A multi-analytical approach was used to study the pictorial layers of a set of 17th century historic glazed tiles (azulejos) of Portuguese manufacture. The pictorial layer was studied by-EDXRF,-Raman, SEM-EDS and OM. Although the established palette comprises few pigments, it was found that the tiles were enhanced by the use of pigment mixtures, which were identified by-Raman and-EDXRF. As expected, the blue colour derives from cobalt oxide, purple from manganese oxide and emerald-green from copper oxide. Regarding the yellow pigment,-Raman results show it is consistent with the composition of a ternary oxide, whereas-EDXRF shows a high intensity of Zn in this colour, indicating a composition close to a Pb-Sb-Zn ternary oxide. Some compounds from the original ores were also indentified: in two very dark blue samples, cobalt and nickel olivines (␣-Co 2 SiO 4 , ␣-Ni 2 SiO 4), and in a dark brown sample, braunite (a manganese silicate).

The non-figurative illumination in five Islamic religious manuscripts of the 16th to 18th centuries held in the National Art Library (NAL) at the Victoria and Albert Museum were analysed by Raman microscopy (RM) and X-ray fluorescence (XRF) to determine the pigments used in each case and to establish whether the range of pigments evolved with time. The pigments identified include lazurite, red lead, vermilion, orpiment and a carbon-based black, which were found on all five manuscripts without exception, as well as lead white, malachite, atacamite, haematite, pararealgar, indigo and Prussian blue, which were found on a more limited number of manuscripts. The presence of gold-based gilding was also established. This range of pigments differs in only a few respects from those already established for Islamic secular manuscripts of the same period. We may conclude that the range of pigments remained stable during the 16th and 17th centuries and began to expand in the 18th century through the introduction of synthetic pigments. On a 16th-century manuscript analysed in this study, the intermediate phase formed by the light-induced degradation of realgar into pararealgar was also identified.

Time-resolved photoacoustic calorimetry (TR-PAC) and quantum chemistry calculations were used to investigate the energetics of sulfur-hydrogen bonds in thiophenol and four para-substituted thiophenols, 4-XC 6 H 4 SH (X ) CH 3 , OCH 3 , Cl, and CF 3 ). The result obtained for the PhS-H gas-phase bond dissociation enthalpy, derived from the PAC experimental results in solution, is 349.4 ( 4.5 kJ mol -1 . This value is significantly higher than recent literature values but agrees with a value suggested some 20 years ago in a widely used review. The PAC result also concurs with the value computed at a high theory level, G3(MP2), 346.8 kJ mol -1 . The data obtained for the substituted thiophenols support the idea that substituent effects are less pronounced on the S-H bond dissociation enthalpy than on the O-H bond dissociation enthalpy of the corresponding phenols. † Part of the special issue "Jack Beauchamp Festschrift".

The mechanisms of red lead degradation were studied in a medieval Portuguese codex, Lorvão Apocalypse (1189), by Raman microscopy (µ-Raman) and micro-X-ray diffraction (µ-XRD). The range of pigments found for the illuminations is mainly limited to vermilion, orpiment and red lead. Micro-Fourier transform infrared spectroscopy (µ-FTIR) determined that the pigments were applied in a proteinaceous binding medium. In the red and orange colours, arsenic (As) was determined, by micro-energy dispersive X-ray fluorescence (µ-EDXRF), to be ranging 1-4% (wt %). For those colours, lead white and calcium carbonate were found as fillers whereas orpiment was applied as a pure pigment. Raman microscopy identified, unequivocally, the degradation product of red lead as galena [lead (II) sulphide, PbS].To determine the main factors affecting red lead degradation, a set of accelerating ageing experiments was designed to assess the influence of extenders and of the two other pigments, vermilion and orpiment. The experiments were followed by µ-Raman, µ-EDXRF and XRD. Raman microscopy results for the simulation of degradation of red lead, in the presence of orpiment, are in agreement to what was found in the Lorvão Apocalypse, galena being the main degradation product; also in common is a Raman band at ca. 810 cm −1 , which was attributed to a lead arsenate compound. It was concluded that in Lorvão Apocalypse, the degradation of red lead was a result of its reaction with orpiment.