\begin{table}%t8
%\centering
\par
\caption{ Electron density indicators in NGC~6153.}\label{t8}
\begin{tabular}{lcccc}
\hline
\hline
Ion &Ioniz. & Lines& Observed &$N_{{\rm e}}$ \\
&pot. (eV) & used  & ratio & (cm$^{-3}$)\\
\hline
\ion{[S}{ii]} & 10.4 & 6731/6716 & 1.66 & 4100\\
\ion{[O}{ii]} & 13.6 & 3626/3729 & 1.92 & 3500\\
\ion{[S}{iii]} & 23.3 & 33.5/18.7 & 0.28 & 4500\\
\ion{[Cl}{iii]} & 23.8 & 5538/5518 & 1.27 & 4500\\
\ion{[O}{iii]} & 35.1 & 52/88 & 3.61 & 2000 \\
\ion{[Ar}{iv]} & 40.7 & 4711/4740 & 1.08 & 2800 \\
\ion{[Ne}{iii]} & 41.0 & 15.5/36.0 & 12.3 & 3400 \\
\hline
\end{tabular}
\end{table}