AN INKY CONTROVERSY LIVES
COURTESY OF BEINECKE RARE BOOK AND MANUSCRIPT LIBRARY, YALE UNIVERSITY
A small but determined group of researchers again argues that the Vinland map is authentic. The 47-year-old controversy isn’t going away. REX GRAHAM
S
ince the Vinland map suddenly and mysteriously turned up in a Geneva bookstore in 1957, its faded lines have placed analytical chemists at the center of a raging debate over the authenticity of one of American history’s most intriguing documents. The drawing on an approximately 550-year-old parchment shows a large island in the western Atlantic in the general location of Canada, described on the map as “even having vines” and hence named Vinland. If authentic, the map would be the earliest known cartographic representation of America. Many analytical chemists are convinced the map is a fraud. But like an extinguished forest fire that flames anew with each fresh wind, the controversy rekindles itself—most recently in four letters in this journal (1–4). The map was also the subject of a talk at the American Chemical Society’s national meeting in August 2004. The linchpin in the skeptics’ case is Walter McCrone’s conclusion that anatase (TiO2) particles taken from the map could only have originated after 1917, from a commercially produced pigment (5 ). McCrone, a distinguished chem-
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ical microscopist who died in 2002 (see “Debunker of legends” on p 411 A), argued vehemently that the anatase particles found on the map, which he said could be distinguished from ground mineral anatase by their rounded shape and reasonably uniform size, were prima facie evidence that the map is a 20th-century forgery (Figure 1). However, other researchers contend that the map could have been drawn in the 15th century. Jacqueline S. Olin, a retired Smithsonian Institution chemist, says that she produced anatase crystals in a simulation of medieval ink-making using ilmenite (FeTiO3), a black mineral, as a starting material (4). In addition, Charles E. Weaver, an emeritus professor of geochemistry at the Georgia Institute of Technology, said that McCrone’s photographs of rounded anatase crystals (~50–500 nm diam) that were plucked from the Vinland map look strikingly similar in shape and size to anatase crystals that occur naturally in kaolin clays (6). “Kaolin is commonly used as a filler in inks,” says Weaver. “It could have been present in primitive inks to give it body.” (a)
(b)
(c)
(d)
(e)
(f)
FIGURE 1. (a–b) Particles of anatase from the Vinland map, viewed at 25,000, and precipitated anatase samples, viewed at (c) 50,000 and (d) 20,000. The bars represent 0.15 µm. (e) Fine and (f) course ground mineral anatase. All images adapted from Ref. 5.
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Over the years, McCrone and other researchers have vigorously rebutted these arguments, in some cases criticizing the reasoning of pro-authenticity scientists and calling for new experiments (1–3, 5, 7, 8). This acrimonious controversy even includes an argument about which methods are best suited to analyzing the map. Thomas Cahill and a group of researchers at the University of California, Davis, used particle-induced X-ray emission (PIXE) analysis to examine the parchment and the ink in 1987 (9). Their results, particularly their estimate of the amount of titanium in the ink, conflicted with McCrone’s findings. McCrone, however, argued that polarized light microscopy, X-ray diffraction, and other techniques were more appropriate for the task. Even now, the McCrone Research Institute website (www. mcri.org) laments the use of “good but inadequate and inappropriate” techniques to analyze the map.
Historical parameters Historical research thrives on controversy, particularly one involving a map with evidence of pre-Colombian exploration of America. The 27.8 40 cm beige parchment that philanthropist Paul Mellon donated to Yale University in 1965 may be the most studied document of its kind. “The map is requested scores of times a month, but access to it is very restricted for the sake of preserving it,” says Robert Babcock, curator of early books and manuscripts at Yale’s Beinecke Rare Book and Manuscript Library. The map was once regarded as evidence that the Viking Leif Eriksson had discovered and explored a fertile land west of Greenland in the 11th century. Three years after the Vinland map surfaced, a Norwegian team’s discovery of 11thcentury Norse ruins in Newfoundland bolstered that theory. To some, the ruins are proof that sailors from Iceland and Greenland had skillfully plied the North Atlantic farther west. Some historians have argued that the Roman Catholic Church, eager to expand its influence, wanted to assemble the best available maps of the farthest corners of the earth for the Council of Basle (Switzerland) in A.D. 1431–1449. It’s even conceivable, some say, that medieval cartographers traced the Vinland map to provide copies to Columbus and other explorers. Indeed, radiocarbon dating of the map’s parchment—which is not in dispute—indicates that it was made in A.D. 1411–1468, decades before Columbus’s historic voyage. The skeptics, however, argue that although the parchment is old, the drawing and text are recent. They point to subtle factual errors that a modern forger might have easily made, such as mention of the 12th-century Greenland bishop Eirik Gnupsson’s visit to Vinland and his return to Greenland “in most humble obedience to the will of his superiors,” according to one translation. Skeptics argue that the bishop didn’t report to Rome, as they say the map suggests. They also say that the outline of southern Greenland is much too accurate to be medieval, and they note that
hypothesis, Fischer sought to embarrass the anti-Catholic Nazis, who claimed that the Norse explored North America before other Europeans did. If the Nazis were to accept the map as authentic, according to the skeptics’ theory, they would have had to accept the distasteful conclusion that the Roman Catholic Church was also involved in exploring the New World.
