Pt.II-Studies of Ancient Glasses and Glass-making Processes
JSGT 1954 V38 T445-T156
Studies of Ancient Glasses and Glass-making Processes. Part II. The Composition, Weathering Characteristics and Historical Significance of Some Assyrian Glasses of the Eighth to Sixth Centuries BC from Nimrud
Among the objects found by Professor M. E. L. Mallowan during excavations at Nimrud in 1951 and 1952 were fragments of two glass bowls, those of one (I) being completely coated with dense weathering product giving the fragments a porcelain-like appearance, those of the other (II) having a translucent, faintly golden tinted mother-of-pearl coating which spalled off to disclose a bright yellowish green glass remarkably free from bubbles and containing, on analysis, 4·5% of adsorbed water. There were also fragments of two small vases, evidently prepared by the sand-core process, and thread decorated; and three large discs or cakes of glass, one 35 cm, the others about 16 cm, in diameter, two of turquoise blue (opal), the other of sealing-wax-red glass, but all three covered with grey and green weathering products. The analyses disclosed that all these glasses of eighth to sixth centuries BC were of complex composition, containing silica, lime, magnesia, soda (mainly), potash, alumina, iron oxide, titania and sulphate, with cupric oxide as the blue and cuprous oxide as the sealing-wax-red colorant and having a composition pattern, accordingly, very similar to that of the glasses of the Egyptian XVIIIth Dynasty, with one exception. This exception, very important, was that the sealing-wax-red glass contained 22·8% lead oxide, the earliest example recorded of a glass containing lead oxide as a major constituent. The translucent weathering product from bowl II showed, on analysis, that attack for 2700 years by water had leached out practically all the alkalis and seven-eighths of the lime and magnesia, leaving a relatively higher silica and a much higher alumina, iron and manganese oxides content. The golden iridescence was associated with the accumulation of iron oxide in the residual weathering product.
W. E. S. Turner
