Percival,Vickers & Co. Ltd: The Archaeology of a 19th-Century Manchester Flint Glass Works

Abstract

The Percival, Vickers & Co. Ltd glass works was amongst the largest glass manufactories in Manchester, and formed one of a regionally significant group of 19th-century glass works in the Ancoats district of the city. All of these works have since been demolished, and the paucity of surviving physical and documentary evidence is in stark contrast to the former importance of the city's glass-making industry. The Percival, Vickers site was recently subjected to a detailed archaeological investigation ahead of redevelopment, providing a unique opportunity to study the buried remains of a 19th-century glass works. In particular, variation in the design of the furnaces provided evidence for the technological development of the later 19th century, which has not otherwise been documented. Additionally, some 110kg of glass fragments recovered from the site furnished important evidence for the composition of 19th-century glass, although the results are beyond the scope of the present paper, which focuses on the documented history, structural, and technological elements of the site.     

CHARACTERIZATION AND PROVENANCE OF LATE ANTIQUE WINDOW GLASS FROM THE PETRA CHURCH IN JORDAN*

Fifth‐ to seventh‐century window glass fragments from the Petra Church in Jordan were analysed by EPMA and spectrophotometry to characterize their optical properties and chemical composition. The objective of this study was to determine the provenance of the raw glass and the secondary production procedures of the window‐panes. Judging from the material evidence, both the crown window‐panes and possibly the rectangular samples were produced through glass‐blowing techniques. The chemical data show that the assemblage forms a homogeneous group of soda–lime–silica glass of the Levantine I type. The green glass, however, has higher silica and lower soda contents than the aqua‐blue fragments. The composition of one sample suggested the recycling of Roman glass. Our results confirm the trade of glass between the Levantine coast and Petra during Late Antiquity. No colouring agents other than iron were detected. Spectrophotometry confirmed the presence of iron and showed that the window fragments absorbed light relatively equally across the visible part of the spectrum. The windows thus seem to have provided an almost colourless illumination for the sacred interior.     

ARCHAEOMETRICAL STUDIES OF ROMAN IMPERIAL AGE GLASS FROM CANTON TICINO*

An archaeometrical study of Roman glass finds recovered in the Canton Ticino area was performed after the finding of traces of possible glass‐working at Muralto near Locarno. The aim of this work is to provide chemical characterization of these glass varieties—never analysed before—and to compare the results obtained with those for glass of the same period coming from other sites (Aquileia, Augusta Praetoria and Modena). The chemical data shows that the composition of Canton Ticino glass remained the same from the first to the fourth century ad . Moreover, the large amounts of Sb used as a decolouring agent in these samples represents a peculiar trait.     

ROMAN AND MEDIEVAL GLASS FROM THE ITALIAN AREA: BULK CHARACTERIZATION AND RELATIONSHIPS WITH PRODUCTION TECHNOLOGIES*

Compositional investigations were performed on 81 Roman and medieval glass fragments (first to 14th centuries ad ) from four Italian archaeological sites. The samples were soda–lime–silica in composition, with natron as flux for the Roman and early medieval glass samples, and with plant ash as flux for the late medieval ones. The varying colours are due to the differing FeO, Fe ₂ O ₃ , MnO and Sb ₂ O ₃ contents. Hierarchical cluster analysis identified six compositional groups related to age, which were compared with those found in the literature. In this way, technological continuity from the Roman to the early medieval period and the appearance of plant ash technology in the ninth century, 200 years in advance of the period previously believed, are demonstrated.     

SCIENTIFIC ANALYSIS OF SEVENTH‐CENTURY GLASS FRAGMENTS FROM THE CRYPTA BALBI IN ROME*

Inductively coupled plasma emission spectroscopy, reflectance spectroscopy and X‐ray diffraction were used to study seventh‐century AD glass fragments from the Crypta Balbi in Rome. All the samples were found to be silica‐soda‐lime glasses. Iron determines the colour of blue‐green, green and yellow‐green transparent glasses; chemical composition suggests deliberate addition of iron and/or manganese in about half the samples. Copper was found as the main colourant in red, pale blue and blue‐green opaque fragments; elemental copper acts as an opacifier in red glass, and calcium antimonate in white, pale blue and blue‐green glasses. Detection of antimony in transparent fragments suggests recycling of opaque mosaic tesserae.     

