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1. Introduction        The Musée des Confluences/Muséeum        d’histoire naturelle in Lyon holds an impressive collection of        Predynastic Egyptian mummies, in particular many animal and several        human mummies. This collection has been initiated by the two “Lyonnais pioneers” – Louis Lortet and Victor Loret        – who aimed to detail this “Nile Valley’s        PaleoEcology” – as defined by J-Cl Goyon (Goyon, 2007) – by        building up an original collection, using both an anthropological and        archaeological approaches. To replace these mummies in their cultural        context, an absolute chronological framework is required. To this        purpose, radiocarbon dating can bring chronological information by the        analysis of various organic materials, in particular hair, skin, flesh        and fine linen strips. Among this collection, three Predynastic human        mummies gave coherent radiocarbon results, showing that they were        buried during the Nagadean period.        In contrast, the observation of two other mummies        (1626 and 1627) revealed classical embalming traces (nose padding,        right side incision) showing that they had undergone a funeral ritual        of mummification. The discrepancy of the dating results performed on        both textiles and organic materials shows that these mummies’ samples        are probably being aged by a 14C depleted product.        In ancient Egypt, several products were used to embalm bodies: natron        was the most common since it was widely employed for many centuries.        It was associated with other materials like myrrh, cedar or palm oils        and different gums (Ménager et al., 2013).        Nonetheless, some Graeco-Roman textual sources testified to the use of        bitumen during the embalming ritual by late period Egyptian embalmers.        Those attestations lead us to suspect that bitumen could be this        radiocarbon depleted polluting substance. Moreover, other studies have        already pinpointed the possibility of bitumen utilization in Egyptian        embalmed mummies (Conan et Dessort, 1989; Harrel et Lewan, 2002), some        of them showing the impact on the radiocarbon dates (Aufderheide et al., 2013). In those studies, GC/MS analyses        were used to characterize bitumen. Extractions using light organic        solvent (benzene) were applied on samples before radiocarbon dating,        but without given consistent dates.        In order to make bitumen identification possible        infrared spectroscopy analyses have been performed on these two        embalmed mummies’ linen strip samples. Then experiments have been        proposed to test the possibility of extracting bitumen from linen        textile and so, to radiocarbon date such mummy textile samples. They        have been tested on modern linen textiles and divides into four steps:        textile soaking in bitumen – linen samples thermal degradation –        extraction protocol – infrared analyses and radiocarbon dating at each        step. The results of these analyses determine the present        state-of-research and the future developments we have to realize in        order to restore these two embalmed mummies to their correct        chronological context, and more broadly, to systematize radiocarbon        dating of Egyptian mummies embalmed with bitumen.              2. Materials and Methods                  Archaeological samples and modern linen          textiles          Six Egyptian mummies held in the Musée des          Confluences of Lyon have been radiocarbon dated by analysing both          textile wrappings and organic material (mixed flesh/skin) to ensure          the quality of the chronological data. Three Predynastic human          mummies coming from the Roda (mummies 2402 and 2403 ; Lortet and          Gaillard, 1909a, p.43-46) and Gebelein necropolis (mummy 2404 ;          Lortet and Gaillard, 1909b) were studied. In particular, an old man          and an old woman (respectively 2402 and 2403) excavated from two          different undisturbed tombs from Roda have been dated by several          analyses on textile and organic material. They were found in similar          positions within the tomb, as explained by L. Lortet: “[…] couchées sur le côté gauche, les genoux très relevés          contre la région abdominale. Les avants-bras          sont ramenés en avant, de telle sorte que les mains se trouvent à la          hauteur de la face […]” (Lortet and Gaillard, 1909a, p. 45).          Besides, a stem plant found inside a jar excavated in Roda, where an          old woman skeleton was discovered (mummy 1252; Lortet and Gaillard,          1909a, p. 39-40), was also analysed. Among the two embalmed mummies,          the first one is a child mummy (1626, Figure 1a), sent to the Muséum d’Histoire Naturelle de Lyon by G. Maspero          on 10th October 1901 with the mention « Rôda, Hte Égypte ». The identification of the          second should be confirmed even if it is also considered as a child          mummy1 (1627, Figure 1b); it          entered this collection a few months before, on 16th August 1901 and in the same way, G. Maspero only          mentioned “Rôda, Hte Égypte”. No more archaeological context is known on          these two Egyptian mummies, and both have been kept by the Museum          since their reception. No conservation treatments involving          chemicals that could be possible pollutants for radiocarbon dating          were subsequently performed (only an anoxic treatment is          documented).          