\begin{table}%t5
\caption{\label{tab5}Electron density indicators in M~1-42.}
\small%\centering
\par
\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 & 1.25  & 1200 \\
$[$\ion{O}{ii}$]$   & 13.6 & 3626/3729 & 1.44  & 1600 \\
$[$\ion{S}{iii}$]$  & 23.3 & 33.5/18.7 & 0.65  & 1400 \\
$[$\ion{Cl}{iii}$]$ & 23.8 & 5538/5518 & 0.924 & 1400 \\
$[$\ion{O}{iii}$]$  & 35.1 & 51.9/88.4 & 2.13  & 800  \\  
\hline
\end{tabular}
\end{table}