## 3 Results  
The first step of the implemented methodological approach was a widespread study of the morphologies and of the elemental chemical compositions of the surfaces of the entire sample set by means of the SEM-EDS instrument having the lower resolution (Hitachi instrument). In fact, just from the simple observation of the images achieved with that microscope, it was possible to establish the necessity of further and deeper analyses with better resolution. In Table 2, the results of the semi-quantitative chemical analysis performed by means of the aforementioned SEM-EDS are reported, normalised to 100%. The values shown for each element as percentages refer to the averages of three measurements. Indeed, the analyses of X-ray fluorescence were carried out three times for each sample; more precisely, every percentage value comes from an average of three X-ray measurements, each realised on an about 2 mm\({}^{2}\) area, performed by moving the probe into three different positions for each sample. Except for samples 1 and 6, no punctual analyses were needed, as all the surfaces, with the exclusion of the two just mentioned and named 1\({}_{\text{p}}\) and 6\({}_{\text{p}}\) for clarity (p = punctual), were quite homogeneous, as is reported in Figure 3.  
All the sample surfaces are characterised by a high content of calcium, whose percentage stands quite often over the 50%, and then by silicon, aluminium and potassium, ubiquitous as well. The high calcium content detected in most of the samples probably reflects intentional addition of a calcareous compound, possibly calcium carbonate, into the various paint layers. It is worth stressing that iron was also quite widespread, although in this case, the outcome was due preponderantly to the presence onto the samples of pigments based on that element, as will be deeper explained in the next paragraphs. The other elements that immediately leap out are undoubtedly mercury and sulphur (samples 1 and 3), lead (sample 2) and copper (samples 8, 9, 10), but it also worth noticing the presence of a large \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline
**Sample** & **Al** & **Au** & **Ba** & **Ca** & **Cl** & **Cu** & **Fe** & **Hg** & **K** & **Mg** & **Na** & **P** & **Pb** & **S** & **Si** \\ \hline
**1** & 2.2 & - & - & 83.1 & 0.4 & - & 2.2 & 5.1 & 1.4 & - & - & - & - & 1 & 4.5 \\
**1\({}_{\text{p}}\)** & - & 95.4 & - & 4.7 & - & - & - & - & - & - & - & - & - & - & - \\
**2** & 2.1 & - & - & 72.1 & - & - & 13.7 & - & 0.7 & - & - & - & 4.7 & - & 6.8 \\
**3** & 2.2 & - & - & 54.7 & - & - & 3.9 & 27.6 & 1 & - & - & - & - & 6.03 & 4.6 \\
**4** & 1.8 & - & - & 61.6 & - & - & 28.6 & - & 0.8 & 0.1 & 0.3 & - & - & - & 6.7 \\
**5** & 11.2 & - & - & 31.6 & - & - & 22.0 & - & 6.4 & 1 & - & - & - & - & 27.8 \\
**6** & 2.5 & - & 3.3 & 78.7 & - & - & 7.3 & - & 1.0 & - & - & - & - & - & 7.2 \\
**6\({}_{\text{p}}\)** & 1.1 & - & 64.2 & 13.2 & - & - & 1.2 & - & 0.4 & - & - & - & - & 17.1 & 2.8 \\
**7** & 2.4 & - & - & 75.3 & - & - & 7.2 & - & 3.1 & 0.7 & - & - & - & - & 11.4 \\
**8** & 2 & - & - & 66.5 & - & 2.3 & 5.5 & - & 1.5 & - & - & - & - & - & 22.3 \\
**9** & 4.5 & - & - & 50.8 & 0.5 & 1.8 & 10.5 & - & 3.0 & 0.4 & 0.5 & - & - & - & 27.9 \\
**10** & 4.1 & - & - & 66.8 & - & 1.5 & 0.8 & - & 0.7 & 0.1 & 0.2 & - & - & 0.2 & 25.5 \\
**11** & 2.9 & - & - & 80.4 & 1.2 & - & 4.7 & - & 2 & 0.2 & - & - & - & - & 8.7 \\
**12** & 1.1 & - & - & 94.4 & - & - & - & 0.9 & - & - & - & - & - & 3.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: SEM-EDS semi-quantitative analyses (wt%); for each element, the value for a sample was inferred from an average of three measurements on three different areas of the same sample. percentage of gold in sample 1p and of barium and sulphur in sample 6p, keeping in mind that the latter are the outcomes of the punctual EDS analysis. The presence of barium was due to a tiny grain of BaSO4 that could be ascribed to modern building fragments in contact with the ancient ones in the same waste trench.