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Appendix A: Model Fits

Figure A.1: "30'' $\mu$m feature modelled using MgS optical properties. We show the observed spectra (black), the modelled continua (dashed), the spectra with the MgS contribution subtracted (gray) and the composite of the continuum and the MgS contributions (thin black line).

Figure A.1: continued.

Figure A.1: continued.

Figure A.1: continued.

Figure A.1: continued.

Figure A.1: continued.

Figure A.1: continued.

Figure A.1: continued.

Figure A.2: C-stars with a weak or without a ``30'' $\mu$m feature. We aslo show the fitted continuum (dashed line). The sources are sorted according to decreasing continuum temperature. We refrain from showing a MgS model. In those cases where the strength of the "30'' $\mu$m feature allowed to extract a temperature of the MgS the value is listed in Table 2.

Figure A.2: continued.