In order to compare the infrared characteristics          of ancient linen samples with the ones from the mummies’ strips, a          set of four “pure” linen textiles samples (fabric, clothes) from          Pharaonic period and held at the Département des          Antiquités égyptiennes from the Louvre museum have also been          sampled. These textiles had not been used in a funeral context, so          had not undergone a funeral embalming ritual. Radiocarbon dating was          performed on them to ensure their chronological context, followed by          an infrared analysis to provide a signature of pure ancient          linen.          Figure 1: Children mummies (?)          excavated in the Rôda necropolis and presently held at the Musée des Confluences in Lyon: 1626 (a) and 1627          (b).Figure 1 : Momies d’enfant (?) mise au          jour dans la nécropole de Rôda et actuellement conservées au Musée          des Confluences de Lyon: 1626 (a) et 1627 (b).                              Then, since archaeological samples remain          precious and scarce, an extraction protocol has been developed to          extract bitumen from modern textile samples dipped in this material.          Infrared analyses have been performed to check their ability to          detect bitumen, and finally, these test-samples have been          radiocarbon dated to verify if the efficiency of this new          experimental protocol was good enough to totally extract          bitumen.                          Radiocarbon dating          Radiocarbon dating has been performed at the Laboratoire de Mesure du Carbone 14 (LMC14, UMS2570          CNRS). Before analysis, samples are physically and/or          chemically cleaned to eliminate carbonated contaminations. For          organic material, the routine pre-treatment (ABA: Acid-Base-Acid)          divides into three successive steps: a first acid wash (HCl, 0.5N)          eliminates secondary carbonates deposited after the death of the          organism, a base wash (NaOH 0.1N) removes humic acids, and then, a          final acid wash ensures the removal of dissolved atmospheric carbon          dioxide that may have been absorbed during the base wash.          Then, samples are dried and combusted at 900°C          with CuO and silver wire. The CO2 formed is          collected cryogenically and reduced to graphite over Fe powder in          the presence of H2 (Cottereau et al., 2007). The mixture iron/carbon is pressed          into a 1mm diameter cathode. Measurements have been performed by          Accelerator Mass Spectrometry (AMS) on the ARTEMIS facility. Results          are given in percent modern Carbon (pMC) and radiocarbon ages (BP),          they have been calibrated using OxCal 4.2 software (Bronk Ramsey,          2009), using the IntCal09 calibration curve (Reimer et al., 2009). The same routine chemical          pre-treatment (ABA) has been applied on all the samples from mummies          2402, 2404, 1252, 1626 and 1627.                          Attenuated Total Reflectance Infra-Red          Spectroscopy (ATR-IR)          Attenuated Total Reflectance Infrared          spectroscopy (ATR-IR) analyses have been performed at the MONARIS laboratory (UMR 8233 CNRS-UPMC). ATR-IR          spectra were recorded with a Bruker Equinox 55 spectrometer coupled          to an IRscope II microscope. An ATR objective is directly mounted on          the microscope. It is equipped with a germanium crystal and allows a          unique reflection at the crystal/sample interface. The analyzed area          is about 60µm with a probing depth of a few micrometers from the          sample surface. The ATR objective has a visual mode, which allows          the user to choose the area to analyze. 64 scans accumulations with          a 4cm-1 resolution were enough to obtain spectra          with a good signal to noise ratio.                          Experimental protocol for chemical          extraction          In order to extract the polluting material in          which the mummies were dipped, in addition to the routine ABA          chemical pre-treatment currently applied for radiocarbon dating, a          more aggressive chemical extracting protocol has been developed and          tested by the Ingénierie de la restauration des          patrimoines naturel et culturel team from the Université d’Avignon (UMR 7263 CNRS – IRD); it          derives from (Buckley et al., 2004) but          involves more non-polar solvents and is adapted for archaeological          matrices, in particular for mummification balms.          To begin with, and as the quantity of          archaeological material remained scarce and precious, this          experimental protocol has been applied on modern linen textile          test-sample. The whole protocol was divided into four steps (figure          2): linen test-samples were locked on a glass slide with a Teflon          plate and impregnated with 300 μL of a Judean bitumen (from Artech,          Avignon, France) solution (30 mg.