\begin{table}%T2
  %\centering
\par
    \caption{ Electron density indicators in \me.}\label{tab-2}
   \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 & 1.37 & 1900\\
  \ion{[O}{ii]} & 13.6 & 3626/3729 & 1.24 & 1800\\
  \ion{[Cl}{iii]} & 23.8 & 5538/5518 & 0.93 & 1600\\
  \ion{[C}{iii]} & 24.4 & 1907/1909 & 1.27 & 1200 \\
  \hline
  \end{tabular}
   \end{table}