Formulas are derived for the time to achieve the ignition temperature as a function of the incident heat flux and the various thermophysical material parameters for thermally thick, thermally thin and thermally intermediate solid combustibles. Predictions are compared with recent experimental data for various natural wood species and wood products, and to previous data for wood and thermoplastics. The correlations are excellent when (1) the physical parameters used as the axes of the plots are chosen consistent with those of the theoretical formulas and (2) the experiments and the materials do not violate any of the restrictions imposed by the theory. From these plots it is easy to estimate the minimum heat flux for ignition, which is of great importance both in practice and for making theoretical predictions.

O:1arring rate of wood is affected by density and rroisture content of wood, external heat flux and oxygen concentration of the surrounding air. A simplified rrodel for charring of wood is presented as v;ell as exper:irra1tal charring rate results for some thennally thick wood species and wood products.The charring rrodel can be used to calculate with ease and comparatively high accuracy relative changes in charring rate when any of the parameters describing the naterial or the surrounding conditions changes. Also the in practice iInportant effect of rroisture is taken into account in the calculations. Results given by the model, are in good agreement with experimental data.:KEYW:)RDS: charring rate, wood, moisture, cone calorimeter INI'ROI:UCI'ION Wood is quite easily ignitible and a lot of energy is released in wood combustion. 'Ihese properties can be utilized in many ways, but they cause problems in the case of unwanted fire. It is essential that time to ignition, rate of heat release and charring rate are known for fire safety of wood structures. Also, the load bearing capacity of a wooden structural element is dependent on the charring rate, because the load bearing capacity of cross-sections depends on charring depth.'!his study contains results of charring studies made with a cone calorimeter. Experimental charring rate results are compared with the simple charring rrodel, which provides a straight forward means for evaluating the influence of different parameters on the charring rate.

The energies and intensities of KL2 → L3 X-ray satellite multiplet lines are determined from high-resolution measurements of metallic samples. The spectra are interpreted in terms of six multiplet transitions arising from 1s-12p-2 → 2p-3 transitions. Lines including 2s holes are shown to be weak. The relative intensities of the electron excited KL2 multiplets show marked deviations from the statistical population of initial states in contrast to the KL multiplets.

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