COURTESY OF THOMAS CAHILL, UNIVERSITY OF CALIFORNIA, DAVIS
Greenland, which is drawn as an island, wasn’t discovered to be an island until the 19th century. However, in keeping with the cosmology of the Roman Catholic Church in the 15th century, maps of the earth were drawn on circular templates with oceans comprising the outer margins (10), and newly discovered distant lands were drawn as islands. On the Vinland map, the continents of Asia, Europe, and Africa are curved, suggesting that they were copied from traditional Catholic maps. The map also incorrectly shows Mount Sinai on the African side of the Red Sea, but that mistake is repeated in other maps of the late Middle Ages. For a convincing proof of forgery, historians have deferred to chemists to settle the debate on the basis of physical evidence involving the ink.
The yellow line McCrone’s research group performed a detailed survey of the map, and he reported his conclusion to a disappointed Yale in 1974 (11). McCrone’s unequivocal verdict, his trademark style, was a blow. The university later announced that the prized map might be a forgery. McCrone, who titled his popular public talks “What every good forger should know”, champi- FIGURE 2. A detail from the Vinland map showing the lack of registration oned a plausible, if complicated and technically de- in the yellow and black parts of the lines. manding, scenario for the map forgery. He argued that “the forger” picked the yellowish commercial anatase The missing anatase pigment to simulate the common yellowing over the cen- Cahill and Olin are among the few academic researchers to turies of ink lines drawn in the Middle Ages. (Later, a publicly dispute McCrone’s conclusions. Cahill is part of a process was developed to remove iron from anatase, and it team of University of California, Davis, specialists in ancient was then used as a base for white paint.) McCrone wrote manuscripts, printing, literature, microscopy, and chemistry that the anatase crystals removed from the map were of that has analyzed hundreds of medieval manuscripts. For the uniformly small diameter, averaging ~0.15 µm. “The larger Vinland map, they used PIXE spectroscopy to provide a quananatase particles can be resolved by PLM [polarized light titative and nondestructive analysis through the entire thickmicroscopy] as rounded crystalline shapes typical of com- ness of ink and parchment at a spatial resolution of 0.5 mm mercial titanium white. This product has been produced (9). They performed 159 multielemental PIXE analyses on only since 1917” (5). the map, including 33 in which they subtracted the content The forger purportedly first drew a yellow anatase line and of elements in clean parchment from adjacent areas with ink. then, after it had dried, drew a slightly thinner black line very They found titanium in 29 of the 33 ink lines—but at a carefully down the middle (Figure 2). McCrone claimed that maximum concentration of only 10 ng/cm2 (Figure 3). “A the forger flaked off ~90% of the black ink to enhance the an- roughly 230,000 ng/cm2 titanium concentration is necessary tique-yellow effect. “There was evidence of some wobble in for a visible line from anatase,” says Cahill, lead author on the placement of the black line relative to the yellow line and in, paper. Thus, the researchers disputed McCrone’s suggestion at least, one area (West Coast of England) the second (black) that the anatase had been used intentionally to create a yelline applied over the yellow line had ‘cut corners’ and missed low line. The group also detected potassium, phosphorous, its registration with the yellow line,” wrote McCrone. He sulfur, and chlorine in the yellow lines—a group of elements also concluded that the forger chipped black ink from the typically found in biological oils, such as linseed oil, which coast of England to disguise the less-than-perfect registration. medieval ink makers typically used as pigment “carriers”. McCrone’s conclusion and scenario were embraced by Cahill is quick to praise McCrone’s skills as a microscopist, those historians who were already skeptical of the map. They but adds, “Analytical chemistry has moved to the point that speculated that Josef Fischer, a German priest who special- you need replicates and quality assurances, which are very ized in mid-15th-century world maps, had created the Vin- difficult with the techniques that McCrone used, because land map sometime after 1917. According to this intricate it’s very hard to analyze those same samples twice.”
