Pietro Baraldi

Thermal behaviour of metal carboxylates: Metal formates

Abstract An analysis of emission spectra recorded on twelve metal formates under heating showed the existence of two crystal forms of anhydrous salts for some of them. The i.r. absorption spectra of these phases are reported. A comparison between final decomposition products and relative temperatures observed in air and under vacuum showed the effects of oxygen on the reactions involved. We discuss the possible mechanisms by which these reactions take place.

Non-invasive investigation on a VI century purple codex from Brescia, Italy

Purple codices are among the most relevant and prestigious book productions of Late Antique and Medieval age. They usually contained texts from Holy Writings written with golden or silver inks on parchment dyed in a purple hue. According to the tradition, the colour of parchment was obtained by the well renowned Tyrian purple dye. From the material point of view, however, very little is known about the compounds actually used in the manufacture of these manuscripts. Presently, the information available is limited to the ancient art treatises, with very few diagnostic evidences supporting them and, moreover, none confirming the presence of Tyrian purple. It is more than apparent, then, the need to have at disposal larger and more complete information at the concern, in order to verify what came to us from the literary tradition only. In this study, preliminary results are presented from non-invasive investigation on a VI century purple codex, the so-called CodexBrixianus, held in the Biblioteca Civica Queriniana at Brescia (Italy). Analyses were carried out with XRF spectrometry, UV-visible diffuse reflectance spectrophotometry, molecular spectrofluorimetry and optical microscopy. The results suggest the hypothesis that Tyrian purple had been used as a minor component mixed with other less precious dyes such as folium or orchil.

Thermal behavior of metal carboxylates: III-metal acetates

Abstract Infrared emission techniques applied to some acetates heated in air or in vacuum enabled a series of transformations and the final decomposition to be clarified. Interesting intermediates such as β anhydrous phases and basic acetates were identified. The possible reaction paths leading to the final products are discussed and compared.

An integrated analytical approach for characterizing an organic residue from an archaeological glass bottle recovered in Pompeii (Naples, Italy)

Within the framework of an Italian research project aimed at studying organic residues found in archaeological objects from the Roman period, the chemical composition of the contents of several glass vessels recovered from archaeological sites from the Vesuvian area (Naples, Italy) was investigated. In particular, this paper deals with the study of an organic material found in a glass bottle from the archaeological site of Pompeii using a multi-analytical approach, including FT-IR, direct exposure mass spectrometry (DE-MS) and GC-MS techniques. The overall results suggest the occurrence of a lipid material of vegetable origin. The hypothesis that the native lipid material had been subjected to a chemical transformation procedure before being used is presented and discussed.

Density, Refractive Index, and Related Properties for 2-Butanone + n-Hexane Binary Mixtures at Various Temperatures

Density refractive index n and the related properties molar volume V and molar refraction R have been investigated for 2-butanone + n-hexane liquid binary mixtures over the entire composition range and a wide range of temperatures. Some well-known relationships have been applied to study the temperature and composition dependence of the measured and derived quantities. Furthermore, the deviations of the respective excess properties VE, nE, and RE have been examined, with the aim of identifying particular intermolecular interaction patterns responsible for the macroscopic behavior of these binary mixtures. The results have been interpreted on the basis of structural and geometric effects between the components.

Study of the bands attributable to crystallization water in hydrated metal acetates

Abstract A comparison of spectra recorded on hydrated, deuterated and anhydrous metal acetates enables the absorptions between 900 and 700 cm −1 and between 580 and 500 cm −1 in hydrated salts to be assigned to librational modes of crystallization water. Bands with wavenumbers lower than 450 cm −1 were assigned to metal—oxygen vibrations. The data reported can be a basis for the study of the dehydration of the salts examined by i.r. spectrometry.

First chemical evidence of royal purple as a material used for funeral treatment discovered in a Gallo-Roman burial (Naintré, France, third century AD).

Violet–purple residues collected from a Gallo–Roman burial dated back to the second half of the third century A.D. and excavated at Naintré (France) were chemically investigated by multi-analytical methodology involving the use of Raman spectroscopy, direct exposure-mass spectrometry (DE-MS) and high-performance liquid chromatography (HPLC–UV–visible). Little is known about funeral treatment and rituals during Roman times. Retrieving valuable information on these by chemical analysis of organic residues was thus a key aspect of this work. Analyses demonstrated the presence of the very precious purple colorant obtained from shellfish glands commonly known as Tyrian or royal purple and its exceptional preservation. Chemical investigation and archaeological evidence have shown that purple was widely spread after the deposition of the body for burial. These results are the earliest chemical evidence of purple colorant used during funeral rituals (not as textile dye) and enabled us to highlight new aspects of funeral practices in Roman times.

A spectral and thermal study on nickel(II) hydroxydes

Abstract A number of nickel (II) hydroxides were prepared and examined by i.r. spectrometry and thermal methods. It was ascertained that the physicochemical properties change according to the preparation conditions. The gross structure can be referred to two forms called α and β. A number of minor components are detected, particularly in the i.r. spectra, which can be referred to compounds present during the phases of preparation.

A multi-analytical approach for the characterization of powders from the Pompeii archaeological site.

AbstractNine black powders found in Pompeii houses in three different types of bronze vessels (cylindrical theca atramentaria, unguentaries, and aryballoi) were characterized in order to assess a correspondence between the composition and the type of vessel and, possibly, to verify if these powders were inks or not. For the compositional characterization, a multi-analytical approach was adopted, which involved the use of scanning electron microscopy–energy dispersive X-ray, Fourier-transformed infrared spectroscopy, Raman, X-ray diffraction, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, gas chromatography coupled with mass spectrometry (GC/MS), and pyrolysis GC/MS. Powders contained in cylindrical theca atramentaria form a homogeneous group, and their organic and inorganic compositions suggest that they were writing inks, while powders contained in unguentaries and aryballoi could have had several different uses, including writing inks and cosmetics. Furthermore, the composition profile of the powders found in cylindrical cases shows that, at 79 ad, in Pompeii, carbon-based inks were still used for writing, and iron gall inks had not been introduced yet. FigurePhotography of the 12724 black powder contained in a cylindrical theca atramentaria.

Some problems concerning infrared emission measurements

Abstract Some emission spectra of supported samples recorded with two experimental arrangements have been discussed. The existence is pointed out of a background emissivity which causes spectra with bands in relief to be recorded only in an optimum thickness range. The experimental behavior observed is in good agreement with the predictions based on some relationships here reported. Application of the latter to emissivity measurements is shown to supply optical constants consistent with the ones obtained by other techniques.