 

 ment of physical techniques of analysis which have very recently been 

 applied to the study of antiquities. This is the electron beam micro- 

 probe analyzer. The unique feature of this instrument is the fact 

 that the electron beam can be focused very sharply on an area as small 

 as two microns in diameter. This means that it is possible to perfonn 

 a chemical analysis of objects too small to be clearly seen by the 

 unaided eye. For this reason. Brill and Moll [18] used this technique 

 in their recent study of ancient glass whereby it was possible to carry 

 out a quantitative analysis of the individual layers in Roman mille- 

 fiori glass, to determine the chemical nature of occlusions in glass, and 

 to examine the products formed as a weathering crust on ancient glass. 

 Such refined analysis was only possible by this technique. 