μL-1) in          dichloromethane (Step 1). After their drying at ambient temperature,          samples were artificially aged in an oven at 60°C for 60 days (Step          2), before carrying out the extraction protocol detailed on figure 2          (Step 3). Resulting samples from each step were analysed by infrared          spectroscopy and then, radiocarbon dated (Step 4) to evaluate the          different treatments’ effects.          Figure 2: Experimental protocol          developed to prepare, extract and analyze the modern linen textile/          bitumen test-sample.Figure 2: Protocole          expérimental développé pour préparer, extraire et analyser les          échantillons-test de textiles en lin modernes/bitume.                    It divides into four steps. Step 1:          Impregnation of test-samples in 300 μL of Judean bitumen (Artech,          Avignon, France) solution (30mg.μL-1). They were          locked between a Teflon plate and a glass skip. 10 mg bitumen has          been run on. Step 2: Test-samples have been placed within a          60°C oven during 60 days to simulate an accelerated ageing of linen          fibres and bitumen. Step 3: Extracting protocol divides into          three sub-steps, using three solvents classically used for          extracting balms to the organic fraction, and following a          non-aggressive gradient: – An extraction with a 2.5mL hexane          solution, followed by an ultrasonic bath during 15 min; – An          extraction with a 2.5mL dichloromethane solution, followed by          ultrasonic bath during 15 min; – An extraction with a 2.5mL          chloroform solution, followed by ultrasonic bath during 15          min.Each step was repeated twice and two different ultrasonic          bath systems have been tested: le bath US 88155 (Bioblock, 35 kHz)          and a prototype US bath PEX 3.Step 4: Test-samples have been          analyzed by infrared spectroscopy and radiocarbon dated.Il se divise en quatre étapes. Étape 1 : Imprégnation          des échantillons-test dans 300 μL d’une solution de bitume de Judée          (Artech, Avignon, France ; 30mg.μL-1). Les          échantillons sont bloqués entre un moule de Teflon et une lame de          verre, et 10 mg de bitume ont été coulés dessus. Étape 2 : Les          échantillons-test ont été placés dans une étuve à 60° pendant 60          jours afin de simuler un vieillissement artificiel des fibres de lin          et du bitume.Étape 3 : Le protocole d’extraction a été divisé          en trois étapes, à partir de trois solvants classiquement utilisés          pour extraire les baumes de la fraction organique et suivant un          gradient d’agressivité : – Une extraction à partir d’une solution          2,5mL d’hexane, puis un nettoyage aux Ultra-Son pendant 15 min ; –          Une extraction à partir d’une solution 2,5mL de Dichlorométhane,          puis un nettoyage aux Ultra-Son pendant 15 min ; – Une extraction à          partir d’une solution de 2,5mL de chloroforme, puis un nettoyage aux          Ultra-Son pendant 15 minChaque étape a été répétée deux fois et          deux systèmes d’Ultra-son ont été testés : le bain US 88155          (Bioblock, 35kHz) et un prototype développé au US PEX 3. Étape          4 : Les échantillons-test ont été analysés par spectroscopie IR et          datés par carbone 14.                      3. Results                  Radiocarbon dating of Egyptian mummies          The set of radiocarbon dates performed on          Egyptian mummies 2402, 2403, 2404 is perfectly coherent with what we          expected, showing that the three Predynastic mummies were buried          during the Nagadean period. Besides, the stem plant found inside a          jar excavated in Roda, where an old woman skeleton was discovered          (mummy 1252; Lortet and Gaillard, 1909a, p. 39-40), gave a younger          age close to the beginning of the Old Kingdom. Nonetheless, this          data has to be taken carefully as the association between the woman          skeleton and the stem plant remains uncertain. Those results allows          for conclusions to be drawn on the possibility of using radiocarbon          for dating non-embalmed Egyptian mummies, whatever the kind of          organic matter analyzed (table 1).          Table 1: Radiocarbon dating results (1σ)          obtained on textile and organic material (skin/flesh) for mummies          1252, 2402 and 2403 (Rôda), and 2404 (Gebelein) held at the Musée des Confluences in Lyon.Tableau 1 : Résultats des datations radiocarbone          (1σ) réalisées sur les          textiles et la matière organique (peau, chaire) des momies 1252,          2402, 2403 (Rôda) et 2404 (Gebelein) conservées au Musée des          Confluences de Lyon.                    The δ13C values are AMS          measures.Les valeurs de δ13C          sont des valeurs mesurées par SMA.          