Attribution Enhanced: an SEM/EDS - LA-ICP-MS Investigation of a Suspected Mid-18Th-Century Wistarburgh Glass Globular Bottle
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Attribution Enhanced: An SEM/EDS - LA-ICP-MS Investigation of a Suspected Mid-18th-Century Wistarburgh Glass Globular Bottle J. Victor Owen, Patrick Cruise, John D. Greenough, and Joseph Petrus ABSTRACT works operating in the Mid-Atlantic states during the 18th century. The data are compared with an analytical database The Wistarburgh glassworks (Alloway, New Jersey, (Greenough and Owen 2016) for 42 samples of this glass. ca. 1739–1782) was the first commercially successful glass The results support a Wistarburgh origin for this artifact. manufactory in what is now the United States. It mostly produced pane glass and bottles, the latter with a distinc- Sample Description tive yellowish green color. Analyzed Wistarburgh bottle glass has calcium-rich compositions, but so too does some The analyzed sample is a yellow-olive green glass, thick- of the glass produced by other prominent 18th-century walled, globular (shaft and globe) bottle with an elongated, Germanic American glass manufacturers on the eastern conical neck and a sheared lip (Figure 1). Although its color seaboard. Distinguishing between the wares originating at closely resembles bottle glass generally attributed to the these factories has traditionally relied on aesthetic criteria, Wistarburgh factory, and more specifically that of a seal but compositional data, particularly trace elements, pro- bottle in the Corning Museum of Glass marked “RW” (evi- vide an objective means of identifying them. dently for Richard Wistar, a proprietor of the glassworks), Compositional data for an intact, blown glass globular its globular form is highly unusual. The “RW”-marked seal bottle suspected to have been made at Alloway are consis- bottle notwithstanding, most Wistarburgh bottles have flat- tent with a Wistarburgh origin for this artifact. Of the 46 tened sides; these are the so-called chestnut bottles. components determined, phosphorus (P), zirconium (Zr), The glass from which the globular bottle described here niobium (Nb), thorium (Th), scandium (Sc), lead (Pb), was made contains numerous tiny seed bubbles; larger air silicon (Si), potassium (K), vanadium (V), and chromium pockets are concentrated near its outward flaring top. The (Cr) best distinguish the products of this glassworks from bottle has an unground pontil mark from which particles other prominent 18th-century Germanic American glass were removed for chemical analysis. Its base shows con- for which analytical data are available. Based on the de- siderable wear, more so than the “RW” bottle. The bottle is piction of similar bottles in contemporary paintings, this 13.3 cm (5.2 in.) high, with a maximum diameter of 9.5 cm form appears to date to the early years of this glassworks, (3.7 in.). Similar bottles were produced by several 18th-cen- and may in part predate the more familiar chestnut bottles tury American glassworks (McKearin and Wilson 1976:plate commonly attributed to Wistarburgh. 51, #6), but they are much less common than chestnut bot- tles. The sheared lip of the bottle differs from the rolled lip Introduction typical of chestnut bottles (and the “RW” bottle) produced at the Wistarburgh glassworks (Marschell 2007). However, Compositional data are increasingly being used to authen- its distinctive color closely resembles much of the bottle ticate various artifacts made of various types of media, glass recovered from the Wistarburgh factory site, as well including porcelain, glass, alloys, and precious metals. as intact bottles attributed to this glassworks. Furthermore, Analytical data provide a degree of objectivity that supple- its glass contains “gall,” a whitish yellow substance caused as ments subjective assessments made using aesthetic criteria. particulate grains breaking away from glass furnace walls This study presents major, minor, and high-precision trace become embedded within molten glass. The presence of gall element data for a blown glass globular bottle suspected to is diagnostic of some Wistarburgh glass artifacts, particularly have originated at the Wistarburgh glassworks (ca. 1739– around their pontil marks (Historical American Glass n.d.), 1782), one of three important Germanic American glass- but is not unique to the products of this factory. TECHNICAL BRIEFS IN HISTORICAL ARCHAEOLOGY, 2016, 10: 1–8 ATTRIBUTION ENHANCED: AN SEM/EDS-LA-ICP-MS INVESTIGATION OF A SUSPECTED MID-18TH-CENTURY WISTARBURGH GLASS GLOBULAR BOTTLE Figure 1. Photographs of the analyzed globular bottle: (left) overview (note the sheared, rather than rolled, lip); (right) base showing pontil mark (note wear). The bottle is 13.3 cm (5.2 in.) tall. (Photo by Patrick Cruise, 2015.) History own son briefly operated the glassworks until its closure in 1782. The Wistarburgh glassworks produced flat glass, The three most famous American glassworks that oper- bottles, a variety of vessels, and, famously, globes for the ated on the eastern seaboard during the 18th century electrostatic machines that Benjamin Franklin used for were founded by German immigrants: Caspar Wistar, scientific research. John Frederick Amelung, and Heinrich Wilhelm Stiegel. Heinrich Stiegel established a glassworks in Manheim, The backgrounds of these individuals and the history of Pennsylvania, making flat glass and bottles. Convinced their enterprises have been described by numerous authors he could produce higher quality glass, he replaced the (Palmer 1976, 1989a, 1989b; Lanmon et al. 1991; Bigelow Manheim factory in 1770, making the furnaces himself. 