\begin{table}%t2
\caption {{\label{tab2}Empirical ionic abundances$^{a}$ and ICF values for two electron
densities.}}
%\centerline
 {\begin{tabular}{lcclcc}
\hline\hline
 Ion  & 500  & 3700 & Ion  & 500  & 3700 \\
\hline 
\foii\  & 17.1  & 25.7 & \fsii\  & 0.38  & 0.54 \\
\foiii\  & 280.  & 279. & \fsiii\  & 3.87  & 4.30 \\
icf(O)  & 3.96  & 3.96 & icf(S)  & 1.82  & 1.61 \\
\fnii\  & 5.42  & 5.62 & \fariii\  & 0.93  & 0.93 \\
icf(N)  & 73.1  & 50.0 & \fariv\  & 1.82  & 1.64 \\
\fneiii\  & 57.4  & 57.4 & icf(Ar)  & 1.01  & 1.02 \\
icf(Ne)  & 4.18  & 4.30 &  &  & \\
\hline
\end{tabular}}
\par
\smallskip
\par
  { {$^{a}$} In $10^{-7}$ by number relative to H.}
\par
\end{table}