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Cahill scanned the Vinland map’s lines microscopically and saw, as McCrone’s assistant Anna Teetsov had, a few crystals ~50–60 µm in diameter surrounded by black material. (Failing eyesight prevented McCrone from taking the samples himself, but Teetsov had no trouble finding ink flakes in 29 locations large enough to pluck with a fine-tipped tungsten needle.)
sis of the map’s broad lines with such a fine-tipped probe essentially led them to focus arbitrarily on a few spots.
Giving the ink “bite”
Medieval ink makers were creative alchemists who jealously guarded their recipes. Cahill and others say medieval inks usually contained both carbon black and linseed oil. To keep that runny mixture from quickly separating on parchment, various black powders were added to the emulsion, providing “bite” and yielding crisp black lines. Cahill says Johannes Gutenberg is known to have used a biting ingredient from ~1440 to get his ink to stick to his moveable type. The PIXE results indicate to Cahill that the third ingredient in the ink of the Vinland map was a black powder containing titanium, iron, copper, and zinc—with titanium the most prevalent of the four elements. Likewise, the anatase found in kaolin clays (Figure 4) contains ~95% titanium and ~5% iron, according to Paul Schroeder, an associate professor of geology at the University of Georgia (12). And Weaver says that Cahill’s elemental analysis of the map’s ink is consistent with the possibility that it was formulated with anatase-containing clay. Members of Cahill’s research team have found similar elemenFIGURE 3. Titanium levels at various points on the Vinland map, as determined by particle2 tal profiles in the inks of other auinduced X-ray emission analysis. The values are in ng/cm . (Adapted from Ref. 9.) thenticated medieval parchments, “These very big crystals just jump out at your eye,” says including a 12th-century Italian manuscript, a 13th-century Cahill. “I could just imagine a technician in McCrone’s Oxford Bible, and a 1457 book of music called the Mainz laboratory looking at the map and seeing these great big Psalter. But Clark says he has seen no evidence that ink makers in crystals and plucking them out.” In other words, he says, it’s possible that McCrone’s assistant selectively removed medieval Europe used ground-up anatase. “I’ve never seen a the most visually obvious, anatase-containing particles, report that claims this,” he says. And even if medieval ink unintentionally biasing her sampling. Such comments makers did use anatase, he says that he is aware of no experevoke strong reactions from Kenneth M. Towe, Olin’s imental evidence to suggest that the mineral anatase crystals Smithsonian colleague, and Robin J. H. Clark of Univer- would be similar to 20th-century commercial anatase. Jill F. Banfield, a professor of earth and planetary science sity College London, who have also analyzed the map. A more recent paper by Clark and Katherine L. Brown at the University of California, Berkeley, agrees with Clark (8) supports McCrone’s findings. It describes an analysis of that natural and synthetic anatase crystals should be distinthe map by Raman microprobe spectroscopy, which uses a guishable microscopically, but she adds, “A statistical comlaser spot ~5 µm in diameter to identify individual pigment parison of the phase composition, particle morphology, and particles at subnanogram quantities. Brown and Clark re- size distribution of natural and synthetic titania [TiO2] ported that their spectrometric interpretation indicates that would be required to answer whether the anatase [found on anatase is present in the ink lines. But Cahill says their analy- the map] is commercial.”