Nonetheless, the study of the two embalmed          mummies (1626 and 1627) shows the difficulty of applying this          technique on mummies that have undergone an embalming ritual          involving materials, sometimes not well identified, influencing          radiocarbon results. Fourteen radiocarbon dates have been performed          on these two embalmed mummies (1626 and 1627), using the routine          chemical pre-treatment ABA; they gave strongly disparate results for          each mummy (Table 2). For the mummy 1626, textile is dated between          4673 ± 25 BP (SacA 22306) and 2772 ± 28 BP (SacA 23673) whereas          organic material extends from 7455 ± 31 (SacA 22305) to 7156 ± 32 BP          (SacA 22304). In the same way, radiocarbon ages for the mummy 1627          ranges from 3378 ± 29 (SacA 23675) to 2153 ± 21 BP (SacA 22308) for          textile samples and from 2241 ± 22 BP (SacA 22309) to 2218 ± 26 BP          (SacA 23677) for organic material. Thus, the mummy 1626 is dated          from 6406 calBC to 841 calBC (2 σ) and the mummy 1627 from 1749          calBC to 112 calBC (2σ) (figure 3). To check the repeatability of          our radiocarbon dates and when we had enough material, a second          radiocarbon dating was performed on the same sample with the          repetition of the entire analysis line          (pre-treatment-combustion-graphitization-measurement) and so far the          results obtained are perfectly accordant with the previous ones          (table 2). Therefore, the disparity of the dating results does not          rely on the method involved but is due to a polluting material,          which has not been extracted by the chemical pre-treatment used.          Consequently, the dating results are older than expected, so the          polluting material is depleted in 14C. This last          substance of fossil origin is consistent with an ageing effect          suggesting that the polluting product, not correctly extracted by          the chemical ABA pre-treatment, could be bitumen. For this study, we          decided to focus on the characterization and dating of linen textile          samples instead of the other organic materials (hair, skin, flesh)          so as to avoid difficulties relating to the separation and          identification of the organic contamination.          Figure 3: Results of radiocarbon          dating performed on the two embalmed mummies.Figure 3 : Résultats des datations réalisées sur les          deux momies embaumées.                    In the Phase “embalmed          mummies”, calibrated temporal densities obtained on organic          material are in red, whereas those obtained on textile samples are          in black. Results are gathered by samples (one phase per sample,          156, 157, 158a, 158b, 159a, 159b, 160), repeated measures on a same          sample give the same results, whereas different samples from the          same mummies give disparate and incoherent results, extending from          6406 to 841 calBC (2σ) for mummy 1626, and from 1749 calBC to 112          calBC (2σ) for mummy 1627. Dans la phase          “embalmed mummies”, les densités d’âge calibrées obtenues sur la          matière organique sont en rouge, celles obtenues sur les          échantillons de textiles sont en noir. Les résultats sont rassemblés          par échantillons (une phase par échantillon 156, 157, 158a, 158b,          159a, 159b, 160), les mesures répétées sur un même échantillons          donnent des résultats cohérents, alors que les analyses réalisées          sur différents échantillons d’une même momie donnent des résultats          incohérents, s’étendant de 6406 à 841 calBC (2σ) pour la momie 1626, et de          1749 calBC à 112 calBC (2σ) pour la momie 1627.           Table 2: Radiocarbon dating results (1σ)          obtained on textile and organic material (skin/flesh) sampled on          mummies 1626 and 1627 from the Musée des          Confluences of Lyon.Tableau 2 :          Résultats des datations radiocarbone (1σ) réalisées sur les textiles          et la matière organique (peau, chair) des momies 1626 et 1627 du          Musée des Confluences de Lyon.                    The δ13C values are AMS          measures.Les valeurs de δ 13C sont des          valeurs mesurées par SMA.                          Infrared spectroscopy analyses on mummies          samples          Infrared spectroscopy analyses have been          performed on textile samples of both the embalmed mummies 1626 and          1627 and the Predynastic mummy 2402. About 3 to 5 analyses for each          sample have been performed and representative spectra are presented          in figure 4. The infrared spectrum of the embalmed mummies 1626 and          1627 are similar. The spectra can be divided in two regions: (i) the          first is around 1480-1780 cm-1 with its maximum          at 1705 cm-1; and is assigned to the C=O and C=C          stretching vibrations (Bellamy, 1975; Daher et          al., 2010) (ii) the second appears as a double band between          2800 and 3000 cm-1 and is assigned to the C-H          stretching vibrations (Derrick et al., 1999;          Daher et al., 2013). For the mummy 2402, the          same absorption bands are also visible with different shape: (i) the          most intense band of the 1480-1780 cm-1 region          is centred on 1638 cm-1 with a quite different          profile, (ii) the CH region do not display such resolute and intense          double band between 2800 and 3000 cm-1.          