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Some Miniature Glass Plaques From Fort Shalmaneser, Nimrud: Part II: Laboratory Studies

Published online by Cambridge University Press:  07 August 2014

Robert H. Brill
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Extract

As part of a long-term research project consisting of scientific investigations of the various types of glasses excavated at Nimrud, the author of this report undertook a study of three of the nine painted glass plaques included among the finds at Fort Shalmaneser. This research is being conducted in co-operation with Mr. J. J. Orchard who, in Part I of this paper, has illustrated the plaques and discussed them in detail. As is the case with so many Mesopotamian glasses, the objects involved here are very heavily weathered, which complicated matters greatly. Such objects are not only extremely fragile and difficult to handle, but also the original glass— where any remains—is completely obscured by decomposition products. Moreover, in this instance, because so few of these plaques have been found, it was not possible to remove samples for all of the experiments which might be expected to yield useful information. Nevertheless, despite these limitations, several interesting findings have come out of our experiments.

Type
Research Article
Information
IRAQ , Volume 40 , Issue 1 , Spring 1978 , pp. 23 - 39
Copyright
Copyright © The British Institute for the Study of Iraq 1978

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References

1 The author is much indebted to Mr. Orchard for his indispensable assistance, and to Professor Sir Max Mallowan for granting permission to work with these objects.

2 For a comprehensive discussion on the analysis and examination of ancient glasses see: Brill, R. H., “The Scientific Investigation of Ancient Glasses”, Proceedings, Eighth International Congress on Glass (1969), 47–68Google Scholar. (The Congress was held in London in 1968.) For details on the lead-isotope and oxygen-isotope studies, refer to the references cited in note 17 of this paper.

3 The examination of ND 7,638 was made under conditions which were far from ideal owing to the December, 1970, power blackouts which were then in effect in London. Consequently, the author has less confidence in his observations on this plaque. We thank Miss Mavis Bimson of the British Museum and Mrs. Prudence Harper and Miss Kate Lefferts of the Metropolitan Museum of Art for their assistance while making the examinations.

4 It is doubtful that the plaques were moulded by transferring already molten glass into the moulds, but we cannot offer experimental evidence to support this. There are, in fact, some small Egyptian amulets which do seem to have been moulded that way. It is somewhat awkward to transfer small quantities of molten glass from a crucible into tiny moulds, especially when limited to the use of relatively low temperatures at which the glass is appreciably more viscous than at higher temperatures and sets up very rapidly.

5 Dr. Harden has expressed a preference for the latter in the case of ND 7,638. Harden, D., Masterpieces of Glass (The British Museum, London, 1968), 29Google Scholar.

6 Some readers will be familiar with the technique of dating pieces of ancient glass by counting the individual layers within weathering crusts. No attempt was made to count the layers in this fragment, because it was so badly disintegrated, but microscopic examination disclosed that the individual layers are about 0·7 microns in thickness. Since the intact weathering crust (on one side of the remaining wafer) was probably about 1·4 mm thick, this would have accommodated of the order of 2,000 layers—not far from a rate of formation of one layer per year of burial. A layer-counting experiment was attempted earlier by the author on a fragment of Nimrud glass given to him by the late Professor W. E. S. Turner. The sample proved unsuitable, because no unweathered glass remained inside it. Further attempts will be made in the near future. For additional information on this dating technique see: Brill, R. H. and Hood, H. P., “A New Method for Dating Ancient Glass”, Nature 189, No. 4758 (1961), 12–14CrossRefGoogle Scholar; R. H. Brill, op. cit. (1969), 65–66.

7 For information on the interpretation of such evidence see: R. H. Brill, op. cit. (1969), 57–58; and Brill, R. H., “An Inlaid Glass Plate in Athens, Part II”, Journal of Glass Studies 4 (1962), 37–47Google Scholar.

8 We especially looked for traces of gold on the plaques but found none.

9 Actually certain glasses, primarily those containing manganese, may be discoloured or solarized through the X-irradiation used for this type of analysis. Because of the nature of this sample (we doubted that it contained much manganese), it was considered unlikely that any solarization would occur; and if it did, such discolouration would have been inconsequential on the small flake of weathered glass used for the analyses. Actually no discolouration did occur. This analysis was carried out by D. A. Stephenson and D. L. Kimble of Corning Glass Works.

10 The spectrographic analyses and the quantitative analyses reported below were carried out by C. A. Jedlicka and R. H. Bell of Lucius Pitkin, Inc., New York.

11 The formulas discussed throughout the text are the oxides of the following elements: Na2O, sodium; K2O, potassium; CaO, calcium; MgO, magnesium; Al2O3, aluminium; PbO, lead; SiO2, silicon; Sb2O5, antimony.