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COURTESY OF PAUL SCHROEDER, UNIVERSITY OF GEORGIA
Schroeder adds that analyses of trace elements in anatase paper, because the exposure to crystals from various sources, including the map, would nar- air induces the formation of ferrow the possible sources of the crystal in the ink. However, ric tannate. The inks are corrosive to parchment over the centuries. Towe, a paleobiologist, argues that the anatase most likely didn’t come from kaolin clays. Although such clays are composed Three decades ago, Olin simulated the formulation of such of as much as 97% kaolinite, Towe “saw no evidence for kaoli- an ink, starting with ilmenite and generating anatase and green vitriol (ferrous sulfate, FeSO4). nite in any of McCrone’s original electron diffraction plates,” and he Olin’s 2003 letter (4), referring to says it’s doubtful that medieval ink her simulated ink and her belief that makers would have been able to sepa medieval ink could have contained arate anatase crystals from kaolinite. anatase, prompted three stinging reIn another crucial difference with buttals. All three cited McCrone’s McCrone’s report, Cahill says the original analyses as convincing eviyellow and black parts of the lines dence of forgery. don’t wobble in relation to each In addition, the letter from Michael other. According to Cahill, they Henchman of Brandeis University are instead extremely parallel—to (1) made several other points. Among within ~0.1 mm throughout the 30 them, “Olin conjectures that the ink m of lines, except for a few centimeof the Vinland map is an iron–gall ters. “When you draw with a hollow ink. At the first scientific examination quill, you draw at an angle, and you of the map 37 years ago, [Arthur generally have more of the black David] Baynes-Cope showed that particles in the center and less on FIGURE 4. Particles of anatase from kaolin clays. the ink was not an iron–gall ink” (13). the edge. This lack of registration Like Baynes-Cope, who was the prinhappens almost all the time in old documents. It’s typical.” cipal scientific officer of the British Museum from 1960 to 1984, Brown and Clark also identified the ink as a carbonbased rather than an iron gall ink. The latest round Another rebuttal came from Towe, who says the crystals A year after McCrone’s death, the controversy resumed when Olin reiterated her belief that the map is authentic and was plucked from the map didn’t look like the crystals Olin prodrawn with an iron gallotannate ink. Leonardo da Vinci, J. duced experimentally. “She and I—we worked together on S. Bach, and other Renaissance artists used iron gall inks, this in 1974—found a poorly crystalline, almost amorphous which were made with various recipes containing tannic anatase precipitate in her ink,” says Towe. “Someone must acid from plant galls and an iron salt, such as ferrous sul- be able to plausibly explain the presence of well-crystallized fate. The mixture is colorless but darkens when applied to anatase with the particle size distribution and the shape of the
Debunker of legends The headline of Walter C. McCrone’s obituary was “Debunker of Legends”. He was analytical chemistry’s high-profile version of Sir Arthur Conan Doyle’s fictional Dr. Watson. His multivolume classic, The Particle Atlas: An Encyclopedia of Techniques for Small Particle Identification, is considered required reading for every serious forensic microscopist. “There is not a single color plate that is out of register or a halftone in which the contrast has gotten out of hand,” James P. Lodge, Jr., the late editor of Atmospheric Environment, wrote in a 1981 review of the second edition, volume 5 of the series. McCrone was credited with helping to convict the Atlanta serial child killer Wayne Williams in 1982, on the basis of a match of carpet fibers—a unique type reportedly manufactured for only a few days and sold in only three places in Georgia. McCrone was not shy about denouncing fakery. He reported in Microscope, the journal that he edited for more than 30 years (Microscope 1980, 28, 105, 115), that he found two red pigments in the famous Shroud of Turin. He concluded that the shroud was a medieval painting, not the burial cloth of Jesus. Dozens of supposedly “real” shrouds, painted with blood, were known in medieval Europe. Indeed, radiocarbon dating of the linen of the Shroud of Turin showed that the fabric was medieval, a finding that seemed to vindicate McCrone. Most scientific papers on the topic supported his conclusion. However, a review published by the chemists involved in the Shroud of Turin Research Project—a group that included McCrone— cited a study that found neither the pigments specified by McCrone nor evidence of solvents commonly used as carriers for such pigments (Anal. Chim. Acta 1982, 135, 3–49).