Figure 4: Representative ATR-IR          spectra obtained on textile samples from embalmed mummies 1626, 1627          and Predynastic mummy 2402, underlining a different signature for          samples where bitumen is suspected.Figure 4 :          Spectres ATR-IR obtenus sur les échantillons de textiles des momies          embaumées 1626, 1627 et de la momie prédynastique 2402. Ils montrent          une différence de signature pour les échantillons où la présence de          bitume est suspectée.                    General profiles are similar for textile          taken on embalmed mummies 1626 and 1627. They are characterized by a          large peak around 1480-1780 cm-1 with a single          band close to 1705 cm-1; and a double band          around 2800-3000 cm-1. Mummy 2402 profile is          slightly different: the single band in the first peak has a lower          wavenumber at 1638 cm-1 and the double band in          the 2 800-3 000 cm-1 region is less          intense.Les profils généraux sont similaires          pour les textiles provenant des momies embaumées 1626 et 1627 et          sont caractérisés par une large bande autour de 1480-1780 cm-1 avec une bande          individualisée autour de 1 705 cm-1, et une double bande          autour de 2 800-3 000 cm-1. Le profil obtenu sur l’échantillon de la momie 2402          est légèrement différent : la bande simple du premier pic a une          longueur d’onde inférieure, à 1638 cm-1 et la double bande dans          la région 2 800-3 000 cm-1 est moins intense.          In order to characterize the embalmed material,          we had to analyse linen free of contaminant and embalming material.          For that purpose, a second set of analyses has been performed on          four “pure” linen textiles from the Pharaonic period and held at the          Département des Antiquités égyptiennes of the          Louvre museum. Dating results are detailed in Table 3 and extend          from the First Intermediate Period to the Hellenistic Period.          Table 3: Linen textiles analysed using ATR-IR          spectroscopy. Textiles E 13595, AF 11293, N 1297, AF 5230 are held          at the Louvre Museum.Tableau 3 : Analyses par          spectroscopie ATR-IR de textiles en lin. Les tissus E 13595, AF          11293, N 1297, AF 5230 sont conservés au Musée du Louvre.                    Radiocarbon ages are given in BP with a 1σ          range (column 3), calibrated ranges are given in calBC with a 2σ          range (column 4); associated historical periods are given column          5.Les âges radiocarbone sont donnés en BP à          1σ (colonne 3), les          âges calibrés sont donnés en calBC à 2σ (colonne 4); les périodes          historiques associées sont données colonne 5.          Figure 5a shows the comparison of the spectra of          the four linen textiles from the Pharaonic period and a modern linen          sample. The five IR spectra have similar profiles confirming that          the four Egyptian textiles are made of linen (Garside and Wyeth,          2003, 2006, Proniewicz et al., 2001, Fanti          et al., 2013), whatever their historical          period of fabrication. They are characterized by three absorption          bands around 850-1210 cm-1, 1240-1500 cm-1 and 2800-3000 cm-1. A single          band attributed to the C-H stretching vibrations characterizes the          last one. This single band is characteristic of linen when included          in textiles (Garside and Wyeth, 2003, 2006), unlike the vibrational          spectra of linen fibres (in their raw state and before any          processing), which show a double band in this 2800-3000 cm-1 region (Proniewicz et al.,          2001, Fanti et al., 2013).          The comparison of the spectra of “pure” and          embalmed mummies linen (figure 5b) shows differences in the region          1480-1780 cm-1 and 2800-3000 cm-1. In the same way, an ATR-IR analysis has also          been carried out on a reference Judean bitumen sample. The          corresponding spectrum (figure 5b) is characterized by absorption          bands at 1375, 1455, 2852 and 2925 cm-1.          The modification of the signal at 1240-1500 cm-1 and the bands at 2852 and 2925 cm-1 in the embalmed mummies’ spectra confirms the          possible presence of bitumen. This would explain the ageing of          radiocarbon dates. Nevertheless, a single band is observed around          1705 cm-1 and is only present on embalmed          mummies. Such signal is due neither to bitumen nor linen textile          (Peters et al., 2005). At this stage of the          research, it could be related to the alteration of the          archaeological sample over time, the interaction between linen and          bitumen, or the use of other embalming materials in conjunction with          bitumen.          