SCIENTIFIC ANALYSIS OF ROMAN GLASS FROM AUGUSTA PRAETORIA

Fifty-five fragments of Roman glass from Augusta Praetoria (Aosta, Italy) were analysed by inductively coupled plasma optical emission spectroscopy determining 15 elements (Si, Na, Ca, Al, Fe, Mg, Mn, Ti, Sr, Ba, Cr, Ni, Cu, Co and Pb) on dissolved samples; in addition, potassium was determined by flame atomic absorption spectroscopy. The analytical results indicate that all the fragments, with one exception, are silica-soda-lime glasses; (he exception is a potash glass. Cluster analysis was performed on the analytical data by accounting for either 14 (all the elements searched for but Ni and Pb) or eight elements (after further removal of Si, Fe, Mn, Cr, Cu and Co from the data set). The results obtained indicate that, once colouring and decolouring agents are removed, the classification of the glasses seems to be mainly determined by chronology; separate groups within coeval fragments may indicate different provenances.     

A STUDY OF GLASS BEADS FROM THE HALLSTATT C–D FROM SOUTHWESTERN POLAND: IMPLICATIONS FOR GLASS TECHNOLOGY AND PROVENANCE*

Eighty‐one samples taken from 68 glass beads found in southwestern Poland on sites of the Lusatian culture from the Hallstatt C and Hallstatt D subphases were analysed by EPMA. A subsample of 18 of these were additionally subjected to analysis by means of LA–ICP–MS in order to validate the results obtained by EPMA. Some glass was made using mineral soda and some using plant ash rich in sodium. Both high‐magnesium soda–lime glass (HMG) and low‐magnesium soda–lime glass (LMG) were identified. A large number of samples are characterized by low MgO content and medium K₂O content (LMMK glass), combined with low concentrations of CaO and high Fe₂O₃ and Al₂O₃. All the LMMK glass contains numerous silica crystals and inclusions composed of a number of elements (most frequently Cu, Co, Sb, As, Ag, Ni and Fe). The LMMK glass was presumably made in Europe during the Hallstatt C.     

MOSAIC GLASS FROM ST PETER'S,ROME: MANUFACTURING TECHNIQUES AND RAW MATERIALS EMPLOYED IN LATE 16TH‐CENTURY ITALIAN OPAQUE GLASS

A recent restoration of late 16th‐century mosaics in one of the vaults beneath the dome of St Peter's Basilica in Rome allowed sampling and analysis of a group of glass tesserae. The aim of this work is the characterization of opaque coloured glasses possibly produced in Rome. The characteristics of the glass from St Peter's were compared with those of Venetian and Tuscan production, in order to assess possible common origins. Chemical analysis of 30 samples was carried out by electron microprobe, while the nature and morphology of opacifiers were determined by X‐ray diffraction and scanning electron microscopy. Almost all the opaque samples were characterized by the presence of SnO₂ crystals. In addition, depending on the colour of the glass, other crystalline phases were identified: lead‐tin oxide (PbSnO₃) in yellow glass, cuprite (Cu₂O) in orange glass and two calcium‐tin silicates with different stoichiometry (CaSnSiO₅ and Ca₃SnSi₂O₉) in the green‐yellow variety. A frame of reference for identifying raw materials and glass‐making techniques is provided by textual sources, here examined in comparison with the compositional characteristics of the tesserae from St Peter's.     

BYZANTINE OPAQUE RED GLASS TESSERAE FROM BEIT SHEAN,ISRAEL*

This paper presents the results of analysis of Byzantine opaque red glass tesserae derived from three separate locations in the ancient city of Beit Shean, Israel. Investigation proceeded using reflective light microscopy, energy dispersive X‐ray fluorescence and energy dispersive scanning electron microscopy. The glass matrix of the tesserae was found to be heterogeneous, with many inclusions. Similarities and differences between tesserae from the two mosaics are examined and discussed. Implications for locale of manufacture and production techniques are considered. Comparisons between the three locations led to conclusions about the use of the tunnel as a storage site and the implications of this for future research on mosaics.     

THE ANALYSIS OF SECOND MILLENNIUM GLASS FROM EGYPT AND MESOPOTAMIA,PART 1: NEW WDS ANALYSES*

A recent analytical study by SEM–WDS was carried out on 226 glasses from the Late Bronze Age, analysing each of the glasses for a total of at least 22 elements, the largest such analytical study conducted on these glasses. The aim of the analysis was first to identify which elements were brought in with each of the raw materials and, second, to accurately characterize those raw materials. Since different glassmaking sites in Egypt and the Near East would probably use at least some local raw materials and these raw materials will vary slightly from site to site, this has potential for provenancing the glass. Analysis showed new patterns in the compositions of glass from the various sites and led to new conclusions about the supply of raw materials and personnel for the glass workshops. This forms the basis for further work by LA–ICPMS to be presented in part 2 of this paper.     