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Bookworm appeal crystals that one finds in the ink of the Vinland map.” In his letter (2), Towe wrote that Olin’s simulated ink “is directly comparable to the initial hydrated precipitates of modern titanium oxide pigments before they are calcined [heated to remove organics] at elevated temperatures above 600 °C. The crystallites found on the Vinland Map are in the 50–500-nm range. Olin’s simulated ink viewed in the transmission electron microscope is that of a hydrolysate. It is a colloidal precipitate that consists of fine-grained aggregates of crystallites in the 4–5-nm range.” Towe also says that for either Olin or medieval ink makers to create highly crystalline anatase from ilmenite, it must be calcined at ~900 °C, the temperature of a roaring wood fire. (The clumps of material must be milled to produce a fine powder.) However, ferrous sulfate, which is needed for iron gall ink, begins to decompose at 300 °C to an insoluble ferric material, hematite (Fe2O3). “Why would any medieval ink maker do such a dumb thing—destroy his green vitriol, which would be worthless for iron gall ink-making? Remember, unlike Mrs. Olin, medieval ink makers were not after anatase. They didn’t even know anatase existed!” Clark also rebutted Olin’s report, saying, among other things, “Olin persists in referring to the VM [Vinland map] as having been drawn in iron gall ink when she has not established that there is any of this material there at all. There is no evidence on or around the ink lines on the parchment of any degradation of the latter, as is often induced by iron gall ink over long periods of time” (3). During her talk at the ACS national meeting, Olin noted that studies of iron gall inks have recently been launched, because these inks are corrosive to the documents. She said she is analyzing inks from other medieval manuscripts to compile a database against which the composition of the Vinland map’s ink could be compared. Like McCrone and other scientists who believe the map is a forgery, Clark is deeply concerned that the map lacks a documented source or ownership history before 1957. “I’m not aware that anything is known of the provenance of the Vinland map,” says Clark. “This is, in many people’s eyes, the whole problem.” However, a majority of the medieval documents in the Beinecke Rare Book and Manuscript Library and most medieval documents in the United States also lack provenance, according to Babcock. “This is clearly an important issue, but the circumstance of not having any idea of where it was before it got into the hands of a dealer in the 1950s is normal for medieval manuscripts,” he says. “While that seems to people to be incredible and somehow suspicious, that doesn’t mean there is anything suspicious about a lack of provenance in a medieval document.” Babcock says the controversy surrounding the Vinland map distracts scholars from studying other medieval docu-
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Experts agree that the Vinland map was once bound with the Tartar Relation, an authenticated 15th-century text prepared by a friar to document a Catholic mission to the land of the Tartars, or Mongols. The Tartar Relation, which is also of unknown provenance, includes nomenclature on Asia that is repeated in the Vinland map. Some scholars suspect that the map, if authentic, might have been produced as an illustration for the Tartar Relation. Several tubular cavities resembling wormholes penetrate both the Tartar Relation and the Vinland map, cutting cleanly through the map’s ink in several places. A much thicker text, part of the vast Speculum Historiale by Vincent de Beauvais, had apparently been sandwiched between the map and the Tartar Relation. The positions of the holes are intriguing. The holes on the battered front of the Speculum Historiale, an authentic 13th-century manuscript, line up with the holes on the Tartar Relation, and holes on the back of the Speculum Historiale line up with the holes through the map. Given the unknown whereabouts of the authentic documents since the 15th century, skeptics point out that a person intent on creating a false impression of the map’s authenticity could have assembled all three and created the holes with either a hot wire or hungry larvae of the Anorbium beetle.
ments in Yale’s collections. He expresses no opinion about the authenticity of the map, adding, “I just wish the scientists would settle it.” Rex Graham is a freelance writer based in San Diego, Calif. Elizabeth Zubritsky contributed to this article.
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(11) (12) (13)
Henchman, M. Anal. Chem. 2004, 76, 2674. Towe, K. M. Anal. Chem. 2004, 76, 863–865. Clark, R. J. H. Anal. Chem. 2004, 76, 2423. Olin, J. S. Anal. Chem. 2003, 75, 6745–6747. McCrone, W. C. Anal. Chem. 1988, 60, 1009–1018. Weaver, C. E. Clays, Muds, and Shales; Elsevier Science: New York, 1990. Towe, K. M. Acc. Chem. Res. 1990, 23, 84–87. Brown, K. L.; Clark, R. J. H. Anal. Chem. 2002, 74, 3658–3661. Cahill, T. A.; et al. Anal. Chem. 1987, 59, 829–833. Skelton, R. A., Marston, T. E., Painter G. D., Eds. The Vinland Map and the Tartar Relation; Yale University Press: New Haven, CT, 1965. McCrone, W. C. Chemical Analytical Study of the Vinland Map; Report to Yale University Library; Yale University: New Haven, CT, 1974. Schroeder, P. A.; Melear N. D.; Pruett R. J. Appl. Clay Sci. 2003, 23, 299–308. Baynes-Cope, A. D. Geogr. J. 1974, 140, 208–211.