Figure 5: (a) IR spectra obtained for the          pure linen textiles held at the Département des Antiquités          égyptiennes of the Louvre Museum, and radiocarbon dated from the          First Intermediate Period (E 13595) to the Hellenistic Period (AF          5230). The five IR spectra are quasi-similar (b): Comparison of the          IR spectra obtained on one pure modern linen textile, on a textile          from an embalmed mummy (1626) and on Judean bitumen. The double band          in the 2800-3000 cm-1 peak is visible on the          embalmed mummy textile as well as on the bitumen spectrum, but is          indiscernible on the “pure” linen textile spectrum. Besides, the          single band close to 1705 cm-1 is absent of both          the bitumen and the pure linen spectra.Figure          5 (a) : Spectres ATR-IR réalisés sur des tissus "propres" conservés          au Département des Antiquités égyptiennes du Louvre et datés par          carbone 14 de la première période intermédiaire (E 13595) à la          période hellénistique (AF 5230). Les cinq tissus ont des spectres          semblables (b) : Comparaison des spectres IR obtenus sur un tissu de          lin moderne pur, sur un tissu de momie embaumée (1626) et sur du          bitume de Judée. La double bande dans le massif 2800-3000 cm-1, présente sur le spectre          de tissu de momie, est aussi présente dans le spectre du bitume          alors qu’elle est absente du spectre de lin pur. Par ailleurs, la          bande simple autour de 1705 cm-1 est absente du spectre du bitume et de celui du lin          pur moderne.                                               Chemical Extraction – tests samples          The experimental protocol described in 1.4 has          been tested on modern linen samples. To test the effects of each          step of this protocol on radiocarbon dating, eight different samples          have been produced. They are listed on Table 4. They have been          observed by binocular microscopy (figure 6): test-sample 2 (step 1)          shows the linen textile dipped in bitumen; it could be compared to          test-sample 7 (pure linen textile). Test-samples 3 and 4 (steps 1,          2, 3) are more blackened and brighter than test-samples 5 and 6          (steps 1, 2), even though the four have undergone the extraction          protocol (but the last two have not been artificially aged).          Table 4: Experimental protocol applied on the          eight test-samples (column 3); Results of IR analyses, presence of          the 1705 cm-1 band, bitumen markers at 1375,          1455, 2822 and 2925 cm-1 (column 4); radiocarbon          dating results obtained for the eight test-samples (column 5): ABA          pre-treatment, δ13C-AMS values (± 3‰),          radiocarbon age in pMC and in BP (1σ).Tableau          4 : Protocole expérimental appliqué aux huit échantillons tests (colonne 3); résultats des analyses          IR, présence de la bande à 1705 cm-1, identification des          marqueurs de bitume 1 375, 1 455, 2 822 et          2 925 cm-1 (colonne 4); résultats des datations radiocarbone          obtenues sur les huit échantillons tests (colonne 5): pré-traitement          ABA, valeurs du δ          13C-SMA (± 3 ‰), âge radiocarbone en pMC et          en BP (1σ).                    Figure 6 Binocular microscopy          observations of the eight test-samples.Figure          6 : Observation à la microscopie binoculaire des huit          échantillons-tests.                    Test-sample 7 and 8 have not been dipped in          bitumen (7: modern linen; 8: modern linen which undergone the          extraction protocol (step 3)). Test-sample 2 shows the linen textile          after being dipped in bitumen (step 1). Test-samples 3 and 4 have          been dipped in bitumen, thermally degraded and extracted (steps 1,          2, 3); they seems more blackened and brighter than test-samples 5          and 6, which have been dipped in bitumen and extracted without being          thermally degraded (steps 1, 2).Les          échantillons-test 7 et 8 n’ont pas été imbibés de bitume (7 : lin          moderne ; 8 : lin moderne extrait qui a subi le protocole          d’extraction (étape 3)). L’échantillon-test 2 montre l’état des          tissus après l’imprégnation de bitume (étape 1). Les          échantillons-test 3 et 4 ont été imbibés, vieillis et extraits          (étapes 1, 2, 3) et sont plus noircis et brillants que les          échantillons-test 5 et 6, qui ont été imbibés et extraits sans avoir          été vieillis (étapes 1 et 2).                          IR analyses on test-samples          The ATR-IR spectra recorded on the test-samples          are presented in Figure 7 and compared to the modern linen and          reference bitumen spectra. The major band around 850-1200 cm-1, attributed to linen, is present on the          test-samples spectra, excepting for the test-sample 2. The          comparison of this sample spectrum with the bitumen one shows that          only the representative bands of bitumen (in 1480-1780 and 2800-3000          cm-1 regions) are present in its spectrum. This          sample did not undergo the extraction protocol. For spectra from          samples 3 and 4 (dipped, degraded and extracted samples), the sharp          representative bitumen bands (2852 and 2925 cm-1) could be suspected as shoulders on the broad          peak centred in this spectral range and attributed to linen. These          same bitumen bands do not clearly appear for the samples 5 and 6          (dipped and extracted) and for the samples 7/8 (only linen          respectively with and without extraction process) where only the          broad linen peak seems to be observed.          