\begin{table}%t1
\caption {\label{table_abundances}Plasma parameters and chemical abundances obtained in the present work$^*$. The quantities
reported in each column are: 
Col.~(1) -- the PNG number; Col.~(2) -- the usual name of the PN; Col.~(3) --
the electron density deduced from the [S~{\sc ii}]~$\lambda$6717/6731 ratio;
Col.~(4) -- the electron temperature deduced from the 
[O~{\sc iii}]~$\lambda$4363/5007 ratio; Col.~(5) -- the electron temperature deduced from the [N~{\sc ii}]~$\lambda$5755/6584  ratio (the value of 
$T_{\rm e}$(N~{\sc ii}) is in        
parenthesis if $T_{\rm e}$(O~{\sc iii}) was chosen for all ions); 
Cols.~(6) to (12) -- the He/H, N/H, O/H, Ne/H, S/H, Ar/H, Cl/H abundance ratios,
respectively. }
%\centerline
$$
\begin{tabular}{
                    r
                    r @{\hspace{0.20cm}}
                    r @{\hspace{0.05cm}}
                    r @{\hspace{0.40cm}}
                    r @{\hspace{0.05cm}}
                    r @{\hspace{0.30cm}}
                    r @{\hspace{0.05cm}}
                    r @{\hspace{0.30cm}}
                    r @{\hspace{0.05cm}}
                    c @{\hspace{0.35cm}}
                    r @{\hspace{0.05cm}}
                    c @{\hspace{0.35cm}}
                    r @{\hspace{0.05cm}}
                    c @{\hspace{0.35cm}}
                    r @{\hspace{0.05cm}}
                    c @{\hspace{0.35cm}}
                    r @{\hspace{0.05cm}}
                    c @{\hspace{0.35cm}}
                    r @{\hspace{0.05cm}}
                    c @{\hspace{0.35cm}}
                    r @{\hspace{0.05cm}}
                    c}
\hline\hline
  PN~G &
  Name &
  $N_{\rm e}$ &  &
  $T_{\rm e}$(OIII) &  &
  $T_{\rm e}$(NII) &  &
                                                                                        He/H &  &            N/H &  &            O/H &  &           Ne/H &  &            S/H &  &           Ar/H &  &          Cl/H  &    \\
\hline
 bulge:~~~~~ &            &             &  &             &  &               &  &             &  &                &  &                &  &                &  &                &  &                &  &                &    \\
  000.1-02.3 &   Bl~3-10 & {\bf ~~446} &; & {\bf 12750} &: & {\bf    --~~} &--& {\bf 0.220} &: & {\bf     --~~} &--& {\bf 4.41E-04} &: & {\bf 6.38E-05} &: & {\bf     --~ } &--& {\bf 1.84E-06} &: & {\bf     --~ } & -- \\
             &            &        846  &  &      13440  &  &               &  &      0.272  &  &                &  &      5.16E-04  &  &      9.41E-05  &  &                &  &      1.95E-06  &  &                &    \\
             &            &        136  &  &      12410  &  &               &  &      0.149  &  &                &  &      3.60E-04  &  &      6.01E-05  &  &                &  &      1.51E-06  &  &                &    \\
  000.1+04.3 &    H~1-16 & {\bf ~5890} &; & {\bf 10430} &: & {\bf (17000)} &: & {\bf 0.113} &: & {\bf 5.83E-05} &: & {\bf 6.76E-04} &; & {\bf     --~~} &--& {\bf 6.08E-06} &; & {\bf 2.94E-06} &; & {\bf     --~ } & -- \\
             &            &      15100  &  &      11000  &  &      (20570)  &  &      0.211  &  &      8.48E-05  &  &      1.12E-03  &  &                &  &      1.15E-05  &  &      4.58E-06  &  &                &    \\
             &            &       3820  &  &       9200  &  &      (10260)  &  &      0.105  &  &      4.86E-05  &  &      5.63E-04  &  &                &  &      4.55E-06  &  &      2.37E-06  &  &                &    \\
%% \vspace{0.1cm}
%% disk:~~~~~~ &            &             &             &               &             &                &                &                &                &                &                \\
\hline
\end{tabular}
$$
\smallskip
$^*$ The full table is available in electronic form at \url{http://www.aanda.org}
\end{table}