STAINING OF ARCHAEOLOGICAL GLASS FROM MANGANESE‐RICH ENVIRONMENTS*

It has been suggested that both internal and external sources of manganese may produce the black or brown staining that often occurs in buried archaeological glass. Modern potash glass of a manganese‐free medieval composition was scratched, etched and immersed in an aqueous solution containing dissolved manganese. After several weeks, immersion samples were sectioned and examined by SEM–EDX. Manganese was shown to be present in fissures and cracks within in the glass, where alkali had been depleted. Manganese from an external source is capable of blackening buried medieval potash glass.     

ARCHAEOLOGICAL VOLCANIC GLASS FROM THE SITE OF ROCCHICELLA (SICILY,ITALY)*

The site of Rocchicella, near Catania, in eastern Sicily, has yielded important archaeological evidence from prehistoric times to the Middle Ages. Extensive archaeological investigations of cultural layers dating from the Palaeo‐Mesolithic to the Copper Age have recently been undertaken, and volcanic glass, mainly obsidian, has been collected in the course of excavation. To determine the provenance of this volcanic glass, a non‐destructive elemental analysis was carried out to measure the concentration of characteristic trace elements. The analysis was carried out using a new XRF spectrometer equipped with a beam stability controller and a quantitative method developed at the LANDIS laboratory of the INFN–CNR Institutes of Catania. In addition to the obsidian, it was demonstrated for the first time that a local vitreous material similar to obsidian, but displaying a completely different composition, was used during all the investigated periods. This material was identified as a basaltic glass, characterized by a superficial product of devitrification called palagonite. Analysis of the obsidians has led to the identification of the island of Lipari as the provenance source. High‐ and low‐power microscopic use‐wear analysis on obsidian and basaltic glass artefacts indicated that soft wood and plant matter might have been processed at the site.     

CHEMICAL ANALYSIS OF COPPER ALLOY TRADE METAL FROM A POST-CONTACT HURON SITE IN ONTARIO,CANADA

Fifty-three copper-based metal fragments, recovered from the Robitaille site in southcentral Ontario, were analysed by neutron activation to establish their chemical make-up and to sort them by their trace elemental chemistries. Three different European copper samples, one brassy copper and 48 brass samples with five different chemistries were found. As few as eight trading actions may account for all of the recovered European metal fragments.     

COLOURED OPAQUE GLASS BEADS OF THE MEROVINGIANS*

Monochrome coloured opaque glass beads of the Merovingians have been examined by different analytical methods. A large number of mostly unprepared beads have been measured by X‐ray fluorescence analysis. X‐ray diffraction was used for the identification of the crystalline colouring and opacifying pigments, and electron probe micro‐analysis as well as scanning electron microscopy were applied to study the composition and the microstructure of a white, brown, green, orange and yellow glass bead. After subtracting the content of colouring oxides of the glass beads and normalizing the residual values to 100% an identical soda‐lime‐glass matrix was obtained. The origin of the colouring metal oxides is discussed.     

STONES FROM MEDIEVAL GLASSMAKING: A SUITABLE WASTE PRODUCT FOR RECONSTRUCTING AN EARLY STAGE OF THE MELTING PROCESS IN THE MT LECCO GLASS FACTORY*

The Mt Lecco glass factory was one of the most important production centres in Liguria (Italy) during the 14th and 15th centuries. Archaeological evidence indicates that the whole production cycle took place here. During the glassworking process, production defects such as ‘stones’ were identified and discarded. Stones are partially melted, glass‐coated relics of raw materials or fragments of crucible. The study of the microtexture of stones together with microprobe analyses of phases provides a key for understanding the glassmaking procedure carried out in the Mt Lecco glass factory. The melting rate can be inferred from the compositional variability of glass, which suggests fractional melting of the batch. Glass composition indicates that the Mt Lecco production was a mixed‐alkali one, probably made of quartz‐bearing material as vitrifying agents, plant ashes as fluxing agents and dolomitic limestones as stabilizing agents.     