12 For information on the composition of Mesopotamian glasses see: Brill, R. H., “The Chemical Interpretion of the Texts”, in Oppenheim, A. L., Barag, D., Saldern, A. von, and Brill, R. H., Glass and Glassmaking in Ancient Mesopotamia, An Edition of the Cuneiform Texts Which Contain Instructions for Glassmakers and A Catalogue of Surviving Objects (Corning, 1971)Google Scholar; and also R. H. Brill, op. cit. (1969), passim.

13 Sayre, E. V., Advances in Glass Technology, Part 2 (Plenum Press, New York, 1963), 263–282Google Scholar.

14 E. V. Sayre, op. cit.; R. H. Brill, unpublished analyses. See also A. von Saldern in Oppenheim et al., op. cit.

15 R. H. Brill, in Oppenheim et al., op. cit., passim; and R. H. Brill, op. cit. (1969), 58–60 and 62–63.

16 Unpublished analyses by the author.

17 Brill, R. H. and Wampler, J. M., “Isotope Studies of Ancient Lead”, AJA 71, (1967), 63–77Google Scholar; Brill, R. H. and Wampler, J. M., “Isotope Ratios in Archaeological Objects of Lead”, in Application of Science in Examination of Works of Art (Boston, 1965), 155–166Google Scholar; Brill, R. H., “Lead and Oxygen Isotopes in Ancient Objects”, in The Impact of the Natural Sciences on Archaeology (Oxford University Press, 1970), 143–164Google Scholar, (also reprinted in Phil. Trans. Roy. Soc. Lond. A. 269 (1970), 143–164)Google Scholar; Brill, R. H., Shields, W. R., and Wampler, J. M., “New Directions in Lead Isotope Research”, Application of Science in Examination of Works of Art (Boston Museum of Fine Arts, 1970), 73–83Google Scholar; Brill, R. H. and Shields, W. R., “Lead Isotopes in Ancient Coins”, Methods of Chemical and Metallurgical Investigation of Ancient Coinage, (Royal Numismatic Society, Special Publication No. 8, 1972)Google Scholar; and Brill, R. H., Barnes, I. L., and Adams, B., “Lead Isotopes in Some Ancient Egyptian Objects”, presented at the Second Cairo Solid State Conference, Cairo, Egypt, 04 1973Google Scholar.

18 There is also one stray specimen, an inlay of yellow opaque glass (Pb-429), which is markedly different from all the other Nimrud leads. It is of Type S which raises some tantalizing possibilities concerning its origin. See: R. H. Brill, op. cit., (1970), 153.

19 A third piece of lead (Pb-352) differs somewhat.

20 R. H. Brill, op. cit. (1969), 58–60.

21 Interestingly, just the reverse seems to be true of Pb-429, the stray yellow Nimrud specimen mentioned in note 18. It appears to be an import.

22 This research is being conducted in co-operation with Professor Robert Clayton and Mrs. Toshiko Mayeda of the Fermi Institute. Preliminary accounts have been published in R. H. Brill, op. cit., (1969), 63–64; and op. cit., (1970), 154–163.

23 R. H. Brill, op. cit. (1969), 56–57; Brill, R. H. and Moll, S., Recent Advances in Conservation (London, 1963), 145–151Google Scholar; and Brill, R. H. and Moll, S., Advances in Glass Technology, Part 2 (New York, 1963), 293–302Google Scholar; Brill, R. H., “Crizzling—A Problem in Glass Conservation”, presented at the 1975 Stockholm Congress, The International Institute for Conservation of Historic and Artistic Works, London 1975, pp. 121–134Google Scholar.

24 Sodium and potassium are usually almost completely removed from glasses by the weathering process, and magnesium and calcium may be substantially reduced. Concerning the copper, see discussion under Pigments.

25 Lead in the form of galena can be ruled out for two reasons. First, no greater amount of lead was present in the painted area than in the unpainted area; and secondly, no particles of galena could be seen by microscopic examination even though these would have been readily recognizable had they been present. Iron, although present, was ruled out as a pigment component because no difference in concentration could be seen between the two different regions.

26 This test was conducted by N. P. Gaboriault of Corning Glass Works.

27 A thorough treatment of this subject appears in Forbes, R. J., Studies in Ancient Technology, Vol. I (1955)Google Scholar.

28 The presence of white lead on these plaques would long antedate the known use of that substance. This is an argument against its being there, but at the same time, it is also a reason for not dismissing the possibility summarily, for very little information is available on the palette of pigments used by Mesopotamian artists and craftsmen. The earliest occurrence of white lead known to the author is in a Fayoum painting. Stout, G. L., Technical Studies in the Field of the Fine Arts I (1932), 86Google Scholar.

29 These examinations were carried out by Dr. Robert Feller of the Mellon Institute.