明墓出土历书的揭取与复原

明墓出土的历书,粘连固结成块,脆硬易于折断。通过实验分析研究,探明其主要原因可能是木质素选择性地吸附的钙铁离子与蛋白质的分解物形成复杂物质,沉积在纸上,渗入书内所致。故揭取该历书的关键是去除钙离子,EDTA二钢,碱性过氧化氢、气相二氧化硅等的分步处理,使脆硬的纸张软化,再逐页分离揭取,然后再去除色素沉淀物,终于恢复了书的原貌。     

Phosphatic mineralization of seeds from archaeological sites

Recent investigations of botanical material from archaeological sites have provided seeds and plant remains exhibiting a crystalline or semi-crystalline appearance. X-ray diffraction and partial chemical analysis have revealed that the particular plant materials had been replaced by calcium phosphate. Using systematic sampling and retrieval techniques a significant body of data has been accumulated. Most mineralized botanical evidence has been recovered from faecal deposits, in particular cess pits and garderobes, and has provided an important source of information about aspects of diet of past populations.     

Distinguishing between calcites formed by different mechanisms using infrared spectrometry: archaeological applications

Infrared spectrometry is a well-established method for the identification of minerals. Due to its simplicity and the short time required to obtain a result, it can be practiced on-site during excavation using portable infrared spectrometers. However, the identification of a mineral may not be sufficient. For example, a lime plaster floor and a crushed chalk surface have a similar appearance and are composed of the same mineral – calcite. Here we exploit differences in the infrared spectra of geogenic, biogenic and pyrogenic calcites for the identification of each calcite type. The infrared calcite spectrum has three characteristic peaks in the region of 400–4000 cm⁻¹, designated ν₂, ν₃, and ν₄. When a calcite sample is ground, as part of the measurement preparation procedure, some grinding dependent changes will be revealed in the infrared spectrum. With additional grinding, the ν₃ peak narrows and the heights of the ν₂ and ν₄ peaks decrease, when both are normalized to the ν₃ height. By plotting the normalized heights of the ν₂versus the ν₄ of several grindings of the same sample, a characteristic trend line is formed for each calcite type. The trend lines of geogenic calcites have the shallowest slopes and highest ν₄ values when compared to pyrogenic calcites, which can be further divided to ash and plaster/mortar samples. This method can assist in distinguishing between the various calcites, and provide insights into homogeneity and preservation state of the calcitic materials in question.     

Stable carbon and oxygen isotopic compositions of wood ash: an experimental study with archaeological implications

Wood ash, composed mainly of the mineral calcite, is an important component in many archaeological sites. Identification of wood ash in the archaeological record is often difficult due to mixing of ash with other calcitic components of geogenic origin and/or due to diagenetic changes. A recent empirical study using the stable isotope compositions of carbon (δ¹³C) and oxygen (δ¹⁸O) in wood ash enabled the identification of mixtures of wood ash with geogenic calcite and to follow diagenetic changes due to partial dissolution and re-precipitation of ash in two prehistoric cave sites in Israel. Little however is known about the processes responsible for the isotopic compositions of wood ash in relation to formation at various temperatures and the influence on isotopic composition of ash from a variety of plant species. Here we present an experimental study of wood ash formed by burning three C3 tree species and one C4 desert bush at different temperatures. The results indicate that there are significant differences in the isotopic compositions of carbon and oxygen between wood ash that forms by combustion at a relatively low temperature (500 °C) and at a higher temperature (900 °C). In addition, we show that the isotopic composition of carbon and oxygen in high temperature wood ash approaches equilibrium over a period of several months and that the carbon isotopic composition of low temperature wood ash may reflect the photosynthetic pathway of the burnt woody species. Lastly, we show that the isotopic compositions obtained from wood ash prepared at different temperatures do not reflect a temperature dependent fractionation process, but a mixing line between calcite that formed by low temperature combustion and calcite formed by high temperature combustion which later underwent re-carbonation with atmospheric CO₂. In addition, we suggest that exchange processes may possibly occur during combustion between decomposing calcium-oxalate and atmospheric O₂, CO₂ and CO. The archaeological implications of this study are discussed in relation to identification of wood ash in the archaeological record, identification of fuel sources and burning temperatures, and diagenetic changes expected in karstic cave environments. The method presented here can be applied at any archaeological site.     

丙酸钙水酒精溶液对纸质文物脱酸效果的影响

为考察丙酸钙作为新型脱酸溶质、水-乙醇作为混合溶剂用于纸质文物脱酸效果.针对不同质量丙酸钙的水-乙醇饱和溶液、不同的水与乙醇的质量比、去酸溶液的量及纸张在溶液中浸泡的时间等因素,对纸张脱酸效果的影响做了系列研究.结果表明,内酸钙为3g的水-乙醇饱和溶液用于纸张脱酸具有较好的效果,纸张在该溶液中浸泡后pH值为7左右,且自然干燥速度快,基本不发皱、不变色.     