THE X-RAY FLUORESCENCE ANALYSIS OF MEDIEVAL DURABLE BLUE SODA GLASS FROM YORK MINSTER

The chemical composition of durable blue soda glass dated to the twelfth century from York Minster, both from the windows and excavated within this building, has been determined by X-ray fluorescence spectrometry. The analytical data are compared with results from specimens of similar date, colour and composition from Old Sarum and Winchester in England and Chartres Cathedral in France. Multivariate analysis of the compositional data reveals that this unusual blue glass may be classified into three principal groups the possible origins of which are discussed. The specimens in one of them are of particular technological interest since they may have been produced from Roman, or slightly later, glass in a manner referred to by the twelfth century monk Theophilus. It is shown that medieval stained glass of the soda-lime-silicate type, vis-a-vis that containing potash as the predominant alkali, is not as rare as hitherto believed.     

THE TRADING OF ANCIENT GLASS BEADS: NEW ANALYTICAL DATA FROM SOUTH ASIAN AND EAST AFRICAN SODA–ALUMINA GLASS BEADS*

The occurrence of similar glass beads at archaeological sites in Africa and Asia bears witness to the trade relationship between the two continents. This paper reports elemental analysis results from a recent in‐depth laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) study of a group of archaeological glass beads with a specific alumina‐rich composition from East Africa, India and Sri Lanka. Based on the concentrations of the trace elements, two different subgroups were identified. One subgroup occurs at early periods (fourth century bce to fifth century ace ) in South India and Sri Lanka. The second subgroup appears at later dates in Africa and was identified at different Kenyan sites dated from the ninth to the 19th century ace , and at the contemporaneous site of Chaul in western India.     

MEDIEVAL GLASS FROM ROCCA DI ASOLO (NORTHERN ITALY): AN ARCHAEOMETRIC STUDY

An archaeometric study was performed on 33 medieval glass samples from Rocca di Asolo (northern Italy), in order to study the raw materials employed in their production, identify analogies with medieval glass from the Mediterranean area and possible relationships between chemical composition and type and/or production technique, contextualize the various phases of the site and extend data on Italian medieval glass. The samples are soda–lime–silica in composition, with natron as flux for early medieval glasses and soda ash for the high and late medieval ones. Compositional groups were identified, consistent with the major compositional groups identified in the western Mediterranean during the first millennium AD . In particular, Asolo natron glass is consistent with the HIMT group and recycled Roman glass; soda ash glass was produced with the same type of flux (Levantine ash) but a different silica source (siliceous pebbles, and more or less pure sand). Cobalt was the colouring agent used to obtain blue glass; analytical data indicate that at least two different sources of Co were exploited during the late medieval period. Some data, analytical and historical, suggest a Venetian provenance for the high/late medieval glass and a relationship between type of object (beaker or bottle) and chemical composition.     

COLOUR ATTRIBUTES OF MEDIEVAL WINDOW PANES: ELECTRON PARAMAGNETIC RESONANCE AND PROBE MICROANALYSES ON STAINED GLASS WINDOWS FROM PAVIA CARTHUSIAN MONASTERY*

Stained glass windows from the Carthusian Monastery of Pavia, dating back to the 15th century, were studied by combining two analytical techniques: electron probe micro‐analysis (EPMA) and electron paramagnetic resonance (EPR). Chemical compositions and oxidation states of the transition ions, present as minor elements, were investigated by EPMA and EPR, respectively, in order to ascertain the role played by chromophorous ions in the glass coloration. The investigated glass can be defined as K–Ca glass, and the panes with red, green and blue colours were produced using flashing techniques.     

ARCHAEOMETRICAL INVESTIGATION OF SICILIAN EARLY BYZANTINE GLASS: CHEMICAL AND SPECTROSCOPIC DATA*

A series of early Byzantine glasses, recovered in Ganzirri (Sicily, Italy), was analysed for major, minor and trace elements. All the analysed fragments were found to be natron-based silica–lime glass. Concerning minor and trace elements, the samples can be divided into two groups: glass with high Fe, Ti and Mn contents ( HIMT glass) and glass with low levels of Fe, Ti and Mn. These results, strictly in agreement with literature data for glass of the Mediterranean region, can be interpreted as a consequence of the wide trade network established in this region and of the intense circulation of raw glass and artefacts from different Mediterranean areas. X-ray absorption spectroscopy studies at Fe and Mn K-edges, performed on HIMT glass, indicate that Fe is in the oxidized form while Mn is in the reduced form.