The spectra of samples 2, 3 and 4 show an extra          feature at 1705 cm-1. The presence of this extra          band is not explained at the moment, but is not induced by the          extraction solvents (no 1705 cm-1 band in the          extracted modern linen). Because this band is only present in the          spectra of embalmed mummies (figure 5b) and in the thermally          degraded samples 3 and 4 (figure 7), it is clearly associated with          the presence of bitumen in aged samples. As the 1705 cm-1 absorption band is absent from non-thermally          degraded samples (5 and 6), its presence seems to indicate that a          degradation reaction occurs on bitumen/linen association.          Figure 7: ATR-IR spectra obtained on          test-samples 2, 3, 4, 5, 6 and 7/8 compared to pure linen and          bitumen ones.Figure 7 : Comparaison des          spectres IR-ATR réalisés sur les échantillons-tests 3, 4, 5, 6 et          7/8, à ceux obtenus sur des textiles de lin pur moderne et du          bitume.                    Test-sample 2, 3 and 4 (steps 1, 2, 3)          spectra have a shoulder at 1705 cm-1 and the          double band characteristic of bitumen in the peak 2800-3000 cm-1 is not clearly identifiable, but could not be          excluded. On the contrary, test-samples 5 and 6 (steps 1, 2) have IR          spectra very similar to those of pure line spectra: no shoulder at          1705 cm-1 and a single broad band in the peak          2800-3000 cm-1.Les          spectres des échantillons-test 2, 3 et 4 (étape 1, 2, 3) présentent          un palier à 1705 cm-1, et la double raie caractéristique du bitume dans le          massif 2 800-3 000 cm-1 n’est pas clairement identifiable, mais ne peut être          exclue. Au contraire, les échantillons-test 5 et 6 (étapes 1, 2) ont          des spectres très similaires au spectre de lin pur : pas de palier à          1705 cm-1 et une          bande simple dans le massif 2 800-3 000 cm-1.                          Radiocarbon dating of test-samples          The eight test-samples have been radiocarbon          dated. To examine if the classical chemical pre-treatment ABA would          provide an efficient cleaning, each test-sample has been shared in          two equal portions: test-samples ‘A’ have been directly combusted          whereas test-samples ‘B’ underwent the ABA pre-treatment before          being combusted. The dating’s results are reported Table 4 (column          5) and illustrated in the Figure 8. Test-sample 1’s results (Judean          Bitumen) are not reported on Figure 8 since they are older than          49,000 BP, as expected. In the same way, test-sample 2 is dated to          930 ± 28 BP (2A) and 1790 ± 22 BP (2B), which confirms the fact that          bitumen ages radiocarbon dates, and that ABA chemical pre-treatment          is not sufficient to extract bitumen from linen textile samples.          Besides, test-sample 8 (step 2) is modern, which means that the          solvents involved in the extraction protocol do not affect          radiocarbon dates. Finally, we note that whatever the test-sample          studied, adding the ABA pre-treatment does not bring any significant          cleaning.          Figure 8: Summary of radiocarbon          dating results obtained for the eight test-samples illustrating the          potential bitumen extraction.Figure 8:          Résultats des datations 14C réalisées sur les huit échantillons-tests illustrant          la possibilité ou non d’extraction du bitume.                    A: samples directly combusted after the          experimental extraction protocol; B: samples which have undergone an          ABA chemical pre-treatment after extraction. Test-samples 3 and 4          are not modern so all bitumen has not been extracted; test-samples 5          and 6 are modern so all bitumen has correctly been          extracted.A : échantillons n'ayant pas subi          de prétraitement chimique après l'extraction ; B : échantillons          ayant subi un prétraitement chimique après l'extractio). Les          échantillons 3 et 4 qui ont été imbibés de bitume, vieillis puis          extraits ne sont pas modernes, ils contiennent encore du bitume ;          les échantillons 5 et 6, qui ont été imbibés de bitume, extraits          sans avoir été vieillis, sont modernes : tout le bitume a bien été          extrait de ces échantillons.          Test-samples 3 and 4 (Steps 1, 2, 3),          respectively, are dated to 1658 ± 20 BP (3A), 1475 ± 21 BP (3B),          1895 ± 60 BP (4A) and 1009 ± 23 BP (4B): bitumen therefore still          remains in those samples despite the extraction they have undergone          (new extraction protocol as well as ABA). On the contrary,          test-samples 5 and 6 (steps 1, 2) are modern: thus for the samples          which have not been artificially aged, bitumen has correctly been          extracted from the linen fibres.                      4. Discussion and perspectives        Three major outcomes arise from the present study.        First, dating results for test-sample 8 show that the solvents        involved in the extraction protocol do not affect the samples’ age, so        this protocol could be applied without impacting the radiocarbon        dating. Second, all test-samples which have not been artificially aged        using a 60°C oven, but which have been dipped in bitumen and        extracted, are modern. Thus, it shows that this extraction protocol is        efficient at extracting “fresh” bitumen impregnation. Third,        test-samples that underwent all the experimental protocol and        especially the thermal degradation are not modern, so bitumen largely        remains on these samples.        