The colour of the facades in Siena’s historical centre: I. Glazings (calcium oxalate films s.s.) and other finishes on the stone materials of the Cathedral’s main facade

This paper focuses on the long-debated topic of the so-called calcium oxalate films: their origin and meaning but also their age and original appearance. The restoration of the main facade of the Siena Cathedral provided a unique opportunity to this end, thanks to the possibility of an extensive and detailed sampling and (as rarely happens) a sufficiently accurate historical knowledge of the construction vicissitudes. This work, mainly based on a polarising microscopy study (coupled with X-ray diffraction and SEM-EDS analyses) of over a thousand thin and ultra-thin sections of 400 microsamples, demonstrates that the current relicts of films are the result of alteration and decay of ancient treatments. In most cases, these were linseed oil-based glazings (the use of this substance is confirmed by historical documents) and pigments. Their role was essentially aesthetic; their use dates the beginning of the fourteenth century and continued at least until the eighteenth century.

Differentiating between anthropogenic calcite in plaster,ash and natural calcite using infrared spectroscopy: implications in archaeology

Infrared spectroscopy provides information not only on the type of calcium carbonate polymorph, but also on the extent of atomic order. In calcite, three major infrared absorption peaks are identified: ν₃, ν₂, and ν₄. It was shown that the ratio between ν₂ and ν₄ bands reflects the order of the calcite crystal structure. In this paper we analyse this ratio in geologically formed calcites, archaeological plasters, modern plasters and experimentally prepared plasters. For the geological calcite, the values of the ν₂/ν₄ ratio are around 3, whereas for the experimentally prepared plasters, the values are around 6.5. The ν₂/ν₄ ratio for archaeological plasters varies from 3 to 6. This shows that a high ratio is indicative of disorder in the crystal, and implies that the calcite was formed from calcium oxide at high temperatures. It also implies that this disorder can be preserved for at least 14,000 years. The ν₂/ν₄ ratio of calcite from archaeological sites can thus be used to differentiate between anthropogenic calcite, such as in plaster, mortar and wood ash, from geogenic calcite, such as in limestone. The ratio may also be used to identify plaster or ash that still retains its original crystals and therefore carbon-14 content.     

A Technological Study of the Elamite Polychrome Glazed Bricks at Susa,South‐Western Iran

This study investigated the technological features of the Neo‐Elamite glazed bricks discovered at the Acropolis of Susa, south‐western Iran, by conducting micro‐Raman spectroscopy, differential thermal analysis/thermogravimetry (DTA/TG), X‐ray diffraction (XRD) and scanning electron microscopy–energy‐dispersive X‐ray spectroscopy (SEM–EDS). The results showed that calcium antimonate white and lead antimonate yellow were used as opacifiers in the white, yellow and green glazes, and that green and turquoise glazes were achieved using copper. Coloured glazes were separated by a Si‐rich brown glaze to prevent them from running together during firing. The glazed bricks most probably were not fired at temperatures higher than 900°C.     

漂白对宣纸性能影响的研究

漂白对中国书画纸,特别是宣纸的影响情况未见系统的研究。为此,首先研究常用漂白剂-漂白粉(次氯酸钙)对宣纸的影响,又将硼氢化钠、过氧化氢、高锰酸钾和次氯酸钙四种漂白剂进行比较。结果表明,次氯酸钙具有加速纸张老化的作用,在文物保护过程中应该尽量避免使用漂白粉。不同的漂白剂对纸张的影响不同。因此在文物保护中,要弄清各种斑点产生的原因,首先采用水洗等物理方法,无法去除时再慎重选择漂白方法。     

Calcium oxalate AMS C dating and chronology of post-Palaeolithic rock paintings in the Iberian Peninsula. Two dates from Abrigo de los Oculados (Henarejos,Cuenca, Spain)

Since 2005 we have been utilizing accelerator mass spectrometry (AMS) ¹⁴C dating in research on calcium oxalate crusts associated with open air rock art of the Iberian Peninsula. In this paper we present two dates linked with three eye-idol pictographs at Abrigo de los Oculados (Henarejos, Cuenca, Spain). Radiocarbon ages for these motifs agree with the expected iconography-based archaeological chronology. Such oxalate dates could provide an independent basis for evaluating chronological theories for post-Palaeolithic sites, designated in the UNESCO World Heritage List as Rock Art of the Mediterranean Basin on the Iberian Peninsula.