2012), so are not repeated in detail here. He succeeded in making exemplary glass vessels, but Wistar established the glassworks that bears his name, none are signed. Stiegel’s advertisements, however, show Wistarburgh, in Alloway, New Jersey, in 1739. This area that his factory produced tableware, some of which was has abundant silica sand (typically >98 wt.% SiO2) es- cut and engraved. This colorless glass has potash-lead sential for the production of good-quality glass, clay to compositions, which contrast with the green soda-lime make firing crucibles, and, at the time, abundant wood glass used to make flat glass and bottles. The factory to fire glass furnaces and to make potash commonly used ceased operation in 1774. as a flux to help melt glass batches. Caspar’s son Richard In 1784 John Frederick Amelung established the com- took over the glassworks when the elder Wistar died in munity of New Bremen, Maryland, and a glassworks near 1752. He operated the factory for 29 years, whereupon his Frederick, Maryland. The New Bremen factory acquired 2 TECHNICAL BRIEFS IN HISTORICAL ARCHAEOLOGY J. VICTOR OWEN ET AL. equipment from a nearby glassworks founded by former Table 1. Composition of the Globular Glass Bottle, Compounds. employees of Stiegel’s Manheim enterprise. The New Symbol Name wt% Bremen glassworks produced flat glass, green glass bottles, SiO2 silicon dioxide 65.11 and, eventually, colorless glass to make tableware, some TiO titanium dioxide 0.27 of which was elaborately engraved. This factory survived 2 Al2O3 aluminum oxide 2.36 until ca. 1795, whereupon the glassworkers migrated to FeOt iron oxide (total Fe as FeO) 0.89 Baltimore, Philadelphia, and elsewhere. MnO manganese oxide 0.63 MgO magnesium oxide 1.67 Analytical Methods CaO calcium oxide 22.74 Na2O sodium oxide 2.91 The major and minor element composition of the bottle K2O potassium oxide 2.3 was determined using an LEO 1450VP scanning electron P2O5 phosphorus pentoxide 0.78 microscope (SEM) operated with a beam current of 20 kV, SO3 Sulfur trioxide 0.05 and equipped with an Oxford Instrument INCA X-max Total 99.71 80 mm2 silicon drift EDS detector. Trace elements were determined by laser ablation Table 2. Composition of the Globular Glass Bottle, Elements. inductively coupled plasma mass spectrometry (LA-ICP- MS). This method uses a laser beam focused on the surface Symbol Name ppm of the medium being analyzed to generate minute particles Rb rubidium 22.14 Cs cesium 0.25 that are then transported to the excitation source of the Sr strontium 957.40 ICP-MS for digestion and ionization. The excited ions B boron 123.62 are then fed through the mass spectrometer for analysis. Ba barium 2295.40 Detection limits are very low, and analytical data pro- La lanthanum 84.00 Ce cerium 51.60 duced by this method are highly precise. The method is Pr praseodymium 12.80 also minimally destructive: analysis can be undertaken on Nd neodymium 47.40 a tiny (<1 mm) flake of sample. In the case of blown glass, Sm samarium 7.70 this is best removed from near the pontil mark. The abla- Eu europium 1.50 Gd gadolinium 6.80 tion procedure leaves a tunnel a few tens of microns wide Tb terbium 0.90 through the irradiated sample. Dy dysprosium 5.30 The equipment employed for the present investigation Ho holmium 1.00 Er erbium 2.70 uses a Resonetics RESOlution M-50 193 nm ArF excimer Tm thulium 0.30 laser ablation system coupled to a Thermo X Series II quad- Yb ytterbium 2.10 rupole mass spectrometer. Ten analyses consisting of 30 Lu lutetium 0.30 seconds of washout/background followed by 30 seconds Y yttrium 35.23 Zr zirconium 182.62 of ablation were made with a spot size of 36 μm, laser rep- Nb niobium 5.09 etition rate of 6 Hz, and a fluence of 6 J/cm2. Data were Ta tantalum 0.36 processed with Iolite software (Paton et al. 2011) using Th thorium 3.02 NIST 612 glass as an external reference and the silicon con- U uranium 1.10 Sc scandium 5.77 centrations determined by EDS as an internal reference. V vanadium 17.79 Cr chromium 17.23 Results Co cobalt 4.60 Ni nickel 25.47 Cu copper 20.07 The globular bottle consists of potassium-bearing, calcium- Pb lead (plumbum) 855.50 As arsenic 23.30 rich (CaO/(CaO+Na2O+K2O) = 0.81) soda-lime glass Sn tin (stannum) 19.90 (Tables 1, 2).