\begin{table}%t1
\caption {\label{table:2}Comparison of the 1.2 mm emission and 8 $\mu$m absorption techniques for deriving masses and column
densities.} 
%\centerline
 {
\begin{tabular}{l c c}        
\hline\hline
\noalign{\smallskip}
Properties &  1.2 mm &  8 $\mu$m  \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
Distance dependence$^{{a}}$ &  + & +   \\
\noalign{\smallskip}
Resolution &  24$''$ & 3$''$    \\
\noalign{\smallskip}
Sensitive to lower column  &  -- & +    \\
density filigree structure &    &     \\
\noalign{\smallskip}
Temperature dependence &  + & --    \\
\noalign{\smallskip}
Background and foreground &   not  &  necessary   \\
 estimation &  necessary &     \\
 \noalign{\smallskip}
Sensitive to column  &  + & --    \\
densities $\gg 10^{23}$~cm$^{-2}$   &   &     \\
\noalign{\smallskip}
\hline                                  
\end{tabular}}
\par
\smallskip
$^{{a}}$ Only for masses.
\par
\end{table}