Those three remarks lead to the conclusion that the        difficulty to extract bitumen is related to effects of time both on        the interaction between bitumen and linen fibres, and/or linen or        bitumen alteration, rather than only to bitumen use. We have also        noticed that IR spectra of pure linen textile remain stable over time        (from First Intermediate Period to Hellenestic one). This suggests        linen alteration over time would not be as a satisfactory explanation.        Therefore, further investigations have to be conducted to clarify the        presence and meaning of the infrared signature around 1705 cm-1, which only appears on the IR spectra of the two        embalmed mummies and on the impregnated test-samples that have been        thermally degraded.        To answer these questions, different studies will        be followed up for this running project. IR analyses will be realized        on modern linen textiles dipped in other embalming materials than        bitumen (oils, resins…) and then, thermally degraded, to verify if the        1705 cm-1 band is present and being persistent for        other organic substances adsorbed by linen. To get a better        understanding of the adsorption process of bitumen in linen fibres, a        kinetic study will be done by ageing artificially both samples by time        and temperature gradients. This study will be lead on three different        kinds of samples: 1) pure and modern linen textiles 2) modern linen        textiles dipped in bitumen 3) pure bitumen samples. For        experimentation on the time gradient, samples will be placed in a 60°C        oven gradually from one week to three months. For experimentation on        the temperature gradient, samples will be placed in an oven gradually        from 30° to 100° during three months. For studying the linen textile        natural degradation, further IR analyses will be performed on a larger        set of pure Egyptian textiles, radiocarbon dated from the Old Kingdom        to the Mamluk period and held at the Département des        Antiquités égyptiennes from the Louvre Museum.        At the same time, other extraction protocols will        be proposed and tested. First, the present protocol will be improved        by using hot solvents to increase their power. According to the        radiocarbon results, other solvents will be added in the present        protocol like pentane, benzene or carbon disulfide that solubilizes        non-mineral fraction of bitumen.        Moreover, more aggressive washes with sodium        chlorite solution (bleach treatment) are envisaged to eliminate the        most mobile fractions such as lignin, waxes and resins. Finally,        extraction of the linen fibres’ cellulose could be a third way to        investigate (Van Strydonck et al., 2004, Brock        et al., 2010).              5. Conclusion        Two embalmed mummies held at the Musée des Confluences in Lyon (1626 and 1627) have        been radiocarbon dated (textile and organic material samples) and the        results are older than expected, disparate and incoherent while four        other Egyptian mummies provide consistent results. The radiocarbon        dates’ ageing is due to the use of a radiocarbon depleted material        involved in the embalming process that is not extracted by chemical        pre-treatment routinely used for radiocarbon dating of organic        material. Ancient Egyptian sources attest the possibility that        embalmers employed bitumen for funeral rituals during the Late Period.        This hypothesis is corroborated by IR spectroscopy analyses performed        on different embalmed mummies’ samples, and compared to “pure” linen        textiles from Pharaonic period and to a reference bitumen sample. A        first experimental protocol has been developed to extract bitumen from        linen textile, and tested on modern linen textile. It divides into        four steps: soaking of textile in bitumen – thermal degradation of        linen samples – extraction protocol – IR analyses and radiocarbon        dating. Eight test-samples have been produced combining the four        different steps of the protocol. Radiocarbon dates show that those        test-samples dipped in bitumen and extracted without being accelerated        ageing are modern, so they do not contain bitumen anymore. On the        contrary, the same samples, but which have been thermally degraded,        are not modern, so radiocarbon contamination is remaining.        Consequently, the difficulty does not rely on the presence of bitumen,        but on the process involved between bitumen and linen fibres over        time. The following steps of this research project will be to focus on        this interaction bitumen/linen over time. New experimentations will be        conducted to more precisely characterize it, and then develop a        powerful and complete extraction protocol. It will enable us to        definitively date these two embalmed mummies and restore them into        their cultural context, and then to extend this innovative protocol to        the dating of Egyptian mummies embalmed with bitumen.